Sandra Faber on the Future of the Earth
Nov 8 2021

astronomy-195x300.jpg Of all the scenarios that keep astrophysicist Sandra Faber up at night, it's not the Earth's increasing volcanism, the loss of photosynthesis, or even the impact of a massive asteroid. Rather, it's the collapse she's certain will result from the unbridled growth of the world's economies. Join Faber and EconTalk host Russ Roberts as they explore what the most inexorable law of physics has to do with economics and whether the world's growing economies pose a problem or provide the solution for the finiteness of planet Earth.

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Explore audio transcript, further reading that will help you delve deeper into this week’s episode, and vigorous conversations in the form of our comments section below.


Nov 8 2021 at 9:58am

I don’t want to dismiss Sandra out of hand, because she is obviously brilliant and takes the question seriously.

But, she is using her physicist tool kit to understand an almost biological phenomenon.  We cannot predict the evolutionary adaptation to the physical reality of the world.  Yes, we are constrained by physics, but the number of states of the universe is very large, and we can rearrange the state of the universe to something unforeseen.  A state where copper is obsolete and where we just rearrange the same plastic for all of our needs….its unimaginable today, but that does not mean it is impossible.

Nov 11 2021 at 8:33am

Exactly. Her final argument was telling – the caveman knows nothing about thermodynamics or entropy but now we do, so somehow our future is more constrained in her view.

The fact that we know more physics does of course not mean that we cannot figure out ways to avoid using copper in some places where we are using it now (or, alternatively, reusing existing copper in better ways).

It really seems like a non sequitur to say that because we understand entropy our descendants 200 000 years from now will have worse lives because copper will no longer be easily accessible.

Ed Kless
Nov 8 2021 at 10:10am

Great job Russ! This is the hardest I have heard you “push back” in quite a while. Sandra Faber’s main error is simply the materialist fallacy.

Cary Balser
Nov 8 2021 at 1:24pm

Ed, I think you hit the nail on the head. So did Ethan. Wrong toolkit for this problem. I’m so inspired by how Russ deals with these situations. He provides an example worthy of emulation!

Stuart Foltz
Nov 14 2021 at 12:03pm

Huh. Given I more often than not see Russ Roberts’ counterarguments as near perfect, I was thinking this was one of his worst responses to highly questionable economic assumptions. Yes, he rightly focused on markets, prices, and substitution. Mentioning Julian Simon was appropriate. While he did question how to reduce entropy, this is where I think he and Faber clearly missed important economic points.

In most if not all respects, markets tend to give us the lowest entropy. I was surprised he didn’t mention the failure of controlled economies. While free markets are messy, they tend to be far more efficient than alternatives.

Personally, I tend to believe our best chances at beneficially addressing existing and future problems come from NOT restricting resources and growth. And while mined resources do have a hard limit, I don’t see any reason to think we are close to those limits. And, as illustrated by Simon, technology to extract them is improving faster than the difficulty of reaching them. I suspect humanity will be unrecognizable to us here now long before we “run out” of any resources.

While there is a small risk of humanity ending, most of the risks she discussed were at worst massive setbacks, not the end. Not stopping a very large asteroid is the only one mentioned that seems a serious if extremely unlikely threat of the end. Climate change, nukes, and even volcanoes seem short of ending humanity. Of course there are unknown unknowns too.

The only point I might concede is one Faber didn’t mention. The species that have gone extinct due to man. In most or maybe all cases this is a loss unlikely to be ever recovered. But in the long term, importance of those species seems rather unclear.


Mark Brady
Nov 22 2021 at 9:59am

Just as there is clearly an evolutionary basis for religion, there is just a clear a primordial basis for Malthusian-ism.

The debilitating worry that there are just too many people seems to arise from the ability to count. The brain witnesses people, and decides to be overly concerned that there is a limiting factor that makes that number unsustainable. Land, food, water, sand, oil… now copper? Each of these concerns has been overcome. We build dykes and skyscrapers, we desalinate ocean water, we build nuclear reactors, we develop new manufacturing techniques that use fewer resources.

Once Dr. Faber took energy off the table, the rest is much easier.


Dave Bern
Nov 24 2021 at 2:57pm

The argument we often hear is that the human population growth is unsustainable, when in reality the population growth is self-regulating, just like in the rest of the nature.  It’s not like we are going over night go from plentiful to scares.  But as (if) resources get more scarce, the reproduction rate will slow down.

Richard W Fulmer
Nov 8 2021 at 1:02pm

Faber has merely dressed up the old “Club of Rome” report in terms of entropy. Julian Simon (“The Ultimate Resource”) and Andrew McAfee (“More from Less”) have decisively answered those concerns.

Faber’s dismissal of energy as the solution to increasing entropy shows that she doesn’t understand entropy. Energy is, quite literally, everything.

“There is no substitute for copper.”  Really?  Why do I care whether my phone call is transmitted over thousands of tons of copper wire, over fiber optics, or through the airwaves?


Scott Gibb
Nov 13 2021 at 4:37pm


Agreed.  See my comment far below showing that entropy of Earth is decreasing.

Energy of the Earth system is constant.  Simple energy balance shows that entropy is decreasing.

S is disorder. T is temperature m.

Q is heat (energy).

S=Q/T. The earth receives Qin (+) from the sun at its mean daytime Td. Then it sends Qout(-) to space at its 24hr ave Tm. |Qin = Qout=Q|. Delta S=Q/Td-Q/Tm<0, since Td>Tm.

So less S means more order = Plants, People, Etc.

Kurt Ada
Nov 18 2021 at 11:55am

Wouldn’t energy be the solution to recycling?  Do we need more copper to exist or do we just need to put the existing copper to the best use?   Energy can be used to mine the landfills for useful materials and recycle them.  There would be some limit to the amount of energy available on earth but that is likely millions of times more than we use today.  Think space based solar arrays or nuclear fusion or something even better in 100 years.

Nov 8 2021 at 1:58pm

To posit an answer with respect to the entropy question: If we take the 3rd law as correct, that entropy is always increasing, then a potential answer (and one that I think Russ was gesturing at) is that the rate of entropy increase can be variable. Therefore, with “human creativity” (define it how you like) we can make the first derivative negative *AND* the second derivative positive, provided that the function never converges on zero.

So to put it to numbers, if the amount of entropy right now is 10. And tomorrow we add 1. then 1/2, then 1/4, then 1/16 then 1/256 then 1/65546 then entropy will increase, but it should in practice never pose an issue.

As to the question of valuing a universe that is full of robots, just because it is “interesting” I have no comment.



Nov 8 2021 at 4:35pm

Great show. I’d love to hear Sandra’s take on asteroid mining for copper and other minerals. Would success in that endeavor change her view?

krishnan chittur
Nov 8 2021 at 4:39pm

The conversation started well … and then when I heard that there is no substitute for copper, I lost interest – I am glad Russ mentioned the Simon/Ehrlich bet – and how Simon won.

It is almost as if people forget that copper was replaced by “fiber” or some – and that materials keep getting replaced all the time.

Bottom line is – that ever since the formation of the universe, entropy (not just locally, but system wide) has been increasing – all the way from the tiny size of the universe at time close to zero to now – So, I have NO IDEA what Faber is recommending – almost as if we need to stop life as we know it to stop entropy production?

Yes, there is no such thing as a “resource” (Russ reminded Faber about oil and how it was a nuisance not now toda)

Very disappointing in the implicit (perhaps even explicit?) message Faber had that human activity has been bad and needs to be curbed.

Nov 8 2021 at 4:47pm

That was fun. I really like that she was asking questions and trying to tie entropy into the conversation. There might be something there. Questions:
-Why is copper in the dirt in Chile better than in a Tesla again?
-Why is copper in the dirt in Chile better than in a more ordered form in a landfill? Because humans don’t like landfills?
-Aren’t humans a marvel of entropic order? Why get rid of them with no remorse?
-Do we really think humans will kill themselves AND Mother Nature? Seems a bit haughty.
-Humans creating more humans with very little energy? Is that worth something? They are a product of the very supernovas that dispersed and created all this matter. How do we separate what is good order and bad order? I’m sure the cockroaches will be fine no matter what we do, but are humans good or bad in the entropic system of governance? I was confused.
-Won’t the universe create more order for billions of years somewhere? Are we sure we can kill this machine? Will we end Big Bangs with our copper mining in Chile?
-When entropy is increasing, isn’t this what pricing is for? If my room takes 1 minute to clean, then I can pay someone $15/hour. When I spill plutonium, I think it will cost more per hour? So, I have an incentive not to spill plutonium and make a mess. She doesn’t seem to understand how prices allocate goods; it is directly related to restoring order (think about a hurricane).
-Let’s let the physicists allocate resources based on entropy. I’m sure that will go well and lead to a reduction of entropic disorder. Knowledge problem.
-And if that meteorite is coming, then could the 10 of us left trying not to disturb anything in the museum will surely be able to nudge the asteroid successfully. Or, wait, we need productivity/growth for that. So are humans a hedge or the problem?

Chris O'Leary
Nov 8 2021 at 7:05pm

I don’t normally comment, but it became more than a bit grating to hear Ms. Faber constantly bring up “Entropy” and fail to acknowledge, except in passing, that the Earth is anything BUT a closed system, driven and doomed by Entropy.

A closed system is Biosphere. Which had a serious Entropy problem.

The Earth has the Sun. And the asteroids.

And the rapidly declining price of solar power, and the efficiency of solar cells and batteries, should be hard for a serious person to ignore.

As for her zero growth point, which didn’t follow, at a minimum, why is it that so many people describe what is basically Cuba, but fail to acknowledge that? They act like they are describing Scandinavia.

Theodore Van Horn
Nov 9 2021 at 6:37pm

Exactly, she discusses Entropy as  “coming from thermodynamics”, but then doesn’t uses the term in a philosophical sense. Entropy is a difficult concept for the best engineering students. To everyone else, the shorthand idea of “Degree of disorder”  must be used instead. Her discussions of isolated rooms being treated as systems doesn’t work when energy is passing across the boundary of her “system”.

That being said, her discussions of how SHE would decide how many people should be allowed to live, and at what level of consumption was scarily autocratic.

Nov 8 2021 at 7:40pm

Fantastic Russ! I loved this interview. Work is force through distance. Keep in mind that the only way to do work is by taking advantage of the concept that hot moves to cold. That is true whether you are moving a diesel train (fossil fuel is concentrated heat) or moving a 20 lb. box from the floor to your table (your cells at work). When the universe is one temperature (including the release of all concentrated/stored heat) maximum entropy will have been reached and it will no longer be possible to do any work. Game over!

I am struggling a bit with the certainty with which Sandra speaks. Currently, those studying the universe have stated that we know perhaps 5% of the universe. Is there any scientist, given full knowledge of 5% of their field, who makes definite claims about the other 95%. Projections are fine, but assumptions that there are no longer any surprises seems a bit arrogant. Sorry, I’m an optimist.

Joe Born
Nov 8 2021 at 9:17pm

Well, I do think her take on the Drake equation was interesting.  That was worth the listen.

However, although I like hearing about astronomy, her argument for it as a background for other pursuits because it deals with statistics and incomplete information isn’t too compelling in my view; there are more-practical studies you get that with.  Econometrics comes to mind.

So her argument for astronomy is no more compelling than my high-school Latin and Greek teachers’ arguments for studying dead languages because they train one’s mind.

And if in her analogy the earth is a refrigerator’s interior, why isn’t, say, the sun the refrigerator’s electric power, which will drive the cooling (her analog for entropy reduction) for as long as the sun keeps going?  In other words, isn’t it a little premature to bother ourselves with a question that future people, who will be richer and more technologically advanced, will be able to deal with better than we can if they find that such a problem looms?

I’m not even completely sure she’s right about copper’s going from a low-entropy state to a high-entropy one.  She may be; I don’t profess to know.  But Leonard Susskind’s characterization of entropy is that it’s a actually a measure of ignorance.  And we may be less ignorant of the copper distribution now than we were before we mined it.

Finally, beyond a certain point we may be able to continue advancing (increasing order?) without increasing power consumption.   We keep learning to do more with less.  As one of Dr. Roberts’ guests has pointed out, our smart phones now have replaced a very large part of  the 1980s  Radio Shack inventory: alarm clock, calculator, compass, camera, etc.

So the entropy problem won’t keep me up nights.

Shalom Freedman
Nov 9 2021 at 1:25am

There is a turning point in the conversation where Sandra Faber suggests she does not place ultimate value in the human but rather in the special conditions that make life on earth, perhaps intelligent life possible. This raises the question which is raised frequently now about a possible AI future, or future of humanly created diverse species, some even without any biological base. And given what we now know about the time and space frames of the universe, or possible multiverse these are more plausible scenarios than the scenario of humanity as we know it now surviving in the distant future. And yet the truth is what most human beings care for and love is the human beings close to them and for some humanity itself. Other kinds of more plausible survivors and invented intelligences made of genetically engineered DNA or silicon do not move the heart of some of us.  So while we might appreciate the idea that earth might continue to be a ‘font of life’ without us it seems poor consolation for the loss of what is of greatest value to us.

Nov 9 2021 at 8:15am

One of the best episodes, I really enjoyed listening.

Medicine is all about trying to fix problems that might kill you now, so that some other problem can kill you eventually. I tend toward the view that resource/entropy exhaustion is one of those problems that would kill civilization eventually, in the VERY long run – but that the more immediate threat is that our own nature will lead us to a nuclear holocaust or some similar end.

David C Jinkins
Nov 9 2021 at 9:28am

“Which is the more interesting situation, a bunch of people living hard scrabble off the land, larger numbers but consuming per capita less, or a much more complex civilization, but with fewer people, net resource consumption the same?  We never talk about things like this.  This has, to my knowledge, never been a discussion that any human beings have ever had.”

Nov 20 2021 at 6:46pm

So true! My jaw dropped when I heard the comment that this hasn’t been thought about. Was glad to hear Russ contest the point.

John Bicknell
Nov 9 2021 at 9:58am

Sandra commented:

Many people, economists included, are now thinking that there are laws of entropy that would apply to society just as they would apply to particles, say, in a gas or the particles in an expanding universe.

Wonder who these economists are?

Anyway, I find this concept intriguing & potentially powerful, if applied.

For example, I believe it is possible to measure ecosystems continually and understand entropy changes in close to real time. Moreover, ecosystems are dissipative structures — meaning they feed off of one another. One system’s energy exhaust is another system’s fuel or intake. So, for example, a company’s energy intake includes ideas, people, and raw materials and then outputs energy in the form of products. These products then get consumed by the consumer ecosystem. And so on.

Companies which do this while lowering or maintaining overall organizational entropy will outcompete rival companies with processes that are less efficient or appropriate for the competitive environment.

So, I believe it’s possible to understand how ecosystems react to various environmental stimuli. An ecosystem could be an entire society, a single critical infrastructure sector, or interacting critical infrastructure sectors. If competitive  ecosystem players can understand in advance how an ecosystem is likely to react (entropy +/-) when various stimuli occur, then the player can use that pre-knowledge to maneuver and out compete other players.

Easier said than done. But, all kinds of implications…

James Oliver
Nov 9 2021 at 10:09am

A just for fun comment:

It might be possible at some time, say 100 years from now, to make copper from other elements in some kind of nuclear reaction.

Dallas Weaver Ph.D.
Nov 9 2021 at 11:31am


Good discussion, however when she started describing thermodynamics, energy, and entropy she was more in my wheelhouse than usual for an economics podcast.   A good way for economists to look at energy and entropy is as fungible commodities.

Given energy, I can reduce entropy such as when a crystal grows from a supersaturated solution or the reverse.  Nature plays continuous games of this type everywhere you look driven by energy flows creating non-equilibrium thermodynamic conditions.   From her discussion, her thermodynamics education may have been more in equilibrium thermodynamics models that are easier to understand than fully dynamic models.  Similar to a lot of economic thinking that assumes that dynamic delays do not create unstable systems in supply/demand situations (which are feedback systems where adding “permission” delays to supply response functions on something like housing markets will create unstable oscillations and cause system crashes).  Knowing some equilibrium economics or thermodynamics can create a Dunning-Kruger effect of not knowing what you don’t know but thinking you do know.

The very nature of life itself is trading energy for decreasing entropy and trading increasing entropy for energy.  She is wrong about looking at what she calls resources as being show stoppers.  They are just locally convenient materials.  Almost all of what she calls resources are made up of elements that don’t change or go away.  Almost none of the copper that has been mined has left our solar system (an lb or so) which means we can trade energy for copper in the future including copper in landfills and even the oceans seawater.

That means that the only resources that will count in the future will be energy and human creativity.   With cheap energy, there is no real limit to humanity.  The long history of man has been increasing energy per capital and effectively decreasing resource costs.  Rockefeller and Standard Oil saved the whales by decreasing the cost of light and fracking made tight oil/gas economically available.

I agree that we are limited by the laws of physics and thermodynamics but we should note that we have far from exploited the possibilities within those limits.    She seemed to like copper as a critical element, but I would like to know what is so critical about copper.  Aluminum conducts electricity better per kg, gold is better at corrosion protection, etc.  Meanwhile superconductive materials are improving and the number of electrons required to do a logical calculation is now down to countable numbers as we head into the world of quantum computing.  Plastic is better for the plumbing of water and copper pipe is better than a lead pipe, but so-what.   Note that aluminum is one of the most common elements on this planet and is a major component of clay and it is made directly using electrical energy.   Look at an airplane as clay with added energy and human ingenuity.

If you think we are approaching the boundary of what is possible within the laws of physics (including thermodynamics) I suggest you pick up an issue of Science Mag (AAAS publication) and see how many of the research articles you even have the vocabulary to read, let alone the knowledge to read.   The boundary of human tree knowledge has more high-hanging fruit than you can even imagine, but you have to stand on the shoulders of giants to pick or even see that fruit.  Even the very low-hanging fruit like Maxwells equations <; haven’t been fully exploited as everything described by those equations continue to improve.

Having discussed these concepts of only energy and knowledge being relevant with my friends, they would come up with things like agricultural area or fisheries capacity in the face of rising human populations.   I claimed that given low-cost energy, I can give them an unlimited fish dinner.

In the era of Covid-19, to prove my claim about energy and knowledge, I built an aquaculture system in my back yard that uses no water and produces no waste by recycling the water, but does use energy and I had to add more solar panels to my house.  I have been using the same water for 2.5 years.  I am presntly using commercial fish feed but some of the components can be produced from energy directly such as using H2 produced from water to grow bacteria to make single-cell protein to feed the fish or using electricity to produce light to grow algae to feed the fish in a 3-D system bypassing the energy limitation of sunlight/M2.   Major facilities going from energy to feedstuffs are being built at this time with the material already approved.

She needs to note that her universe also takes high entropy dispersed gas with gravity and collapses it into concentrated energy and heavier element production creating a lot of non-equilibrium thermodynamic situations.   We can then take those heavy elements and convert them into energy if the politicians and no-nothings activists allow us to use the energy.  Perhaps, we will solve economical fission and we will have enough energy for the life of the universe.

Note her 17 factors and 10% reductions have implicit assumptions about life being on surfaces not underwater and gravity being in the same range as earth.  Higher mass would keep gases above the water and deep water would take too long to go away from solar winds making the mag. field irrelevant.   You could probably do most of her 17 factors the same way and why a factor of 10 other than having 10 fingers?  For example close binary solar systems will have some planetary instability issues but stars that aren’t binary are much more than 10% of the total stars.

The three laws of thermodynamics

1- You can’t get something from nothing (mass-energy is conserved)

2- You can even break even.  (a perpetual motion machine is impossible even if you “believe” it)

3- You die.  (unstable entropy increase)


Nov 9 2021 at 12:20pm

One form of hubris is when confidence about expertise in one area leaks into energetically advocated but idle speculation about other areas. It’s a kind of ideological entropy, if you will; a dispersal and degradation of logic. Faber’s discussions of [basic] astronomy and astrophysics and the very low probability of other life-supporting planets were interesting. After that the discussion departed the science gravity well into a strange, stilted talk–about humanity; an apparently hyper-entropic gravitational field. I have great admiration for Faber’s astronomical accomplishments which include advocating for more high-resolution observatories. But astronomers build rather grand theories (see Faber’s on cold dark matter) based on limited observation. When it comes to humanity, we seem to have a field with LOT more evidence but one posing a more sticky analytic challenge.

Dallas Weaver Ph.D.
Nov 9 2021 at 1:35pm

When she started into thermodynamics, energy, and entropy she entered my wheelhouse.  She failed to explain how energy and entropy are related and fungible.   Energy can reduce entropy as it does on crystal growth from a supersaturated solution or as gravitational energy creates a star or as life itself.

Exchanging energy and entropy is what nature and life are all about with all the excitement and interesting behaviors being in the area of non-equilibrium thermodynamics created by energy flows.  Her thinking appears like equilibrium models of an economic system that do not include the dynamics induced by human innovation, which is a poor model of reality.   Equilibrium thermodynamics is taught at the lower levels in chemistry and engineering, but an understanding of how the world works require non-equilibrium models for everything from crystal growth and material science to life itself.

If you extent her thinking to include the dynamics and the fungibility of energy and entropy you will conclude that only energy and human ingenuity are relevant for the long-run future and a focus on conserved elements like copper are irrelevant (elements don’t go away except for fission/fusion nuclear reactions) in the long run.   Aluminum is a better conductor per Kg while superconductors are evolving by innovation into a real alternative making her copper irrelevant.

She is effectively using some thermodynamic buzz words to make short-term local linear extrapolations into long-term predictions.  Much like the Club of Rome error half a century ago.

She, like some economists, seem to believe that innovation from the “tree of scientific knowledge” had been picked clean with all the low-hanging fruit removed.   I suggest she pick up her recent issue of Science from the AAAS and see how many of the reports section articles with the real scientific papers she can read and fully understand outside her specific field.  If she can fully understand 10% I would be astounded, unless it is a special reports section in her area.

The tree of knowledge has tons of fruit for future innovation and is expanding at an exponential rate, but you now have to stand on the shoulders of giants to even know what is possible.  The only physical limitation on humanity are the laws of physics but they allow the capture of enough energy to last the lifetime of the universe and with that much energy we can reduce whatever entropy we want.

Humanity just has to decide what type of Japanese garden that we want this planet to become during the Anthropocene.



Dallas Weaver Ph.D.
Nov 9 2021 at 1:52pm

When she started with thermodynamics, energy, and entropy she entered my wheelhouse and her view of the subject seemed to include only equilibrium thermodynamics when everything that is interesting in the world requires non-equilibrium thermodynamics and kenetics.   Energy and entropy are fungible and changing one into the other is the game of nature, life, and reality is all about.

If she extended her thinking to non-equilibrium thermodynamics, energy flows, and kinetics she would conclude that only energy and human ingenuity are relevant to the future.   Her focus on conserved elements like copper is just a rehash of the Club of Rome error in thinking half a century ago using buzz words from thermodynamics.

David Zarecky
Nov 9 2021 at 3:07pm

Russ is horrified by machines (albeit) sentient machines replacing humans. The most horrifying vision of future ever. Why wasn’t I surprised. I’ve listened to Econtalk for so long by now that I can reliably predict Russ’ reactions to what his guests are suggesting. Like for example when someone suggests that human happiness can be measured, there are studies for that that. Horrors. All bogus science. Humans are too complex. There’s something deeply mystical, transcendent and of course religious about human experience. Russ’ mystical religious humanism would then invariably clash with guests on the show (atheists, mostly) daring to suggest that humans may just be a highly successful breed of monkeys that developed consciousness, there’s complexity to them, sure, but certainly nothing mystical or transcendent about them. No transcendent realm beyond this world either – the cold physical world is all you get, and human monkeys can just as well be replaced with another low-entropy species and all will be well with the planet Earth and the universe. That’s kind of where Sandra was heading, but of course it was way too horrifying a vision for Russ to stomach so a disagreement ensued. Loved it.

Richard W Fulmer
Nov 9 2021 at 8:01pm

The real problem is that Dr. Faber doesn’t fully understand entropy.  As other commenters have pointed out, the Earth is not a closed system; there is a constant energy input from the sun and from cosmic radiation.  Energy can be used to lower entropy in a subsystem, though entropy must increase overall.  So, the Earth can become more ordered at the cost of the sun and the universe becoming less so.  As long as we have sufficient energy – a thought that seems to horrify Faber – we can continue to increase the order of our physical world.

Faber is just another in a long line of people who latch onto physical science laws and theories that they don’t really understand and misapply them.

Newtonian physics gave rise to the concept of the “clockwork universe” and the idea of an economy being analogous to an engine that experts can tweak to improve efficiency.  Darwin’s Theory of Evolution got twisted into support for ideas of racial superiority, eugenics, and Hitler’s “final solution.”  Einstein’s Theory of Relativity and the Heisenberg Uncertainty Principle have been used to deny the existence of objective truth.

Physical laws apply to physical objects, they don’t apply to ideas.

Nations, economies, societies, organizations, companies, universities, families, and institutions are ideas.  They all have physical things associated with them – not least human beings – and to that extent physical laws must be taken into account.  But they are not, themselves, physical objects.

Steve Ravet
Nov 9 2021 at 3:45pm

Just came here to say a couple things: We replaced copper wires with glass fibers, and glass is made from sand, and we have plenty of sand.

And, as scary as it would be to have today’s economists in charge of the earth, it would be even more scary if the scientists were in charge.

I enjoyed the episode Russ, including the extended length. Thanks again for all you do.

Adam Sitte
Nov 9 2021 at 3:51pm

This reminded me of a short story by Asimov, the Last Question, which is a poetic take on solving the entropy issue.

Nov 9 2021 at 3:56pm

Perhaps I’m a member of the 5% in Dr. Faber’s lectures but I’m about an hour in and I can’t see why I or anyone else should subscribe to this way of viewing the future. It’s a bit of a pet peeve of mine when irreligious people make normative claims and seem to be essentially saying “look if you’re honest with yourself you’ll see you think about it this way too.”

Michael Joukowsky
Nov 9 2021 at 6:57pm

I do not know which I had more fun reading all the comments, listening to the podcast or rereading the transcript. So thank you for all three joys.

Newton was the first person to give to humanity the concept of proof through math. If a mathematical can be created, then an idea was proved. Einstein showed that again, that meansurement is what science depends on for it validity. But measurement is not an impersonal event and it does not occur with impartial universality. It is a human act. It comes from the lens of the observer, from a specific point of view in time and space. There is no precise determinable objective universe, there is only imprecise series of approximations. And those approximations have a series of mistakes which amplify the band of inaccurate approximations. This is the problem with practitioners of Keynesian economics and econometric calculations. They actually think that the world is determined by demand and therefore easily calculable. It is not. It is driven by the human’s point of view. it is driven by supply. Which is incalculable.

Dr. Faber is trapped in demand side orientation and calculation. She does not appear to understand that growth comes from creation and therefore the supply of goods and the market. I believe in God, but not a human god, king or all seeing scientist or economist. Dr. Arthur Laffer and the Supply Side School are correct. If you want more creativity, tax it less. If you want a wealthier and more prosperous country, tax it less. But there is no calculation, no equation, no inspiration which will predict the future. It is unknowable.

Nick Ronalds
Nov 10 2021 at 12:37am

There’s a crucial qualification in the principle of entropy: entropy increases in a closed system, but the earth is not a closed system. Hence order can increase “locally”, e.g., on earth, as a result of the constant infusion of energy from the sun. It ends up fueling human brains, which have a way of regularly coming up with creative solutions to problems. Why on earth was Faber so stuck on copper? Why can’t copper be as obsolete a few years down the road as whale oil is to production of energy? The episode was a reminder that familiarity with at least the core principles of economics is essential to grappling with social and economic problems.

Nov 10 2021 at 4:07am

The copper comment struck me as bizarre as well. Though as an astronomer, excellent in her field, not economics, she must have something particular in mind – something that copper does that we for physical reasons cannot replace. Any ideas?

To be fair, I find a lack of basic economic literacy among educated people all over. Even among some economists. And I am not an economist.

Scott Gibb
Nov 13 2021 at 4:34pm

But notice my comment below and the excerpt from it pasted below with added comments.  Entropy on Earth is decreasing.  Energy of the Earth system is constant.  Simple energy balance shows that entropy is decreasing.

S=Q/T. The earth receives Qin (+) from the sun at its mean daytime Td. Then it sends Qout(-) to space at its 24hr ave Tm. |Qin = Qout=Q|. Delta S=Q/Td-Q/Tm<0, since Td>Tm.
S is disorder.
Q is heat (energy)

So less S means more order = Plants, People, Etc.

Nov 10 2021 at 3:51am

As someone who normally agrees with Russ (perhaps with a bit more confidence in our ability to provide a social safety net), I found this interview mind-blowing – one of the few instances where I felt prompted to rethink some pretty basic convictions.

What she is doing is actually pretty simple, almost Socratic. She simply applies our short term logic to the long term (or the geological millisecond to the geological minute and beyond). In that context, Russ points about the power of human ingenuity struck me as beside the point.

The fundamental question is: what is our responsibility and in which time frame? Do we have some kind of cosmic mandate to stay alive as a species and preserve our earth well beyond the 30 k years we have already been around? If so, why and what does that entail?

Concepts like circular economy frustrate me for the simple reason that I simply cannot understand why we are not asking why we are not circular already, importantly because prices should reflect scarcity. But this line of thinking has something too it, far deeper than the striking superficiality and virtual signalling of that and similar shibboleths.

Richard W Fulmer
Nov 10 2021 at 11:07am

My grandfather was born in 1876 and died in 1975.  In his lifetime, he literally went from the horse and buggy to the landing on the moon.  If we could travel 99 years into the future, I suspect that we’d think that the world was populated by wizards.

Human ingenuity is hardly beside the point.  Faber herself is relying on human ingenuity to ensure that humanity doesn’t destroy the earth.  Her path, though, likely leads to totalitarianism and death.  If nothing else, the 20th Century should have taught us that vast, noble causes can justify lies, terror, and slaughter.

Nov 11 2021 at 5:00am

I actually agree with you – or at least, your comments reflect, as the host puts it, my priors. And I admit to struggling a bit to get past some of her economic illiteracy and her tendency to use logic in a way that leads to morally egregious, but nevertheless at some level logical, considerations.

But what I found fascinating was how incompatible these different lines of reasoning are for one simple reason: the time perspective we apply. We think in terms of generations; astronomers and physicists in terms of millions and billions of years. Nassim Taleb did, I think, a good job of showing how our thinking can fail even when thinking of centuries – when we get to millions of years, everything will be different.

So I do not really agree with anything she says. But it is not often that listening to someone I disagree with prompts me to rethink several assumptions. And it takes courage to do what she does.

Nov 10 2021 at 11:07am


>  The 17 (plus or minus) Drake equation extensions were covered by John Gribbin in Alone in the Universe a decade ago.  These “coincidences” are even more evidence of the fine tuning of the universe for life.  (Gribbin remains an atheist and states his case in the Epilogue.)

>  All life uses energy to locally and temporarily reverse entropy.  Econtalk has covered how man has progressed from $1/day of productivity for 200K years in a hunter/gatherer economy to $3/day in an agricultural economy for 12K years to $15/day since the industrial revolution 250 years ago.  Although economists disagree on what the change agent was (Wealth of Nations, democracy, business becoming respectable), in my mind it is obviously the harnessing of carbon based energy on a mass scale with the advent of the steam engine.  Our modern civilization is entirely built on energy.  To progress further, we will need more (if only to increase the standard of living of the bottom 3B people.)

>  The counter-hypothetical to her doom and gloom assumption is “Assume that in a thousand years, we are all substantially wealthier, happier and live longer and it is all our “fault”?”  The basis for this conjecture is of course the last thousand years.  Her imagining limits has no evidence.

>  Yosemite WAS a parking lot 25 million years ago.  And will be a parking lot again in some millions of years.  And we had nothing to do with it.

>  I am sure that her house was a pleasant environment before it was bulldozed to build the house.  Is she returning it to its original, beautiful, natural state?  (I often use this analogy with my anti-“sprawl” friends in CA – “Lets roll back sprawl to the day before your house was built”)

>  Landfills are currently valueless.  We will know when they become valuable when we start mining landfills for their highly dense metal content.

>  Morals are not universal.  Case in point, look at Afghanistan in July and then two months later (and at the moral choices that abetted that change).

>  As mentioned above, she is rehashing the Club of Rome that my professors were preaching 40 years ago.  Still waiting.  People got richer.  Population growth slowed tremendously.  Food production soared.  Life is demonstrably better.  The biggest problems now are supposed to be questionable computer simulations for 100 years from now.

>  I am surprised that she doesn’t understand the scale, ROI, logistics and environmental consequences of covering vast amounts of land with solar arrays.

>  As mentioned above, her utilitarian utopia will never work due to Hayek’s knowledge problem.  But autocrats always like to imagine that they are smarter than the whole.  And as pointed out, it is talked about endlessly (and it is interesting that she is not aware of it).

>  AI makes for great marketing and capital raising.  It is an extremely limited, extremely expensive technology that is nowhere near the hype level that it garners.  Have fun dreaming what it might look like in a thousand years, nobody will go back and fact check you.

>  In a billion years or so we will be a toasted rock.  The universe will not give a hoot.

Nov 10 2021 at 11:34am

Dr. Faber’s own words actually show why a foundational assumption she makes is necessarily false. Removing that false assumption impacts all of her subsequent questions.

Sandra Faber: To stay alive, you have to reduce entropy. This is what biological organisms do.

So, it’s very interesting. We are simultaneously refrigerators and power plants in our bodies. …

She is right about this, which is why even the simplest possible cell must have numerous molecular machines of many different kinds to convert energy into the different kinds of essential work needed to stay alive.  As examples, these include power plants (short animation) and machines walking on dynamic highways to transport cargo to where it is needed (short animation).

All of these machines are composed of building blocks that must be arranged in different reduced entropy arrangements to provide different kinds of work.  As with Lego blocks, the individual blocks cannot know the plan and cannot self assemble.  Nor can the laws of physics possibly dictate an arrangement, since many different arrangements are necessary.  They must be arranged according to stored recipes and programmed systems (more machines) to implement those recipes.  DNA holds those stored recipes. That’s why, as she says, “Whenever our cells divide, we have to create very, very ordered strands of DNA in the new cells.”

The origin of life cannot presuppose that life already exists in the prebiotic universe. Nor can physics and chemistry provide the recipes or force the origin of any arrangement, including the arrangement of building blocks in the recipes. It is necessary to life that, similar to Lego blocks, life’s building blocks are physically and chemically undetermined and free to take on the many different arrangements that are required.

Expecting matter and physical laws to write the required recipes would be exactly like expecting ink itself to write a functional software program.  Dead matter, operating by the laws of physics, will not do this.

Regarding “magical thinking”, it is good that the advance of science has pushed aside naive animistic thinking (still present in science fiction) that energy on its own can act with intention and purpose as a “life force” seeking to create life.  Energy must be harnessed by specific physical structures to do useful work.  Therefore, if we imagine that there is some other physical prebiotic system that does work so that, through trial and error and luck, it supposedly discovers and records the recipes that are needed, that system itself would necessarily have reduced entropy physical structures to harness energy to the work of doing the search.

Naturally occurring sun beams, gases, water, and rocks don’t work to design and create life.  In all the universe, science has never found a single example of unguided non-living nature that has produced specified complexity, which is required for life.

Since that life-search system would require reduced entropy structures suited to do the functional work required, that merely pushes the problem of the origin of reduced entropy structures back a step.  Apply the same implications, the necessary consequence would be an infinite regress of physical reduced entropy structures, each depending on one before it — a stack of reduced entropy “turtles all the way down”.

Natural laws in a universe with finite age cannot provide that.

For those not put off by equations, the technical but readable book The Mystery of Life’s Origin surveys the research on origin of life and devotes three chapters to the thermodynamic issues.  The problem is not the absence of energy in an open system.  As summarized in the Epilogue, the permanently fatal problem is the absence of any unguided means by which to convert energy into the specific ordering required for life, both in the structures and in the recipes and machinery to create those structures.

If “we are limited by the laws of physics, and that has many implications” as Dr. Faber said, one of those implications would be that the dead prebiotic universe would be doomed to remain perpetually dead, never creating living organisms with the complex specified information (programmed recipes) needed to maintain reduced entropy, regardless of the time allowed.  The fact that life exists proves that reality is not limited to the constrained worldview assumed by the philosophy of materialism.

Obviously, if life is the intentional result of a designing intelligence that transcends the confines of the material universe and its natural laws, then this would have profound implications for all of the questions that Dr. Faber asks in this episode.

For any who want to examine and consider how the advance of science over the last century indicates that Dr. Faber’s assumption of materialism is mistaken, this topic is explored at length in Return of the God Hypothesis: Three Scientific Discoveries that Reveal the Mind Behind the Universe, by Stephen C. Meyer.

Greg J Stevenson
Nov 10 2021 at 8:06pm

Until there are more people on the planet that believe there is no do-over, than there is who believe there is, in the form of a super-natural event, (unfortunately prophesized to include an apocalyptic event) then meaningful conversations along the lines that Sandra would like, won’t occur. What many actually want is that apocalyptic event, they say bring it on, lets get it over with, time for the afterlife for everyone.

The one economist I follow that takes the 2nd law of thermodynamics into account is Steve Keen. I keep waiting for him to turn up on Econtalk.  He has a new book out
The New Economics – A Manifesto
Time to reach out for an interview Russ.

Doug Iliff
Nov 10 2021 at 8:09pm

There are a whole lot of materialists in the world who imagine themselves soulless, but do not live their day-to-day lives in accord with their philosophical convictions—fortunately, for the rest of us.  It was charming and delightful to finally hear one of them stand up for herself— and not back down as Russ was rendered breathless as she defended her dystopian vision of the future.

At the other end of the spectrum we have C S Lewis, as ardent a soulful immaterialist as one could ever hope to hear.  This is from a sermon he preached at Oxford in 1942 entitled “The Weight of Glory”— although he was a professor of Medieval and Renaissance literature, not a theologian, it is the best I have ever heard from a pulpit:

It may be possible for each to think too much of his own potential glory hereafter; it is hardly possible for him to think too often or too deeply about that of his neighbour. The load, or weight, or burden of my neighbour’s glory should be laid daily on my back, a load so heavy that only humility can carry it, and the backs of the proud will be broken. It is a serious thing to live in a society of possible gods and goddesses, to remember that the dullest and most uninteresting person you talk to may one day be a creature which, if you saw it now, you would be strongly tempted to worship, or else a horror and a corruption such as you now meet, if at all, only in a nightmare. All day long we are, in some degree, helping each other to one or other of these destinations. It is in the light of these overwhelming possibilities, it is with the awe and the circumspection proper to them, that we should conduct all our dealings with one another, all friendships, all loves, all play, all politics. There are no ordinary people. You have never talked to a mere mortal. Nations, cultures, arts, civilization—these are mortal, and their life is to ours as the life of a gnat. But it is immortals whom we joke with, work with, marry, snub, and exploit— immortal horrors or everlasting splendours. This does not mean that we are to be perpetually solemn. We must play. But our merriment must be of that kind (and it is, in fact, the merriest kind) which exists between people who have, from the outset, taken each other seriously—no flippancy, no superiority, no presumption. And our charity must be a real and costly love, with deep feeling for the sins in spite of which we love the sinner—no mere tolerance or indulgence which parodies love as flippancy parodies merriment.

There— that’s a world we want to inhabit for a million years.

Nov 11 2021 at 4:59pm

What a great episode. A very interesting guest and some amazing work by Russ to tease out the moral implications and make things clear for everyone to see. I appreciate Russ’ humanistic outlook. Sandra came out with a position that the humanity bit is optional. We have a greater mission to ensure the bigger “anti-entropy” project comes to pass. “Trans-human,” “post-human,” it’s all a variation on Nietzsche’s Over-Man. Russ was absolutely justified to mention 20th C. totalitarian regimes.

A recent essay in the Æon e-zine came to mind: “Against Longtermism”. It’s an interesting read:


Nov 12 2021 at 9:52am

Tremendously interesting episode that covered a lot of new ground. Dr. Faber is obviously extremely accomplished, yet I don’t understand how she loves a 4,000 year old vase (high entropy) and hates mining and usage of copper (high entropy). Both take resources from the plant and apply a (higher) order to these resources. Why would mined copper used to provide energy for cities and countries be less beautiful than clay taken from the planet, shaped, and burned?

Nov 12 2021 at 3:11pm

I hope an upcoming podcast will discuss copper.

I thought it was interesting to learn that we only have a few hundred million years of photosynthesis left.

I’m surprised the topic of Europa and Enceladus, two icy moons in our solar system that may host life or the idea that as incomes grow, birth rates decline, with some countries being below replacement rate (which might ease the strain on ‘carrying capacity’). Or, as someone else mentioned, mining asteroids.

As much as she is endeared by entropy, Sandra seems to under appreciate human ingenuity and emergent order.


Nov 12 2021 at 3:19pm

As much as Faber is enthralled with entropy, she seems to have a blind spot for human ingenuity and emergent order.

Also, I would love to learn more about how copper is a key limiter for human growth.

Larry Rice
Nov 12 2021 at 6:50pm

Russ, nice job with many interrelated subjects.

I found it interesting that with so many broad assumptions and futuristic musings, Dr. Faber felt philosophy grounded enough to express rejection of religion.  Dr. Faber’s core tenets and predicted outcomes require much greater faith than does a life of religious faith.

Scott Gibb
Nov 13 2021 at 2:56pm

I’m listening to this episode right now and find myself being disappointed in the discussion of entropy.  This is an important topic and I believe has an easy explanation as most things in Newtonian physics do.  I’ve always wondered how it applied to economics.  Julian Simon touched on this in his book, “The Ultimate Resource,” but he doesn’t seem to have made any progress on the topic.  I emailed Don Boudreaux about this years ago, but never got a response.  Don?  See my email to him below.

My heat transfer professor touched on this topic in one of his lectures in Mechanical Engineering 109 – Heat Transfer: Prof. Pagni of UC Berkeley, mechanical engineering department, now retired.  He has a very short, simple mathematical explanation showing that the entropy of the Earth is deceasing.  See it below.

After graduating from UC Santa Cruz in economics and UC Berkeley in mechanical engineering I’m fortunate to have been exposed to these ideas.  Unfortunately I’ve not been able to find anyone to agree with me or discuss with me how it applies to economics.  Hopefully now I can get some feedback on this and persuade people in the social sciences that entropy on Earth is decreasing.  Just look around you.  The world is getting more orderly: flowers are blooming, technology is improving, people are living longer, ignorance is decreasing, poverty is diminishing, and overall things are getting better.  Sure politics has been and will always be sad.  But despite politics, the world is getting better.  Billions of people are solving little problems everyday.

The entropy of the universe is increasing, but here on Earth it’s decreasing.  This great fact should be written about and discussed by the natural and social sciences and used to show that the doomsayers are wrong.  Julian Simon and his descendants are right.  I’m so glad to see so many books now being published that follow in the footsteps of Julian Simon, my favorites being “Factfulness” and “Progess.”


Email to Don Boudreaux

From: Scott Gibb
Date: Monday, October 1, 2012
Subject: Julian Simon’s Grand Theory in Ultimate Resource II
To: Don Boudreaux


I’ve made little headway in the Ultimate Resource II, but about a week ago I started reading Chapter 4 called “The Grand Theory.”  Prof. Simon reaches outside his area of specialization in the second half of that chapter in his attempt to dispute the doomsters argument that the supposed increase in the entropy of Earth proves that things are getting worse.  At least that’s what I believe he’s saying after my first skim through of that section.

As I was reading this I thought back to one of my undergraduate lectures at U.C. Berkeley.  Prof. Pagni lectured and provided a proof that the entropy of the Earth is decreasing, not increasing!  Along with the proof he said this makes sense because as you can see around us, things are becoming more ordered.  I can provide the proof to you if you’re interested, but just wanted to know if you or anyone else have any updated information about Prof. Simon’s entropy statements in that chapter.  Maybe people have decided he was wrong in that part of the book?  Do you know of any such discussion?



Email correspondence between myself and Prof Pagni is below.

“Patrick J. Pagni”

01/23/2009 01:28 PM

Scott Gibb


Re: Entropy of Earth

Sure Scott. It’s easy. S=Q/T. The earth receives Qin (+) from the sun at its mean daytime Td. Then it sends Qout(-) to space at its 24hr ave Tm. |Qin = Qout=Q|. Delta S=Q/Td-Q/Tm<0, since Td>Tm.
I’m retired now and sending this from the beach in Melaque, Mexico. Thanks for the mental exercise. As you recall, S is disorder. So less S means more order = Plants, People, Etc. Thank God for that fact!
Prof. Pagni

Professor Patrick J. Pagni

At 01:29 PM 1/14/2009, you wrote:

Hello Professor Pagni,

You probably don’t remember me, but I took your ME 109 class in 1999 or 1998.

At lunch today I was discussing entropy with some co-workers and was remembering one of your lectures about the entropy of the Earth decreasing and the entropy of the universe increasing.  I was trying to remember your argument for why the entropy of the Earth is decreasing but was not able to recall.  Any chance you would be able to restate your argument.

Hope you’re doing well.

Scott Gibb
Member of Technical Staff
The Aerospace Corporation
El Segundo, CA

[Comment edited to remove email addresses.–Econlib Ed.]

Justin Dugger
Nov 13 2021 at 10:56pm

The conversation here strongly reminds me of the Asmiov story about asking Siri how to human civilization might avoid collapse induced by the heat death of the universe:
There is as yet insufficient data for a meaningful answer.

Sid Booksh
Nov 14 2021 at 9:35am

A most enjoyable conversation. I suggest that the size of the economy/GDP is a sigmoid curve rather than an exponential one as we are now experiencing, i.e. the ‘left’ half of the sigmoid. The limits on both are the human imagination (I think probably infinite), the energy incident on the earth from the sun (the ultimate source of all energy) and our ability to radiate waste heat to the universe (an infinite sink). Our progress over the last 500 years is the result of our ability to extract resources from ever more inaccessible sources. Since matter can be neither created nor destroyed (for all practical purposes. A 30,000 HP engine annihilates approximately 1 gram of matter each hour by relativity E=MC^2), we’ve simply made all the resources that we’ve consumed less accessible. We have not destroyed them. When we figure out how to extract rare materials from our waste stream economically we’ll be back in business limited only by imagination, our ability to collect incident solar energy, and to dispose of the waste heat.

David Longstreet
Nov 15 2021 at 4:52pm

Fiber optic cable an incredibly better substitute for copper wire. Did anyone imagine the wide spread usage of fiber optic cable in 1960?
PEX:  better substitute for Copper Pipe for hot and cold water. Copper pipe is 3x more expensive than PEX.  It reduces labor costs because it reduces the skill required to install water pipes.   Who saw this substitute in 1960?


Nov 15 2021 at 6:48pm

Very interesting episode. It saddened me that she would say that earth is the most interesting planet in the universe, but not that mankind is the most interesting species. It is getting really common these days for intellectuals to like earth more than mankind.

Robert Ware
Nov 24 2021 at 7:33am

I know this comment is a bit late, but I am wondering if anyone has contrasted Dr. Faber’s ideas with those set forth by Cesar Hidalgo in his book Why Information Grows.  As I recall, Hidalgo explained that human activity was essentially able to avoid the process of entropy by developing and using information – which is the opposite of entropy.

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TimePodcast Episode Highlights

Intro. [Recording date: October 17, 2021.]

Russ Roberts: Today is October 17th, 2021 and my guest is astronomer Sandra Faber of the University of California, Santa Cruz. We're going to have a conversation about humanity. We're going to go back about 14 billion years and we're going to go forward about a million years. So, hold on to your hats.

Sandra's field is the formation of galaxies. She's published hundreds of scientific papers. She's won a lot of awards, medals, prizes, delivered many named lectures, a bunch of honorary degrees. She's an extraordinarily a successful academic astronomer. We connected, the two of us, because Sandra is interested in the question of what would the economy a million years from now be like; and she and I had the beginning of a conversation about that. We're going to continue that here. And, we're going to talk about what an economist thinks about that question, which I think will be maybe amusing and fun. We're going to start with a little bit of astronomy. So, Sandy, let's get started.


Russ Roberts: Now, you have suggested to me, and I suspect elsewhere, that astronomy is expensive. How expensive is it?

Sandra Faber: A few years ago--by the way, Russ, I should say how glad I am to be here, and really looking forward to this wonderful conversation.

As to your question, a few years ago, I estimated that the typical Ph.D. from our department--if we were completely honest about it and tried to incorporate and include all the things that went in to supporting that student, including the expensive telescopes that they used--was half a million dollars.

Russ Roberts: For one. To train a Ph.D.

Sandra Faber: That's right.

Russ Roberts: That's a lot of money.

Sandra Faber: It is.

Russ Roberts: Where does that come from right now?

Sandra Faber: It depends on who you work for. I work for a public institution, so it all comes from taxpayers, basically. So, my dad used to tell me constantly--this is the refrain I remember from childhood, 'Sandra, make yourself useful.' So, in my later years, I imagined having a cocktail party and needing a ready answer to a skeptic asking me, 'Why the heck we should support you people?'

And, simply out of a sense of self-preservation and aggrandizement, I began to ruminate on the worth of astronomy to the human race.

Now, you know, roughly half the people I meet are intrinsically interested in these questions, but that wasn't enough for me because roughly half the people are interested in the Beethoven symphony; and I didn't really want to think that astronomy was just as an aesthetic endeavor. I wanted to think that it actually had some much more practical applications. So, that's what I've been thinking about.

And, coming to the conclusion that astronomy actually is very important because, especially at this moment because the human race is at a juncture, as so many people say--what we're doing for the first time here really influences future generations. And to plan, and to have a sense of values--I hope our conversation gets on to the subject of values later--we need to have a story. And, astronomy tells us the first chapters of the story: the beginning of the Big Bang, how we got here. Then the geologists take over and tell us about the history of Earth. Biologists tell us about the origin of life and so on. These three sciences, put them together, they tell us who we are, how we got here; and that's the foundational knowledge we need for thinking about where we're going.


Russ Roberts: So, I'm a big fan of all three of those things. I'm in that half that's interested in these questions, deeply. I think an educated human being, unlike an animal, should have some idea of where we've been. Just forget about the practical idea that it might help us about where we're going, but certainly about where we've been. On some recent episodes we've had some question of whether examined life is worth living. To me, if it is, if the examining part is important, certainly what astronomers have taught us over the last few hundred years is rather extraordinary. It is aesthetically very pleasing. And, it's not cheap to put on a performance of a Beethoven symphony either, by the way. We have to be very[?] honest about that. There's a lot of training, a lot of hours, a lot of opportunity cost. as we say in economics--things the musicians could have done otherwise--and the conductor, the space that hall is in, and so on.

So, when we think about the practical side, there's some practical sides to astronomy that are extremely valuable--like, an asteroid is about to hit the Earth, we'd like to know when. Right? Those kind of things.

Sandra Faber: You know, I'd like to start with something even more basic. So, I think maybe we'll touch on this later and how astronomy relates to religion, but the point is that astronomy tells us--together with these other sciences, I don't mean to think that astronomers answer all questions--we have put forward a story that doesn't have any miracles. It doesn't have any supernatural inputs. This is the most profound message. We live or die by the laws of physics. We are prisoners of the laws of physics.

And, no supplications, no hopes, no dreams, misplaced trusts are going to solve that problem.

So, if we're confronting issues as I think we are on Earth, the first thing we have to keep in mind is that we are limited by the laws of physics, and that has many implications, but that, above all, is the most important lesson.

Russ Roberts: Yeah. I don't know if you know--I'm a religious person; and I think I saw one of your talks where you talked about how--the way you phrased what you just said was that science was the end of magical thinking, which is another way of capturing this idea that we're constrained by the laws of physics, what we might call reality. That we can't hope for a miracle. But, I have to say, when I look at modern astronomy and physics, there's--maybe you don't want to call it magical thinking, but it's very different than the experimentally-based approach that has been the dominant successful aspect of these sciences over the last three--going back to Francis Bacon, I guess, if you really wanted to be fair about it. So, maybe we'll come to that. But, I accept the point that we are--you're looking at me like I'm crazy. You want to say something, Sandy?

Sandra Faber: Yeah. You can see I have a very puzzled expression. So, I'm looking forward to that topic.

Russ Roberts: Well, let me just say one thing about it. I mean, I'm thinking about the multiverse. I'm thinking about string theory--things that are highly speculative, not as grounded in empirical science as other parts of our understanding of the cosmos. That's one thing I meant.

The other thing I meant is that that first 10-to-the-minus-43rd of creation that we can't see, and then the 10-to-the-minus-35th where things get a little more normal, and then we get about three minutes in and then it's just smooth sailing sort of--sort of. There's a lot of--magical is too dismissive, but I don't know how firm our knowledge is of all these things. We have a lot of confirmation, which is extraordinary. Right?

I mean, when I think about your field--let me say it this way and then you can react. For a long time, what astronomy was, was curious people looking through a tube with some glass in it. And you could argue that's still kind of what it is. But, what we've been able to do with the fact that we weren't around 14 billion years ago, and yet we seem to have quite a bit of knowledge of how we got here from there. That, I think, is one of the great triumphs of the human imagination and human creativity. For me, that's part of the reason it's worth paying something for--maybe not $500,000 per Ph.D. and maybe not many more going forward, but certainly it's been an extraordinary run.

Sandra Faber: Well, you've sounded another theme. This is why I think astronomical training is really valuable. We are training more graduate students and Ph.D.s than can be absorbed by the field, and more and more of our students are going into other lines of endeavor--which I think is wonderful because I believe that astronomical training has some aspects that are unusual.

First of all, there is a grasp of statistics, which most people don't have. Second, astronomers always have imperfect knowledge but try to come to conclusions anyway. And so, we're not paralyzed by the fact that we don't know everything about something, but for trying to generate a hypothesis. And this is useful for policymakers and planners on Earth today who need to react, need to make decisions without complete knowledge.

So, the astronomical state of mind sort of prepares you to do things like that.

But the last point you just mentioned, and that is the knowledge that things change and change profoundly, and, therefore, the ability to imagine a world, a universe, a system, which is totally different from what you see today.

You see, I think most people--and to some extent myself included--we're trapped in a small space of time. People often say, 'Well, human beings are so small,' thinking, that we're physically small or we don't control that much energy compared to the universe. That's not our problem. The main[?] limitation we have that keeps us from thriving better in the universe is having short lifetimes compared to the time spans on which other important things are changing.

You're born into a society as a child. You are taught that this is the way things are. You're taught a little bit of history, but it's sort of peripheral; and evolutionary trends encourage you to adapt to that moment as you're growing up. And all of us are trapped in our childhood moments, and that's the problem in planning the Earth's future over long time scales, or even a few decades now, because things are moving so rapidly.

So, I think astronomers bring something, a new perspective, to the table that's useful, and maybe I'm just really speaking of myself because that's why I'm coming to the table now. It's really driven by my cosmic interests and perspective.


Russ Roberts: We're going to go into that in a little bit, no doubt, but I first want you to talk about something that surprised me when we talked before, off the air, that I've seen you talk about in some of your online talks. When I was growing up, we were told, 'Well, we've never seen another planet.' So, it's possible--because we couldn't reach it with our telescopes. We weren't sure there were other planets. We weren't sure what their quality was for sustaining life. But then there came a view--because of for a lot of reasons. Actually, there's tons of them. There's 10-to-the-22nd stars. Many of them have planets. So, there's nothing unusual about the Earth. And, you've said that actually that's not quite perhaps true. So, tell us what we know, at least now, about the ability of life to be sustained outside of the Earth on, say, in other parts of the universe.

Sandra Faber: Well, first of all, I think when you said we had never seen another planet, you meant an extrasolar planet, an exoplanet.

Russ Roberts: Correct. Correct. Sorry. Yes, outside of our solar system.

Sandra Faber: Yeah. Okay. So, yes, you're correct. There's been multiple ways of discovering them, and one particular space mission in particular, the Kepler Telescope, discovered thousands of them. Yes.

So, you ask, 'What do astronomers think about whether Earth is rare or common?' Now, implicit in that question is: What is an Earth? And, the answer to the question hinges completely on the answer to that.

So, I think, implicitly, when people ask this question, they have 'Earth as we know it,' and 'Earth as we know it as a haven for life.' What we don't understand is whether we could change Earth somewhat in different ways and still have intelligent life. I think what we're really interested in is whether intelligent life can thrive all over the universe or whether only in extremely limited areas like Earth.

So, there are two schools of thought. One school puts together an equation with a small number of factors, multiplies by the number of eligible stars, and comes to the conclusion that there are suitable planets everywhere. Another school of thought called the Rare Earth Hypothesis, puts in more factors; and it doesn't take that many more factors before you conclude that Earth, really, is incredibly rare.

In my talk that you're mentioning, I wrote down 17 different factors. I don't think anybody has ever tried to write that many before. So, maybe we'll call this the Faber Equation. And, if you said that each factor reduces the chances of having an Earth-like planet that can support intelligent life by a factor of 10--i.e., each factor is one-tenth--10-to-the-minus-17. How small is that number? Well, there are 100 billion stars. That's 10-to-the-11 stars in the galaxy. 10-to-the-minus-17 times 10-to-the-11 is a very small number. It's one in a million. You could very well persuade yourself that Earth is the only planet of its type in the galaxy. I've already persuaded myself of that--but other astronomers, I'm sort of out on a limb. I don't think it's generally agreed to.

Russ Roberts: That does blow my mind. I mean, the Milky Way, if you've ever seen it at night--if you've been lucky enough to see it or in photograph just to get a pretty good idea--it's got a lot of stars. The idea that there's not one of those stars that has an Earth-like planet in terms of, like, carbon-- I mean, temperature. Is temperature the main thing? Of the 17, what are some of the factors?

Sandra Faber: Probably the most important is a temperature that supports liquid water on the surface. It's called the Habitable Zone. That's where people started.

But, there are a lot more factors there. For example, we here at Santa Cruz just wrote a paper on the magnetic field of the Earth. And, that is necessary because the sun is putting out energetic particles all the time, which, if unopposed or allowed to impact the atmosphere, would ablate the atmosphere, and would also be energetically unfavorable to life on the surface.

So, somehow we have to protect ourselves from the solar wind and solar flares. And, the way we do that is something called the magnetosphere, which is a region of space where the Earth's magnetic field energy dominates over the solar wind and deflects it.

What does it take to make a magnetosphere? You need a liquid iron core; and you need a proper structure of the planet in which the core can't cool off too fast, and that means the covering has to be sort of hot for longer than you would think. How does the covering--the mantle--stay hot? It stays that way through radioactivity. You have to have the right amount of radioactive heating in the Earth's mantle. But, if you have too much, you have volcanism. Volcanism is probably the greatest long-term enemy of intelligent life on the surface of Earth right now--not asteroids maybe, but volcanism.

It turns out that there's a window of plus or minus a factor of two either way. And as we look at other stars in the galaxy, we can see that their amounts of radioactive elements--uranium and thorium--aren't right. So, there's another one that's at least another 0.1, one-tenth factor, in my equation. It was number 17 in the equation.

Russ Roberts: But, as 100 billion stars approximately--long time listeners will nod and want to say, 'Well, it's really about 100,384,000,760.' Anyway, precision is not really relevant here. But, the Milky Way is only one of maybe 100 billion galaxies, which is, of course, a crude estimate, but probably in the ballpark. There's lots of other places. There could be Earth-like things.

Sandra Faber: Yes. So, let's pursue this game of multiplying by powers of 10.

So, you're right. 10-to-the-11 stars in the galaxy, 10-to-the-11 galaxies in the visible universe: 10-to-the-22. Times 10-to-the-minus-17: 10-to-the-5, okay? What's 10-to-the-5? That's 100,000 Earth-like planets in the visible universe. How are you going to get to them? I mean, they're dispersed over enormous space. It's effectively zero--even though it's not zero, quite.


Russ Roberts: I was talking to a physicist about what you told me before and you had suggested to me we probably won't be able to leave the galaxy as human beings. We might be able to leave the solar system but not the galaxy. Why is that?

Sandra Faber: Just the space distances are too large.

Russ Roberts: Too big.

Sandra Faber: Yeah. So, it's this lifetime problem. That's what's preventing us--more than an energy problem--from voyaging the stars.

So, people solve it by putting living organisms in suspended animation and then you wake up at the other end of the trip. You know, well, that might work, to a degree.

Another way of doing it is to make a machine, which one imagines doesn't degrade. That reminds me of a Long Now Foundation here in San Francisco, who have set out to make a clock that will operate unattended for 10,000 years. It turns out that that's a very, very hard thing to do. That's because biological organisms repair themselves, but machines don't automatically repair themselves. So, we have not found a solution to the time problem.

Russ Roberts: So, that means that our home--our home right now is the Earth. It might eventually be somewhere else in the galaxy, but it probably isn't outside the galaxy. I just want to raise one thing, which is just my all-time favorite thing. Okay--not really my all-time favorite thing, but I do love it--which is that when you look up at the nighttime sky, no matter where you are--meaning whether you're in New York City where you might see literally a handful of stars on a night or if you're in Hawaii or Yosemite in California or the Negev here in Israel, you can see thousands of stars. It's magnificent. All those stars are in the Milky Way, aren't they? Except for maybe a galaxy cluster you might be able to see.

Sandra Faber: Oh, yeah. Well, we can see in the Southern Hemisphere the two Magellanic Clouds, which are separate galaxies, small ones--

Russ Roberts: But, individual stars--

Sandra Faber: and if you know where to look in the Northern Hemisphere. Yeah. Basically, you're right. Yes. They're all--

Russ Roberts: So, that blows my mind. So, as busy as the nighttime sky is on a cloudless night in a desolate place, you're still only seeing a hundred billionth of the number of stars in the universe that could be seen if you had a different telescope.

Sandra Faber: Oh, yeah.

Russ Roberts: That's really amazing. It blows my mind. Especially because you can see the Milky Way--which looks like it's over there--but all these other stars that you're seeing are still part of it.

Sandra Faber: Yes.

Russ Roberts: Okay. Glad we got that straight.

Sandra Faber: Okay.

Russ Roberts: So, we're stuck here, but we've got some time, right? Because--talk about the sun. The sun is going to run another billion years? Is that right?

Sandra Faber: Yeah.

Russ Roberts: Long time.

Sandra Faber: A long time, yeah. Something on that order--we lose photosynthesis. It gets too warm here to support photosynthesis. That's probably the first predictable cosmic catastrophe for us. It's on the order of several hundred million years.

Russ Roberts: So, we have some time to think about if we could survive as human beings until then to--

Sandra Faber: Well, let's mention two other things. First of all, there's the asteroid that you alluded to. So, that's a problem we have to solve. We're now at least watching for them, but steering them away from Earth--that's a technical issues that I think is not quite properly solved.

Let me return to the volcanoes, because the most massive extinction on Earth was 250 million years ago, and that was caused by not explosive, but lengthy volcanic eruptions. And, I think we need more models of the interior of the planet. The planet is cooling. So, over time, these things will become less likely; but how likely, I don't know.

Russ Roberts: When you say cooling, you mean over, like, a really long period of time, I assume.

Sandra Faber: Yes. That's right.

Russ Roberts: When you say 'we're watching for them'--the asteroids--who is 'we'? Who's we? I haven't looked for one lately. Is there somebody who has that job? I'd like there to be. Is there someone?

Sandra Faber: Yeah. NASA [National Aeronautics and Space Administration] has a program to watch--patrol for--moving asteroids.

Russ Roberts: How much advance warning would we get?

Sandra Faber: Probably depends on the size of the object. So, we know where all the big objects are, but there's a range in which you can do a lot of damage, but they're also hard to see.

So, the last time I looked at this, we were seeing all the really big ones, but there's an intermediate range that we don't have the capability yet of seeing. Although NASA is working on this. So, yeah.

But then: What do you do if you see it? You would have probably, at least, I would think--

Russ Roberts: Call your loved ones--

Sandra Faber: You'd have a year to think about it.

Russ Roberts: So, let's play with that for a sec. When you say they're intermediate size--the bigger ones I assume you get more warning because we know where they are already or have some idea.

Sandra Faber: Yeah.

Russ Roberts: What's the definition of a big one versus an intermediate one? Would a big one be the size of a city? What are we talking about here?

Sandra Faber: Roughly, yeah. A kilometer. We know where everything is with the size of a kilometer or bigger. But, a tenth of a kilometer, that's another matter. And even, yeah, 100 meters can do a lot of damage. So, yeah. So, it's in that area.

Russ Roberts: What kind of damage would it do other than the unfortunate creatures that were under its direct attack? A lot of dust? Is that what we're worrying about?

Sandra Faber: Well, two-thirds of the Earth is water. So, it's going to land in the ocean.

Russ Roberts: Most likely.

Sandra Faber: There's going to be an incredible tsunami. That's probably the most important thing.

Russ Roberts: So, what options do we have for--you're smiling. I don't know why you're smiling, Sandy. It makes me smile, too, kind of. I don't know: there's a certain hopeless charm to it, I suppose. But, what kind of options would we have to do something about it? We couldn't steer ourselves. Would we attack it? Try to obliterate it?

Sandra Faber: People have thought about this. You're pursuing an area that I'm not so expert on. So, let me say a few words and then hope that we'll start talking about something else soon.

Russ Roberts: Okay. Fair enough.

Sandra Faber: Okay. So, the issue is whether you should try to--so, let's say you have a certain amount of energy available to transfer to this object. You have to distinguish between energy of the object--its kinetic energy, which goes as the velocity [V] squared--versus its momentum [M], which is proportional to velocity: MV2 versus MV. We don't want to change the energy of the object. We want to change its momentum. We want it to go in a different direction. And it turns, out people thinking about this, that if you send a spacecraft to it with a certain amount of energy, it is better not to try to blow it up all at once, but rather to somehow use your store of energy in a series of small taps that delivers, in the end, more total momentum change to the object.

So, don't think about sending a nuclear bomb to explode it or something like that. That's not going to work. It's going to be something more sophisticated. It's challenging, though.

Russ Roberts: I'm pretty sure I saw a newd story today--which I did not click on--about nuclear weapons being used against asteroids, but I think certainly for the people in the spaceship, they'd certainly prefer the tapping to the nuclear bomb. So, that's good all around: it's a win-win, as they say.


Russ Roberts: Let's talk about entropy. What is it and why is it important to you?

Sandra Faber: Okay. So, I'm going to start with a couple of sentences about why it's important, in an effort to motivate people to listen through the explanation.

So, entropy--people have all heard about the Second Law, I'm sure--the Second Law of Thermodynamics--which says that entropy can only either stay the same or increase. It can never get lower.

So, there are people who think that this is probably the most important law of physics and the most incontrovertible law. Maybe we'll find that our theory of gravitation, general relativity, is wrong somehow. We're still dickering around with the nature of the other three forces, etc. But, somehow people believe that we will never find a contradiction to this. So, this is regarded as the most inexorable, unavoidable law of physics. And I said before that we're subject to the laws of physics. So, this is an important one.

What is it? Well, it had its origin in the study of thermodynamics. Basically, here is a system. Let's make it simple. A bunch of atoms in a container, they have a temperature, and they're moving around. The hotter the temperature, the faster they move. Let's consider the number of ways in which we could arrange that system microscopically in order to have the same total energy content.

So, here is the system. It has a certain amount of entropy. Entropy is a number like energy. It's not the same, but you can calculate what that entropy is; and the number is bigger when the number of microscopic ways we can rearrange the system to have the same total energy is bigger.

So, consider two arrangements of gas in two different containers. One container--they're the same temperature, so the speeds of motion are the same of the molecules, and they're the same number of molecules--but in one case, the container is smaller than the other. So, you can just see intuitively that the ways in which I can arrange the molecules in the bigger container is bigger because I have more space available to me to put them in.

So, that is why, if I take the walls away from the small container, the gas will expand to fill the bigger region because the number of states available to it are larger. There's a suppressed assumption here that conditions are always--that systems have the ability to move from micro state to micro state, and that they will distribute themselves with equal probability across all the micro states. So, if a system has more micro states available to it, it will take that configuration.

Russ Roberts: A micro state--you just mean possible arrangements of the molecules, right?

Sandra Faber: Many people, economists included, are now thinking that there are laws of entropy that would apply to society just as they would apply to particles, say, in a gas or the particles in an expanding universe.

Let me give you an example, okay? Things get messy. It's hard to keep things ordered. So, the analogy here would be the refrigerator. How do I make an area that is cold, if entropy just wants to have heat flow and the temperature even out? You know, it's very hard to make things cold. You have to build a machine. You have to put energy into it, and it takes work in a refrigerator in order to move heat from the contents to the surrounding kitchen. What have we done? We cooled the material inside the refrigerator. That is lowering its entropy. And, it took work and effort to do so.

Consider a parent trying to get a child to clean up its room. Rooms get messy. One of the reasons they get messy, the reason is that there's so many ways they can get messy. There's only one way in which a room can be ordered, right?--

Russ Roberts: Mmm, kind of--

Sandra Faber: So, the laws of entropy tell us that it is very improbable that a room be ordered. It's going to find its way into these other much more probable states, and there are many of them. So, the parent must intervene. That takes energy. It takes effort. A parent had to eat dinner in order to be able to stand in the room and browbeat the child, etc., etc., right?

So, now here's a very interesting thing that I'm beginning to worry about. The refrigerator took work in order to cool, and it had to have a reservoir to put the waste heat--which was the surrounding kitchen. We didn't mind because the reservoir was big. What if human society is governed by the laws of entropy and it takes work--which is energy: we're all eating and metabolizing; that provides the work--but where is the waste? Is there a waste heat? Where is it going? And: Is this one of the limitations that will govern the evolution of an intelligent life on Earth?

So, let me give you an example of the waste heat that we have in mind, right? So, one of the ways in which the economy increases entropy is it mines ore. So, ore deposits are very organized. They're not dispersed. If I took all the silver in the world and spread it out uniformly over the surface of the Earth, I couldn't use it. The only reason I can use it is, it is in lumps, and I can access it because it's a low-entropy resource.

So, this is what people mean by the circular economy. If I keep mining silver over the years, what happens to the waste silver? Know[?] it goes into landfills or in some way it's dispersed in a way that's not usable anymore. Every resource that we are using like that is an exhaustible resource. And, we should think about that mining ores and things like that, but as mining low-entropy and, therefore, extremely valuable assets.


Russ Roberts: Well, we're going to come back to that fairly shortly, I have a feeling, in our conversation, but I wanted you to talk about how you saw entropy and the fight to reduce entropy as central to the human project, because you told me off air that you saw the fight against entropy to be part of a central piece of human meaning and purposefulness.

Sandra Faber: To stay alive, you have to reduce entropy. This is what biological organisms do.

So, it's very interesting. We are simultaneously refrigerators and power plants in our bodies. So, on the one hand, we're refrigerators, because we are creating greater organization. We are lowering the entropy of our atoms to create new versions of DNA [deoxyribonucleic acid]. Whenever our cells divide, we have to create very, very ordered strands of DNA in the new cells.

How are we doing that? We're ingesting things that aren't DNA, that are much more disordered. Somehow we have to create order out of disorder; and that's a refrigerator, to my way of thinking. Okay?

But, we also ingest low-entropy materials that we metabolize. So, in that sense, we're power plants, and that's why we stay warm. That's why we have heat.

So, our entire existence as biological organisms is manipulating entropy--on the one hand trying to reduce it; and then on the other hand ingesting low sources of entropy and metabolizing them, combusting them, and getting energy out of it. So, that's what a heat engine does. The refrigerator is the opposite of a heat engine.

This is how we work.

Now, I don't think we have so much of that instinct of what's going on in our bodies, but we see entropy around us all the time. We know, inherently--I think a chimpanzee knows--that arranging things in a particular way takes effort and is unusual and is deserving of respect and awe because it took effort. And, I told you before my analogy of the sorrow that we feel when something that has been artfully arranged then dissolves.

So, my favorite example is the 4,000-year-old vase, which has somehow defied entropy for thousands of years by maintaining its high level of organization. It has not dispersed. It has not degraded. It's been lucky. And then somebody drops it. 'Oh, my God!' We feel horrified at this, instinctively, because we know how unusual it is for complex systems to survive over such long periods of time.

This is the same as the sorrow we feel when a living organism dies. This was a highly ordered system, and now it's going to decay, it's going to disperse, information is being lost. All the effort that went into creating that organism, it's been lost. It's no longer useful to us, and so on.

So, I think as we got through life even as children we understand that the inexorable pressures of entropy and everything that we must do in order overcome and withstand them.

Russ Roberts: So, it's maybe a less poetic--or maybe a more poetic--way to talk about, say, the Twin Towers, right? Putting aside the lost of human life on 9/11, they were an architectural achievement. They took enormous amounts of effort to build. And they were destroyed. There's something sad about that independent of the human life that was lost, which, of course, is also the same point.

But I guess on the other hand--tell me what you think of this. I heard you say on one of your talks that you're the product of maybe--was it a million supernova? or was it a thousand? Million?

Sandra Faber: It's a million. Yeah.

Russ Roberts: So, what you meant by that was that there were elements produced in supernovas in the past that created the elements that allowed life to be created here on Earth, that eventually collected themselves in ways we don't fully understand into various organisms and then higher forms of life--a very anti-entropy experience as they got more and more complex. I think we're more complex in some sense than an amoeba. I assume we are. And so, when we die, whether we leave children or not is one question; but there's also just: our molecules are not going to go away. They're preserved. It's true that the form of them will be different, right? Is there any comfort there for you?

Sandra Faber: No, if my molecules just disperse and don't reorganize into something interesting. Now, we're getting at, I think, the core question, what is valuable? What is interesting? What should we try to preserve? And, I am not a religious person. I think that we have a whole set of moral values that are kind of practical, that aid and abet and underlie our business plan, so to speak--our business plan being our strategy for surviving as an individual and procreating.

But, there's a bigger yearning, I think, that human beings understand and really is an admiration for the creatively organized structure. This is why we admire a beautiful scene, a beautiful painting, why we would feel awe, as I did, when I watched the Chinese at the opening Olympic ceremony--the unbelievably synchronized, intricate movements that they had programmed there. We know intuitively how difficult it is to do those things. We respect it because it requires our effort and our effort is in short supply. So, this is why it's important to know whether Earth is rare or not.

Russ Roberts: Why?

Sandra Faber: Because my analogy is beautiful places on Earth. My favorite is Yosemite.

Russ Roberts: One of my top five.

Sandra Faber: Okay. If somebody told me that Yosemite had been purchased by a developer, had been paved over, was now an airport and some hotels, I would feel outraged. I would feel a huge loss because I understand intuitively that Yosemite is a very lucky thing to have existed in the first place.

If Earth is rare, it's the same thing. Earth is a very lucky rare place where wonderful things can happen. You can't have life like this on Jupiter. Jupiter doesn't support the creation of low entropy enclaves that we call intelligent life. And, the number of places in the universe where this can happen might be incredibly small. And we would respect that as human beings. We would even worship that as human beings, and maybe develop the will to preserve just as we've developed the will to preserve Yosemite.


Russ Roberts: I guess I have a couple of thoughts. I don't think the amount of work--for those students of history of economic thought there's something called the labor theory of value, which said the value is something that comes from how much work gets put into it. That theory, it's in Marx. It was rejected, because if I spend hours tying a giant knot versus hours creating a magnificent new vehicle to travel in, say, or a new phone, some new gadget, the gadget is more valuable even if it had fewer hours: that the hours alone are not sufficient.

Now, I can understand some of the poetry you feel for that. There's an aesthetic beauty in it. But certainly value is not solely the overcoming of entropy. It also has to have its implications for human flourishing, wellbeing. Best example: the vaccine against COVID might have taken fewer hours than it took to organize the opening ceremony of the Olympics. Probably did, actually. You could define it differently because you get to talk about what was necessary to get to that point and it gets complicated. But just--at some level that's true, and I don't think they're equally valuable. I don't think the Chinese, the opening ceremony, is more valuable. So, I'm curious. Do you agree or disagree?

Sandra Faber: I'll probably disagree.

Russ Roberts: Why?

Sandra Faber: Because at the outset, you put human beings into the equation and whether they would personally and individually benefit from some activity. So, I don't think that human--

Russ Roberts: You don't want to do that?

Sandra Faber: No, I don't necessarily want to do that. Because I don't think that human beings will last forever. And yet, I would like to think that Earth will continue as a font of creativity. It's really the environment that I'm interested in and the circumstances that give rise to ever greater complexity and organization. And, I don't think it has necessarily anything to do with human beings per se. Although human beings at the moment are kind of the acme instantiation of that process. There might be something further in the future.

Russ Roberts: Now I'm really mystified. So, let me challenge you on one level, and then a second.

So, the Nazi genocide of the 1940s of the Jews and some others, but mostly Jews, was very organized. They were really good at making the trains run on time and to make sure that trains were used with incredible efficiency. The Gulag of Stalin is also was an enormous undertaking. He had a number of projects, and that was slave labor building giant canals and other things that were inhuman but were very anti-entropy, right? They built some incredible things. Many dictators have built incredible things with slave labor. Are you going to say that those are admirable because they reduced entropy?

Sandra Faber: In and of themselves they are, but they violated other moral norms. So, I haven't really discussed my entire normal moral picture.

Russ Roberts: Yeah, I think we need the rest of it.

Sandra Faber: Right, which is more normal and 99.9% synchronized with your view.

I think in terms of value on two levels. On the low level, which is the immediate one, we have a set of moral codes which were developed to help us thrive in relation not only to our environment, but to each other. Those are the codes that Stalin and the Nazi violated, and that's a horrible thing that they did. But, that by itself isn't enough to help us plan for the future. There's nothing in those moral codes that would encourage us to value the futures.

Many people have said that a basis of morality is a transaction--that moral codes are basically transactional. How do we have a transaction with the future? What can the future give us today? That's the question I'm asking myself.


Russ Roberts: Okay. Let's turn to that, but before we do, I just want to raise one last question about what you said before. Why do you care? Why would you care about whether--I mean, we could think of a lot of really unpleasant outcomes for the Earth: nuclear war, climate change that heats the planet through human error, volcanism that you talked about, bad turns of events that come along--the asteroid that's bigger than the city of New York and just it can't be tapped and moved away. So what? So, the Earth gets destroyed, and the universe loses a little bit of anti-entropy in this corner of the Milky Way. Why would you care?

Sandra Faber: I think that's the central question. And, the fact is I think we do care and I'm trying to figure out why we care.

At the beginnings of many of my talks, I take an audience poll and I ask people, 'Take this as a given. Assume a thousand years from now the Earth is a smoking ruin. It's not hospitable for higher level, maybe microbes, but nothing bigger. And, it's our fault. This is the key point. Our generation didn't do the whole damage, but set the stage for this terrible or this outcome. Is this good, bad or you don't know, or you don't care?' 95% of the people in the audience say it's bad. Why do they say that?

Russ Roberts: It's a deep question.

Sandra Faber: Yes. This is exactly the question. And I think it's because people respect the Earth as a miraculous vehicle for reducing entropy; and the loss of that--that was my hypothesis that that capability had gone away--is an inexpressible sadness and is to be avoided. And, the question is how much effort and cost are we willing to put in to taking actions that will avoid it? That's the question. People say it's bad, but how bad?

Russ Roberts: Alan Lightman on this program said, gives the analogy of the ant colony that flourishes for 400 years. Somehow this colony creates language and music and is very creative. And then a big storm comes along and washes it away. It has this unbelievable run for an ant colony of 400 years or 40 years or four years. Any of those would be impressive if they had a symphony or two. He says, 'We're just in a big ant colony. The sun is going to go out. We might flee to another star, but it's limited, and it's all just a matter of time.'

Now, I don't agree with that--'agree' is not the right word. I don't see it the same way he sees it. But, how do you answer that, because you seem to have a different perspective?

Sandra Faber: I think--I'd like to think that it can be avoided if we're clever, but this is why--

Russ Roberts: Which part? We can't regenerate the sun, right? Which part could be avoided?

Sandra Faber: We would have to flee to another star. I agree with that. But I think that's--

Russ Roberts: But then it's just a matter of time--but then--okay. Maybe. But, so what? Then that star will go out; and eventually we'll run out of stars and the whole thing will just be a meaningless thing.

Sandra Faber: I would say that you have pinpointed the central question for me that I am grappling with. And, I still feel that as a human being, I feel it is sad that our run is cut off, especially due to our own thoughtless actions. I mean, the sun is one thing. We don't have to take responsibility for that. But, we are responsible for Earth now.


Russ Roberts: So, let's turn to the economics. Finally. We're only an hour into the conversation, or so. So, you challenged me when we first talked off the air to imagine an economy a million years from now. Before I give you my response to that--which has evolved since we first talked, a little bit--why don't you tell me why we need to worry about it? Talk about growth and what concerns you.

Sandra Faber: Well, a million years is 40,000 generations. If you look at the recent history of world GDP [Gross Domestic Product], it's doubling--roughly doubling per generation. It's roughly a 3% growth, something like that. So, if you--how big is that number if growth were to continue for 40,000 generations? I just did it before this conversation. Got out my calculator. It's 10 with 500 zeroes. Okay. So, it's impossible.

Russ Roberts: It's a big number. It's a big number.

Sandra Faber: Yeah. It's not 10-to-the-17, but it's large.

Okay. So, the point is that, if our present economy is predicated on growth--and I'd like to know your opinion on that--then it can't continue very much longer. We're reaching the boundaries of the planet. Many people are saying this. We could grow for a long time, but we can't grow much further.

So, we have to figure out how we're going to be truly sustainable. Truly sustainable is zero growth.

So, I'm worried about in the pretty near term--not a million years, but on the order of decades--I'm worried about things like bank accounts. How can I get interest on a bank account in an economy that's not growing? How can I--how can Harvard run on its endowment? Why will its endowment pay it anything if the economy isn't growing? Are we in for imminent social collapse when these economic institutions which we take for granted start to fail because growth fails? I'm asking those questions. What do you think?

Russ Roberts: Well, I think there's a couple of questions, a couple. There's a lot of questions there.

To back up to the beginning: I don't think our economy is predicated on growth. Because no one is in charge of it. I think it's really important to remember that. No one has a plan.

There are people who talk about what they think will happen in a year, five years, or ten years, but it's not planned. So, it's not--'predicated' I don't think is the right way to think about it.

What is true is that for a long, long time--not long by your standards as an astronomer, but by our lifetime standards, over our lifetime--the growth, we've been very blessed, fortunate to have growth. Which has many pluses; has some minuses, but many pluses.

What has sustained that?

I think there's two questions to think about. One is, is it decades or is it centuries before we start to press against the limits of the planet? I think that's a very open question.

The deeper intellectual question for me is how might we cope with whatever comes in the wake of that reset when growth is not available--

Sandra Faber: Yes. Yes--

Russ Roberts: So, I want to talk a little bit about that, give you my take on it, and then you can respond.

The reason I say it's not obviously true that growth will eventually have to end--and, by the way, it's easy to have zero growth. We can just kill off everybody. And I say that because, you know, it reminds me of when people say, 'How do we reduce the risk of--how do I make airlines safer?' That's easy. Ban air travel. The reason we don't ban air travel is because many of us have decided--not everybody--that the risk of dying in an airplane is a risk we're taking for the return of being able to get to places we wouldn't otherwise usually get to. That's true of many, many things we do. Car travel is even more dangerous than airline travel, though we don't always think of it that way. Things we eat are dangerous. We take risks all the time.

And we generally decide, you know, that they're worth or not. If we said, 'Nope. I don't want any risk. I think risk is bad,' we'd have to, you know, sit by the campfire and not move, or lay in bed all day; and even then, of course, you're at risk of all kinds of things because you're not moving.

So, I think it's an illusion to think--I don't think the goal should be zero growth. It might even be negative growth, depending on what your values are and what you think is to be cared about; and maybe we'll get to that. But I think if we just get away from those deepest of philosophical questions and we just ask the question, 'How should we deal with this?' Let's pretend you're right. Let's assume that you're right.

Well, I have one more thing to say, actually, which is that: What is a resource? This is something I learned from Don Boudreaux, longtime guest on the program, former colleague, still a friend of mine who channels Julian Simon, the economist. 'What is a resource?' is--it's not easily defined. Oil, crude oil was not a resource in 1600. It was a nuisance.

So, some of the things that we call nothing today might become resources. Other things that are resources today we might decide we don't need because there's better ways of achieving them, of the uses we get from them now in other ways.

The one resource that is not finite is our creativity. The question is, is it imaginable that we could, our human creativity, our productivity--which has been unleashed over the last few hundred years in unimaginable ways--whether that could overcome the finiteness of those elements.

It's hard to say to me. I'm agnostic about it. I wouldn't say that because the Earth is a physically finite place, that's undeniable. Although I could say that--no, I won't. I was thinking about shoreline. I always love that paradox of the shoreline--if you take enough detail, you can make it long as you want.

But there's something kind of intuitive about the way we use resources, too. So: Is it possible that a drop of oil could power the entire energy needs of the planet and then maybe eventually half a drop and then a quarter of a drop? It seems unlikely, but it's not impossible that we could learn ways to use oil and then if we couldn't use oil, after a while if it got more scarce, the price will go up. That would encourage people to look for other things.

That process of innovation steered by prices and scarcity is what has worked for the last few hundred years.

Now, you're suggesting there might come a future where that wouldn't work anymore because everything would, quote, I think "be used up." Is that a fair way to characterize what you're worried about?

Sandra Faber: It seems to me as though you're asking the wrong question. Somehow you've focused on the availability of energy. Energy isn't the issue. There's a lot of energy reaching the Earth from the sun. We can put out acres of photovoltaics and get a lot of energy. I think that would just make the problem worse. There are other issues. There's the problem of pollution and there's the problem of mining--that is to say exploiting other low-entropy deposits that are not renewable.

So, in some sense, finding huge, copious supplies of energy that would be adequate to support our enormous economic activities are[?our?] economic activities of and by themselves, are creating problems.

And I return to the question of entropy, because this is central to our problem. Our problem isn't energy availability. It's a problem of increasing entropy here on Earth. By mining--I mentioned that--and also by creating dispersed pollution, which is like waste heat from our refrigerator.


Russ Roberts: Sure, but I think we produce--my impression is we are--I'll take an example. I don't know how this fits with entropy. The number of trees in the United States, I think, is increasing over the last 50 years. There are a lot of things like that. There are a lot of things we do badly because we don't have good property rights, like fish stocks. Fish stocks are declining badly because no one owns the ocean. Stuff that's owned and protected tends to be doing pretty well. Air is cleaner in the United States than it was 50 years ago, much less pollution.

In fact, we're getting better and better at producing.

I mean, pollution is an example of inefficiency, right? Pollution is that heat coming out of the refrigerator; and the better we can produce things more effectively and use things without waste--which we have an economic incentive to do--we're going to make less pollution over time unless we forget how to do stuff or can't innovate. I'm not as worried as you are, I think.

Sandra Faber: Yeah. So, how do you think we'll be set for copper 500 years from now?

Russ Roberts: So, I think--I'll give you a--I don't know if I'll need it. I doubt it. There would be less of it underneath the Earth's surface. Copper is really valuable. So, copper is something that's recycled without government mandate. People steal copper from abandoned houses because it's worth it.

So, copper is valuable. It still gets thrown away. It has to be reused with additional energy. But, you know, right: Maybe in 500 years we'll be out of copper. I don't think we'll use the last ounce of it. As it gets rarer and rarer, it will get more and more expensive, as it gets harder and harder to find and dig up. And that will encourage us to find substitutes. That's been the history over the last 350 years of human experience. The things that rare--

Sandra Faber: There really isn't--there really isn't any substitute for copper. There's no substitute for water, for example. We already use--

Russ Roberts: That I agree with. That I agree with.

Sandra Faber: But, I've lost the track of your question. The question--are you defending some sort of future that's feasible and asking me why I don't believe in it?

Russ Roberts: No. I'm trying to make you feel better about how the future is going to unfold.


Russ Roberts: I've got two things to--I want to make you feel better about--you're worried about the future. You think we ought to be proactive and take steps to put in place systems and alternative ways of organizing economic activity that are better than the ones that we have now. That's the way I take your original question.

Sandra Faber: And that's a near-term issue with me, not a million-year issue.

Russ Roberts: Well, it's both. It's clearly both, right?

Sandra Faber: Both, both, yes.

Russ Roberts: So, I have two thoughts. One is to comfort you that the short-term prognosis is better than you might think; and the second is to make you worry more about your alternative to mine, which would be a more organized effort to rearrange things.

So, on the first count, I think the role of prices are pretty extraordinary. Although I'm a little worried about, in recent months in the face of COVID how badly we've had to deal with shortages that normally I would have thought would it be eliminated by changing prices--which suggest to me that we don't really like the way the price system works, and we might not be willing to take its signals and use them.

But in general, things that get scarce get expensive. That encourages our conservation, and it encourages the search for alternatives. Yes, there may be no substitute for copper, but as copper gets more and more expensive, we'll look for different ways to do the things that copper does. It's people's incentive. We don't need a plan. It will happen naturally if we let the prices rise and don't artificially try to stop them.

We may not like the social consequences of those higher prices. Could be some people can't afford to pay for copper things in the meanwhile, in the short run. Those are serious social issues I wouldn't say irrelevant. But, just the question of how we cope with the ever smaller amount of copper available under the surface of the Earth doesn't strike me as an apocalyptic crisis.

Sandra Faber: Yeah. I think that would be a mistake to be so sanguine because--one way of dealing with the copper shortage is you now mine lower quality ores, which is what we're doing. That costs more energy. And so the return is lower. That's the problem: As we deplete resources. And the long way of saying it is that we're using up the low-entropy, lowest-entropy assets and going to somewhat higher. Our standard of living will go down simply because it will take more effort and energy to get the stuff that we are living off of.

Russ Roberts: That assumes no change in our understanding of how to organize the resources that we already have and the resources we have yet to discover that may substitute for them.

You would have said the same thing in 1973. People did. They said the amount of oil in the world is finite. We're going to run out soon. They picked a date, actually--I love this. They picked a date and they said, 'If we don't do something about it, we're going to have chaos, crisis, famine, riots in the streets.' They didn't see two things. They didn't see the fracking revolution. That's the least interesting part to me. But the more important thing they didn't see is they didn't see the ways that we would figure out to use energy more effectively.

I mean, you're optimistic about photovoltaic alternatives to petroleum. Even till recently, people said, 'Oh, it's too expensive. It can't scale.' I don't know. I don't know what our options will be. But let's pretend you're right. Let me grant you your--

Sandra Faber: Let's be clear about what--before saying I'm right, what am I right about?

Russ Roberts: Let's say you're right that the finitude of various resources, ore and other things--and I should just say we had Paul Sabin on this program as a guest talking about the debate between Julian Simon and Paul Ehrlich over whether we're running out of stuff and what the consequences would be, and they made a bet. And the bet was contingent on the price of these resources. The prices got lower, not higher. And so, Julian Simon won the bet and Paul Ehrlich lost.

You could say, 'Well, that was then. Eventually there will be a time when that constraint will kick in.' So, that's the part I want to concede might be true.

The reason I--I don't think you should be convinced of that, because I think there is the opportunity for human beings to find ways to deal with substitutes--that we have done successfully for hundreds of years. But maybe that run will end because as we get increasingly into the most expensive, the hardest-to-reach ores and other resources, perhaps it will become so expensive--the amount of energy needed will become so high that we won't find newer ways to do it as we have in the past. We won't find better, more effective ways to find it where the oil is, and etc., etc. or the ore. So, eventually, we'll have to run up against these constraints.

I think your best argument is, 'Okay. Maybe it's not the next 20 years. Maybe it's not the next 100. Maybe it's a thousand years from now. Maybe it's a hundred thousand years from now.' But surely at some point we will run up against the finiteness of the Earth and we don't know what population is going to be then. There's no way of knowing. Maybe we'll have found ways to live together in smaller amounts or maybe we won't; but that could make the problem worse, easily. So, eventually we'd have to deal with it.

So, the question is: How do we deal with it? What is the structure? What would be the governance, the process to deal with that? What you think is the reality--and I think it may be reality--I can concede that. So, that's the toughest question, for me.

The ingenuity of human beings to cope with what we might call economic challenges is really pretty impressive. Will it run out? Perhaps. Fine. Let's say it will. What should we be doing in the meanwhile? That's what I think is your real question, right?

Sandra Faber: That's my real question. And if you're hoping to get an answer from me about how we should live then, I don't have one. My goal is to get us talking and thinking about it and to generate scenarios for what a future would look like. And I would start by trying to enunciate some boundary conditions.

Russ Roberts: Go ahead.

Sandra Faber: The boundary conditions, first of all, would be resource consumption of all kinds, and waste production on the other--I'm just thinking of the economy as one of these heat engines. Stuff comes in and stuff goes out. And, understanding the law of entropy and energy we can actually--a physicist could sit down and write down those boundary conditions. I can't do it right now, but I think it can be done.

Then, the next thing you have to do is you have to decide what you want. And that's the value question. So, within some constraint of resources and waste production, you could probably have more people living at very low levels versus a smaller number of people living at higher levels. What do people want? This is where, I think, the discussion of values comes in. And you see it--at that level has nothing to do with our morality, we were on the subject of, before, namely: how we treat each other. This is a bigger question.

And this is why I'm very interested in the value of Earth--if it has one--of cradling and nurturing complexity. Which is the more interesting situation: A bunch of people living hardscrabble off the land--larger numbers, but consuming per capita less--versus a much more complex civilization but with fewer people; and net resource consumption the same. We never talk about things like this. This has never been a discussion, to my knowledge, that any human beings have ever had.

Russ Roberts: Well, I think it gets talked a lot about in philosophy classes, but I don't think they come to any answers, right? One answer--I find it unattractive--is just to invoke a utilitarian principle: that it's the greatest good for the greatest number of people.

Sandra Faber: What is good?

Russ Roberts: Well, that's my--I have a lot of problems with it. But, I think if Peter Singer were here, he would say: the right number of people--we should try to maximize the total amount of happiness that is sustained on the Earth. I don't think that's a measurable question. I think it's a meaningless statement. It has no content. I don't mean to criticize Peter Singer. Maybe he'd be able to come up with something more creative than that. Talk about the ultimate straw man, right?: I don't like utilitarianism and here I am criticizing the most prominent utilitarian I know--his plan for the future that he hasn't articulated--in response to your question. But, I do think people try to answer your question: What's the good life? They might have preferences over those two worlds either for themselves or their children. You don't agree?

Sandra Faber: I don't think they're answering it the right way.

Russ Roberts: Go ahead.

Sandra Faber: They're focusing on one's immediate happiness--'Do I have enough to eat? Am I warm?' and so on--missing the bigger question of the bigger issue of value: What is lost to the universe, if anything, if a higher level of civilization ceases to exist on this planet?

I think something will be lost, because I think the planet as a device for creating complexity and interest is something that we value as human beings.

Remember that saying, 'How're you going to keep 'em down on the farm after they've seen Paree [Paris--Econlib Ed.]?' We as human beings love innovation. We love change. We love complexity. We admire all of these things.

And that's not happiness. It's something different--

Russ Roberts: No. Oh, it is, but--

Sandra Faber: It's something different. And, probably, using our expressions for entropy and information, probably could be quantified--

Russ Roberts: Mmmm--

Sandra Faber: And, I would submit that a large number of people living very simply off the land would have a lower quotient in that index than a smaller number of people living a more complex life with each individual having a larger amount of energy and resources at their command, but nobody--

Russ Roberts: Sandy, you're not going to like this, but you sound a little like God, right?

Sandra Faber: I am.

Russ Roberts: Who's this thing? What's this thing out here, somehow separate from you and me and the Earth that feels sad when the Earth disappears or when there's less civilization? Who is feeling this loss? Right? I mean, it sounds like a hardscrabble life for a lot of people. A lot of people living near a subsistence level--that sounds horrible. But I'm using very traditional morality on that. What else would you use? Who's this creature, this entity that's feeling sadness that there's no Eiffel Tower?

Sandra Faber: No. No, there's no external creature feeling sadness. It's us feeling the sadness. It's us imagining. It's we imagining future scenarios and seeing some that are barren and some that are fruitful by way of our innate way of judging things and our respect for--

Russ Roberts: Okay, so I'm going to--yeah, go ahead. Sorry. No, go ahead.

Sandra Faber: I was just going to say--I think our respect for entropy; I think our moral system, our day-to-day moral system--is a product of evolution. Just, you know, came out of what chimpanzees do. They have all the basic essences of it, as far as I'm concerned. I'm talking about a higher level of value, which I think is also born out of evolution, because we understand, intuitively, as creatures who observe things on this planet, how hard it is to create organization and complexity. We respect that and we value Earth as a place where that can happen.


Russ Roberts: Do you feel that way independently of the people who are going to inherit that Earth, right? The next 40,000 generations? I mean--

Sandra Faber: Well, we know--look, a species only lasts for a million years or so. So, to speak of people over long periods of time, you don't mean that. You mean our descendants, somehow. Beings that descended as a result of cause and effect in a chain, which we are at the beginnings now and they are the result. I don't know. They might be machines. I doubt that, because I have great--yes--

Russ Roberts: Whoa, whoa. Let's go there.

And the--let's suppose they are machines. Let's suppose we create some artificial intelligence in a box that expands and destroys all of humanity to feed itself--which some people are worried about--very smart people. We've had some of them on the program. Would that make you happy? sad? Irrelvant? You're saying that it was a different matter. That they're just a different thing that we were the ancestors of?

Sandra Faber: I pretty much would agree with that. Yes.

Russ Roberts: Hmmm. I'm not quite sure what to do with that. Interesting. I disagree, but that's just a matter--you could argue it's just a matter of taste.

Sandra Faber: You sort of built in the result you wanted from me by saying that they destroyed humanity.

Let me put it another way. Supposing humanity sees that the long-term solutions to problems of pollution, resource-generation is: If we switch from being biological entities to machine entities, that there would be somehow an advantage to Earth as a creative, by making this switch. It's voluntary and we designed it and there are descendants now. That's fine. That's great.

Russ Roberts: That's horrifying.

Sandra Faber: You built in the bad thing by saying--

Russ Roberts: No, no. That's still horrifying. I don't need to build in the bad thing. I think it's horrifying.

Sandra Faber: Really?

Russ Roberts: I have no interest in that future. Absolutely.

It comes back to my point before: Who's excited about the Earth being this great generator of creativity and order when it's just a bunch of machines? I don't get it. Explain it. Help me here.

Sandra Faber: I'm taking it for granted that there'd be--

Russ Roberts: That's one of the darkest futures I can think of.

Sandra Faber: Really?

Russ Roberts: Yeah. Really. Totally.

Now, I try to be a little bit self-aware. I understand that as a person who is religious that this is part of it. But I have a feeling a lot of nonreligious people also would be uncomfortable with that. I don't know.

Sandra Faber: Well, they'd be sentient.

Russ Roberts: Maybe. It's unclear.

Sandra Faber: Take it as part of my hypothesis that they are.

Russ Roberts: They have consciousness.

Sandra Faber: Yes.

Russ Roberts: Do they have consciousness? That's what you mean?

Sandra Faber: Yes, and they have feelings. They have feelings. They have emotions. That's very important.

Russ Roberts: Okay. So, I get it. I get it.

Sandra Faber: I'm really more and more thinking that we are prisoners of entropy and that the generation of waste entropy and the consumption of irreplaceable low-entropy assets on Earth will be our own doing. Eventually. And then, returning to your question, what does it matter on the timescale if it's short? If we go out in a blaze of glory, why not? Why prolong things? Why keep matters moving?

I guess I would say that as long as we're functioning, there's always the possibility of solving new problems, moving to another planet, whatever. I mean, the machine is moving. If we commit suicide here on this planet, it's over. And that saddens me. I would not like to see that happen.

Russ Roberts: But, the reason it saddens you is not the reason it--it would sadden me, too. I don't think we're headed in that direction, although politics around the world gives me pause right now in this particular moment. But, what I'm having trouble with for the last 15 minutes of our conversation is: I don't understand why that makes you sad if--does it make you sad for the Earth?

Sandra Faber: Yes, for the Earth as--

Russ Roberts: Why do you care about the Earth independently? That comes directly on point about the external observer, God, whatever. You care about it because you're looking ahead to--that this is a precious environment that we are squandering. Is that a fair way to say it?

Sandra Faber: Yes. That's right. It's one of the very few places in the universe where machines can--processes can operate to create low-entropy enclaves. Most of the universe isn't like that. And, only in such enclaves can interesting things happen.

Russ Roberts: I'm just trying to understand.

Sandra Faber: Otherwise, all of the distinctions--everything comes in to thermodynamic equilibrium. We have heat death, that kind of thing. It's not interesting. I keep using that word for lack of anything better.

Russ Roberts: But it's going to come after you're gone. Why do you care?

Sandra Faber: I think everybody lives for the future. You're living for the future. This is, again, part of the human organism.

Russ Roberts: It's true.

Sandra Faber: We are all oriented towards the future. The problem is we're oriented towards futures that are rather near-term, probably associated with our direct progeny. It's hard for us to have an intimate connection with the far future, and that's the basic challenge in trying to plan for the future of Earth.

I've thought about it now, and I'm trying to figure out why I do feel this urge to preserve Earth as a creative environment. All I can say is when I talk to other people, they have the same urge. It all depends on how strongly we feel that urge, because we have to make sacrifices today or changes in order to preserve Earth long-term. Are we willing to do that?

Russ Roberts: Well, what we didn't get to is that it's not enough to want to make changes or to make sacrifices. You have to make sacrifices that lead you to an outcome you're going to like. My worry is that we don't have a process to make those decisions. Go head.

Sandra Faber: I worry that there's no outcome that we like, because I think we're all impressed by the status quo--a planet with an enormous economy, many things going on. It's fascinating. It's a miracle. There's no question about it.

But, when we look at the current rate of resource consumption and waste production, I feel that that can't go on very much longer. So, the future a million years from now, is smaller in order to be sustainable. It's much smaller. I'd like to know how much smaller. What's the carrying capacity for an interesting civilization over millions of years? We don't know that. I'd like to know that.

Russ Roberts: Can't be answered. Can't be answered. And it can't be answered for the same reason it couldn't have been answered when the first Neanderthal wandered out of the cave with a stick and hit a creature and had something to eat. Just think about those changes, that extraordinary--I mean, civilization is an unbelievable transformation of the--look at the surface of the Earth. I mean, in one sense, it's trivial because they're just little bumps. They're not very impressive. But, we've certainly found some unexpected ways to do things. Can we not find those again down the road?

Sandra Faber: No, because I think we know much better the laws of physics, including the laws of energy and entropy. The caveman didn't know anything about those things, and that was all new territory to be explored. We know much more about those things now.

Russ Roberts: My guest today has been Sandra Faber. Sandy, thanks for being part of EconTalk.

Sandra Faber: Thank you.