The Great Simplification with Nate Hagens - Thomas Murphy: "Physics and Planetary Ambitions"

Episode Date: May 11, 2022

On this episode, we meet with Professor of Physics at UCSD and the Associate Director of CASS, the Center for Astrophysics and Space Sciences, Tom Murphy. Murphy shows us how continued growth and energy use is an impossibility if continued at our current trajectory. How does physics constrain our planetary ambitions? Murphy helps us do the math. To help us align with a post-growth trajectory, Murphy offers suggestions for how humans can begin to treat nature as well as we treat ourselves — and why we must care about the future in order to create a brighter one. About Thomas Murphy Thomas Murphy is a Professor in the Physics Department at UCSD, the Associate Director of CASS, the Center for Astrophysics and Space Sciences, and is the author of Energy and Human Ambitions on a Finite Planet. From 2003–2020, Murphy led the APOLLO project as an ultra-precise test of General Relativity using the technique of lunar laser ranging. Professor Murphy's interests are transitioning to quantitative assessment of the challenges associated with long-term human success on a finite planet. For Show Notes and Transcript visit: https://www.thegreatsimplification.com/episode/18-tom-murphy

You're listening to The Great Simplification with Nate Higgins. That's me. On this show, we try to explore and simplify what's happening with energy, the economy, the environment, and our society. Together with scientists, experts, and leaders, this show is about understanding the bird's-eye view of how everything fits together, where we go from here and what we can do about it as a society and as individuals. Today's guest is my friend Tom Murphy, a professor of astrophysics at UC San Diego, but perhaps better known for his longtime blog, Do the Math. Today we do the math on how continued growth in energy use is an impossibility, which at today's pace would result in more energy use than the entire galaxy in a short few thousand

years and other topics relating to the path ahead for humans living on a finite planet. Please tune in for Professor Tom Murphy. Welcome to this podcast. Let's get started. I have a lot of questions for you. I've been a longtime follower of your writing on do the math. And of course, we've been friends. So could you personally just say, what is your current job?

And for how long have you been doing that? I am currently a physics professor at UC San Diego. I've been in that job for coming on 19 years. Okay. And during that time, what has been your main area of research? So it's been astrophysics of various flavors, started out as colliding galaxies, and then moved into a project that's occupied the last 20 years in my life on measuring the distance to the moon to millimeter precision as a test of Einstein's general activity. That sounds important. Is it important? In some circles, it certainly is important because the fundamental disconnect between quantum mechanics and general activity, they're fundamentally incompatible. So we thought we'd better test gravity as well as we can and maybe try to resolve this gaping hole in physics.

So it was always easy to write proposals to get funding for it because it's widely viewed to be a very important thing. Among other aspects of our society, that pursuit might be what we refer to as energy blind. But is that research important to you, or is it still important to you? Well, it definitely was when I started. I felt like I was really lucky to be doing something that had fundamentally, you know, consequential elements to it, you know, probing the very foundations of physics. and I got to play on telescopes and build instruments and shoot a laser at the moon. I mean, who can do that? I felt like I was really integrated into that world.

You shoot a laser at the moon, and then how long does it take for the laser to arrive at the moon? It's 1.25 seconds there and another 1.25 seconds back, so 2.5 round trip. Dang. So shooting lasers at the moon, and all of a sudden you started, to write blogs and ultimately books about energy. So what's the change in your mind, your philosophy, your recognition from being a professor to being kind of an educator on the issues of sustainability? It was all in slow motion.

It started in 2004 when one of my first teaching assignments was a course on energy in the environment. And I went in very eager to learn what that landscape looked like. I had a lot of computational skills and just quantitative physics skills. And I thought, I'm going to try to sort out what our future looks like, you know, solar, wind, geothermal, hydroelectric nuclear. What's it going to be? I knew that fossil fuels were finite, but didn't really know much more than that.

What happened is I came out confused because it's a very difficult challenge. Fossil fuels are incredibly addictive and hard to replace. And I did my own experimentation. I built my own little solar setup with batteries and experimented and kept expanding it and learned a whole lot about the pros and cons. I'm a big fan of solar, but I also know practically how hard it is to be completely reliant on something like solar. And so over the years, I became more and more concerned until I eventually reached a breaking point and had to start writing this stuff down. And that's when do the math started. And do the math eventually ended in a book which I have a copy of called Energy and Human Ambitions on a finite planet, which is probably one of the best energy textbooks I've ever seen.

Well, that's great. Thank you. So now what? What are you doing now? So now I'm really transitioning away from astrophysics because I have come to the conclusion that so few people have their eye on the ball here that we could really botch it, that if we just assume that things are going to work out and that. we're transcendent as a species, we're going to fail. And that looks like collapse. And in the worst case, that means that we lose all of our scientific knowledge. We lose everything I've worked for on all our, my colleagues have worked for. And that's very difficult for me to bear. And so I think maybe I should apply what talents I have toward this more existential predicament. And, you know, in the worst case, I'm wrong about all this, but every time I re-evaluate that, which is almost constantly,

I have a hard time believing that this is not a serious issue. And so it just feels like the other stuff I did was playtime. It was recess. And now I need to step up and try to do something that I think is more important. That's how I feel as well, as you know. How many of your colleagues in the physics departments are moderately to extremely aware, of the topics we're about to discuss? Very few, honestly.

I mean, why is that? That's a good question. And I ask myself that all the time. I think it's partly that they haven't needed to be more aware. We work in a society in a world that allows specialization and focus into, you know, minute little areas. And you can become, you know, the world's expert on some topic that's very esoteric. And, you know, the whole system works for you.

And it's there for you, you wake up. It's almost as consistent as the sunrise. And so why do you need to be that aware? Because all the incentive structures are built around kind of a continuance. Yeah. I mean, if I got paid a good salary to shoot lasers at the moon and write papers about it and I was knowledgeable on that, that would be a pretty good deal. So unfortunately, the story that you and I spend a lot of time delving into is not a pleasant, happy, happy. one because we're looking at two or three steps ahead, how the system of energy, materials,

money, human behavior, the environment fit together. So with that intro, thank you. I hope you'll be willing to engage in a sort of speed round on topics of your expertise. I'm going to ask you like eight to ten questions, Tom. Maybe just give short 15 to 30 second answers. And then we'll get into a deeper discussion if you're willing. Sure. That sounds great. All right. So you are an astrophysicist. Let's start with some core fundamental questions for our listeners that might not have a lot of expertise in this field. So first of all, briefly, what is the first law of thermodynamics and why should people care? Well, the first law of thermodynamics is basically conservation of energy. That energy is neither created nor destroyed. It just can be sloshed around from one form to another. And so we don't create any.

any energy, we just transform it from, say, a chemical form into a mechanical form or so forth. So that's the first law. And what is the second law of thermodynamics? The second law is a little more subtle, and it's that this quantity called entropy is something that can never decrease in a closed system. So that it's a measure of microscopic disorder at some level or how energy can be distributed in a system. And it can't spontaneously decrease the entropy.

has to go up. And why is that relevant? It becomes relevant in sort of the quality of energy sources. And it's also relevant in just dictating the direction of time and how things flow. Most videos that you watch, you can spot right away whether it was filmed backwards or forwards. And that tells us how deeply ingrained. I mean, think of something splashing into water or a coffee mug shattering on the ground, you know, that that entropy dictates the direction at flows in a sense. And it's something that's actually very intuitive to us because we live in this world where entropy only ever increases. So the way that I think about it is every time we do a transaction, a good or a service or an activity, there's energy spent and there's waste heat

dissipated and there's always a loss. There's always a loss of the ability to do work with what we had before. Yeah. In terms of the second law, you'd say that the sort of let's say organized motion of, say, the coffee cup sailing toward the ground, that's a very organized state of motion. And then it is going to turn into a much more disorganized state of motion and eventually is heat. All of that mechanical energy just ends up as heat in the environment. And now it's a very diffuse form of energy that's got high entropy and it's practically useless to us. So how much of our energy is directed towards actual output and how much is wasted roughly? Well, you know, in the long term, all of it's wasted.

We get some use out of it along the way. But, you know, okay, so a power plant might turn 35, 40 percent of its chemical energy into electricity or a nuclear plant is very similar. A car driving down the road might turn 20 percent of the energy and the gasoline into useful mechanical. But let's take the car going down the road. All of that energy that we think that provides some utility for. ends up as waste heat because we're stirring the air. We've got friction on the brakes, friction tires in the road, friction in the car. You know, your car gets hot. The engine is hot. But even the stuff that's useful propelling us down the road turns into heat eventually. And where does all

this waste heat go? Well, so if it just stayed on Earth, Earth would get hotter and hotter and hotter to the point where climate change is a laughing matter. But there is an escape from the earth, and that's in the form of infrared radiation. So the earth sort of cools off to the coldness of space by just radiating that thermal energy out to space. All right. So what is power? Power is in the physics definition, simply the rate at which we use energy. So I like to think of it as a speedometer. So energy is the odometer. And power is, just the rate at which you're moving down the energy road. And why is that important?

Well, actually, in some sense, it's my favorite unit is the watt, if I'm allowed to have a favorite unit, because many things are power limited. And our society is somewhat power limited, our metabolism, the sun. So power is usually how much energy we use depends on how much time we're expending a certain power, but the power is the thing that is more a useful measure. So what does that mean power limited? Am I power limited? You are power limited. My physical body? You are. Absolutely. You can actually get a very good sense of how much power you're spending by your caloric intake. So if you divide the amount of calories, convert it to something more useful like joules and divide by seconds in a day,

that's how much power you're spending. So 2,000 calories or really kilocalories per day, translates to about 100 watts. Like a light bulb. That's like an old incandescent light bulb. Yeah. And so when you are active and say performing a lot of labor or being athletic, you might ramp that up to maybe a few hundred watts. Now, a horsepower is 750 watts roughly.

So you would expect a horse to be able to sort of deliver almost 1,000 watts of mechanical power, we can't do as much as a horse. So we're not up to a horsepower. Maybe for short bursts, we can, you know, for a few seconds we can manage. We're power limited. So the power limited means no matter how much food I eat, I'm still going to only be able to generate the power of around 100 watt light bulb or a little bit more if I'm a elite athlete or something. Right. And if you try to eat more than that, well, you know what happens. Yes, I am well aware of what happens. But in another sense, I'm not power limited, right? Because I can generate the power of a 100 watt light bulb with my own body, but I have an exosomatic wand that I can use by ordering

stuff on Amazon or flying to California or the embodied energy in my office here. Absolutely. And that amplification factor is quite large, as you well know. Yeah. Okay. Let's keep going with the speed round. what is exponential growth as opposed to linear growth? Well, exponential growth is what happens when something grows in proportion to the amount that it already has. So a bank account, for instance, gathering interest where the interest is computed on the balance in the bank will grow exponentially because as that bank account grows, then the basis over for which that interest is computed is growing.

And so it tends to be a runaway process. because the bigger it gets, the faster it grows. And it's a positive feedback runaway. And when we talk about growth, there is the rule of 70, I assume you teach your students. What is the rule of 70 or the doubling rule briefly? Yeah, the rule of 70 is just a convenient numerical thing where if something that grows at 1% per year will take 70 years to double or if it's 1% per second, it'll take 70 seconds to double. So whatever the time unit is, it's a factor of 70. And then if it's 2%, well, now it's 35 time units. And if it's 10%, it's seven years or seven time units. So when our economy is growing at 3% a year, it would double in every 23 years plus or minus. Yeah, 7.23. Yeah.

Got it. So thinking ahead to, since you're the do the math guy, I want to ask you these questions. So what is the relationship between economic growth, which has been around two and a half to three percent a year for the last 50 years, between economic growth and energy consumption? Well, there are multiple ways to answer that question. One is historically they've been basically identical. I mean, economic growth maybe goes a little bit faster than energy growth. And some of that's improved efficiency. Now, the economists would say that it doesn't have to be a rock-solid relationship. you can have things that are decoupled and you can have economic activity without a physical footprint.

You know, we haven't seen our global energy system do that as a whole, nor do I think we ever could. So I think that these are always going to be very closely tight concepts. Real briefly, why do you think we never could decouple economic growth from energy consumption? Well, yeah, because and here's where people can get tripped up, because it's, very easy to point to activities that are very well decoupled. You know, the funny one I like is psychotherapy. You know, you pay a therapist, you know, an insane amount of money and hardly any energy gets spent in that process. But trading art or, you know, a lot of things can be decoupled, but the basics of life, food, transportation, thermal energy, heating yourself or heating your

homes, those things are just going to never be free from energy and can. can in fact exact quite a hefty toll on the energy front. And those things are always going to be a significant part of what we do. We can't go without them. So the psychotherapist has an office and a home and an education and a life and vacations and an internet and all those other things. And that makes the coupling of that person's vocation and the economic goods and service of the $300 an hour for psychotherapy contribute to almost a one-for-one correlation worldwide

on GDP versus energy. Right. Okay. So you are a physicist, to my knowledge, the first physicist I've had on the program. How are physics and economic theory similar? I think they're similar in that they use math. And I think that's it. I think that's the end.

Okay. How are they different? They're different because physics is a self-correcting enterprise that uses nature as the final arbiter. So you can theorize till you're blue in the face, but if the experiments don't back it up, then it's junk. So we have ideas in physics not because we like them. In fact, we don't like a lot of our physics, but nature crams it down our throats. So it's constantly challenging its core assumptions. Economics is a little bit too eager to follow its model.

You had Herman Daly as a guest on this podcast, and I think he put it very well as I think the fallacy of misplaced concreteness, I believe, were the words to describe overindulgence in believing the model over the assumptions, you know, not revisiting the assumptions that underlie the model. But didn't the early economy? try to mimic physics and apply physics to the broader human condition? They did, and they were actually somewhat successful in the sense that they had a much firmer grounding in physical law and nature, and in fact thought about growth as a temporary

phase. And then you have heroes or villains, depending on your point of view, like Malthus, who really understood limitations. Now, he didn't understand the fossil fuel craze that was coming, but. his basic idea will certainly be correct. It is correct that physical limitations will impose a limit on economic growth. Okay. So let's get into it.

Thank you for the short answer part of the conversation. Now we'll get into the longer answer. So you're an astrophysicist. What can your work, your field, your expertise contribute to this idea that the world is becoming more aware of that we're facing planetary limits. Yeah, I think a number of facets of being an astrophysicist lend well to this. First of all, we're used to looking at very vast tracts of time and space and understanding ourselves as insignificant in the universe.

We're really, you know, specks of biological matter on a speck of dust around a star that's really just a speck of light in a swarm of hundreds of billions of stars in a galaxy. and that galaxy itself is kind of a speck or smudge among the rest of the universe. And so that really is, you know, bring some humility to the story. So that's one thing. The time scale is very important because, you know, if we talk about billions of years, then what's happened in the last 200 years, what does it matter? I mean, it's just such a blip that we need to think longer term.

And, you know, it's very easy for me to think about, you know, the 10,000, your time scale of agriculture and civilization. I mean, that still is very short compared to the many processes that astrophysicists consider. You know, planetary limits, it's got the word planet right there. That's an astrophysical concept. We understand the matter and energy interactions between the planet and the solar system and the sun. We understand, you know, the fundamentals of energy and light. And I think astrophysicists are also accustomed to doing a approximate calculations. These are not precise laboratory conditions.

You're looking at messy systems in the sky that are far away and you have imperfect, you know, data quality and you're doing very approximate work. Those skills of quantitative kind of fuzziness lend really well to some of these big societal scale messy problems because you just try to get a overall capture of the most important elements And so that kind of fearless approach to let's tackle a messy problem and quantify it somehow. That comes in very handy. So one of your most famous essays, which when I was teaching at the University of Minnesota, I assigned in the energy section, was called galactical scale energy or galactic scale energy. And in it, you teased out the concept that energy and GDP are.

are tightly linked and that contrary to conventional economic thinking, which basically says we can grow forever, you showed that at 2.3% per year energy growth, if I recall, we would within 2,500 years, consume all 100 billion stars in the Milky Way galaxy worth of energy. could you walk me through the math, if that's possible, on how you arrived at that conclusion and why that's relevant? Yeah, certainly. And, you know, one thing I will say about economic assumption is that if your model starts to be able to replace interchange labor and capital and energy and it's just all factors

of production and you can just slosh them all around, then you can understand why the model would suggest that any one thing like energy isn't that important. And so you can just replace it by something else. Wait, wait. So hold off there. So an economist would say, yeah, energy is important, but in our model, if we run out of energy, we can substitute it for labor or capital. That's right. That's the effect of thinking. Okay. If you can call it that. Okay. Yeah. So I wanted to focus on the energy story and then later tie this into the economic reality. And, you know, in terms of energy, if you look at the last few centuries of energy use, it's a fairly convincing exponential climb in terms of, you know, something like a 2 to 3% growth

per year. So I picked 2.3 for the mathematical convenience that it's a factor of 10 every century. And now I can think about it without using a calculator. What do you mean a factor of 10 every century? So at a 2.3% per year increase, the size of the system would increase by a factor of 10, become 10 times larger every century. And it's relentless. If we grow something at 2.3% a year, it doubles every 25 years or whatever. But in 100 years, it will go up 10x, is what you're saying.

Exactly. Right. So it's very similar to the law of 70. It's just another convenient handle. And so a factor of 10% of you find out that we would, at the current rate of energy growth or the rate that's been present for the last few hundred years, we would hit the amount of solar energy that reaches the earth in 400 years at 100% efficiency. So if your idea is that, oh, well, fossil fuels are finite, sure, but we can, you know,

the sun is so plentiful solar energy that we can outfit the entire all the continents and all the oceans with solar panels and surely the efficiency will be at 100% because we're just so clever. So even then you're at 400 years. And then the techno optimist would say, but it doesn't stop there. We've got the whole sun.

Why would we confine ourselves to Earth? We're space cadets. And so we can have a shell around the sun that collects all the solar energy and that buys you another thousand years. By the way, the earth, if you use the Earth, if you destroyed the Earth to make the shell,

because where's the material going to come from? It would be a thin, three millimeters thick surrounding the sun at the distance of the earth. And most of that's useless rock. It's not structural material that you want. Okay. So at 2.3% a year, we go 10x in 100 years, which means 100x in 200 years, a thousand X in 300 years. Exactly. But that's just the energy use.

But the material use, which you just suggested, over the last. century or so is even more tightly linked to our economy than energy is. It's basically one for one. We double every 24 years in the amount of gigatons of aggregate, asphalt, concrete, metal, wood, etc., that we add to the system. So where are we going to get that from? I mean, forget about the galactic scale example. Where are we going to get it from for the next three doublings? Right. I think, you know, that's a huge concern and it's one that we can basically turn a blind eye to because it hasn't been fundamentally limiting so far. And so if that's if that's what we decide that if it hasn't gone bad so far, then it won't go bad, then we deserve what we get. We can see the writing on the wall. We can understand that the first resources we grab are going to be the easiest ones, the low hanging fruit. So yeah, you're right. The material demand. On our planet have never been higher.

We're already starting to have trouble meeting the current rate of demand, let alone a factor of 10. It's just inconceivable that we could go there. So if we do make the A switch to either mostly renewables or partially renewables because we recognize our energy limits, we still have these material limits. Do you have any comments on that? I do. And one thing I would say about it is addressing the idea of substitutability that, you know, okay, well, when we run out of copper or something, we'll find something else. But the problem is the periodic table doesn't cater to our whims and doesn't expand just because

we want new things. You know, there are only so many elements and they all have their own unique properties. And it's not a one-to-one substitution if you go to some other thing. you know, we've optimized, we've found the best materials for many purposes. And what's left is inferior in a lot of ways. So the superior substitute story is just a limited time prospect. So my view is we optimize for the least available input. And if liquid fuel like oil starts to become scarce, we're going to make some decisions

to rectify that situation. But then some other thing will become limiting. And eventually there's a lot of things that are limiting and they interrelate. So what would an economist, and I know you've had both official and unofficial debates with friends of yours who are economists, what would economists say taking a steelman argument of the things that you've said so far? How would they reframe the discussion that we're having right now? Yeah, that's a good question. And it's something that definitely deserves consideration. and I can't claim to 100% represent how they think,

and maybe that would be damaging to my brain if I tried. I think one thing that they would likely point out is that even if you do run into material limits, that that will not stop growth because you can have growth in other domains that are not energy intensive. This is the decoupling idea. You can have more virtual reality so that you're going to Bali without doing. the air flight, they would stress just utility in the generic sense and say that the real question is, let's say that you did stabilize in your material footprint, which by the way, how do we even stabilize?

That still is a drawdown on non-renewable resources. That's just relentless. Even if you're not growing, it's hard to maintain. But that aside, even if you did maintain so you've stopped growth materially and energetically, The question would be, is life 500 years from now unambiguously, undebatably better in terms of the overall quality? So what you're getting out of those resources, is it better? And the answer is, well, probably all of the things being equal and things being stable. Yes, but that's a different kind of growth.

That's not a quantitative growth. That's a qualitative growth, which is not precluded by this line of argument. But it's not the kind of thing that leads to loans and investments and social security programs and all of these mechanisms that we've built that rely on the quantitative growth. Well, if I make love more often with my girlfriend and I take my dogs for more hikes and I meditate out in the forest, all those things improve my qualitative well-being. But none of those things contribute to GDP. And right now, GDP is our cultural score. And some of that is our cultural choice, but some of it is the metabolism of biological species seeking power, not power like social power, although that's related.

But power is in energy use per unit time. Do you have any thoughts on that? Well, I absolutely agree that we're kind of fixated on the wrong metric and happiness can be found in a very low tech, low energy, low material resource way. but that so many of our lives are dictated by how to gain enough money to buy ourselves the happiness that we're after. And in some sense, that's the wrong road and it's leading us to a bad place. It's a monkey trap. We can't let go of the banana.

We're grabbing it too hard. Okay. So earlier you mentioned waste heat. And we had an email exchange about this. And I thought it was really interesting because I learned some things. So given your galactic scale energy example, setting aside fossil fuel emissions, which create kind of a blanket around the earth that trap in heat via the greenhouse effect, every time we start our car or turn on a light or take an airline flight, not only is there the emissions, set aside those for now, but there's actually the heat that's generated. So how does the scale of our waste heat of right now is 19 terawatt global economy? The power of the global economy right now is 19 terawatts, which means we have effectively

190 billion 100 watt light bulbs turned on all the time. So how much waste heat does that generate relative to the forcings that are happening because of the blanket of the greenhouse effect from our emissions? Yeah, that's a very good question. And right before I get to that, I will just complete the galactic story that going from our sun to all 100 billion stars in our galaxy would buy you 100. So here's how the math works. A hundred billion is 10 to the 11. So that's the scientific notation for 100 billion. And so it's very, it becomes very easy at a factor of 10 per century, that 11 is how many centuries you have. So in 1100 years, we're using how much energy? We would go from the sun to the

entire galaxy. So it would take 1,400 years to get to the level of the sun at our present rate. And then only another 1,100 years after that, so 2,500 years total to get to the galaxy. And that's physically impossible because it takes light 100,000 years to cross the galaxy. There's no way that we would be able to capture the energy from all those stars in just 1,100 years. Physics says absolutely not. So basically, even though it was absurd when we had all continents in all oceans using 100% efficient solar panels in 400 years. That's already absurd. And then we went one more level of absurdity to this shell surrounding the sun.

But you can't say physically that's impossible. But by the time you get to the galaxy, yes, you can say physics will not allow it. And you're just shut out. Growth has to stop on a time scale that's short compared to civilization. That's important. So we've grown at 2.5% a year since the 17th century, on average, our energy consumption. So at that rate, we will use more energy than the entire galaxy in 1,400 years. The gap, it's the sun in 1,400 galaxy in 2,500. Okay. And we stopped Hunter gathering and moved to

the agricultural revolution 10,000 years ago. Right. So our physical growth, our energy consumption growth will not continue for even a fraction of that time. Right. We're closer to the end than the beginnings. Of growth. Of growth. Well, personally, and you know me, I think we're much closer to the end than the beginning. I agree with that. But you're just pointing out that even if you would disagree with that premise, because we have trillions of barrels of unconventional oil, and we have the technology to grow solar and wind, et cetera, they're still on a long time civilization timeline, we're still near the end of growth. That's right. That even if you pull out all the stops and, you know, allow almost magic to happen that's at least not physically impossible, you run into physically

impossible before 2,000 years is up. I mean, really just 1,500 years. And what if you tried that math on an economist? I have. And they swallow hard and this is not familiar territory to them. And but they can't argue with it. And so they sort of will, accept, okay, but you know, you are going to absurd extremes here. And, you know, maybe it's a bit of a straw man because they're not advocating galactic domination. But the point still is that, yeah, but you can't keep growing, right? Energy can't keep growing at this rate, right?

And they eventually have to say, yes, okay. And if they agreed with you, really, wouldn't somewhere that changed their models or not? Well, so yes and no, by putting a time scale on it that's centuries, they don't feel obligated to do anything. It's someone else's problem. It's an economist of the future's problem. That's right. It's not relevant to the here now. Well, I think that's been the problem all along because we're a biological species with an 80-year lifespan.

And a lot of my Wall Street friends, I talk to them about all this stuff. and ultimately they don't disagree with any of the logic of the story of the great simplification other than the timing. You're right, Nate, but this is going to happen in my children's lifetime, maybe not in mine, which I disagree on. But I think the math, as you're an expert in, is somewhat inescapable. And what you just said, Nate, is that their kids must be jerks if they don't even care about what the kids have to go through or grandchildren.

I mean, that's another issue. And it's one of the reasons that I'm doing this work on advanced policy that I've found that people between 25 and 65, this story is too emotionally potent to actively engage with because it's too threatening to their own status quo and getting paid to send lasers to the moon, et cetera. But younger people, teenagers, early 20s, And older people who have grandchildren and have retired and don't have a status loss at risk from saying uncomfortable things, it's very potent to them in a way that they want to know what to do. So, I mean, I really think the world is converging on this story. It's somewhat inescapable. I used to think that telling the story better and providing more facts and more math like you've just done is what was missing. And I'm almost now thinking it's more fear that we don't

have an answer and cognitive dissonance and denial about this because it's such a huge thing is why more people aren't getting involved in the story. Yeah, I think that's hugely important. But you, you, I remember, you wrote an essay back in the day about some of your readers on your blog that fit into a certain Myers-Briggs category. that you hypothesize that personality type was more conducive to these sorts of conversations. Why is it that some people gravitate towards the energy, climate, growth, limits, thermodynamic, biophysical, ecological reality and are kind of energized and dedicated to it and other people

look at us like we just grew antlers? Do you have any hypothesis on that? Yeah, well, actually, you know, when you say it like that, it reminds me that on my website, I've got this very old picture of myself at the UCSD website in which I am actually holding up caribou antlers. So I didn't know that. So it's really fascinating to me that the things that worked for me, the things that got me into this were very quantitative, very physics-oriented. And fear, fear worked on me. I thought, oh, my, gosh, this is really worrisome stuff. How do we get out of this? But for other people, fear is immobilizing.

And the numbers aren't really there for them. They're not fluent. They're not really quantitatively geared. So what works for me definitely doesn't work for a lot of people. One thing I found is that the people who were attracted to my blog, readers in my blog, so the majority came from two personality types in Myers-Briggs. Now, Myers-Briggs gets a lot of flack for some very obvious. It's a guide.

It's a guide. It's a guide. You know, you don't take these things literally, but they can still be useful. And here the useful aspect is that when only two or three percent of the population is INTJ, but 45 percent of the traffic to the site is INTJ. Whoa. That is saying there's something there to that metric, right? It's not astrology.

It's real stuff. And the next biggest lump comes from the adjacent group of INTP. And those are classic physics type or scientist mentality. The INTPs tend to be more theorists and INTJs tend to be maybe more experimentalists. It's not hard and fast. But 75% of the traffic were from those two. That's out of 16. 16 potential combinations.

And those already are small. That's like a total of 4% of the population in those two. So what's the inference of that? What's your takeaway? The takeaway is that the, The most important of those letters, the four letters, is the N, in I-N-T-J. And T is pretty important, too. I'm E-N-T-P, by the way.

Okay. Yeah. But the E is just very mild. I'm like 51% extrovert, 49% introvert. And my extrovert manifest on this podcast, but then I'm going to go for a walk with my dog after this. Exactly. Well, you know, as a lecture, I have to put on the extrovert thing to be an instructor.

Right. So you can morph a little bit into these different things. But the N is very important. That's abstracting. That's the N is the N and intuition. What's the opposite of N? It's S or sensing. So it's how you get your information.

Do you get it from direct sensory input, what you can taste, touch, see, feel here directly from your own experience, your own life? Because that stuff is important. Or do you prefer theoretical abstractions where you synthesize, ideas and pull your stuff from ideas. And so the ends are idea people and they are only 27% of the population. Really? And so right away, you've got 73% who are in the S camp and just they look out the window. Things seem fine to them. What are you talking about? You're just rattling. And that's a real problem because a lot of the interrelated systemic risks that you and I are working on are in the future.

They are in the future. We don't see them until they happen. That's right. You need abstraction to understand things that haven't happened ever before. And now you can see that there's a lot of adaptive benefit to having mostly S types because usually the world is the same today as it was yesterday. And so if you're a hunter-gatherer group, relying heavily on that experience is much more, I think, relevant than listening to the idiot in your group who's, who's,

talking about things that have never been seen before in, you know, generations. You can understand why that person should be laughed out of the room. Dude, I think the climate is going to warm in the future because of our behaviors. Okay, that was helpful. Let me get back before I forget, because this is something that I learned from you that I didn't understand. So we're burning fossil fuels in our airplanes and our factories and our commerce and our global system. and that is creating a blanket of heat over the earth that many of the models and our daily realities on our sensing of the world, we can see that things are already changing, let alone 50 or 100 years from now.

But that's from the greenhouse gas effect. But you're also saying that our burning of these things is generating waste heat. So how is that waste heat quantified relative to the forcings of the, uh, of the emissions. Yeah. So right now, if you put an apples-to-apples comparison to the primary thermodynamic input

to the Earth system is from the sun. And so the sun is intercepted by disk that's pi R squared is the area of the projected Earth where R is its radius. The surface area is four pi R squared. But what the sun sees is just this flat projection pi R squared. And so we compute the, you know, the sunlight that has. the Earth divided by that pyre squared is about 1,300 watts per square meter, a little over a

kilowatt per square meter. Now, the climate change problem right now, the imbalance that we're facing is at the level of about one watt per square meter. So that's what we're all in a tizzy about is that there's this 0.1% modification to that solar input, which is not something you should dismiss. I mean, it's a real concern. And the 1 watt per square meter is projected under the real, grotesque emission scenario, RCP 8.5 to 8.5 watts per square meter or around eight times what it is now.

Yeah. And so today it's at one and that's already a problem. Now, if you take our 19 terawatts of global, you know, industrial power and divide that by this pyro square, you get about 0.1 watts per square meter. So right now, this waste heat and I want to also clarify that even though some of that energy is being used for what we think of as useful purposes. It all ends up as heat. So all 19 terawatts is heat after we've used it. Oh, so just some fraction of it is immediately wasted, but the rest of it does some, gives us some dopamine in the interim and then turns into waste.

And then it's waste heat. So don't go off thinking, oh, well, we just make things more efficient and then we don't have waste heat. No, it's all going to heat. So if we continue to grow at 2.3% a year, our energy in a century from now, just the heat from our activities alone, forget about the greenhouse gas effect, just the heat will be the equivalent of what the greenhouse gas effect is today.

Exactly, because it's 0.1 today, and 100 years it's 1. And 100 years after that, it's 10 and absolutely dwarfs are concerned in global warming. So forget about the energy and material limits to growth. We have heat constraints on the planet to growth, like absolutely urgent ones. Yeah, I'm not out there holding signs up saying worry about waste heat because this is just a way to illustrate that if we wave magic wands and get past some of our current troubles, we would ultimately run into this as a real problem. I don't think we ever get there.

I don't think you think we get there either. Growth is going to end and we're going to have all kinds of other problems on our hands before waste heat actually becomes a serious. issue. No, I agree with that, but I'm just trying to create the boundaries of the problem that a lot of other people who think we can just continue, well, look at the International Energy Agency, a bridge petroleum. A lot of these international entities think we will continue to grow throughout this century at two or three percent a year, but we'll do it by using renewables, for one example. So I don't think that's going to happen, and that's a whole other podcast. But even if that were to happen,

you would still have this heat generation issue, which you just brought up. Yeah, I use this as a tool to say, hey, I don't care what your assumptions are. You can't just keep growing. There are thermodynamic consequences that I don't think are what's going to get us, but they're there. And they close the exit, right, of saying, well, we're just going to sort of imagine sailing off into this glorious future. We can't just do whatever we want just because we think we want to. So broadly speaking, Tom, is human civilization in its infancy or near its end than the beginning? Setting aside the growth because we can have a civilization without growth. So are we near the beginning or near the end? What do you think? Well, when I think about that question, I think

civilization is 10,000 years old. As you said, that's when we started agriculture and started building cities. And so that forces us to think in 10,000 year time frames. And so the question becomes, what can we be doing in 10,000 years from now? And it helps define what I would call success or failure. So success would be an uninterrupted continuation of our civilization so that we preserve our knowledge and the things that we've, you know, the hard won truths about science and the universe and life, and that we prosper in some form for 10,000 years. So that success, And when we think on those timescales, almost nothing that we do today can continue. Obviously, the growth is long over because we're talking about just century time scale for that to end or sooner in practical terms.

But even things like mining, you know, you can't tolerate deforestation or resource depletion or anything that's non-renewable just cannot be part of the story, period, unless it's at 0.001% per year growth rate or something, it's just, it's out. And almost nothing we do today is in that category, which means that almost everything we do today is pointing us toward failure and not success. So success really means sustainability, and we don't even know what sustainability means or what it looks like, but if we're not pursuing that, we're just piling on the failure and making it come sooner. Well, the Chinese at least have a five-year plan.

That's better than we have. have five years great. No, well, I mean, the issue is we're not optimizing for sustainability. We're optimizing for the dopamine and experience of the 8 billion people alive and aspiring to more right now. And if truth be told, those people, most people don't care about the upcoming bottlenecks. They want to avoid them and they're not even aware of them. So this gets to governance and cultural oversight and values and why I'm doing this podcast. So do you think our species is capable of leaving some of Earth's goodies on the shelf, including ecosystems, low entropy resources, other species that right now we're just

grabbing because we can. Generation after generation under some sort of global cooperation is, possible? Yeah, I mean, that question also is one that makes my head explode a little bit because, I mean, no. But, you know, we don't know what global cooperation is. We're always in global competition. We don't know what it's like to leave things on the shelf within easy reach. I happen to be someone who I get a large chocolate bar and have one square per night and it drives other people crazy that I have to discipline to do that and make it last a month. It's within the usual reach and even then I'm depleting it right so were you that way when you were a kid or a

teenager I'm not sure I think to some extent that's always been a part of me but just just sort of a moderation instinct and don't do it just because I can ask if I should well you're a rare individual because I teach steep discount rates and I teach transcendence and the agenda of the gene but the reality is I probably would eat the whole freaking chocolate bar Tom well and I think that's the reality for the human species. And I'm not singling us out. I think most species would behave that way too. We're not exceptional this way. And it's just that we have the ability to destroy whole ecosystems and run other species extinct in large numbers. And so that's how we're exceptional. We are exceptional in that way. And that's almost the only way that we're exceptional, it turns out.

And that's a problem in our mentality of who we think we are. But one of my colleagues, who's another astronomer put it in a very nice way that if we really want to sort of preserve a good outcome for the far future, we have to care about the future. And as to the extent that we're a transactional species, what can you do for us? There's nothing the future can possibly do for us. It's just physically, causally impossible. And so if we are transactional in nature, then we can't. We can't prioritize the far future. Now, I'd like to believe that that's too pessimistic and that we could adopt a different model. The model that we need is one where humans are not the dominant species, but we're a partner to the rest of nature, a subordinate partner, in fact.

And we need to learn to treat nature at least as well as we treat ourselves. And stop thinking that anything that's good for humans in the short term is something we should do because that is the road that leads to failure. So all of my guests so far and probably almost all of them in the future are going to agree with that statement. But still, we're a tiny minority of people. How does this happen where we subordinate ourselves to nature? And is it a long term cultural value change? Do we have to start teaching ecology to four-year-olds? What's possible?

Well, I don't know what's possible. I think that if you tried to do that sort of on the educational front, you're going to get a lot of resistance from the people who don't see the things the way you do. And why are you inculcating our kids to care about, you know, newts, not about human rights? By the way, I mean, all things human can lead to a bad end in the sense that if we prioritize human rights and equity and liberty and all those things, they put us first and that fails. That, that destroys ecosystems. We have to put the ecosystems first and then see what we can afford after that. And that might sound inverted, but we are a part to think the opposite is almost

insanely inverted to think that we're above somehow the life support machine we live on. And yet most people, if they were asked that question, probably do believe in human exceptionalism. that somehow we are different. And on top of that, technology will figure it out. And I don't understand everything that Tom Murphy just said about galactic's scale energy, but technology will find a way because it always has. Yeah, that's the religion, if you will. And it's got a good basis.

We've got a good track record. And it looks like that's a really good model for the way the world works. But you step into the astrophysic mindset, and that few hundred years is nothing. That is just a tease and there's nothing to it. So conceptually understanding galactic scale energy, understanding that humans are exceptional primarily in their ability to produce waste heat and destroy ecosystems and become technologically clever in the near term. As an astrophysicist, if you were able to or any astrophysicist to be benevolent dictator, what

would be some of the decisions or directions that you would advise our society to go in? I would, I suppose, and it's not something I've really thought deeply about because I'm not in that position, nor will I ever be. But I think we need to appreciate nature. And if I just look at the way I approach the world, I'm still a part of this modern system. I still, I'm living completely unsustainably. And it's really hard embedded in the system to do otherwise. I mean, I really try to cut down my resource use. I think hard about buying any new thing. And is it really something I need?

It's not that I can't afford it. I can afford plenty of things, but can the earth afford it? It's not money is the wrong metric. Money is an amoral system that misses a lot of very important pieces. It doesn't have any real long-term vision. And so when you make decisions based on money, which is 99.9% of the decisions that are made in this world, seems, you're going to have bad decisions. So by discounting the future, you're almost guaranteeing a worthless future.

So you've arrived at your own personal ethos and a hygiene of your daily behaviors. I envy you and I'm very happy for you. I wish there were tens of orders of magnitude more people like that. But applying that to the broader circumstance, do you have any practical things? that our society might be able to do in the coming decades that would be able to prioritize nature and either prepare us to use less energy or allow us to use less energy once we hit a wall in our current model. Yeah, and this is something I definitely thought a lot about because I have made a lot of

personal choices in terms of how much energy I use with a thermostat setting in my house, travel. Everything is in consideration of that. But when I confront anybody else on on similar topics, they say that, well, individual choice is just a waste. It's great that you're doing that. But unless everybody does it, it doesn't amount to anything. And I, you know, my response is, yeah, well, then everybody should do it. But why would they do it if they don't understand the mentality?

If they don't, if they haven't seen, if they haven't stared into the abyss, why would they do this? It just seems like punishment. Well, it's a collective action problem. I mean, if no one else is doing it, you are receiving less benefits than you could because everyone else isn't doing it. However, in your case, you're probably getting more psychic benefits from your behaviors than the actual pecuniary dopamine benefits from eating the whole chocolate bar because you've constructed your life around your ethic.

Right. And for me, it's personal and it's a personal journey and it's rewarding because it's my personal journey. But if it's imposed from somebody else, says, you should do this, you should do that, then it's not fun. But I think about voting as an example of a collective action that your individual vote, really, let's face it, it never matters. It's never down to just one vote or almost never down to just one vote. But you still vote because you understand that that's part of your civic duty. I'd like to see a similar mentality that your individual action, you know, take it or leave it. It's not going to make a difference. But it's part of your responsibility to our world.

to nature. The fact that we have so much power and we can do so much damage gives us great responsibility and we're not using that power responsibly at all. I do think that, I mean, a new religion is too strong of a word, but a new culture, a new tribe, a new meme or way of living around what you just said is just around the edge of our current cultural conversation. You've got organizations like extinction rebellion and Fridays for the Future. And some of those things are kind of energy blind. But I do think there is a higher ask for many humans alive today following the logic of this story that they want to play a part of and they're willing to sacrifice or change their behaviors. It just needs to be organized a little better because I feel a terrible shame isn't the right word.

but you're right. I have my foot in both worlds. I'm part of the energy hungry superorganism and I'm part of at least the N part of my Myers-Briggs is conceptualizing the abstractions of what sort of future culture might be in more harmony with our one living blue planet that is slowly experiencing massive metabolic impacts from one species. Well, and you ask what we could do to actually get people, you know, could you educate them? Could you start early at four years old? And I think, you know, really what it's going to take is it needs to become evident to a lot of people. So you need to get the S people.

And you kind of need to have a crisis. And it needs to be serious enough. By the time and the S people are aware of our planetary limits, it's going to be too late to change anything in a large way, yes? That's why I think we should collapse now and avoid the rush. I mean, really, it's going to. be better for us if we get a taste of what can happen early. I don't know how to engineer that, but that would help. Well, that's a whole other conversation. I don't know that we can have a mini collapse now. We should have collapsed in 2008 and the central banks did everything

possible perfectly to keep the system going. 2020 was another example. Now the Russia, Ukraine, I mean, that's another potential risk to the system, but I hear you. So moving into the typical closing questions of my guest, Tom, what kind of advice would you give to young people? And I expect you do give advice to young people because you're a college professor. What advice would you give to young humans who today discover and understand that they're alive during the time of the energy economic limits and that risk to nature, climate change and the general human prediction? What advice you give to the people that are figuring this all out and come into terms with it? Well, I think it's kind of three-pronged. And you're right.

I do talk to a lot of young people. And so one is to be an early adopter, not in technology. We're used to thinking of being early adopters of technology, but an early adopter of dropping the technology dream, dropping that false sense of salvation through just more of the same. It's not helping us. And so, and this leads to part two, which is, keep your wits about you. If the dream collapses around us, the people who have already given it up

will be in much better shape psychologically. And they're going to, everybody else will be out of their heads, you know, and you're going to be able to say, yeah, of course, this is kind of what's happening. And I sort of understand the way the currents are flowing. And I can position myself to be resilient in the face of this. And then the third is kind of along those lines as well, is to develop a plan for your future that is somewhat resilient to various outcomes. None of us can predict what's going to happen. And I could be completely wrong in my worries or the time scale. And so pick something that will be valuable no matter which way things go.

So don't pick a career that only makes sense if the world continues as it does. Pick some basic skill that will still be useful today, but also useful in a much changed world. I use different words, but those three things you just said are exactly what I tell my students as well. What do you care most about in the world, Tom? Uh, newts. Seriously? Half jokingly, I'm in an area that has a lot of newts around, uh, in Washington state. You're in, uh, Western Washington, yes? That's right. And just, you know, sort of split, splitting time right now. But they're newts around and they're, they're absolutely adorable and fantastic. And my wife thought I was crazy when I first talked to her about it, but she has fallen in love too because they're just

amazing little creatures. And, you know, I don't spend all night and day thinking about nudes, but when I see them, it gives me great pleasure and other wildlife. And so that's just a placeholder when I say nudes. I really just mean biodiversity. I mean life. I mean that this planet, as an astrophysicist, I can appreciate how rare this planet is. And we've got this thin shell. If you took all the biomass on earth and collapsed it into a uniform shell around the earth, it's four millimeters thick of wet mass. That is really thin and it's really precious. And it's diverse.

The fact that life could spring up and this self-replicating organism and all its variety. I just think the universe is amazing. Physics is amazing. The wildlife is amazing. And notice I'm not saying humans in that. I mean, human is one of those life forms and that is amazing. And I could admire some of our skills and our intelligence, but let's not put that above into the exclusion of all those other things.

So that's what I care most about is the non-human world. Well, I now better understand why we get along so well. I totally agree. So of all the things we talked about or didn't, what are you most worried about in the coming decade or so? So at some level, I've gone through all the stages of grief and at this level of almost just being a spectator. I'm not really worried about how things are going to go because at some level I can't control whether there's going to be a nuclear war or anything like that. So I don't

bother myself with that. I guess I worry most about inattention that the denial that we tend to exercise that, you know, we think that things can't really go bad, can't, can't really go wrong. That is our biggest danger. That we just say shrug and say me? Right. And so, if we took these ideas seriously and started gearing our lives around a different approach that didn't depend on growth, didn't depend on, you know, exploitation and non-renewable resources, at some level, you know, the sooner, as I said, the sooner we, we collapse the better because we're going to have more available to pull ourselves out of it. The longer, the more successful, as you say in 2008, we're extremely successful and incentivized to avoid collapse. And if we continue being that

successful, it's going to be the most devastating possible outcome. So I think I worry about that most, that we're not going to get the message until it's far too late to recover gracefully. In contrast, what are you most hopeful about in the coming decade or so? I think it's almost the flip side of that, that I'm hopeful that we can have enough shake-ups and that say the younger people will get that this is not normal, that this life that we live is not normal. It's a blip. It's, it's, it was the wrong path. And so just kind of a waking up to, you know, breaking the spell. That's what I'm hopeful can happen. Now, the young people, I deal with a number of young people in classes and so forth. They tend to get that growth can't continue. So

they're on board with that. But they, they direct their, their energies elsewhere. It's the billionaire's problem, not their own habits. It's not their own place. It's not their own demands that they place in the system. And so that's still a barrier. But long-term hope, yes, for a decade, but if I think longer term, the plasticity of humans is rather amazing, as adaptable as we are. So somebody who's born in, say, a post-collapse situation, will just see that world as normal. Absolutely normal. Couldn't imagine different scenario. And so that human will probably do fairly well for themselves. And if nature is forcing that existence to more sustainable, then that's not a bad outcome.

I happen to agree with that. Thank you so much, Tom, for your time and your continued work on these issues. Do you have any other words of wisdom, advice, or closing thoughts for our listeners? Yeah. Thanks. I think, you know, I said before that we need to learn to treat nature at least as well as we treat ourselves, that we need to learn to be a part of nature. I like the phrase that we're not a part as a single word from nature.

let's not ruin at all, you know, we could ruin the whole thing for all of us, not just other species but ourselves. So we need to step out of this weird anomaly that we're in and understand that we're sort of in some sense a victim of bad timing that we were born during this period when we're kind of at the apex of just a phenomenal fireworks show and firework shows end. But we have a hard time seeing that. I would encourage people to step back and realize that, you know, what we've been doing for a few generations is very temporary. I agree with that. Well, thank you so much, Tom. I expect I will have you back again and to be continued, my friend. Thank you. Great. Thank you. If you enjoyed or learned from this episode of

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