Mindscape 215 | Barry Loewer on Physics, Counterfactuals, and the Macroworld

Patreon: / seanmcarroll
Blog post with audio player, show notes, and transcript: www.preposterousuniverse.com/...
The founders of statistical mechanics in the 19th century faced an uphill battle to convince their fellow physicists that the laws of thermodynamics could be derived from the random motions of microscopic atoms. This insight turns out to be even more important than they realized: the emergence of patterns characterizing our macroscopic world relies crucially on the increase of entropy over time. Barry Loewer has (in collaboration with David Albert) been developing a theory of the Mentaculus - the probability map of the world - that connects microscopic physics to time, causation, and other familiar features of our experience.
Barry Loewer received his Ph.D. in philosophy from Stanford University. He is currently distinguished professor of philosophy at Rutgers University. His research focuses on the foundations of physics and the metaphysics of laws and chance.
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[@trevorcrowley5748]

My micro-states enjoyed listening to this conversation across the two cultures. Doctor of Natural Philosophy, indeed. And long live the Mentaculus-verse!

[@dj098]

Awesome convo, as always. Very clear and engaging exploration of topics that I personally find extremely interesting and important.

[@rollingrock3480]

Yayyyyy, new Dr. Carroll!

[@sir_Edguhh]

No, it’s the same ol’ dr. Carrol

[@denisvoronin2048]

One of the more difficult Mindscapes but still very interesting. Thanks Dr. Carroll.

[@rumidude]

That right there is good stuff! Seriously hard stuff for me to contemplate but that drives me to further explore the subject matter.

[@anneliesleeuw]

I like that Putnam quote Barry used, “The mind and the world make up the mind and the world”. Going to chew on that for a little while.

[@anneliesleeuw]

@@brothermine2292 I guess I agree that the statement is so pithy as to be almost meaningless, but for me it hints at the difficulties in disentangling the interactions between the mind (as shaped by the world) and the world (as perceived by the mind). And it piqued my interest in the work of Hilary Putnam.

[@producer2123]

Sean Carroll gives excellent lessons in how to listen well.

[@bryandraughn9830]

Awesome interview as usual! When I hear the intro music, it reminds me of the old 'moon patrol ' video game. I have learned so much listening to you. The way that I question things and draw conclusions has evolved, and I really appreciate it! Peace

[@skre1170]

Request for timestamps. Love the show.

[@LeeLightfoot]

27 minutes, on "laws": I'd say it appears to us in a monoverse as a "constraint", limiting the option space of a random walk, but from outside our monoverse, in some sort of branching, big "E" Everettian many worlds, Hilbert space, "is" a result of a random walk.

[@spaceinyourface]

This was great ,,lovely to hear he's been influenced by Sean's books,,,who hasn't. I don't follow much philosophy other than David Albert & whatever Sean has to say about it.

[@astee58]

Great and clear work-through.

[@bentationfunkiloglio]

Really enjoyed discussion. Thank you for creating such original and interesting content.

[@The1belal]

I really like the way you lay things out in the intro. And also this whole podcast idea you've taken on. You have some very interesting and thought provoking episodes. I'll look forward to all of your future interviews. And it's nice that I only need my ears for these and not my eyes...this allows me to multitask while I advance my intellect. Thank you Sean .........(and you have a very pleasant tone of voice, very easy to listen to)

[@SandipChitale]

The notion that the microscopic laws are the same in both time directions is brought up in these discussions. But given the state of the universe in terms of the position and momentum of particles, and the laws of physics why is it that the particles move to the next state predicted by laws, not the previous state. And if one wanted to make them do the opposite, work will have to be done. IMO what is more correct to say is that if the velocities were reversed (not time) we would deduce the same laws of motion from them.

[@michaeljfigueroa]

I enjoyed this a lot. Thank you

[@SandipChitale]

Barry's example at 47:14 of ice cube in warm water and then melting due to random motion does not sound right. The reason it melts is because of the temperature difference between ice cube and surrounding warm water. That is a non random fact. The fast moving warm water molecules transfer kinetic energy to the ice molecules and knock them off the ice cubes crystalline structure. Also, when the surrounding temperature is lower hexagonal, structured snowflakes can form, sure they are not ice cubes. The example of split box with closed door with gas on one side and then opening the door and gas spreading throughout the whole box is more correct example of random motion. Also the above (idealized) examples assume that only kinetic energy can be transferred between particles of gas. But what if the two gases had chemical reactivity e.g H and O, they might end up with lower entropy thru random motions as water.

[@fraktalv]

Fantastic conversation, thank you Sean!

[@kathrynlittle2523]

Your best podcast conversation ever! But… as a Philosophy/English double major in the early 70’s who’s been tackling physics since my retirement…. I’m prejudiced. I wish there’d been a professor in natural physics when I was a college student.

[@bendavis2234]

I love that your title is now ‘natural philosopher’ at your new position. I wonder if more people will follow and bring the name back from the grave!

[@Life_42]

Thank you for sharing.

[@tomsear1]

the Australian slang term Lewis utilised to explain 'Humean Supervenience', is addressed in multiple contexts on page 58 of Lewis., 1994, “Reduction of Mind,” in Samuel Guttenplan (ed.), A Companion to Philosophy of Mind, Oxford: Blackwell Publishers, pp. 412-431.

[@tomsear1]

i had in great detail utilised this term and unpacked it's meaning extensive Australian context in comments with references, however this platform deleted this commentary, because i talked about what actually happened, but the platform wanted to limit this folk psychology which was reductively anti-Humeian example of US culture's prudishness extended at planetary digital scale. ;]

[@LeeLightfoot]

only 8 minutes in but on that conversation: counterfactuals are important to the brain as a set of option states can be lost but cycle back to a similar entropic configuration (talking micro but mainly macro) ; looking at, for instance, behavioural and political change that cycles around deep attractors. So, to recognise what could be or could have been can sensitise to a lost state as it potentially comes back around and hence can be re-established.

[@NajibElMokhtari]

Does anyone have the einstein quote that Barry is referring to in munute 34:10 + ?

[@tomsear1]

unverified but i **think** this might be the following quote: “The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. He to whom the emotion is a stranger, who can no longer pause to wonder and stand rapt* in awe, is as good as dead -his eyes are closed. The insight into the mystery of life, coupled though it be with fear, has also given rise to religion. To know what is impenetrable to us really exists, manifesting itself as the highest wisdom and the most radiant beauty, which our dull faculties can comprehend only in their most primitive forms-this knowledge, this feeling is at the center of true religiousness.” which again unverified may be found in 'Living Philosophies A Series of Intimate Credos' Einstein, Albert, John Dewey, H.L. Mencken, Hilaire Belloc, Bertrand Russell, Julia Peterkin, H. G. Wells, Hu Shih, J.B.S. Haldane, Theodore Dreiser, Joseph Wood Krutch, Fridtjof Nansen, George Jean Nathan, and more Published by Simon & Schuster, New York, 1931

[@tomsear1]

pls see page 6.

[@ashikpanigrahi]

Sean interview David Deutsch already!!

[@andersonl819]

they got beef?

[@sucrose]

Nice talk!

[@andanssas]

1:26:45 🤣that Australian slang name for the world view will end up in a dictionary.

[@SandipChitale]

Excellent episode. However, once again I find the point that entropy IS the CAUSE of the direction of time to be not correct. I can see how the corollary is true i.e. the entropy increases as time marches from past to future (also sometimes called forward). That simply is the statistical effect of random, not-direction-preferred, non-goal-oriented, natural motion. But that "entropy is the CAUSE of the direction of time" does not make sense to me. Even when the universe reaches equilibrium, the precise microstates will continue to change from moment to moment - even though the macroscopic concept of entropy will be maxed out - the time will continue to flow. That is implied when we say "moment to moment". And in fact, if the universe was not going to be ripped apart by dark energy, and by random fluctuation over infinite time the universe may go to a lower entropy state just by chance. And I am talking about the whole universe not the subpart of the universe. And that then is an example of "entropy is the CAUSE of the direction of time" being false. At 46:51 what Barry says implicitly assumes the direction of time and the result of which is higher entropy. So the direction of time causes higher entropy. Not the other way around. Maybe I am missing something? Also, I find the use of the term "forward direction of time" to be problematic. It is as if time could have a choice between going forward or backward. +3 and -3 are opposites but only +3 apples can exist and -3 apples cannot. Similarly, even though "forward" and "backward" are opposite, "backward" flowing time is meaningless. The direction of the flow of time is by definition "forward".

[@lukeewing4274]

The universe will arrive at a maximally entropic state, at which point the arrow of time disappears. Forward in time makes perfect sense given this, one can normalize between the initial state and the first maximally entropic state and identify forward and backward in time by its relationship to those two states. Hence entropy providing the arrow of time, and hence it makes sense to mark progress on the spectrum.

[@SandipChitale]

@@lukeewing4274 My definition of the direction of the flow of time is from before event to after event irrespective of entropy going up or down or not.

[@robinbrowne5419]

Beelzebub's Bases Covered: Maxell's Demon says "I know everything that is happening". The Devil's Advocate says "I know everything that is not happening". :-)

[@ddavidjeremy]

Thinking about philosophy parties makes me nauseous. Maybe if Barry Loewer were there it would be ok. And wine. Lots of wine.

[@radical137]

Congratulations Professor of Natural Philosophy, Sean Carroll.

[@isedairi]

Finally Barry!!

[@WildMessages]

Hello thanks

[@Robinson8491]

Promises to be a great episode

[@ezbody]

Whether we have free will or not seems to depend solely on how one defines it, which makes for a pointless discussion.

[@HarryNicNicholas]

more great stuff.

[@bjpafa2293]

Vectorialzation, description of Hilbert Space (physics), Anti deSitters, "Branching" and another derivations of MW are open questions

[@TypicalHuman1.0]

Hi Sean, I attend West Blocton High School in Alabama and I am hoping that you wouldn't mind doing a video call with my class and explain your thoughts on the big bang.

[@baedenmckell5043]

for the algorithm ❤️

[@SandipChitale]

Free Will should be called Freeish Will or Effective Free Will and all the questions about it will go away. The decisions we make (especially significant ones) are taken in the context of our desires, our life experiences, and our real or imagined capabilities, constrained by the societies and cultures we live in and the laws of physics. If you take out our desires and memories, we will not be able to make any meaningful decisions. We feel like we have free will because we do not have Laplace daemon-level knowledge of what is happening in the brain. Our brains have evolved to coarse grain a lot of low-level brain processing and created abstractions of human language and thought. That is why I suggested "freeish" or "apparent" or "effective" free will. Basically a compatibilist stance.

[@nowhereman8374]

Thank Mr.(Dr.?) Loewer on presenting the idea that the universe might just contain facts and maybe not physical laws to guide those facts. Personally I always believed that universe must contain physical laws, now I am not so sure. It puts meaning to the saying, "It is what it is!"

[@realcygnus]

Does this mean you'll be rethinking that "ontic" wave function of yours ? 🤪

[@longcastle4863]

✓

[@ddavidjeremy]

Statistical mechanics are people who flip a coin to decide which part to put on your car.

[@tleevz1]

Space time doesn't really exist fundamentally. It exists a concept to us, in this universe. And this universe is result of source energy (universe of all possibilities) slowing down at different rates, obtaining structure and the accompanying attributes. That slowing process results in space and time, a new set for the show about source energy becoming separated from itself. The universe of all possibilities is where reality comes from. The first particle adhered to something called 'structure'. Structure had to be a possibility before that first particle utilized it. Further, in that universe of all possibilities, potentialities are differentiated. Otherwise everything would manifest all at once. So we are experiencing a time limited perceptual/experiential reality that evolved from that first utilization of structure to whatever it is we have here now. Intelligence exists, which means it existed as a possibility first. That being the case it seems pretty obvious that some kind of intelligence intended that first particle to have attributes that would evolve into a reality like this one. You have to start there.

[@lukeewing4274]

The first structure had to be possible, as did everything that followed, of course. But if the space of possibility was broad, why would you need an intelligence involved? Now if the structure was inevitable, it would be a different story, but still not one resolved by positing some intelligence. Arbitrary rules could allow for structure, structure might not even be rare in possible universes. I think it is a bigger stretch to imagine the tweaking of the laws of physics as an intentional 13 billion year design process by some intelligent being, especially given the incredible hostility to life we find in almost every square inch of the universe.

[@tleevz1]

@@lukeewing4274 The intelligence is needed to differentiate the possibilities and selecting one seed possibility that will grow into an experiential reality. If you think it is more reasonable to assume order and structure and the potential within this reality to evolve into us on KZbin, then ok, but I'm not feeling it. And the time element is a compelling mystery. The way I see it is our brains and time prevent the energy of all possible futures of this reality blasting information into our faces, which I'm thinking we wouldn't survive that one. It is almost like there is a directive to learn as much as we can in this incarnation. If that metaphysical narrative has any truth to it, I think it kind of makes sense from the perspective of a higher plane wanting to get information on what possibilities become reality, which ones almost did, which ones were never close, etc. What if you could look at the past and it was like a comic strip with thought bubbles and stuff but on the edge of the page was the same scene with an almost imperceptible difference, and with every level further from what actually happened it gets fuzzy and random? If so it would be like we're riding on a zipper as nature and our decisions are creating the future teeth of the zipper and it is unknown what path the zipper takes until we experience reality in real time. Sorry for the detour through my imagination but I think it fits in a way with what you're asking.

[@bryandraughn9830]

You're confusing me with all of that data and mathematical structure.

[@tleevz1]

@@bryandraughn9830 My apologies friend.

[@aaron2709]

Philosopher on the street.

[@williambrandondavis6897]

This goes nowhere fast.

[@-ring-a-ding-my-dingaling]

It's funny how badly this guy misunderstands David Lewis

[@silentbooks3879]

First

[@CaptainTae]

Why do you make it sound like religion?