Mindscape 76 | Ned Hall on Possible Worlds and the Laws of Nature

Blog post: www.preposterousuniverse.com/...
Patreon: / seanmcarroll
It’s too easy to take laws of nature for granted. Sure, gravity is pulling us toward Earth today; but how do we know it won’t be pushing us away tomorrow? We extrapolate from past experience to future expectation, but what allows us to do that? “Humeans” (after David Hume, not a misspelling of “human”) think that what exists is just what actually happens in the universe, and the laws are simply convenient summaries of what happens. “Anti-Humeans” think that the laws have a reality of their own, bringing what happens next into existence. The debate has implications for the notion of possible worlds, and thus for counterfactuals and causation - would Y have happened if X hadn’t happened first? Ned Hall and I have a deep conversation that started out being about causation, but we quickly realized we had to get a bunch of interesting ideas on the table first. What we talk about helps clarify how we should think about our reality and others.
Edward (Ned) Hall received his Ph.D. in philosophy from Princeton University. He is currently Department Chair and Norman E. Vuilleumier Professor of Philosophy at Harvard University. According to his web page, “I work on a range of topics in metaphysics and epistemology that overlap with philosophy of science. (Which is to say: the best topics in metaphysics and epistemology.)” He is the coauthor (with L.A. Paul) of Causation: A User’s Guide.

[@TheOriginalRaster]

Ned Hall is a very good communicator. I am pleasantly surprised when a guest (yet again) does not talk at ten kajillion miles per hour. Everything is right on with this guy. He's great. I appreciate Sean stopping at times to explain. I noticed that I really needed this explanation. I also got the sense that i could get more out of the author's ideas by listening a second time. His words are nicely full of information and it's difficult for me to form an internal mental model fast enough. I find this a somewhat pleasant and slightly surprising state. This is a really good podcast. Thank's Sean! Cheers!

[@victordennett]

Great episode! Also first mindscape that I'll definitely have to listen to a second time.

[@pettiprue]

I love feeling intrigued and mind boggled. Thank you both very much. It took me a few listens. Each time I picked up a bit more. It is compelling. You are both beautiful communicators and I love your passion for 'what is this"? Thank you both again.

[@alexeiyur2452]

The most intriguing question to me remains, what is the most simple set of laws of physics (in the entire set of all possible worlds) that would still provide for the emergence of the phenomena (for the lack of the better term) of the world comprehending and introspecting into itself (as exhibited by humans in *this* world.

[@ljuan5000]

I wish there was video. I'm old fashioned. Like seeing ppl talk.

[@Homunculas]

That's not old fashioned, radio is old fashioned.

[@ljuan5000]

@@Homunculas I was thinking face to face but your analogy makes more sense. If I can't see the people talking, I lose interest.

[@jessemontano6399]

If there was video, then everyone would see the incense and the bong they are passing around. . Heh. Philosophers... Jk

[@RandyH524]

Could you get Dr. Sabine Hossenfelder on your show to discuss many worlds and anthropic principle? Thanks Sean!

[@cryptocrush-823]

Randy Hanna amen!

[@RandyH524]

@@david-joeklotz9558 lol ya know, I just discovered her yesterday and after binge watching her channel, i totally agree with you on that sentiment. However, she has some pretty valid arguments against the status quo.

[@jtinalexandria]

Yes!!

[@nibblrrr7124]

I'd also love to see her & Sean talk. I'd be more interested in hearing them talk about structural problems in how science is currently done in practice, the concept of elegance/beauty in physics, and how to go about testing beyond-the-standard-model theories.

[@LearningWithSuj]

Hi Dr.Carroll, I love your podcast and enjoy all your talks. I hope you invite on Dr.Sabine Hossenfelder soon and have a conversation about anything (direction of modern physics, super symmetry, funding a larger hadron collider, strong/weak anthropic principle, multiverse, the Holographic principle, her awesome music videos, etc.) It would be fascinating! Thank you, and keep doing amazing work, sir !

[@jessemontano6399]

Yes, as a person suggested, Sabine hossenfelder would make for a very interesting episode for sure

[@HarryNicNicholas]

i wish her videos were longer and more involved, and she had guests too. and she was as prolific as mr carroll.

[@leftblank6036]

I don’t care if the guest is a celebrity, I just like people who can discuss some good science

[@WitoldBanasik]

Thank you so much both Professors for your in-depth, scientifically meaningful and inspiring -as always- discussion. Yes !!!!! This is the real name of the game Sir Carroll... how to struck a balance between/among mindsets and senses-scapes and imagination and intuition. Happiness is pursued by the westerners, occidental folks, intellectuals if you will- like me and you both gentlemen. While how to oppose pressure of time while tackling poverty and misery is the crucial issue for Hindu people for example, for Japanese citizens and for me for instance finding a balance in life is fulfillment and joy in my idiosyncratic/spooky and agnostic world. I love versatility in people. That s why I love da Vinci/ Rennaissance type of people... I mean Gene Kelly, Judy Garland, or a concert pianist of Russian descent who is also a mathematician by profession... his name has just slip my mindscape... sorry for that. On the other side of the same coin Newton was a lonely genius so were Tschaikovsky and Balzac the writer. Being a specialized genius or a versatile guy fluent in many languages dancer and an actor may be important or not to the very person involved... all that seems much more important to the observer or/and to the audience. You have poked me Sir- so to speak- to write another sort of essay.... life cannot be boring anyway dear Professor Carroll. Have yourself a merry little Christmas... Aloha !!!!

[@disinclinedto-state9485]

Thanks, Sean! Love your work. Philosophically speaking, what is it about the completely understandable and necessary ad-breaks that bum me out so much? I can't afford to patreon support, so I'm lucky I get to enjoy these for the cost of some ads. So why do they bug me so?

[@volaireoh883]

Need to get David Wallace and David Deutsch.

[@lucasthompson1650]

Guest suggestions: Nima Arkani-Hamed, Ed Witten, Frank Wilczek, and I'll also add another vote for Sabine Hossenfelder.

[@HarryNicNicholas]

seconded, i wanted to learn more about nima and watched a couple of his lectures and was lost within five seconds, so a talk with sean might clarify the work he's doing. everyone loves sabine. except the people who hate her.

[@jakelabete7412]

Hi Sean, I'm a new subscriber, but I'm familiar with your activity as a science popularizer. I have a question. We hear a lot about incompatibility of GR and QM and I'd like to know more about it. Is there a 'situation' where predictions of one cannot be reconciled with those of the other, or is it an issue of esthetics - one, GR, being essentially a classical theory (continuous, deterministic and all that) and the other being discrete and probabilistic. ,

[@Mandibil]

Thanks for sharing

[@sekoivu]

Cool. Just checked new science and philosophy vids, and found this. Good stuff, I expect....

[@Failsafeman100]

Great podcast! Sean, I'm not sure to what extent you have input into the placement of your ads, but extolling cat litter in the middle of a discussion about mankind's grasp on the universe was verging on slapstick comedy - maybe this was intentional, but if not: please review!

[@joaquinluka3997]

i realize it is quite off topic but does anyone know of a good website to watch new movies online?

[@alessandrokyree9271]

@Joaquin Luka I would suggest FlixZone. You can find it by googling =)

[@HarryNicNicholas]

if you take a hammer to the forward arrow on your keyboard, or tap the rgiht hand side of the video playback, you can skip 5 seconds at a time, doing this quickly and many times might save you 30 seconds of your obviously very important existence.

[@myothersoul1953]

Could Occam's razor, that the simplest explanation that fits the data is best one, be shown to be wrong? Would it matter at all if Hume was right or wrong?

[@danielskipperrasmussen161]

Ed Witten would be great. Also, Patrick Hayden.

[@richtrishfryberg-jones2209]

Video would grab my attention a bit more.

[@johnnybourgeois13]

Whatever the endless waffle, it's worth keeping in mind that Quantum Mechanics, & General Relativity, ....... work. Both theories are absolutely practical, real. Like GPS and transistors... what us net-freaks are using Right at this very simple moment. & Work is a central concept in thermodynamics, statistical mechanics.

[@alexeiyur2452]

The main point for me is defining causality in trickier ways in terms of "possible worlds" doesn't really help with endeavors in physics but maybe helpful in social "sciences" and other quasi-scientific fields that are removed from the fundamental laws of reality by the cause-and-effect chain that is too long to be of any utility.

[@perjespersen4746]

Im rewatching this in 2020 and, sorry Smewton, gravity still works.

[@charliesteiner2334]

Hume was wrong about induction because he never had the chance to read the excellent textbook Li and Vitanyi (1993) on algorithmic information theory. Modern philosophers, on the other hand, have no such excuse. Algorithmic information theory answers a huge amount of our questions about induction - its justifiability, the role of simplicity, and the number of Isaac/Scmisaac (grue/bleen) type choices we should expect to get wrong.

[@charliesteiner2334]

@@dylan9966 Let's start off with a surprising but simple fact: if you have an infinite number of things that could happen, it's mathematically impossible to expect them all equally. If you try to spread your expectation infinitely thin, it becomes equal to zero everywhere, which is equivalent to not expecting any of the options at all, which is a contradiction. Therefore, whenever you have an infinite number of things that could happen, and you try to predict the future, you're placed in this very unusual situation where if you want to predict the future at all, you have to arbitrarily pick some things as more likely than others, because assigning them all equal probability is inconsistent. This arbitrary choice is sort of like Hume's non-rational basis for induction. It's something that we didn't understand very well, and we thought we just sort of made it and hoped that *mumble mumble divine grace* or *mumble mumble evolution* steered us well. What we learned from the branch of math called algorithmic information theory is that there's a lot of structure to this choice that Hume didn't know about. If we "arbitrarily" choose to predict that simpler things are more likely than complex things, this turns out to be really good at predicting the future, and we can can quantify how good. There are an infinite number of definitions of simplicity, and we can quantify how different they are, and explain why they all suffice to produce induction. This is the sort of a priori justification for induction that Hume didn't know about because he lived before the math that makes it possible was even invented.

[@jjjccc728]

There is a difference between imagining that something could happen and that something actually happening. The project of science is the distinguish between the imagination and the actual. There may be an infinite number of ways of imagining that something could happen. I don't think there is an infinite number of ways that something actually could happen.

[@nibblrrr7124]

​@@jjjccc728 AFAIU algorithmic information theory boils data down to strings of bits, and universes/laws of physics/models of reality to algorithms that generate those bits. I haven't checked, but it seems easy to prove that, given any finite string of bits, you can construct an infinite number of Turing machines that produce it in their output.

[@jjjccc728]

@@nibblrrr7124 are you agreeing with me?

[@micosair]

Please post the videos,they are a LOT more engaging.

[@bekle6555]

He sounds like Jonah hill

[@mattsteffens7370]

This guy sounds just like jonah hill

[@HopDubstep]

It's striking and I'm glad I wasn't the only one who thought this ha

[@kristoferbitney6268]

The Neyman-Rubin causal model (also called potential outcomes model) seems pretty strong. It's worth mentioning since it's the industry standard in some fields. Also, maybe early 20th century statisticians weren't thrilled about the concept of causality because they didn't have the statistical tools to talk about it. Someone (Fisher) had to invent the randomized trial first, right? Then people had to analyze and generalize the notion.

[@phoule76]

"how ya like dem apples?"

[@GoatOfTheWoods]

yes yes Yes YES

[@HarryNicNicholas]

34:00 colour is invented in the brain, what colour is an atom / molecule / photon? they are grey. do we all see the same colour is an old conumdrum, i see a strawberry, i label it red, you see a strawberry, you label it red too, but your brain might assign blue to the "red energy level".

[@mitchkahle314]

Peloton bikes?

[@volaireoh883]

Got loads in the other world's.

[@Soupy_loopy]

Great for when you want to go nowhere fast.

[@woody7652]

First and thank you!

[@NathanMian]

You are welcome! I'm only joking 😅

[@nemesis4785]

Ned Hall speaking from the bottom of a fish tank?

[@rickr.5836]

nut

[@ulenrich]

Please Mr. Sean Carroll : The sound of your partner Ned Hall in the dialogue is torturing me: Despite I am an old man having had over half a century Ned Hall is twittering in high sounds at the end of his words. Which really not is amusing my ears. There is is an additional handicap for me not having the english language as my mother tongue. Although you speaking is deliciously praising my understanding of the english language but Ned Hall is not with his technique of transmission.

[@pansepot1490]

What do you expect your complaining about Ned Hall’s voice is going to achieve? It’s his voice, not a bad microphone that can be changed. Just skip this video if something about the guest is torturing you. I am sure your life will not suffer if you watch/listen to something else.

[@ulenrich]

@@pansepot1490 I was so hot awaiting to hear the dialogue. But they selected a transission just a little too downsized. For sure that was a 64bit ogg stream only. Probably they watched each other on video also. Which is consuming 10 times the sound got for us.