Laws of Nature workshop: what can we tell from the program?

[marcus]

This month at PI there will be a 3 day workshop on the Laws of Nature. As outsiders, what can we learn?
http://www.perimeterinstitute.ca/en/Events/Laws_of_Nature/Laws_of_Nature%3A_Their_Nature_and_Knowability/

Smolin and Unger have a book in the works about this (time and the laws of nature) and they will be giving one of the 11 invited presentations.

Here is the list of participants. I'll highlight a few names that I think are likely to be familiar to people participating in Beyond forum:

Niayesh Afshordi, Perimeter Institute
Anthony Aguirre, University of California, Santa Cruz
Julian Barbour, College Farm
Ariel Caticha, University of Albany (SUNY)
Paul Davies, Arizona State University
Doreen Fraser, University of Waterloo
Marcelo Gleiser, Dartmouth College
Philip Goyal, Perimeter Institute
Lucien Hardy, Perimeter Institute
Sabine Hossenfelder, Nordic Institute for Theoretical Physics
Jenann Ismael, University of Sydney
Kevin Kelly, Carnegie Mellon
Kevin Knuth, University of Albany (SUNY)
Janna Levin, Columbia University
Huw Price, University of Sydney
John Roberts, University of North Carolina-Chapel Hill
Lee Smolin, Perimeter Institute
Chris Smeenk, University of Western Ontario
Rob Spekkens, Perimeter Institute
Roberto Unger, Harvard University
Xiao-Gang Wen, Massachusetts Institute of Technology & Perimeter Institute
Mark Wilson, University of Pittsburgh

Here are the titles of the 11 scheduled presentations:

http://www.perimeterinstitute.ca/en/Events/Laws_of_Nature/Schedule/

 

[marcus]

The days are Thursday-Saturday, 20-22 May.
Each of the 11 main presentations is given 80 minutes (which includes time for discussion).

Some sample titles:

On Thursday, Smolin and Unger talk on Laws and time in cosmology

On Friday,
Kevin Knuth on The role of order in natural law
Ariel Caticha on Law without law: entropic dynamics
Kevin Kelly on How does simplicity help science find true laws?

On Saturday,
Niayesh Afshordi on Cosmological constant problem: rethinking quantum and gravity
Julian Barbour on The case for geometry
Steve Weinstein leads discussion on The limits of mathematical description.

The Weinstein discussion session is not one of the 11 presentations. I guess limits of math description is really what the whole workshop is about, basically. So any and all participants could have ideas about that which they want to put on the table.

 

[MTd2]

Marcelo Gleiser is very famous around here. He usually appears to talk about about science in general in the biggest TV networks of my country. He also wrote several books too. But he always insisted on string theory.

So, I am kind of surprised that he forfeited strings, hmm...

 

[Fra]

Thanks again Marcus for bringing attention to interesting things.

Sounds like a really good workshop. I hope that they will put them up as videos afterwards like they sometimes do, I'd be very interested to heard the updated opinions on some of those people and hopefully those that have somewhat contradicting opinons will comment each others talk in a way that can be constructive. I'm happy to see smolin there, I was worried that he abandoned his evolving law idea as there's still no book and no new talks/papers on the topic.

Looking forward to this.

/Fredrik

 

[John86]

Any of those talks online ? I would love to hear what Unger has to say..

 

[Omnie]

Any of those talks online ? I would love to hear what Unger has to say..

They are indeed.

http://pirsa.org/C10001"

EDIT: You might want to add this to the original post for interested readers.

 

[marcus]

They are indeed.

http://pirsa.org/C10001"

EDIT: You might want to add this to the original post for interested readers.

Thanks for posting this link. I can't edit it into the original post (only moderators can edit after the first 24 hours) but your giving it is just as good.

I watched the Smolin/Unger presentation recently. Was impressed by Unger's delivery and appreciated the clarity of ideas.

It seemed to me that those two have got their act together, leading up to the appearance of their book. I guess that the book will appear within the next 6 months, because they clearly ready for launch. Their publisher needs to get the book out to distributers and get someone to schedule speaking tours for those guys to give talks at various university campuses etc. The timing would be good now, before the "Multiverse" fad wilts of its own accord and evaporates or someone like Roger Penrose takes revenge on it. Revolutions always do better when they appear as restorations of righteousness. E.g. The 19th Century Meiji Restoration in Japan.

 

[Omnie]

Thanks for posting this link. I can't edit it into the original post (only moderators can edit after the first 24 hours) but your giving it is just as good.

I watched the Smolin/Unger presentation recently. Was impressed by Unger's delivery and appreciated the clarity of ideas.

It seemed to me that those two have got their act together, leading up to the appearance of their book. I guess that the book will appear within the next 6 months, because they clearly ready for launch. Their publisher needs to get the book out to distributers and get someone to schedule speaking tours for those guys to give talks at various university campuses etc. The timing would be good now, before the "Multiverse" fad wilts of its own accord and evaporates or someone like Roger Penrose takes revenge on it. Revolutions always do better when they appear as restorations of righteousness.

I'm surprised more people don't know about PIRSA. It's a great resource and virtually all talks at PI are on there.

Will the book be at at a more technical level? Or is it more directed towards popular science? I'll definitely be checking out their talk now.

Also, I know Rob Spekkens is writing a book on interpretations of quantum mechanics that I hope is published soon.

 

[marcus]

I'm surprised more people don't know about PIRSA. It's a great resource and virtually all talks at PI are on there.
...

It's hard to tell who doesn't know about PIRSA. i think everybody I talk to here does, since we have been posting PIRSA links here fairly regularly. But probably a lot of folks don't and it's good to put more spotlight on it.

In the QG bibliography thread I have gotten accustomed to posting pirsa links right along with arxiv preprint links. I agree with you. They are both great services!

You could tell us more about your particular interests. Do you come at the Laws workshop more from a philosophy of science (PoS) direction? My interest is more Quantum Gravity, Cosmology, hopes of a unified understanding of spacetime geometry and matter. I see PoS as being helpful because analysis of basic concepts is sometimes required before progress can be made. Both Smolin and Rovelli approached QG with some PoS sophistication. They did not just "shut up and calculate" or pursue a mirage of pretty mathematics. Earlier greats like Einstein and the originators of quantum mechanics were also philosophically engaged. So it seems to help sometimes.

 

[Omnie]

It's hard to tell who doesn't know about PIRSA. i think everybody I talk to here does, since we have been posting PIRSA links here fairly regularly. But probably a lot of folks don't and it's good to put more spotlight on it.
...

Right off the bat, let me state I'm at the University of Waterloo and have spent a bunch of time at PI so I know quite a bit about PIRSA and use it all the time.

As for what angle, I've taken philosophy of science (with Doreen Fraser I might add) and have dabbled into interpretations of quantum mechanics. Check out the course by Emerson and Laflamme which is up on PIRSA. That course has influenced me quite a bit. In fact, I most identify with the viewpoints of Chris Fuchs. I do believe that a solid understanding of the fundamentals of our theories to really understand what is going on. Being able to simply postulate some Lagrangian is all well and good, but I don't think it is always the right path.

As for my interests, I'm still an undergraduate, but I am doing gravitational research right now and am enjoying it quite a lot. As for where I'll end up, who knows. I think it is very important to keep an open mind and being exposed to the vast ways of doing science has been helpful.

 

[marcus]

...
As for my interests, I'm still an undergraduate, but I am doing gravitational research right now and am enjoying it quite a lot. As for where I'll end up, who knows. I think it is very important to keep an open mind and being exposed to the vast ways of doing science has been helpful.

Thanks. Must be great to be at Waterloo. About gravitational research, I know somewhat about the QG research going on at Perimeter. But I don't know what other lines of gravity research are being pursued at Waterloo. Or what kind of research an undergraduate can get into, there.

 

[Omnie]

Thanks. Must be great to be at Waterloo. About gravitational research, I know somewhat about the QG research going on at Perimeter. But I don't know what other lines of gravity research are being pursued at Waterloo. Or what kind of research an undergraduate can get into, there.

Indeed it is. I've been very lucky to have an in at PI. It's a great place to work and the people who come through are amazing. It's opened a lot of doors. Same with the IQC. Having both so close to campus is excellent. Especially since I want to do theoretical work, I can interact with the best and brightest. As for gravity research, it's mostly just a simple "do this calculation" type thing, i.e. here is some metric we want to try, go grind through the calculation and see the result. Simple work, but it's somewhere to start. In fact, one of my supervisors is at this conference. For sake of privacy (not that's it hard to work out) I won't mention who.

So as not to derail this topic I watched Smolin/Unger presentation. I was able to follow some of it, but not all. I have very little knowledge of the subject area and many of the problems they bring up I either can't see as problems or am unclear as to why they bring them up. Obviously they are going to publish a book on the subject, but do you know of any literature available to check out?

 

[marcus]

... Obviously they are going to publish a book on the subject, but do you know of any literature available to check out?

Smolin has several talks on Pirsa about the substance of the book. 2007-2008.

He also has an article in the monthly magazine of the NY Academy of Sciences called something like "One Universe is Enough!"

I absolve you from checking this stuff because IMHO an undergraduate had better focus on learning and mastering UNCONTROVERSIAL stuff. I would feel funny if I steered you into a storm of controversy.

But I do suspect it will be a valuable and important book. Smolin will want it to be popular because paradoxically that will cause it to have more impact on the minds of fellow physicists. They tend not to think about anything conceptually out of the box hard unless it has been reviewed in the Times of London, the Wall Street Journal, and the Sunday NYT. They are too busy to read philosophical crit unless they feel the boat rocking. So it will be written as a popular wide audience book even though the main targets are the senior physics colleagues. That may sound perverse and convolute but it's what I think.

I think the title of the book will be something like TIME AND THE MEANING OF PHYSICAL LAW.

It will analyze the concept of physical law and show that our naive existing idea of law does not apply to cosmology (it only can apply to isolated subsystems---not to a onetime history containing the observer). It will show that time is essential to understanding the natural history of the universe. Time is real. And it will show that the laws of physics can (and perhaps even must) change with time.

It will attempt to demolish the "anthropic principle" type of multiverse fantasy, and it will show at least one example of how what we once thought was an immutable law is actually evolving with time. It may show an example of how certain observed regularities in nature could have arisen by a process of natural selection. This is merely to illustrate the possibility that laws can evolve---something to look into.

Some scientists engage in battles which help decide the future direction of research. It is an essential part of how science works. I'm looking forward to seeing the book (though can only guess as to title, contents, and date of publication.)

 

[Fra]

http://pirsa.org/C10001"

I just got around to to watch this talk!

I'm happy to see that Smolin is still thinking about this, and it was also the first time I've seen Unger. He is an interesting character and his personality seems to be quite different than Smolin's :) Very interesting to see and hear him speak.

Since I've seen the other talks and are already quite tuned in on their main message, for me the most interesting part of the talk was that it revealed a couple of points where Smolin and Unger don't quite agree.

1) It's on the issue to what extent there exists in some sense a priviliged moment of the present, such as a kind "global time" or not. Unger didn't seem to think that these implies such a thing, and I'm personally more with Unger on that point. I think Smolins seems to have a different view here.

What Unger means with "reality of time" is not quite the same thing as thining there is a preferred time or global time. That makes good sense to me, but I have a feeling Smolin has some other idea there which I don't understand how he sees that as consistent with Ungers points.

2) Similary they seemed to a differ a bit is wether the past is more real than the future.

I think it was a good talk, but they did not provide much more progress on how to make this into a new framework than the past talk from Smolin. It seems the main point is still to convey the idea that the old Newtonian framework has limitations.

The last talk from smolin on evolving laws, I only listened to the mp3 and didn't see the video, but I detect one voice in the audience, from a lady that this time made an analogy with chess games, and the same voice(?) made a point in the old talk about theories and laws are like tools for interacting with the open subsystem that smolin couldn't elaborate but he said the thought unger might. Was this the same lady like I think? and did they really interpret her question right this time?

I'm not sure who she is, I had a feeling she was a philsopher rather than physicists but I'm interested to know if someone knows who she is, and wether she happens to have some own papers on this.

/Fredrik

 

[Fra]

many of the problems they bring up I either can't see as problems or am unclear as to why they bring them up.

They sort of presenting philsophical arguments, based on observations about scientific development, also analogies to biology and social theory, that part of the framework that dominates in physics, called the Newtonian paradigm, may not be as viable as we think.

But as Smoling also pointed out, this "strategy" implicit in the Newtonian scheme, is certainly worth a try! but this is what more or less everyone has been doing up until know, and still this issue with unification of forces as well as qm and gr is still open. There are several problems of current attempts, that originate (in their view) from this "flawed schema". This is the idea of multiverses some people engage into as a way to solve problems, also landscape problems, "initial value problems" etc.

I think before one can appreciate their ideas, one has to somehow see the difficulties of the current scheme, and their idea is that MAYBE a lot of the problems are due to that the scheme is wrong.

I've read all Smolins books and listed to only some of this talks. Maybe only one talk isn't enough. But another one is this one: http://pirsa.org/08100049/

It's the "old" talk I referred to in my previous post.

/Fredrik

 

[marcus]

...
I've read all Smolins books and listed to only some of this talks. Maybe only one talk isn't enough. But another one is this one: http://pirsa.org/08100049/

It's the "old" talk I referred to in my previous post.
...

That's a good one to cite. I'll copy the abstract here for easy reference:
http://pirsa.org/08100049/
On the reality of time and the evolution of laws
Lee Smolin
"There are a number of arguments in the philosophical, physical and cosmological literatures for the thesis that time is not fundamental to the description of nature. According to this view, time should be only an approximate notion which emerges from a more fundamental, timeless description only in certain limiting approximations. My first task is to review these arguments and explain why they fail. I will then examine the opposite view, which is that time and change are fundamental and, indeed, are perhaps the only aspects of reality that are not emergent from a more fundamental, microscopic description. The argument involves several aspects of contemporary physics and cosmology including 1) the problem of the landscape of string theory, 2) cosmological inflation and the problem of initial conditions, 3) the interpretation of the “wavefunction of the universe,” and the problem of what is an observable in classical and quantum general relativity. It also involves issues in the foundations of mathematics and the issue of the proper understanding of the role of mathematics in physics. The view that time is real and not emergent is, I will argue, supported by considerations arising from all these issues It leads finally to a need for a notion of law in cosmology which replaces the freedom to choose initial conditions with a notion of laws evolving in time. The arguments presented here have been developed in collaboration with Roberto Mangabeira Unger."

I can't identify the voice you heard asking questions in both this and the recent Smolin/Unger talk. If later I think of a woman philosopher of science who it might be, I'll suggest a name.

How about Janna Levin? She was very active during Marcelo Gleiser's talk. She and Lee Smolin had a backandforth lengthy exchange of comment on what Marcelo was saying re "what can we know of the world?" She is quick and agile, with a reedy highpitch voice, and does not get boring. Could she be the participant you were thinking of?

 

[Fra]

I can't identify the voice you heard asking questions in both this and the recent Smolin/Unger talk. If later I think of a woman philosopher of science who it might be, I'll suggest a name.

If anyone else wants to be sherlock, I just checked the time stamps and the female in the audience is

1) on the video at 01:17:46 on the latest video.
2) on 49:55 on the mp3 of the the the old "evolution of time" talk

Maybe it's two different persons, but my ear and the type of question suggested it is was possibly the same person?

/Fredrik

 

[Omnie]

If anyone else wants to be sherlock, I just checked the time stamps and the female in the audience is

1) on the video at 01:17:46 on the latest video.
2) on 49:55 on the mp3 of the the the old "evolution of time" talk

Maybe it's two different persons, but my ear and the type of question suggested it is was possibly the same person?

/Fredrik

The first talk (i.e. the latest talk) it looks like Jenann Ismael.

 

[Fra]

The first talk (i.e. the latest talk) it looks like Jenann Ismael.

Thanks! I checked her website http://homepage.mac.com/centre.for.time/ismael/

I skimmed some of her papers and it seems to be more pure philosphy, rather than just using sound philosophical arguments as a guide to reconstruct a new mathematical framwork.

(Compare to E.T JAynes work for reconstructing the axioms of probability in his book "Probability theory - the logic of science"; that is still a "philosophical book" in my view, but not PURE philsophy, it's still physics and mathematics).

I wonder how much mathematics that are in Roberto Unger's work. After all, any quantiative prediction, must incorporate computations somehow. I'd be quite interested to see what mathematical formalism that would follow from Ungers pretty clear verbal reasoning.

I think we need to combine the skills of beeing able to perform a sound analysis of the situation with the skill of beeing translate that into some kind of mathematical models; even if it's not of the eternal rigid type that they object to.

/Fredrik

 

[Fra]

I wonder how much mathematics that are in Roberto Unger's work. After all, any quantiative prediction, must incorporate computations somehow. I'd be quite interested to see what mathematical formalism that would follow from Ungers pretty clear verbal reasoning.

I'm not sure which arhives to look for this work? I guess what I hope to find is a mathematical model for social interactions including decision theory of the individuals or something like that?

I found he has some websites

(1) http://www.robertounger.com/
- I'm not sure if it's my connection or a temporary problem but almost all links on that page are broken? I get nothing out of it.

(2) http://www.law.harvard.edu/faculty/unger/
- but that pages loads empty for me? maybe it's a sevier problem?

(3) http://www.law.harvard.edu/faculty/directory/index.html?id=75
- there are some references to books and such but I find no online material for skimming.

Does anyone know what a "social theorist" do? Do they work out mathematical models for group dynamics for computer simulations of groups, societies, economical systems etc? What archives would one find that?

/Fredrik

 

[jackmell]

You asked what can we tell from the program? Not much in my opinion as I found the the three talks I attempted to watch, virtually intolerably annoying for the following reasons:

The video and voice are poor quality, the speakers are constantly interrupted by audience members compounded by the fact that the poor audio quality prevents the viewer from understanding what the audience is saying. Some of the presentations are done on black-boards with handwriting often illegible or at best difficult to read. And the extreme informal style seriously disrupts the continuity of the presentation. I really wanted to watch "The Limits of Mathematical Description" but after 15 minutes of informal rambling between the speaker and audience, virtually nothing of substance was discussed and as I suspected it would be another round of poor video and voice quality with speaker constantly interrupted by inaudible audience members, I just stopped watching it.

Someone in my view should really make this group aware of this or does this just not matter in this particular setting? Personally, I would expect clear video, voice, and slides only, minimal interruptions until after the presentation, only presenters that can speak clearly without a lot of nervous hand-waving and jittering about, and only a presentation that is coherent, continuous, and meaningful. And if these people can't do this, then they should either spend some time learning how to give a better presentation, or just not record it.

 

[Fra]

Maybe you found some bad talks, I only listened so far to smolin, and it was similar in quanlity with the oldre sessions I've seen.

The quality has clear compression arfitacts, but I still find it quite acceptable. I've tried it both in mp3 player, my car and with computer speakers. But what's really poor at points, is the audience comments since they start talking before the microphones are redirected.

But overall I think it's still great to be able to watch these talks from the other side of the planet.

/Fredrik

 

[ccdantas]

Does anyone know what a "social theorist" do?
/Fredrik

Hi Fredrik,

Over at Backreaction, I wrote this:

http://en.wikipedia.org/wiki/Roberto_Mangabeira_Unger" is quite well-known in Brazil. He served as Minister of Strategic Affairs a few years ago. Considered a very controversial figure here. He is collaborating with Smolin, and is a professor at Harvard.

http://en.wikipedia.org/wiki/Marcelo_Gleiser" is also a well-known physicist in Brazil. He has several books in Portuguese on science outreach published here.

Notice that both do not live in Brazil, but still they do have some participation here one way or another.

And also:

Well, I am particularly very curious about what Unger has to say. He is a very interesting figure, and as I mentioned previously, also considered a very, very controversial figure here in Brazil, to the point of some questioning whether he is a genius or a madman. In a private email, some time ago, Smolin mentioned that he was the most "challenging philosopher" that he ever worked with. If you are interested in something new, unexpected, even if you may not agree with, then listen to this man, even if for just fun. Or you may feel to take him seriously, as Smolin does. Maybe Sabine has some impressions to mention here?

I still have to watch the video, no time yet. I'm naturally curious on this. I believe Sabine will post some of her impressions on this conference.

 

[Fra]

Thanks for your comments Christine!

Well, I am particularly very curious about what Unger has to say. He is a very interesting figure, and as I mentioned previously, also considered a very, very controversial figure here in Brazil, to the point of some questioning whether he is a genius or a madman. In a private email, some time ago, Smolin mentioned that he was the most "challenging philosopher" that he ever worked with. If you are interested in something new, unexpected, even if you may not agree with, then listen to this man, even if for just fun. Or you may feel to take him seriously, as Smolin does. Maybe Sabine has some impressions to mention here?

To be honest I was a bit dissapointed by the lack of a more detailed suggestion of how to implement mathematically the ideas Unger describes verbally quite well. I was probably expecting too much progress.

I am now getting the idea that Unger has some original thinking / not cast into quantiative form, or directly applicable to physics, that Smolin tries to "understand" and be inspired from and maybe it's Smolins job to produce the mathematics? I'm not sure if that's a correct observation or not, but it's the feeling I get.

If so, my feeling is that so far Smolin does not yet quite realize what I interpret Ungers means with reality of time, as it's apparenly not the preferred simultaneouty/global time kind of time. This was one of their points of disagreement. I still think Ungers point is good. I don't think the evolution law has to mean there is a preferred simultaneity. It's somewhat unclear to me what Smolin thinks.

But I see Ungers apperance as eccentric, extremely confident but also incredibly charming to the point of slightly amusing. I had a big grin on my face during large part of the talk from the point where Unger took the mic, mostly due to this fascinating personality.

/Fredrik

 

[Fra]

Christine, from my perspective there is a conceptual similarity with the idea of evolving law (and defining time like Unger does as transformation of transformation), and deadlock avoidance that you wrote about in some essays some time back, what do you think?

/Fredrik

 

[marcus]

http://en.wikipedia.org/wiki/Roberto_Mangabeira_Unger" is quite well-known in Brazil. He served as Minister of Strategic Affairs a few years ago. Considered a very controversial figure here. He is collaborating with Smolin, and is a professor at Harvard.

http://en.wikipedia.org/wiki/Marcelo_Gleiser" is also a well-known physicist in Brazil. He has several books in Portuguese on science outreach published here.

Notice that both do not live in Brazil, but still they do have some participation here one way or another.

And also:

Well, I am particularly very curious about what Unger has to say. He is a very interesting figure, and as I mentioned previously, also considered a very, very controversial figure here in Brazil, to the point of some questioning whether he is a genius or a madman. In a private email, some time ago, Smolin mentioned that he was the most "challenging philosopher" that he ever worked with. If you are interested in something new, unexpected, even if you may not agree with, then listen to this man, even if for just fun. Or you may feel to take him seriously, as Smolin does. Maybe Sabine has some impressions to mention here?

I still have to watch the video, no time yet. I'm naturally curious on this. I believe Sabine will post some of her impressions on this conference.

What about Ariel Caticha? Does he have some connection with Brazil?
I was impressed with his originality---which is partly stylistic but may contain a kernel of real mathematical innovation.

He gave the same talk to a small PI audience of mathematically sophisticated Quantum Foundations people, including Rafael Sorkin, on 4 May, and then repeated it to the philosophers at the LoN workshop a few days later. In my opinion the first presentation came out better, and is well worth watching. He has an extension of Bayes to describe what he calls the "entropic dynamics" evolution of probability measures. All I can say is that I found it novel, impressive, and intriguing (but sensed that Sorkin was skeptical). Maybe someone more insightful than I am will be able to see through it and show that Caticha's work is vacuous and useless after all.

To me after sampling a good many talks, it seems that the only interesting talk was Smolin/Unger, plus tentatively unless someone disillusions me: Caticha. (And Caticha's 4 May presentation of the same stuff went better.)
However the EVENT ITSELF of the workshop was surely a significant success. It means that Philosophy of Science, like the Golem, is awake and prepares to defend the righteous. Or if you prefer, it means the philosophers are doing their war-dance and sending up their smoke signals. Some of the discussion at the workshop was interesting and informative. Different ideas of science, theory, and knowledge struggling for survival.

I should be careful not to minimize my regard for Philosophers of Science. When the chips are down, their work is very very important. They are like the "conscience"---where the moral sense resides. They guard the collective ethic of empiricism which is the ultimate guarantee of its unity and progress in the long run. This is why I feel that i got more out of the event as a whole than I did out of most of the individual talks which I sampled.

 

[Fra]

What about Ariel Caticha? Does he have some connection with Brazil?
I was impressed with his originality---which is partly stylistic but may contain a kernel of real mathematical innovation.

He gave the same talk to a small PI audience of mathematically mature people, including Rafael Sorkin, on or about 5 May, and then repeated it to the philosophers at the LoN workshop a few days later. The first presentation was much better, and is well worth watching. He has an extension of Bayes to describe what he calls the "entropic dynamical" evolution of probability measures. All I can say is that I found it novel, impressive, and intriguing (but sensed that Sorkin was skeptical). Maybe someone more insightful than I am will be able to see through it and show that Caticha's work is vacuous and useless after all.

Ariel is one of a few favourites I have which I've also reference to in several posts in the past. I haven't had time to listen to his talk yet but I plan to. It unfortunately takes several hours to listend to all talks, and it will take me some time.

Ariel is continuing the logic of reasoning initated by E.T Jaynes I mentioned in post 19. Several papers of Ariel references E.T JAynes work. I think this view are excellent and very much in line which my preferred thikning, except that I think this proper darwinian element is missing. So my own view would use parts of Ariels thinking, parts of smolin/ungers thinkg etc. But all of them are great I think.

What I know of Ariel he is from Brazil, and used to be long time ago in São Paulo but now he also works in USA.

Here is part of his mission visionary statements on his website

"My recent work explores whether the laws of physics might be derivable from principles of inductive reasoning. These principles - consistency, objectivity, universality and honesty - are sufficiently constraining that they lead to a unique set of rules for processing information: these are the rules of probability theory and the method of maximum relative entropy.

Among various forms of dynamics thermodynamics holds a special place because it provided the first clear example of a fundamental physical theory that could be derived as a procedure for processing relevant information using general principles of probable inference.

My work suggests that a second example is provided by quantum mechanics. Many features of the theory that are traditionally considered as postulates follow from the correct identification of the subject matter plus general principles of inference. Briefly, the variables that encode the information relevant for prediction are the amplitudes or wave functions assigned to experimental setups. These ingredients plus a requirement of consistency (namely, that if there are two ways to compute an amplitude, the two results should agree) supplemented by entropic arguments are sufficient to derive most of the standard formalism including Hilbert spaces, a time evolution that is linear and unitary, and the Born probability rule.

One can also approach these problems from a different direction. Instead of asking 'Can dynamical laws be derived as examples of inference?' we ask 'What sort of dynamics can one derive from the rules of inference?' More explicitly: Given an initial and a final state, what trajectory is the system expected to follow? The answer is a equation of motion obtained, not from a law of nature, but from a rule of inference - the principle of maximum entropy. The resulting “entropic” dynamics turns out to be elegant: it is time reversible and the system moves along a geodesic in the space of states. This is simple but not trivial: the geometry of the space of states is curved and possibly quite complicated. The many formal similarities with the theory of general relativity suggest that the latter might be a form of entropic dynamics.

An interesting by-product of this research program has been a clarification of the role played by relative entropy as a tool for reasoning for both classical and quantum theories of inference.
"
-- Ariel Caticha, http://www.albany.edu/physics/ariel_caticha.htm

Ariel was also(some years back) supposed to be working on a book on "information physics", according to someone knowing Ariel that posted on here some time ago, that I expect to continue the tradition from Jaynes "probability theory - the logic of science".

So I think Ariel has excellent thinking. I think all of these people have parts of the keys to success.

There are a number of talks on that list I hope to get around to watch or listne to as well.

/Fredrik

 

[Fra]

Maybe someone more insightful than I am will be able to see through it and show that Caticha's work is vacuous and useless after all.

I'm most probably not the person to say this but I think sometimes there is a thin line between "seeing through" and "missing the point" ;-)

I think Ariel's thinking as well as E.T Jaynes has some open issue, but so does almost everyone. But I'd be quite sceptical if someone said it was vacous.

I'll get back when I've had time to listen to his last talk.

/Fredrik

 

[ccdantas]

Christine, from my perspective there is a conceptual similarity with the idea of evolving law (and defining time like Unger does as transformation of transformation), and deadlock avoidance that you wrote about in some essays some time back, what do you think?

/Fredrik

I think I'll only have time to listen to this video next weekend.

 

[ccdantas]

What about Ariel Caticha? Does he have some connection with Brazil?
I was impressed with his originality---which is partly stylistic but may contain a kernel of real mathematical innovation.

Hi Marcus,

I can't tell for sure. But, yes, he studied and taught at http://www.ifi.unicamp.br/" , Brazil. I'll try to watch his video.

I think Brazilian scientists/thinkers -- at least those who are really capable -- tend to be more creative and original in their ideas and research; this is part of, well, being Brazilian in the first place...

 

[marcus]

Christine, in case you do get around to watching the video of Ariel's talk, I want to express my preference for the 4 May version of it, over the version he gave in the Laws of Nature workshop. Here, in case you want it, is the link to the 4 May version.
http://pirsa.org/10050021/
Entropic Dynamics, Time and Quantum Theory
Ariel Caticha
"Non-relativistic quantum mechanics is derived as an example of entropic inference. The basic assumption is that the position of a particle is subject to an irreducible uncertainty of unspecified origin. The corresponding probability distributions constitute a curved statistical manifold. The probability for infinitesimally small changes is obtained from the method of maximum entropy and the concept of time is introduced as a book-keeping device to keep track of how they accumulate. This requires introducing appropriate notions of instant and of duration. A welcome feature is that this entropic notion of time incorporates a natural distinction between past and future. The Schroedinger equation is recovered when the statistical manifold participates in the dynamics in such a way that there is a conserved energy: its curved geometry guides the motion of the particles while they, in their turn, react back and determine its evolving geometry. The phase of the wave function--not just its magnitude--is explained as a feature of purely statistical origin. Finally, the model is extended to include external electromagnetic fields and gauge transformations."

For comparison, here is the same talk delivered to the LoN workshop:
http://pirsa.org/10050056/
Law without law: entropic dynamics
Maybe my reaction is too one-sided. There may be valuable aspects of both presentations.

 

[marcus]

Thanks for your comments Christine!

To be honest I was a bit dissapointed by the lack of a more detailed suggestion of how to implement mathematically the ideas Unger describes verbally quite well. I was probably expecting too much progress.

I am now getting the idea that Unger has some original thinking / not cast into quantiative form, or directly applicable to physics, that Smolin tries to "understand" and be inspired from and maybe it's Smolins job to produce the mathematics? I'm not sure if that's a correct observation or not, but it's the feeling I get.

If so, my feeling is that so far Smolin does not yet quite realize what I interpret Ungers means with reality of time, as it's apparenly not the preferred simultaneouty/global time kind of time. This was one of their points of disagreement. I still think Ungers point is good. I don't think the evolution law has to mean there is a preferred simultaneity. It's somewhat unclear to me what Smolin thinks.

But I see Ungers apperance as eccentric, extremely confident but also incredibly charming to the point of slightly amusing. I had a big grin on my face during large part of the talk from the point where Unger took the mic, mostly due to this fascinating personality.

/Fredrik

Your questions are to Christine, but I hope it will not be inconvenient for me to jump in. I think Unger has a paradigm of understanding the universe which is more like Darwin's understanding of evolution or our understanding of geology in which there is a NATURAL HISTORY without a central dominant mathematical model.
Mathematics comes in as an occasional servant, to assist the progress of natural philosophy.

One can see this paradigm in e.g. sociobiology, behavioral genetics, and in population genetics. At a critical moment of the analysis one can bring in math tools and show that given a certain diploid haploid reproductive structure one can prove that the ant or bee can evolve a program in the brain that makes it act for the common good. The mathematics of behavior evolution can get very complicated. But there is always the central, non-mathematical, reasoning process of the natural philosopher which analyzes the concepts and develops the ideas and governs the overall understanding.

A mathematical model cannot analyze its own concepts. In natural philosophy the concepts co-evolve with the undertanding. And of course to achieve greater rigor and certainty the mathematical tools should be brought in wherever and whenever possible but they are not the main course of dinner, they are side dishes.

I think that is his overall idea about how to study the universe. It is a onetime unique natural history. So we must all try to be like Mr. Darwin in how we try to understand it.

BTW earlier I could not get the video of Philip Goyal to work. So I missed sampling it. I now think his is one of the best.

My favorites are now Smolin/Unger, Caticha, and Goyal. And the 4 May version of Caticha IMHO is better than the LoN conference one.

 

[Fra]

I think I'll only have time to listen to this video next weekend.

I'll take me some time as well. I had the ambition to try watch it last night before I fell asleep but sandman beat me to it.

/Fredrik

 

[Fra]

Hello Marucs, thanks for your comments.

I think Unger has a paradigm of understanding the universe which is more like Darwin's understanding of evolution or our understanding of geology in which there is a NATURAL HISTORY without a central dominant mathematical model.
...
And of course to achieve greater rigor and certainty the mathematical tools should be brought in wherever and whenever possible but they are not the main course of dinner, they are side dishes.

Yes, this makese sense but I tend to see a distinction here in

a) understanding our understanding, which is clearly and undeniably evolving, no same human could argue with that that,

b) and the idea that this is how nature itself works, and that the mutual interaction "rules" between parts of matter, and governed by simlarly evolving "laws"(understanding).

And in this latter view, the "mathematical systenms" somehow representing present states of "laws" has I think a deeper meaning just beyon human mathematics and just philosophy and it would also have implications beyong traditional "cosmological" models since even the actions of the SM model of particle physics is - to the inside observers - a cosmoloigcal interaction. So I think our deeper acknowledgment that this may be how nature and matter is constructed, and not just how human science is constructed, might even provide good insights into the problem of the choice of parameters even in the home-domain of regular QM or QFT.

So I'd expect to find some idea out of this, how the inside-mathematics itself evolved. This is why I have tried from the discrete perspective, to reconstruct the continuum probability (which is often the basis for entropic models) and instead consider how the complexity of the observer, in fact limits what mathematics is possible! Here fits my arguemtn for why I think the continuum is non-physical.

Here in the end I mixed in some of my personal ideas, but the point is that I expect outo smolins and ungers reasoning - in the end - some means to describe the evolving mathematics. Because something is "evolving" and not deterministically predictacble3 doesn't necessarily mean it's totally unpredictable. There should still exists like "expected" evolutions, in analogy with the schrödinger equation (in between) measurements.

So I guess wether ungers ambition at all, is to attempt anything such, or if he is content with the philosophical and verbal part? And that the hope is for SMolin to pick up the philsophical thread and construct some evolving mathematical system? (even though a you point out, the mathematical system can not rule it's own evolution)

I think that is his overall idea about how to study the universe. It is a onetime unique natural history. So we must all try to be like Mr. Darwin in how we try to understand it.

This sound like it could touch the point of controversy of smolin and unger, namely is history really unique and certain? or maybe with "unique history" you meant something different?

/Fredrik

 

[Fra]

I guess an implication of what I tried to say above, is paradoxally, that I think we need to take mathematics more seriously than we do. And with this I do not mean that the axiomatic way is right.

I mean that we must take the correspondence between mathematics and reality more serious. If we just see mathematicla as a "calculational" tool then we are loosing some of the handles I think we need to make sense out of ungers thinking.

I mean, I think if not all, at least many of physicistis would agree that the mathematical continuum isn't necessarily one-2-one with the physical reality down to inifinite resolution right? While that is true, and I agree. This should instead encourage as to find a BETTER mathematics that is better in match with reality?

If find it a bit amusing that some of the most philosophical arguments here, suggests that we should take the correspondence of mathematical and reality more serious.

/Fredrik