String Theory’s Strange Second Life | Hacker News Reader

String Theory’s Strange Second Life

quantamagazine.org

77 pointsjonbaer29 comments

A rather skeptical perspective on this article: http://www.math.columbia.edu/~woit/wordpress/?p=8778

Woit's language is usually so measured it's actually shocking to see him straight up call someone 'embarrassingly incompetent'

As someone who goes against the tide, they have to be careful regardless. You certainly don't see the same restraint from string theorists.

I actually think it was bordering on generous to the Quantum article, and I'm not sure that in a similar position I would have been satisfied with only restrained mockery.

Unfortunately as a lay-person I think that modern physics has grown to complicated that I have no basis for really judging who is right or wrong in an argument like this. Wolf's article seems more persuasive, but that doesn't mean that he's right.

Internal realities are all valid. People who insist of making their internal reality everyone else's external reality (to the limit of understanding) are judgemental. It's a paradox.

Non-physicist here.

Woit makes very negative comments about Cole, but my impression was he has the same basic view about the status of string theory as the one expressed in the article. Could someone explain how they are different?

A few comments as someone who works on the periphery of this field:

1. I started my PhD doing quantum information. People in quantum information spend a lot of time thinking about properties of entanglement. Someone below mentioned "a lack of new ideas". There have been quite a few important ideas in AdS/CFT (as a subset of string theory) over the past decade. One of the most exciting is called the Ryu-Takayanagi conjecture and it relates the amount of entanglement in a subsystem to the area of a minimal surface bounding said subregion.

2. Again, as someone who started purely as a QI person, it's shocking how much of the MATH of string theory has entered my research.

3. In my opinion, it's true that string theory hasn't made much progress over the past 20 years or so towards elucidating its potential role as a theory of quantum gravity; but in parallel there are amazing connections being made between string theory and quantum information. Look at the work being done by the "It from Qubit" collaboration for a sampling. This latter point is ~equally related to the recent decoherence of string theory as a subdiscipline. It's more like it tunneled to a state closer to QI.

4. The Firewall paradox is fascinating and it was originated by a bunch of string theorists (Almheiri, Marolf, Polchinski and Sully.)

5. Supersymmetry is in a corner; which is bad for string theory. But string theory is proving to be a powerful lens through which to study quantum entanglement. One step back, one step forward?

Anyways, saying that "string theory is our savior" or anything like that is bad etiquette. But the community is doing interesting things today.

the problem of blackhole firewalls were really interesting to see what kinds of techniques and rules modern physicists are using.

I'm curious, do you have an opinion about Stephen Wolfram's idea of graph/knot theory being the underlying principle of reality? To me, it seems much more ontologically acceptable than string theory and many-worlds interpretations of quantum mechanics. I remain unconvinced that pilot-wave-like non-local, hidden-variables interpretations are flawed; they certainly seem the most ontologically tractable. From that perspective, a graph/knot basis for the explicitly non-local hidden-variables theories seems like a reasonable solution to the ultimate basis of physics.

IANAP and I don't know about Wolfram's ideas but some thoughts anyway. Graphs are incredible general, like sets, you can model almost everything with them and that looks like a bad thing to me if you want explanatory power.

The very few basic principles of relativity and quantum mechanics like the frame independence of the speed of light and unitarity put very strict constraints on possible theories, for example only particles with spin 0, 1/2, 1, 3/2 and 2 are possible. String theory on the other hand turned out to allow a ridicules large number - like 10 to the 500 - of different vacuum states and therefore you can have more or less whatever you want by fixing parameters in this way or another.

I may of course be totally wrong but that were my first thoughts, unless you can somehow derive a lot of constraints, using graphs to explain the universe seems a way to general idea to me. But again, I never read anything about Wolfram's ideas, at least nothing I can remember.

We're running in a simulation that appears to provide compute/causality on one hand and infinite knowledge on the other (albeit limited to short access times). The most logical conclusion is that the software we're running on is highly reliable, given things here are...highly reliable. It's a wonder we all wake up Us in the morning, which is sorta the point. What does it take to write software like that?

What if it's not a simulation?

What if it's both?

The universe does not seem to care all that much about what we find ontologically tractable. Besides quantum mechanics, consider relativity.

Wolfram shows quite convincingly that the key properties of special and general relativity can be captured in a graph model. As for quantum mechanics, most of the ontological complications are a consequence of attempting to abolish nonlocality. If, instead, you model the nonlocality explicitly, as in pilot-wave theories, all of the ontological complications evaporate.

Prior to reading his proposal, I likely would have agreed with you that ontology is lost; I'm less sure now. After reading his ideas, I see a glimmer of hope for discovering a small, simple set of primitives and rules for modeling the universe. A graph/knot-based theory would be composed of far more simple primitives than differential equation based theories; the more abstract differential equation models would arise through statistical mechanics.

Pilot wave formulations of QM and graph based or otherwise discrete theories of space are two very different things. The reasons to like the latter are similar to the reasons to dislike the former. At a large scale physics looks continuous, but like matter turned out to be made of atoms, perhaps space is similar. Extrapolating our everyday experience of continuous physics to the fundamental laws may be a mistake. However, that's precisely what pilot wave theories are doing: trying to fit the fundamental laws into our everyday experience and intuition. At the end of the day it doesn't matter which mathematical formalism we use to express the laws, so we may as well use the simplest and most elegant one rather than picking based on our ontological commitments based on our everyday experience. The simplest model also tends to be the one on which further progress is built, like QFT.

By the way, I think in some sense space is already discrete in QM. E.g. for a particle in a box you have a discrete set of states.

Several big warning signs, if you read between the lines:

1) All the string people are saying they are applying strings to different fields. That means funding is drying up.

2) No new blood: they are quoting all the same people as 10 years ago. No breakthroughs since Maldacena, it sounds like.

In the case of 1), the string theoretic tools, including AdS/CFT appear to be more effective in condensed matter physics than in their originally-intended use.

I've been glad to see the emergence of the Grassmannian/'amplituhedron' ideas, as they're different, and different would appear to be good.

Silverstein is fairly new, but yeah I really hope that young people are wise enough not to join. The masters are for the most part way past their glory days and super symmetry all but dead.

Read more carefully. About half the people quoted in the article are postdocs or junior faculty.

Keep this in mind when you read the article:

https://web.archive.org/web/20061002142756/http://www.ncswa....

"Really good science writers need to lie, cheat, and steal, said K. C. Cole in the first plenary of the workshop. She outlined 15 rules for writing in her talk, but focused most on the value of lying."

As a layman I got the impression the issue was essentially settled with the AdS/CFT correspondence - string theory is equivalent to quantum field theory. Just in the same way one can convert a boolean satisfiable problem into a graph coloring problem or a Sudoku puzzle or any other NP-complete problem. Different representations and ways of looking at the same thing.

The details of the correspondence are currently only known for (toy) theories not describing the actual physics of our universe and it is a matter of debate whether it is possible to extend the correspondence to realistic models but nonetheless those are just two different ways of describing the same thing.

I am not sure whether the correspondence has anything to say about what point of view is more fundamental - are both really equivalent or just in some limit, i.e. does string theory for example survive for very high energies while quantum field theory breaks down implying that there are really tiny strings while fields and particles are just a very good approximation?

This latest book by R. Penrose might be of interest to those looking for a serious analysis of what is happening to the theoretical physics research today: http://press.princeton.edu/titles/10664.html.

Just got my copy from Amazon.

Cannot recommend Penrose highly enough ... a truly brilliant mathematical physicist who is not afraid to call out Emperor's new clothes as it were (which of course is an indirect reference to another of his books about AI and consciousness). "Road to Reality" also gets my vote as "here's the utility belt you need to really get a handle on modern physics".

Good stuff.

I feel like we need Second Life's Strange String Theory to balance this headline out.

. MNM.

For those who do not care about paradigms and use the Solomonoff induction (Occam's razor) and falsification as a guiding principle:

After carefully checking basic assumptions made long ago against newer research, als well as using a different interpretation of the measured effect - you can build up a fully deterministic and logical model compatible with GR, SR while also explaining quantum mechanical effects and cosmology.

I take falsification very seriously - if there are multiple unexplainable phenomena or different measurements contradicting a theory, it's of the table for me and I don't care if the rest of the world still believes in it. History has shown that theories die slowly despite contradictory evidence. Secondly, nature does not care about the artificial borders in science we humans create - there is exactly zero difference between quantum mechanical world, chemistry, classical physical objects and cosmology - there is only physics. Every proposed theory must also be paradox free - paradoxes should make your internal alarm ring that something is wrong and should never be ignored.

Now the fun fact: We already have a unified theory that only requires the most minimal and logical assumptions you can possible do. But as it breaks many beloved paradigms and is obviously not a weekend read as every complete physical model is at least very complex - it is not even discussed in contemporary physics. The name of the model is: "Basic Structures of Matter - Supergravitation Unified Theory" by Dr. Stoyan Sarg.

https://www.amazon.com/Basic-Structures-Matter-Supergravitat...

There are some papers about this theory, but I have to say, when I started with them, I did not really understand it well from them. I got some raw picture, but no real understand of the model - the large book is the only source for this model - unfortunately.

When I explain this model these days, I usually take a different order and explain many parts of Chapter 12 right at the beginning. How those fundamental particles crystallize into higher structures that later build up protons/neutrons/electrons/... is one of the most beautiful processes I have ever understood and actually so simple once understood. So I usually start there now and then explain the CL space, electrons, protons/neutrons and then some chemical topics.

My perspective changed quite dramatically while understanding this model. The world is now so much more complex and much much deeper then the standard model. In fact, the standard model and even quantum electrodynamics now look like very rough approximations. To give you a perspective, a electron has easily 2.44e+19 fundamental particles with very complex arrangement (the very exact number unknown due some missing facts not yet determinable. There is a partially finite recursive process involved those depth is not clear yet, only the minimum depth is clear.

I asked many scientists about this theory, my old physics professors, famous ones, local ones - also those who clearly state that something in our current understand must be wrong. Sad truth is, they either don't know the model or simply don't care.

So far, I have not found anything wrong with this model. Apart from the many typos and sometimes a index error that you can easily spot, I only stumbled upon one equation so far that I don't understand or is wrong - can't say yet. But this would in the worst case, only change the distances between two neutrons in tritium and that can't cause larger problems with the model itself.

For those open minded people that have a deep interest in a true revolutionary model, read this book. If I could only have one book, that's the one I will pick ;)

isn't Sheldon working on this topic too?

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