If y've read Wilczek's book (comment on ideas of chapter 8)

[marcus]

If you've read Lightness of Being, which just came out, then you may see that the core ideas of the book are presented in Chapter 8. I'd be interested to read comment on the main ideas from other people who have read the book.

The book aims to communicate a new intuitive idea of what the world is made of---what the entity we call empty space consists of. A key notion is condensate.

For general reference see Physicsworld
http://physicsworld.com/cws/article/print/22275
The revolution that has not stopped

also see wikipedia on various condensates, chiral symmetry-breaking cond. or more simply chiral cond.

Wilczek explains the idea of what he calls QQ condensate, quark-antiquark (I write underline Q for Q-bar which I can't write easily)

He imagines a composite of condensates, thinking of the vacuum as figuratively consisting of layers and he lists various layers each one a condensate, the QQ one, ..the Higgs one,.. a possible gravity one.

He says what he wants to get from the LHC (which many are not as definite about) and where there is a range of possibilities he indicates the range. He says how what he expects to come out of LHC fits into his paradigm of what the world is made of. What the vacuum is made of (matter fields are just excitations of the vacuum, or as he calls it the Grid.)

So far I haven't told you anything about what he actually says or how he describes these things. I'd like to get your reactions to the book, from people who have read it, and especially enlightening comment on Chapter 8

 

[marcus]

I'll tell you an impression I have about what Wilczek is doing in Chapter 8, which I think is the heart of the book and has the core message that many of the other chapters, appendices, glossary etc connect into and expand out from.

If you've read the book then you can say whether or not you think I am right about this, and give a different interpretation if you want.

He works hard on a description of the QQ condensate, which comes out of what he knows very well namely Quantum Chromodynamics:
how quarks and gluons which have no mass or very little mass bind together in an energetically favorable way and the energy of their interaction is what actually what give the proton 95 percent of its mass.
He uses this picture from Quantum Chromodynamics very hard, and he gets you to imagine a seething bunch of virtual particles and antiparticles in some detail and consider why some combinations are more favorable.
the two ideas he works hard at developing are condensate and superconductor, and he works hard developing analogies between them, both are going to function as metaphors and they are going to be metaphors for the same situation.

Now the guy is both a great theoretical physicist and a great science writer, so look at what he is doing. What is his strategy as a writer?

Remember that a metaphor never takes the place of the mathematics. The metaphor is a way to exercise your imagination so as to make the mathematical model more intuitive. Don't ever treat a metaphor as the real thing. the math model is the real thing (or the closest you ever get) and the metaphor is a way to teach your mind to have intuition.

Like in cosmology a very good metaphor is the expanding balloon. You can learn a lot about how to picture expansion of space from imagining the balloon, with painted dots for galaxies. But don't confuse the balloon with the universe. Space is not made of rubber. It's really about distances, not about material stretching.

OK, Wilczek has a job of communicating what the world is made of and he tells you about QuarkAntiquark condensate, which he knows a lot about and is sure about and can describe very well. QQ condensate is, for him, like the rubber balloon. Likewise the superconductor as he describes it. These are the metaphors of an active dynamical Vacuum (almost like a material.)
And these are his guides to what he expects to be able to put together when the LHC tells him how many and what kinds of Higgses there are. That will be another layer or facet of empty space, a condensate that attributes inertia to things.

That's just my overview of what's going on in Chapter 8. It isn't necessarily right. You may see it in a totally different light. If so, please let us know what you think.

 

[marcus]

If y've read Wilczek's book (Daney can help understand chapter 8)

If you've read LoB and, as I do, see chapter 8 as the heart of the book presenting the main ideas, you may want some supplementary material on the Higgs mechanism to help in understanding what Wilczek is saying. I'd recommend browsing a bit in Charles Daney's website "open questions". He is a gifted and hardworking science writer with a lot of stuff online. Just go to openquestions.com and look at the site map--some of what is there may be useful to you.

As a sample excerpt, here is a portion from his page on the Higgs mechanism:
http://www.openquestions.com/oq-ph008.htm
==excerpt from Open Questions Higgs page==
The Higgs mechanism
Let's review where we stand so far.

* We have a nice, well-behaved (i. e., mathematically consistent, renormalizable) Yang-Mills gauge theory of the electromagnetic force, based on U(1) gauge symmetry.
* We would like to have an equally nice Yang-Mills gauge theory of the weak force, and it should be based on a SU(2) symmetry.
* Experimentally, it is known that the particles which mediate the weak force are massive, instead of massless as required in a Yang-Mills theory.
* The electromagnetic and weak forces are intertwined, because the weak SU(2) symmetry exchanges particles that have different amounts of electric charge.
* Yet any potential symmetry between electromagnetic and weak forces can't be exact, since the forces have different strengths.

A series of profound insights by Sheldon Glashow, Steven Weinberg, and Abdus Salam, mostly as independent contributions, led to the unified theory of the electroweak force. This was accomplished by taking the above givens, making a few inspired assumptions, and synthesizing everything in a new -- and quite effective -- way.

The insights were as follows:

1. Most of the theoretical difficulties result from the existence of nonzero rest masses of the various particles. The masses break the symmetry between electrons and neutrinos (and other particle pairs), they are incompatible with a straightforward Yang-Mills gauge theory, and they are the root of the problems with renormalizability.
2. At very high energies, the energy contributed by a particle's rest mass becomes insignificant compared to the total energy. So at sufficiently high energy, assuming a particle rest mass of zero is a very good approximation.
3. A consistent, unified Yang-Mills theory of electromagnetism and the weak force can be formulated for the very high energy situation where particle rest masses are effectively zero.
4. At "low" energies (including almost all levels of energy which are actually accessible to experiment), the symmetries of the high energy theory are broken, and at the same time most particles acquire a nonzero rest mass. These two "problems" appear simultaneously when symmetry is lost at low energy, much as symmetry is lost when matter changes state from a gas to a liquid to a solid at low temperature.

The "Higgs mechanism" is basically nothing more than a means of making all of this mathematically precise.

The key ingredient not yet specified is to assume there is a new quantum field -- the Higgs field -- and a corresponding quantum of the field -- the Higgs particle. (Actually, there could be more than one field/particle combination, but for the purposes of exposition, one will suffice.) The Higgs particle must have spin 0, so that its interaction with other particles does not depend on direction. (If the Higgs particle had a non-zero spin, its field would be a vector field which has a particular direction at each point. Since the Higgs particle generates the mass of all other particles that couple to it, their mass would depend on their orientation with respect to the Higgs field.) Hence the Higgs particle is a boson, a "scalar" boson, since having spin 0 means that it behaves like a scalar under Lorentz transformations.

The Higgs field must have a rather unusual (but not impossible) property. Namely, the lowest energy state of the field does not occur when the field itself has a value of zero, but when the field has some nonzero value. Think of the graph of energy vs. field strength has having the shape of a "W". There is an energy peak when the strength is 0, while the actual minimum energy (the y-coordinate) occurs at some nonzero point on the x-axis. The value of the field at which the minimum occurs is said to be its "vacuum" value, because the physical vacuum is defined as the state of lowest energy.

This trick wasn't created out of thin air just for particle theory. It was actually suggested by similar circumstances in the theory of superconductivity. In that case, spinless particles that form a "Bose condensate" also figure prominently.

The next step is to add the Higgs field to the equations describing the electromagnetic and weak fields. At this point, all particles involved are assumed to have zero rest mass, so a proper Yang-Mills theory can be developed for the symmetry group U(1)xSU(2) that incorporates both the electromagnetic and weak symmetries. The equations are invariant under the symmetry group, so all is well.

Right at this point, you redefine the Higgs field so that it does attain its vacuum value (i. e., its minimum energy) when the (redefined) field is 0. This redefinition, at one fell swoop, has the following results: the gauge symmetry is broken, the Higgs particle acquires a nonzero mass, and most of the other particles covered by the theory do too. And all this is precisely what is required for consistency with what is actually observed.

In fact, the tricky part is to ensure that the photon, the quantum of the electromagnetic force, remains massless, since that is what is in fact observed. It turns out that this can be arranged. In fact, the photon turns out to be a mixture of a weak force boson and a massive electromagnetic boson that falls out of the theory. The exact proportion of these two bosons that have to be mixed to yield a photon is given by a mysterious parameter called the "electroweak mixing angle". It's mysterious, since the theory doesn't specify what it needs to be, but it can be measured experimentally.

So, the Higgs mechanism is a clever mathematical trick applied to a theory which starts by assuming all particles have zero rest mass. This is especially an issue for the bosons which mediate the electroweak force, since a Yang-Mills theory wants such bosons to be massless. While the photon is massless, the W and Z particles definitely aren't. Where, then does their mass come from? Recall that we observed that spin-1 bosons have 3 "degrees of freedom" if they are massive, while only 2 otherwise. It turns out that this extra degree of freedom comes from combining the massless boson with a massive spin-0 Higgs boson. That Higgs boson provides both the mass for the W and Z, as well as the extra degree of freedom.

In fact, the mechanism furnishes mass to all particles which have a nonzero rest mass. This occurs because all the fermions -- quarks as well as leptons -- feel the weak force and are permuted by the SU(2) symmetry. And since quarks acquire mass this way, so too do hadrons composed of quarks, such as protons and neutrons, which compose ordinary matter as we know it.

But this mechanism is more than just a trick. If the whole theory is valid, then the Higgs boson (or possibly more than one), must be a real, observable particle with a nonzero mass of its own. This is why the search for the Higgs boson has become the top priority in experimental particle physics.

What about renormalizability? Has this been achieved in spite of all the machinations? It seemed plausible that the answer was "yes", which was of course the intention, since the high-energy form of the theory has the proper gauge symmetry. But it took several years until a proper proof could be supplied, in 1971, by Gerard 't Hooft.

Supersymmetry
It should be pretty clear by now that Higgs physics is very much tied into the standard model. Indeed, it's necessary in some form to make sense of many features of the standard model -- such as electroweak symmetry breaking and particle masses. In fact, it -- or something very like it -- seems to be necessary just to make the theory consistent.

And yet it's not quite a part of the standard model either. It has a bit of an ad hoc feel to it. If, in fact, the Higgs mechanism exists in more or less the form outlined here, then the standard model certainly has no explanation for why it's there, for what makes it happen. We shall want more than that. We want to know the source of the Higgs physics itself.

There may be a number of ways to do that (which might be related among themselves). But there is one body of theory which can provide exactly the explanation of Higgs physics we're looking for, and which has been in gestation since the early 1970s (i. e., since the time the standard model assumed its present form). It's called supersymmetry. ...
==endquote==
and at that point he moves on to talk some about SUSY. Go to the Daney site to read more. Thanks to Wolram for alerting us to Open Questions as a resource.

 

[marcus]

As I see it, Daney's explanation dovetails with what Wilczek says and could make it easier to grasp.

 

[marcus]

See if you agree with this:

One of the best ways to understand Wilczek's message is to see how it gets translated into more technical language by another particle physicist!

In particular, I think the Robert Percacci has nearly the same perspective on the new physics he hopes will come out of LHC and his vision of unification over the next 10 or so years.

Percacci outlined his point of view in a talk he gave at Sussex in September:
Here is the conference programme.
http://www.ippp.dur.ac.uk/Workshops/08/CLAQG/Programme/

Here are slides for Percacci's talk "A particle physicist's view of gravity"
http://www.pact.cpes.sussex.ac.uk/~dl79/CLAQG/Percacci.pdf

Sometimes it is good to hear the same message in both an intuitive non-mathematical style and a concise technical style. One gives metaphors and intuition and the other some additional clarity.

Do you think they are saying essentially the same thing? Enough the same so that Percacci gives a useful angle on Wilczek?

 

[MTd2]

Hmm, amazon sent me an email yesterday that my copy of this was shipped... Now, let's see how fast it can travel 12,000km.

 

[Fra]

I am also waiting for this book, but mine hasn't even shipped yet :) I order my books from a local company that has the same selection as amazon and great prices and free shipping.

/Fredrik

 

[Fra]

"distinction without difference"

At least I got the book some time ago but only read a few chapters so far. In general I like the book so far.

One think that seems to be of his signature of his reasoning is his take one symmetry as a guiding principle.

The phrase "distinction without difference" is interesting. I think this is the old paradox of symmetry. Is symmetry real? I mean, if we turn it around, how do you arrived at a distiction without a difference in the first place? And if a distinction makes no difference, what is the nature of this apparent redundancy?

So far in the book he doesn't seem to address those questions. And I think this problem is fully analogous to the "problem/paradox" of background indepdendence in the most general sense. IE. can "symmetry" be absolute AND relatable to a real observer? If not, what are the consquences to the guiding symmetry principles for theory building?

Those who advocate background independence in one way or the other, argue from a symmetry argument that any chose of background is completely arbitrary and can not be motivated. Thus a fundamental theory must be independent of such a thing.

Other notes that the notion of background indepedence is kind of bunk since it does not make sense to talk about anything without a reference. Any statement, or measurement must related to a "background reference". Therfore to do away with this background is to suggest a statement living in thin thin air - and that seems to make no sense.

IMO this is just the same argument behind the symmetry paradox.

So which is it? IMO both views are partially valid points. I always liked slightly
along smolins suggestive weird evolutionary law think, that the evolutionary concept
is the solution to the paradox that can please both sides of this paradox.

I was hoping to find Wilczek's point on this, how he put this grid idea in this context. I am roughly in liking of this idea to consider mass as confined energy, but is this entire construction absolute? I am looking for the inside observer perspective in his reasoning. I didn't see it so far.

This was just the first things that popped up in my head when I read this. I'll probably get more enlightened as I keep reading the rest of the book.

If MTD2 has started reading I'm curious to hear this idea as well.

/Fredrik

 

[MTd2]

If MTD2 has started reading I'm curious to hear this idea as well.

/Fredrik

The book was shipped 2 weeks ago! But it's a looong path to arrive down here! :D

 

[Fra]

The book was shipped 2 weeks ago! But it's a looong path to arrive down here! :D

So where are you located?

/Fredrik

 

[MTd2]

Brazil, Rio de Janeiro...

 

[Fra]

Ah that's cool. I've never been there but it would be an interesting place to visit someday.

I think Ariel Caticha (now in US) is originally from Brazil and his brother is I think a professor in Sao Paulo. I am somehow curiously awaiting his book that I think Ariel is working on on "information physics" to pop up at some bookstore near me :) Some user on here knowing Ariels brother wrote on that here some year ago I think. He was kind to supply my some drafts of the early chapters, which is more or less the material from his published papers. I'm curious to see if he takes anything to another level in the book.

/Fredrik

 

[MTd2]

Well, Caticha looks like a hispanic name, not a portuguese name... Although ther is a lot of superposition between surnames between these languages, "ticha" of caticha sounds like hispanic... But it seems that he worked at UNICAMP, indeed.

 

[Fra]

More reflections...

I finished chapter 8 last night. His opinion of the analogy between all forces are clear. I think the key issue, to which he presents no clear suggestive solution as I can see, comes in the end of the chapter, is what gives his grid the very small but non-zero mass (as observations suggest), or basically the cosmological constant problem. This is made more interesting by noting that the vacuum field fluctuations predicted by the various quantum fields are way off chart in scale.

I can't help associate this apparent "overcounting" of the degrees of freedom with the lack of the inside perspective regarding the concept of symmetry. Because I again insist that there is a common issues here emergent or absolute symmetry, emergent or absolute background, and various ergodic hypothesis. I think the "right observatioanl perspective" is supposedly what renormalization is set out to "cure", but the question is if the current way of doing it is the best way?

This was a nice chapter. I'll get on to the next chapters!

/Fredrik

 

[Fra]

I like Wilczek's thinking of "profound simplicity". Mmm perhaps it's a bit like the devil reading the bible but at least the parts of his expressions of simplicity can be interpreted as IMO truly relative - to my liking.

When you make the comparasion to datacompression, like Wilzcek does. Then clearly the notion of optimum compression, relates to stuff like memory size and computations times regarding both compressiond and decompression. An ultimate compression, compressed beyond practical DEcompression is clearly totally useless. Therefore, I think one angle of what he says, is that the notion of simplicity, is basically relating to a memory and a computing device for compression/decompression. And what is this device? As I see it the only sensible connection is the observer! Thus simplicity is observer dependent. So it seems each observer makes his own optimations, and the feedback lies at the population dynamics of observers.

/Fredrik

 

[Fra]

Wilczek's view on Popper

In chapter 19 he makes this note that I found to be quite amusing and made me smile while reading it, but also quite deep statement that I think is a hint that he has some deeper visions that really trace down to the scientific method. This is also in line with his datacompression analogy of "profound symmetry".

"We succeeded in producing a theory that was not just falsifiable but outright false. Very scientific, says Karl Popper. But somehow, we are not left feeling gratified"
-- F. Wilczek, p183, The lightness of beeing

I feel a connection here to his vague idea of thruthification, as a kind of more "contructive" version of falsification. It seems closely related to what I have called the "logic of revision or correction". He seems to suggest, to which I totally agree, that some more focus should be not only on "falsifiable hypothesis generation" but on the deeper mechanics for evolving a falsified hypothesis into a new hypothesis. I think this is what Wilczek calls truthification. But the not is short, so perhaps is emphasis is not too strong.

/Fredrik

 

[marcus]

Fra, your recent comments are helpful in more ways than one. For me, because I have been lending my copy of the book to friends and don't have it handy, your comments remind me of Wilczek's intriguing reflections and so keep me thinking about its thought-provoking ideas even when the book itself is not immediately at hand.

 

[Fra]

Fundamental symmetry - the new form of "realism"?

Now I've finished reading the book, and here is another thing that hit me in the face as a reader...

Wilczek relies heavily of various kind of symmetry principles, and the search for larger symmetries seems to be almost like a methodology of howto make progress.

I can not help asking, what exactly is the physical basis of this symmetry. In some parts of the book I think Wilczek reasons in a way that suggests that perhaps there is a deeper (not yet spelled out) logic around the concept of "simplicity" and "symmetry". In other parts of the paper, he argues in a way that gives the impression that he thinks of the existence and uniqueness of the fundamental symmetries almost in the old spirit of realism. IE. that the SYMMETRIES are the ontological elements that exists, in a realist sense.

To me there is a slight tension between these views and even though the concept of symmetry, invariance etc is a very simple concept, that we have also in classical physics, there is something about this that I think isn't understood in depth. In particular when it's brought together with the problem of what elements in theory is really to be though of as "observable". It's a bit fishy, almost like the ergodic hypothesis is somewhat fishy in classical physics. Neither can one help associating this "issue" to SMolins ponderings of the problem of distinguishing initial conditions vs law. IE. we sometimes use "symmetry principles" as a rule of reasoning, or "law". But what about the origin of the laws?

Does people really find it satisfactory to consider "physical law" as realism elements? I personally can do that.

/Fredrik

 

[friend]

I can not help asking, what exactly is the physical basis of this symmetry. In some parts of the book I think Wilczek reasons in a way that suggests that perhaps there is a deeper (not yet spelled out) logic around the concept of "simplicity" and "symmetry".
.
.
.
In particular when it's brought together with the problem of what elements in theory is really to be though of as "observable".

This doesn't seem like so much a mystery to me. If we were to have a mathematical formulation of physics, then what is observable is that which does not vary, at least while you are observing it. This means observables must comply with some sort of symmetry principles associated with invariances of this mathematical formulation.

 

[Fra]

Friend, thanks for expressing your view!

To explain on my previous post - I am not suggesting that the concept of symmetry is useless. On the contrary do i think it's important, but I think there is a difference in how you think of it, and then ultimately treat it, when builing models. It's the latter part here, our guidance in model building that I think is what may distinguish this discussion from fruitless philosophical or interpretational issues. In particular do I think these things get important when discussing, emergence of symmetry, and breaking of symmetry.

This doesn't seem like so much a mystery to me. If we were to have a mathematical formulation of physics, then what is observable is that which does not vary, at least while you are observing it. This means observables must comply with some sort of symmetry principles associated with invariances of this mathematical formulation.

I sort of understand your construction here, but you construction contains two variables. It's "we", and it's "vary with what". We would hopefully refer to an observer, right? And then the first issues comes into play, there are more than one observers. There is in fact a large class of observers. Often we assume a symmetry class, that generates all possible observers. Observer-frame transformations for examaple. But usually when we think of this, it's the scientific community of Earth whose collective knowledge maintains these "transformations", and the "observers" really refer to say particles, small subsytems like measurement devices we have constructed. This IMO is a typical emergent symmetry. One might argue that human science are not observers on the same footing, but I think we are. I think that perhaps this emergence of symmetries, when applied also to particle particle interactions, MAY possibly be a key to unification.

And then varying what what? time? what is time? who's clock? I think the story is the same, that an observer does not have real a priori knwledge of the global transformations that connects his view to another party. I think again that it should be emergent.

This IMO is at least partly well in line with Wilczek's datacompression analogy, because as he points out there is not simple solution to that problem, and obviously part of the problem is that simplicity is relative! Relative to memory available, relative to computation power available. Therefore if we are to be really pragmatical, we must note that simplicity when it comes to physical laws, must ensure that they are computable. If predictions requires a computer the size of the universe then clearly that is a completely usless theory.

But this is just my view, I suspect that your not the only one to not see what bugs me here. Indeed these realist type of symmetries has and is still a heavy guide in model building and I think many simply doesn't see the benefit in asking these questions.

I don't think the symmetry guide is wrong, but I think we will benefit from a reflection of the nature and origin of these symmetries, and this may suggest that these guides are not as solid as it may seem. The question, is how can an instance of a symmetry class, encode the meaning of the full symmetry class? i don't think it can. This encoding I think lies elsewhere.

/Fredrik

 

[Fra]

To explain what I mean with the "fundamental symmetries" beeing the corresponding to realism elements in QM it's this. I ask, how much information is required to specifiy a symmetry? If we look at this, then a fully certain symmetry suggests to me infinite information. Ie. it is as physically realistic as is a classical observer, relating to quantum measurement.

/Fredrik

 

[marcus]

Fra and anyone else familiar with the book,
I'm interested to know how you expect the book to do as far as reaching a wide public,
so today I set up a poll: How will Lightness do in December?
https://www.physicsforums.com/showthread.php?t=270620

 

[MTd2]

I just got the book! :O :D :D

 

[Fra]

I just got the book! :O :D :D

Congratulations! :)

/Fredrik

 

[Fra]

Smoling vs Wilczek

I finished Wilczek's book and just started to read Smolins TWP which unavoidably makes me compare their reasonings, wether that makes sense or not.

In the first 5 chapters talking about symmetry and unification together with Smolin's confession of beeing a realist, I get the same feeling as when reading Wilczek's argument on symmetry.

I have a feeling that both authors appears to have what I would call a "realist view of symmetry". With this I mean that, sure symmetry is not a "thing", like say matter, but the very representation of it, must have a physical basis, and this IMO put "thing" and "principle" on closet of close equal level. I am still unclear as to wether Smoling presents his own thinking in the early parts, or just tries to give an accurate historical perspective. Anyway, some of the realist views of symmetry does not commute with my idea of emergent symmerty, which I thought was Smolins game. It seems the solution to thta would be a realist view of the emergent process then?

From a practical viewpoint, Wilczek's book was better for late night bed reading. The fonts was larger, and the chapters were shorter, and the probability of falling asleep in the middle of a chapter was smaller.( TWP also reminds me from 3 roads, that Smolin tends to be writing in a style of a story teller, including occasional personal details. I almost forgot. This can be very fun and makes you feel close to the author, but it also gives you the sensation that you have to read a lot of extra words and that you aren't given the shortest path to the target.)

/Fredrik

 

[marcus]

...
I have a feeling that both authors appears to have what I would call a "realist view of symmetry". With this I mean that, sure symmetry is not a "thing", like say matter, but the very representation of it, must have a physical basis, and this IMO put "thing" and "principle" on closet of close equal level. I am still unclear as to wether Smolin presents his own thinking in the early parts, or just tries to give an accurate historical perspective. Anyway, some of the realist views of symmetry does not commute with my idea of emergent symmerty, which I thought was Smolins game. It seems the solution to thta would be a realist view of the emergent process then?

I think you are right---Smolin acknowledges the enormous depth and power of symmetry principles. But he would certainly like to discern something underlying them, from which they emerge.

I think his core belief is in something he can't fully articulate---the idea that natural laws have evolved. OK a bird or a horse has bilateral symmetry, but bilateral symmetry is not a fundamental feature of living things, it evolved. Things crawling on the floor of the ancient ocean discovered it, probably. But how can physical law evolve? How can the symmetries of space time and matter have evolved? He speculates on occasion, but he can't say.

Consequently Smolin will show that he admires and respects the beautiful symmetry of nature as much as anybody else, but privately he will always harbor a suspicion that it wasn't a Given. It came about somehow from something more simple and primitive. Just my opinion.
===================

In a sense Wilczek is more practical. He also has so many things to tell you that he can't stop to insert personal anecdotes. It is a brilliant book. Not as philosophically deep maybe.

Maybe I am just echoing things that you have already said.

 

[marcus]

I just got the book! :O :D :D

Great! What I am hoping to get in this thread, especially, is other people's views on the physics ideas presented in Chapter 8. I hope you comment---on that or any of the other content---when you have had a look at the book.

What impresses me, as a general observation, is that Wilczek seems to have fairly clear ideas about what he wants to come out of LHC.

He has placed some heavy bets, as I see it. He is actively anticipating. More so than others I think of. He seems to have an intuitive graphic vision of how the vacuum is put together. And he badly wants it to be proved right. Tell me what you think about his vision of the vacuum and his expectation of a new age of rapid advances in physics theory, or if you think I'm missing something.

My copy of the book is still loaned out, have to get it back!

 

[Fra]

I think his core belief is in something he can't fully articulate---the idea that natural laws have evolved. OK a bird or a horse has bilateral symmetry, but bilateral symmetry is not a fundamental feature of living things, it evolved. Things crawling on the floor of the ancient ocean discovered it, probably. But how can physical law evolve? How can the symmetries of space time and matter have evolved? He speculates on occasion, but he can't say.

This is in line with my impression of his reasoning, and this is why I like his reasoning because he seems to at least fire questions which seems to me to be in a sensible direction. But even in Wilczek's reasoning I sensed a tension, that he was aiming for something higher. In particular his analogy with datacompression. But I suspect he still maintainst a realist view, and not fully acknowledges the relativity of simplicity, because IMHO at least the natural consequence of this is emergent symmetry. Or maybe he acknowledges it but doesn't talk much about it since no one yet can elaborate on exactly how.

My opinion is that of the evolving population selection of observers (which can be seen as an extension of the observer-observer symmetry) that I've mentioned too often already, but the full formalism is still in the air. This would IMO be close to Smolins evolution of law, if the physical basis of law, is the observer traits.

/Fredrik

 

[Fra]

Marucs, I don't remember if you revealed clearly your personal opinon on this. I'm curious to hear what your opinon is on the idea of "evolution of physical law", "emergent symmetries" etc?

Does this make any sense to you? Or rather, since we don't know what it is yet(ie there is no clear spelled out theory), do you see any promising way to make it "make sense", which is I think the question, or do you think these things are just too speculative and do you prefer a more conservative approach?

/Fredrik

 

[marcus]

Marcus, I don't remember if you revealed clearly your personal opinon on this. I'm curious to hear what your opinon is on the idea of "evolution of physical law", "emergent symmetries" etc?
... do you prefer a more conservative approach?
...

Fra, I don't have a clear personal opinion about evolution of physical law. I revealed my unclear opinion in this thread:
https://www.physicsforums.com/showthread.php?t=262171

That was where we were discussing "Physics law evo" and the two PIRSA video lectures by Smolin.

People with brilliant prophetic insight are sometimes out of synch. It may simply be a matter of timing. In the stock market they would sell off too early or they would buy too early. To make money one should be only a little early. It may be too early to be talking about physics law evo[lution], even though it is a fundamentally sound idea!

So I look at Rovelli and Wilczek and they seem to me both in their separate ways to be very timely and practical. Rovelli certainly wants a general relativistic quantum field theory to be constructed----this is the outstanding problem facing everybody. Usual quantum field theory is only special relativistic. This clearly isn't good enough. Minkowski space, put in by hand, is not real space. Both those people, in their separate ways, want the next achievable unification. They want to see the next logical step.

So my personal attitude is bifurcated---I keep two contradictory perspectives. The evolutionary origins of physics law, including possibly symmetry, is extremely interesting but on the other hand I think it is right for people to be working in the presentday context, working from the bottom up, with whatever astronomical and collider data becomes available.

One additional vague thought. In the two Smolin videos, he argues that cosmology is qualitatively different from studying subsystems where there can be a classical outside observer. He argues that therefore, because of the qualitative difference, we need a different understanding of physical law (if we consider the universe as a whole rather than an isolated piece of it.) Rovelli has a relational QM perspective, where the separation between the observer and the observed is not so sharp. For him, I don't think quantum cosmology is qualitatively different. For him, this may blunt the force of Smolin's argument.
I'm not sure how important that is, however.

 

[Fra]

So my personal attitude is bifurcated---I keep two contradictory perspectives. The evolutionary origins of physics law, including possibly symmetry, is extremely interesting but on the other hand I think it is right for people to be working in the presentday context, working from the bottom up, with whatever astronomical and collider data becomes available.

In the larger sense I certainly share your dual view. As I see it, those who do the first-line processing new data simply has no other choice but to do that using the currently best theories (since this is somehow our measuring-stick). Or even in an inside model where the physicists are players rather than just outside observers(which we are), there are parts of the evolving model that represents that currently most accepted expectation, and this is relative to the data is judged.

Then the other view is the work of the theorists, by which I mean no those who make first like computations, but those who has generate hypothesis for testing, and those who use the data of compliance of deviation from first line experiments with current models to come up with a modified model (ie how to EVOLVE the measuring-stick).

One additional vague thought. In the two Smolin videos, he argues that cosmology is qualitatively different from studying subsystems where there can be a classical outside observer. He argues that therefore, because of the qualitative difference, we need a different understanding of physical law (if we consider the universe as a whole rather than an isolated piece of it.) Rovelli has a relational QM perspective, where the separation between the observer and the observed is not so sharp. For him, I don't think quantum cosmology is qualitatively different. For him, this may blunt the force of Smolin's argument.
I'm not sure how important that is, however.

I am totally onboard with Smolin on that argument. However, I am willing to take it one step further. Not only does this argument IMO apply to cosmology, it might applies to particle physics, if you consider that the point of view of say a proton looking out into the big world, is not totally unlike our human-cosmology perspective *informationwise* since a proton can not hold as much information about it's environment as a human Earth based lab can. This is the beauty I see in evolving law, the same principle can apply to particle physics as well, if you picture the inside-view, of these "miniature observer". This is why I am thinking in terms of "scaling physical law", what exactly happens. And is there simply a LIMIT to the complexity of LAW that a simplest possible observer (say the "elementary particles") can RELATE to? IF so, that's simply one nice inside view of "unficiation" right? So the question of unification isn't what laws there ARE, but what laws that becomes distinguishable to the observers that are STABLE at the excessively high energies of unification?

I also think the spirit of rovelli's RQM belongs to this context. The first time I read it, I was very impressed by his reasoning. But what he makes out of it, is I think not perfect. Or if it is, it could be that I simply doesn't see it.

I like the common denominator of Rovelli and smolin, but Smolin focuses very hard on the cosmological scale. I have not seen him make the suggestions I tried to make about, that connects evolution of law, to perspective at all scales, not ONLY the cosmology scale. And therefore evolution of _observable law_ should logically go hand in hand with evolution of observers, which in this terminology is another way of talking of emergence of "elementary particles", and thus perhaps the link to incorporating matter.

/Fredrik

 

[marcus]

http://www.newscientist.com/article/dn16095-its-confirmed-matter-is-merely-vacuum-fluctuations.html

"It's confirmed, matter is merely vacuum fluctuations."

A year of supercomputer time at the Jülich research center.

Looks like what is confirmed is the essentially the vision of matter that Wilczek's book aims at conveying.

The general idea of matter consisting of vacuum fluctuations reminded me of a passage in The Lightness of Being that starts around page 91.

Technically (it's not the quite the same as determining hadron masses!) it's about the formation of a chiral symmetry-breaking condensate. Technically sigma mesons which he calls Q Qbar pairs. The passage begins with a kind of thought experiment, or at least an interesting "What-If" gambit.

What if you could completely clean out a patch of space? Then he presents the idea that the empty space would have an explosive potential to actually liberate energy by bringing Q-Qbar pairs into existence. Because the quark masses are small and so the energy cost of realizing them can be LESS than the binding energy released as they form what he calls "little molecules".

Have a look on page 91 and see if you understand it better than I do. I think it is a central message of the book, and raises nagging questions. He corroborates this puzzling paradoxical story on page 93 by referring to experiments at the Brookhaven RHIC (relativistic heavy ion collider). He says that a collision of two gold nuclei creates a fireball with enough energy to clear out a small region, hot enough to evaporate the condensate---and then we get to witness the aftermath, as the region cools back down and the Q-Qbar condensate forms in it again.

==============
Here are some links related to the news about the successful determination of hadron masses. The point is that the three quarks that make up a proton have themselves very little mass. Most of the proton's mass is somehow the result of the interaction of those three component quarks.
http://www.durr.itp.unibe.ch/

http://www.sciencemag.org/cgi/content/abstract/sci;322/5905/1224
Ab Initio Determination of Light Hadron Masses
S. Dürr,1 Z. Fodor,1,2,3 J. Frison,4 C. Hoelbling,2,3,4 R. Hoffmann,2 S. D. Katz,2,3 S. Krieg,2 T. Kurth,2 L. Lellouch,4 T. Lippert,2,5 K. K. Szabo,2 G. Vulvert4

"More than 99% of the mass of the visible universe is made up of protons and neutrons. Both particles are much heavier than their quark and gluon constituents, and the Standard Model of particle physics should explain this difference. We present a full ab initio calculation of the masses of protons, neutrons, and other light hadrons, using lattice quantum chromodynamics. Pion masses down to 190 mega–electron volts are used to extrapolate to the physical point, with lattice sizes of approximately four times the inverse pion mass. Three lattice spacings are used for a continuum extrapolation. Our results completely agree with experimental observations and represent a quantitative confirmation of this aspect of the Standard Model with fully controlled uncertainties."

1 John von Neumann–Institut für Computing, Deutsches Elektronen-Synchrotron Zeuthen, D-15738 Zeuthen and Forschungszentrum Jülich, D-52425 Jülich, Germany.
2 Bergische Universität Wuppertal, Gaussstrasse 20, D-42119 Wuppertal, Germany.
3 Institute for Theoretical Physics, Eötvös University, H-1117 Budapest, Hungary.
4 Centre de Physique Théorique (UMR 6207 du CNRS et des Universités d'Aix-Marseille I, d'Aix-Marseille II et du Sud Toulon-Var, affiliée à la FRUMAM), Case 907, Campus de Luminy, F-13288, Marseille Cedex 9, France.
5 Jülich Supercomputing Centre, FZ Jülich, D-52425 Jülich, Germany.

http://www.sciencemag.org/cgi/content/summary/sci;322/5905/1198
The Weight of the World Is Quantum Chromodynamics
Andreas S. Kronfeld

"Ab initio calculations of the proton and neutron masses have now been achieved, a milestone in a 30-year effort of theoretical and computational physics."
Theoretical Physics Group, Fermi National Accelerator Laboratory, Batavia, IL 60510, USA.

 

[gpitynski]

In chapter 19 he makes this note that I found to be quite amusing and made me smile while reading it, but also quite deep statement that I think is a hint that he has some deeper visions that really trace down to the scientific method. This is also in line with his datacompression analogy of "profound symmetry".

"We succeeded in producing a theory that was not just falsifiable but outright false. Very scientific, says Karl Popper. But somehow, we are not left feeling gratified"
-- F. Wilczek, p183, The lightness of beeing

I feel a connection here to his vague idea of thruthification, as a kind of more "contructive" version of falsification. It seems closely related to what I have called the "logic of revision or correction". He seems to suggest, to which I totally agree, that some more focus should be not only on "falsifiable hypothesis generation" but on the deeper mechanics for evolving a falsified hypothesis into a new hypothesis. I think this is what Wilczek calls truthification. But the not is short, so perhaps is emphasis is not too strong.

/Fredrik

what's actually a very interesting idea...truthification I have to use this concept with my colleagues.

 

[MTd2]

I will post little by little abouty my thoughts regarding his book.Alright, after all this time, I finally finished reading this book. As I said elsewhere, I was turned down because it seemed this books was aimed at a general public and it didn't have any mathematical insight. Because of this, I delayed to start reading it for a long time. But last week I started with that and I finished today.

Thinking about chapter 8 and Appendix B made me thought that Wilkcez could have speculated much more of cosmology. For example, he didn't think of finding an analog for the superconductor condensate in gravity.

Given the low coupling constant of gravity, I would expect a really low temperature for a gravity condensate. Perhapes that is the event horizon? That is, the eveng horizon is the boundary of a gravity condensate media, and behind it, gravity would be a low range force and graviton would give rise to a similar particle with mass. Call that eventon. Given that the graviton has is 2 spin particle, perhaps it would give rise to some weird eventon particles, that is, massive Eventons, with integer or half integer spins, =<2.

 

[Fra]

Hello Mtd2, I'm sorry about your dissapointment! I hope I'm not guilty of "hyping" the book.

I agree the book is definitely a non-technical. I've been in a period where I read up on a number of different people, both more techincal papers but also some popular books. My main reason to read these books is a very specific one: to try to extract the reasoning used. And sometimes for this task, some of the more philosophical style writings are more revealing, that is a condensed technical paper. Technical papers containing say mathematical deductions are usually making use of an implicit reasoning, that is often not question in that particular paper, for good reasons. During this mission, lack of mathematics does not always strip out the information.

From my point of view, all mathematical model make sense withing a choice of reasoning, or an abstraction of physics. Without accepting that, the mathematics loose contact with reality. Take string theory as a good example, if you find the basic principles of string theory convincing and plausible, then to analyse possible mathematical implications will be very interesting. But if you do not, then the technical papers that are conditional on the foundations, come out as so speculative that you might think it's not worth the time reading.

I have personally spent a lot of effort on the conceptual foundations the last year, which has motivated my strong interest in choice of reasoning and abstractions in physics, more so than what the reasoning results in. This is why I think wilczeks view and comments on symmetry, is the most revealing, because it's somehow one of the main abstractions in the standard model. He doesn't IMO present in clear any novel views, but it's nontheless always interesting to see how some of the big names reason. This is in the same spirit I really enjoy some of the old writings of dirac. The logic is clear, clear enough to both show the virtues and the flaws of the reasoning. And the significance of the choice of reasoning on the development of theories.

/Fredrik