Radical new take on *uni*verse questions by Smolin, could be important

[marcus]

Smolin has a new book (Time Reborn) coming out this month. Amazon has a page on it, with advance reviews.

He gave a talk on the main ideas at Perimeter in February. I was impressed by the depth and cogency. It is a 60 minute talk followed by a lengthy discussion with Rob Myers, Laurent Freidel, Neil Turok and other members of the Perimeter audience. Here's the video:
http://pirsa.org/13020146/

The first 35 minutes lays out the main ideas for wide audience and is readily understandable. I think it would well repay anyone's time to listen to it. He presents certain principles (buttressed by quotes from Dirac, Feynman, Wheeler, Peirce) some going back to Leibniz. In the next 25 minutes he presents new work on a spacetime and quantum dynamics based on those principles which he and a collaborator are currently attempting to simulate in toy version on computer. Some advanced background is needed to understand the final 25 minutes of the talk. He constructs one or more actions/Lagrangians based on simplified models under study.

The enterprise is high risk. As I recall, the most active audience member is Rob Myers, who keeps commenting and asking questions both during the first hour and in the following 20 minute discussion. But Laurent Freidel is pretty active too. The enterprise could clearly fail. However I find it very interesting and having a real potential to change the foundations.

I'd appreciate comment from anyone who has listened to (at least the first half hour or so of) the talk.

 

[marcus]

There was a 2011 pirsa video talk by Smolin that could be viewed as a kind of preamble to this talk:
http://pirsa.org/11100113/

One nice thing about the pirsa format is you can click on the slides PDF and get stills as a convenient way of reviewing the talk. I will keep the PDF for the February 2013 talk on my desktop for a while, to have as reference.
http://pirsa.org/13020146/

===example, slide 6 of PDF, quote===
We start with Leibniz:
Priciple of sufficient reason (PSR): Every question of the form why does the universe have property X rather than Y must have a rational answer.

Principle of the identity of the indiscernible (PII): Any two events with the same properties are identical.

Consequences:
No unreciprocated actions: No non-dynamical background structures. No unalterable, timeless laws somehow acting inside of time.

Causal completeness: Explain the universe only in terms of itself. No reference to other universes, non-realized ensembles, or other, Platonic, realms.
==endquote==

 

[marcus]

I think those 4 principles in post #2 are worth thinking about so I'll put them by themselves.
No multiverse.
At least some laws of nature would seem to be emerging and evolving from a temporal process.
This is a radically distinct viewpoint, although he cites antecedents for it.
Laws not standing fixed and eternal outside or above nature, but being an evolving part of nature.
At first sight it seems so radically different that it would HAVE to be wrong!
But maybe it isn't.

Then in the next few slides he lays out some QUESTIONS to be addressed:

==sample excerpts taken from slides 7 and 8==
...
...
Here are two big questions that we lack sufficient reason for:

Why these laws?

Why these initial conditions?

Both appear to have been finely tuned.

...
...
Here are two other issues we will address:
Why does the universe have a strong arrow of time?

What causes events?
==endquote==

 

[Chalnoth]

I would say that the statements about time and timesless laws don't make sense in the context of this work by Albrecht and Iglesias:
http://arxiv.org/abs/1003.2566

Basically, you can always re-cast whatever laws you might write down in terms of some laws that are time-invariant.

 

[marcus]

How much of Smolin's talk did you watch? I ask because your comment and the paper you cite do not seem to connect at all with what I was saying or with the talk.

You seem to be using the word "timeless" to describe a law whose statement simply does not involve the time variable.

 

[Chalnoth]

How much of Smolin's talk did you watch? I ask because your comment and the paper you cite do not seem to connect at all with what I was saying or with the talk.

You seem to be using the word "timeless" to describe a law whose statement simply does not involve the time variable.

I didn't listen to it. I skimmed the PDF. Maybe he's trying to use it in a way completely different from what his slides seem to imply, but it just doesn't make sense to me the way he writes it, though I guess in part that's because I don't at all know what he means by the claim that time is somehow "real".

In any event, I really do think the most likely description of our universe is one in which there is a single mathematical structure which describes all interactions, and the slides make it seem like that is precisely what he is attempting to argue against.

I also am incredibly skeptical as to the idea that he lays out that the fundamental laws of physics should be asymmetric in time and coarse-grain to time-symmetric laws with asymmetric initial conditions. That does not strike me as a pursuit that is likely to bear fruit.

 

[marcus]

... I guess in part that's because I don't at all know what he means by the claim that time is somehow "real"...

Listening to the first 30 minutes is a really good way, I find, to understand what he's driving at. I'll try to give a secondhand explanation too, but it is no substitute.

What you say about not "likely to bear fruit" is true about a lot of highly original ideas that people try out. Most do not succeed. I mentioned earlier that this is a "high risk enterprise". Part of why it looks interesting and valuable to pursue. But it has other important merits in its favor as well, I think. This is not just any off-the-wall gambit.

To paraphrase, to give additional clarification for those who have watched the first 30 minutes or so, I think he's saying that the "block universe" is a fiction. We know that already, just as "continuous trajectory" of a non relativistic particle is a fiction.

And the idea of unchanging physical laws is a fiction. The idea of block universe being created together with what we think of as the unchanging laws of physics, which are imagined to govern that block universe without themselves suffering alteration by interaction with it, is contrary to the basic (Leibniz) principles he has adopted. He's following out the consequences of a couple of basic assumptions that I quoted earlier.

So there is some kind of "meta-law" or process (not necessarily representable in equation form) according to which the emergent regularities (which we think of as the laws of physics) evolve. Those regularities are part of the universe and they evolve along with the rest of the universe that they are part of. They only appear to us to be unchanging fixed proportions or formulae.

This "meta-law" process, vaguely analogous (one could imagine) to the evolution of biological species where the species takes the place of an "event" in the meta-law scheme, defines a kind of TIME. I would picture this as LAYERS of an evolutionary process, you see pictures of that in the slides PDF. This time is not necessarily the coordinate or real-number parameter sort of time you may habitually think of. It could be more like the layers in sedimentary rock, more like geological or bio-evolutionary time. It is the time which is intrinsic to the evolutionary meta-law process itself.

However later in the talk, after minute 35, he does get into writing Lagrangians and talking about equations of motion (EoM). To do that he has to use a kind of normalization number r, which you could think of as like a cutoff parameter. Each event is required to have r parents and r offspring. A layer of time is complete when each event in it has the expected number of parent and offspring. This seems to be an arbitrary condition to impose, but it gives him traction so that he can move ahead with the computer simulation.

It means that the Lagrangian treatment of the second half of the talk, and the computer simulations he and collaborator are working on, are exploratory toy model stuff.

Anyway it's an interesting adventure, and because what we think of as physical laws evolve along with everything else in the universe according to this process of causation, the time intrinsic to this process must be real and fundamental.

It is not the t ∈ ℝ calculus time pertaining to some imagined eternal law of physics (that sort of time could be subsumed into some static picture as a coordinate) because what we think of as laws of physics are themselves evolving regularities. In response to your comment then, time in Smolin's sense must be real because the process of evolving nature is fundamental and requires time---other stuff are ephemeral patterns of regularity which appear or develop in the process.

He is trying to explain the existence of what we consider to be the laws of physics, see the slides 6, 7, 8 where among other things he asks "Why these laws?"

 

[Chalnoth]

Listening to the first 30 minutes is a really good way, I find, to understand what he's driving at. I'll try to give a secondhand explanation too, but it is no substitute.

Maybe I'll take a look when I get home later.

What you say about not "likely to bear fruit" is true about a lot of highly original ideas that people try out. Most do not succeed. I mentioned earlier that this is a "high risk enterprise". Part of why it looks interesting and valuable to pursue. But it has other important merits in its favor as well, I think. This is not just any off-the-wall gambit.

To me, this particular feature makes it an off-the-wall gambit. He's basically saying that a macro property which isn't at all visible in our currently-known micro laws, but can be understood as a result of particular initial conditions, must actually be a result of even more microscopic laws. It's a strange sort of averaging that causes an effect to disappear only at intermediate scales, but is clearly-visible both at microscopic and global scales.

 

[marcus]

Maybe I'll take a look when I get home later...

Good. Looking forward to your comments.

 

[sheaf]

Pretty early on in the talk, he said something like "There are no global Killng vector fields on the config/phase space of GR with cosmological boundary conditions". Can anybody clarify what was meant, or provide a reference?

 

[Adrian07]

It may be felt that my thoughts are not worth putting down but watched the first 40 mins, finally someone with thoughts similar to mine regarding time, he's going in the right direction. Be interested to see if he can put things together or loses sight of the basics in complexity of his own making. If he gets it right then string theory RIP.

 

[Chalnoth]

Pretty early on in the talk, he said something like "There are no global Killng vector fields on the config/phase space of GR with cosmological boundary conditions". Can anybody clarify what was meant, or provide a reference?

It may help to read up on what a Killing vector field is:
http://en.wikipedia.org/wiki/Killing_vector_field

 

[sheaf]

It may help to read up on what a Killing vector field is:
http://en.wikipedia.org/wiki/Killing_vector_field

I'm happy with Killing vector fields, but the familiar Killing vector fields of GR generate isometries *of spacetime*.

However, Smolin says "there are no Killing vector fields or conformal Killing vector fields on this configuration space of general relativity".

I was thinking maybe when he mentioned the "configuration space of GR", that he was referring to something like Wheeler's superspace. It has a metric (the supermetric), and hence it has the concept of Killing vector fields. But I've never heard a statement like that before in this context. It was supposedly a theorem due to Karel Kuchar.

However, "configuration space" may have been misleading and he may have just meant something like "cosmological metrics don't admit Killing vectors".

 

[Chalnoth]

I'm happy with Killing vector fields, but the familiar Killing vector fields of GR generate isometries *of spacetime*.

However, Smolin says "there are no Killing vector fields or conformal Killing vector fields on this configuration space of general relativity".

I was thinking maybe when he mentioned the "configuration space of GR", that he was referring to something like Wheeler's superspace. It has a metric (the supermetric), and hence it has the concept of Killing vector fields. But I've never heard a statement like that before in this context. It was supposedly a theorem due to Karel Kuchar.

However, "configuration space" may have been misleading and he may have just meant something like "cosmological metrics don't admit Killing vectors".

I think it's a statement that you can always generate a killing vector field locally, or in certain special cases where there is a high degree of symmetry, but you can't apply one to all of space-time (at least not in an expanding universe).

 

[Boy@n]

Smolin has a new book (Time Reborn) coming out this month. Amazon has a page on it, with advance reviews.

Here is a link for those interested:
https://www.amazon.com/dp/0547511728/?tag=pfamazon01-20

It's great to see that they have a Kindle version too:
https://www.amazon.com/dp/B00AEGQPFE/?tag=pfamazon01-20

I haven't managed yet to watch the video or read reviews, but for now I'd just like to ask if ideas by Smolin are any near to ideas by Barbour?

Barbour's book from 2001 titled 'The End Of Time', link:
https://www.amazon.com/dp/0195117298/?tag=pfamazon01-20

 

[skydivephil]

I haven't had a chance to watch the video yet, but it seems that Smolin is saying the opposite to Barbour who argues time is an illusion. Is that correct?

 

[Tanelorn]

This is very interesting to me. Does anyone have a list of physical laws and/or constants that may have, or will change from the BB until now, and into the very distant future?

 

[marcus]

I haven't had a chance to watch the video yet, but it seems that Smolin is saying the opposite to Barbour who argues time is an illusion. Is that correct?

That seems correct, though someone who knows Barbour's position on time better than I do should probably answer. For Smolin time is real and fundamental. Not an illusion.

There is a slight chance that the difference is semantic however. I have to go, back later to address this possibility.
Back now. I don't really know enough to speculate properly but the way it could turn out to more of a semantic difference is that both are talking about change as being fundamental. That is, no "block universe". So there is no "fourth dimension". In that sense Barbour might say that "time" the fourth dimension does not exist. There is the world, and it changes, and Barbour in a purely classical non-quantum way can show you how, by watching dynamical systems change, you can see time being measured out by change.

Smolin is certainly more ambitious in that he wants physical law to emerge and quantum probabilities, he wants the whole business to arise from very simple primitives: a set of primitive events that keeps on growing as existing events cause the next generation of events.

But it seems that for him also there is no block, there is no fourth dimension, there is only a world that keeps changing. So change is the real thing for him (just as I think it may be for Barbour) the difference could be, primarily, that Smolin calls this process of change "time" and Barbour does not call it "time". A basically semantic difference not a deep philosophical opposition, IOW. Just a two cents worth of guess.

The thing to remember though is that whatever their basic fundamental similarities/differences, Smolin is trying for much much more. He is trying to schematize the whole caboodle, explain why the Laws are these Laws and not some other Laws, and how they came to be, from an extremely simple generic kit of primitives. It is wildly ambitious and so, in that sense, not to be compared with Barbourism.

 

[Tanelorn]

I thought that space and time had no properties and no real existence of their own, unlike sub atomic particles of ponderable matter. All the Physics we have is based ultimately on the way all these particles interact with each other. Their fields and energies and relative locations create the illusion of space and time in our minds like an electron beam creates the illusion of a picture on a CRT.

A specific Time isn't a location that you can ever travel back to in a time machine, it is an exact position, state and energy of a virtually infinite number of particles thoughout the whole cosmos. Hence reordering this condition is the only way to go back in time, which of course is effectively impossible.

 

[sheaf]

I'm happy with Killing vector fields, but the familiar Killing vector fields of GR generate isometries *of spacetime*.

However, Smolin says "there are no Killing vector fields or conformal Killing vector fields on this configuration space of general relativity".

I was thinking maybe when he mentioned the "configuration space of GR", that he was referring to something like Wheeler's superspace. It has a metric (the supermetric), and hence it has the concept of Killing vector fields. But I've never heard a statement like that before in this context. It was supposedly a theorem due to Karel Kuchar.

However, "configuration space" may have been misleading and he may have just meant something like "cosmological metrics don't admit Killing vectors".

I think it's a statement that you can always generate a killing vector field locally, or in certain special cases where there is a high degree of symmetry, but you can't apply one to all of space-time (at least not in an expanding universe).

Actually, I think Smolin was referring to symmetries of superspace (or lack thereof!), since this is what Kuchar was talking about in thishttp://jmp.aip.org/resource/1/jmapaq/v22/i11/p2640_s1?isAuthorized=no

... However, the curvature scalar in the super‐Hamiltonian breaks the conditional symmetry of the supermetric term and turns geometrodynamics into a theory without any symmetry...

 

[negativzero]

marcus gets creds for finding this entertaining and challenging lecture.
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I've watched Smolin's video numerous times over the last week., taken copious notes, cross-referenced, listed quotations, and wondered.
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If the lecture has a punch line, it's that, "...Spacetime emerges when there are consistent solutions to all the equations..." And further, "...Spacetime inherits its metric from momentum space..." Note, he's not claiming physical spacetime emerges from momentum space, he's saying that given his simple combinatorial algebra represented by causal trees, a mathematical spacetime emerges. [He declares it is a flat spacetime.]
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Why do i call this the punch line? He uses this discovery of emergent spacetime to illustrate how his new "...framework from which to do quantum calculations..." can reveal physical laws. That's the point of the lecture. His framework is a limited success! He stated clearly that the framework is his goal. He spends the first 40ish minutes explaining the need for his framework, then he reveals his model. Playing with the model reveals that what starts out as a sequential momentum space implies a embedded spacetime. Moreover, he connects this emergence of spacetime repeatedly to his previous discussions and study of relative locality. As he says, "...relative locality also assumes energy precedes position..." When one audience member asks where spacetime comes from, Smolin stalls him a little but refers to another discussion of relative locality as a "hint" as to how spacetime evolves from his model. In other words, the emergence of spacetime is a continuing theme for Smolin. This emergence is important not so much for the result, but that his method produces results at all. His framework is a success, and showing how spacetime can emerge from the fundamental ideas of his framework proves the framework succeeds. [Another limited success is that he can distinguish past from present unambiguously with his algebra. Past events have 2 daughter events, present events have 1 or none. But this declaration doesn't act as a punchline, at least not in this talk.]
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He points out that, "...there's a lot of people who... discuss frameworks for fundamental physics... for whom energy and momentum play no role..." He explains his contemporaries' predilections by referring to their dependency on Noether's theorem which provides that any differentiable symmetry corresponds to a conservation law. Smolin thinks this is too easy, and dubious logic to boot. He argues that eternal laws don't cause things, physical things cause things. He would rather start with something physical such as momentum which generates events according to rules he calls constraints, and describes with Lagrangians. With an algebra describing such a universe, he seeks to discover any laws. This is an intrinsically empirical approach compared to prevailing cosmology, even though the experiments are purely thought experiments. And it's different, very different from prevailing cosmological treatments. It's a kind of chicken or the egg dispute. Do we describe the universe using immutable symmetry and conservation laws? Or do we start with physical events and figure out what possibly mutable ideas are to be discovered? These are colossally different approaches.
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Besides the content, the structure of his lecture also tells me that the emergence of spacetime is the punchline. He spends 40 minutes priming his audience to understand the need for his framework, then he reveals his model over a 5 minute period finishing by declaring that spacetime emerges. At that point he opened up to questions (he was open to questions through out the talk but the frequency of questions increased.) He spends much of the last 40 minutes spelling out details and reassuring the onlookers that he is not proposing a new cosmology, but just a new set of models showing how his method can uncover new truth. Rather than assuming eternal laws a priori, he seeks to discover laws in this case by first describing momenta as edges and events as vertices in a simple 1+1 dimensional model.
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His polemics are multitudinous, and tons of fun. I could take off on several subjects he touches on, but for now I would like to ask fellow posters if anyone has any insight as to how one determines that such a space is "flat." Yes, i see it as a mathematical space, and it seems flattish i suppose, but does anyone understand the topological analysis that would reveal a flat curvature?
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Just to be forthright, i must admit that i personally favor any theory that begins with energy in time and derives space as a result. Thus my apprehension of the emergence of spacetime being the punchline may be colored by my own prejudices. So if other readers find that his comments on emergence of spacetime are merely conclusory to the body of the lecture, I'm fine with that. But the word "punchline" has more zing, and I think he meant to come up with something zingy.
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Regardless, i appreciate any comments.
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[negativzero]

Smolin does mention the emergence of massless particle dynamics circa minute 49.
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He takes the case where the sequence of events is characterized by a long chain of momenta going preferentially to one daughter at the expense of the other, sequentially. This is like the path of a free particle. When the sum of the "orphaned" daughters' events' momentum is small, and t is small, his equations reduce to standard form for a free relativistic massless particle. {i use the word "orphan," referring to the event which
gets negligible momentum.}
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Okay, i admit. This too is punchline material.
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[marcus]

You've probably dug into it deeper than I. There's not much I can add to what you say here. With a creative paper like this there can be several different interpretations of what the punchline is. Probably there is not just one correct reading of its significance. An original paper can spawn several different lines of thinking and research. So I won't quarrel with your "emergence of space" punchline. It would be pointless to argue which interpretations are better than which others. But I'll tell you how I see it.

For me, the only reason to be interested in the emergence of space is as a set-up for the emergence of laws of motion and other laws (regularities) of nature that require a geometric framework simply to state them.
For me, space (i.e. geometry) is just a bunch of geometric relationships like near far inside outside between angles adding up and volume or area related to radius and plus the way these relationships are always changing. The angles change what they add up to, the relation of volume to radius changes, distances change etc.

It would be incredible if Smolin (and or others) could get dynamic evolving geometry to emerge from a simple basis like a set of primitive "events" and a breeding rule or "causation" principle according to which parent events cause offspring events. It is such a tall order. It almost has to fail. But how great if it succeeds to some degree! Maybe simply to generate a flat geometry, as you said, that would be great already!

But that is not the goal as I see it. Once one had something that looked like a geometric framework the "real" goal would be to explain laws, how can laws of motion have evolved? How can all this regularity that we see have developed?

Because he is doing something totally new here: he is challenging the Newtonian paradigm in which Laws stand above and outside the universe and just Are what they Are, eternally, and our job is to discover those laws, and the initial conditions that (under the operation of the laws) led to the present state of affairs.

That is kind of a pre-Darwinian picture where the animal and plant Species are the Species and they are given, eternally fixed just so. And then Darwin and others figured out how species develop and that you could explain why we have the species that we have. Smolin wants to explain why we have the physical laws that we have.

It is such an ambitious program that you could almost count on it turning out to be a grandiose debacle. But I find the attempt fascinating. Anyway, for me, it is not just about the emergence of "space" (whatever one imagines that to be).

But I have to acknowledge that you have plenty of reasons to back up your interpretation. Both interpretations could be valid---one of these things it's useless to argue about.

I'll try to get a quote from one of his slides that relates to the idea that physical law regularities evolved over time.

 

[negativzero]

You (meaning marcus): "...dug...deeper than I..."
Actually i fixated on the one video. That's all. I'm shallower than a sheet of graphene.
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You" "...With a creative paper like this there can be several different interpretations... not just one correct reading... can spawn several different lines of thinking and research..."
i agree. The emergence of spacetime and massless relativistic particle dynamics, along with a conveniently simple definition of past and present are modestly successful results. But a particular almost idiosyncratic set of assumptions underlie his selection of algebraic models.
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His is truly a unique style of quantum cosmology. You could call it, "Inside Out Cosmology." Instead of starting with rules and plugging in values, the theory is to find the values, the only values that consistently solve the equations in his algebra (since this is a thought experiment), and then induce rules from outcomes, which he calls events.
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The inquiring soul however can sing along with his 40 minute introductory ballad of fundamental soul searching.
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You: "...For me,... the reason to be interested in the emergence of space is as a set-up for the emergence of laws of motion and other laws... "
My first interest in time was just after Grampa died. i was almost 5. We got 2 tv stations. i could watch the McCarthy hearings or Flash Gordon. Flash went back in time by exceeding the speed limit for light and saved his buddy. i felt a duty to make a pitch for going back in time to save Grampa. My dad got his best friend to explain enough relativity to me that i understood Flash could never pack enough rocket fuel to go back in time. And importantly, we couldn't save Grampa. The interest in time remained. Space comes in various forms. Physical, mathematical, empty space, vacuum, occupied space. Defining space is difficult and what people wind up with are frequently self assuming definitions. For now, i define physical space as anywhere energy can go, and getting there is time. i get two main things out of my definitions. Trivially, where propagation can't happen, there is no space. Significantly, with a math model, describing where particles can go defines the space of the particular algebra. My question generally is whether the same applies for physical space? It is the presence of physical particles which generates the potential to be elsewhere, not some rule about space? In this sense, physical particles would create space in much the same way that algebraic rules create mathematical space. And that is what we want out of physics after all; to come up with rules that mimic reality. But that's just me.
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You: "...It would be incredible if Smolin (and or others) could get dynamic evolving geometry to emerge..."
Interesting you should mention this. i got the strong feeling that he was trying not to hotdog. He was definitely soft pitching the overall significance. But i noticed a young woman in the audience [perhaps a co-author?], seemed more gung ho on the idea that they have a discernible cosmology. In the lingo between researchers, that, "they are on to something!" It was hard to pick up on the personal interplay there, but he did mention something about her enthusiasm. She's the one who launched into an explanation to another audience member for why no two things could have exactly the same traits, but it's hard to hear her with my set-up.
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The Principle of Precedence looms large. You could say it is the single most different thing about his cosmology. With it, by analogy, he would take a basketball, a hoop, and some guys, and bounce the ball around, and shoot some baskets, play team keep-away for a while, and then try to write good rules. This, is instead of buying a book, building a court to suit, manufacturing a ball to suit, and starting a league with rules in hand.
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He says he wants cosmology where there's an objective difference between past present and future but I'm stumped as to where he explains the nature of the future. i personally have never seen any example of the future that wasn't just talk about the future, predictions, probability amplitudes. My simple headed interpretation as a result is that the future is at most a subset of the present, consisting of predictions about it. Otherwise, the future DOES NOT exist. He clearly rejects Platonism, thus i would assume he rejects the notion that the future exists too. But not so, i fear. The fact is he plainly said there is an objective difference between future and present. Dang if i can find it in his lecture, though.
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i don't see Darwin here, at all. Darwinian logic is a little circular. The animal survives to replicate because it's fit. It's fit because it survived. It doesn't explain anything, or predict anything. In that sense Darwinian evolutionary theory is not even a scientific theory at all, because you can't make any predictions from it. At least no one has yet. It's little more than a comfortable way to review history. Regarding Darwin i quote Mata Hari on Lancelot Link, "They got pies too, Lance!"
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You: "...It is such an ambitious program that you could almost count on it turning out to be a grandiose debacle..." Yeah, like i said, i get the feeling he doesn't want to hotdog it, for just that reason. And of course, as you say his approach is not just about the emergence of space. Emergence of space, particle, and past/present, are just pretty feathers in his bonnet. He's trying not to do an overt victory dance in the endzone punctuated by spiking the ball, He still has to get further funding. Decorum. Competitors are jealous.
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Back on the flat space question: his algebra looks fractal for short sequences. That would imply less than 2 dimensions. It wouldn't be linear, and i guess you could always map it onto a plane, so being 1.67 dimensions or so wouldn't mean it's NOT flat. How smooth does it have to be to be flat? i assume he's working with the flat topology because it's simpler for now. But you know he's keeping it in mind that experimentation shows space is flat, but he needs a hedge, just in case. U is the hedge. Flat is U=1. He said something about having problems finding any solutions where U is not=1. This could be a fatal flaw, at least for the 2D version. i assume he expects that his findings can be extended to more dimensions. He says the momentum space embeds it's flat algebra in the resultant space, but the momentum space looks more like a fiber to me. Yet being able to put fibers into a plane would seem like a good test for flatness. As an undergrad student i learned that it's really flat because a PhD says so. At any rate, the more i look at flatness the more i feel like a cartoon character myself.
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[negativzero]

i think i clarified one issue:
Smolin says, "...Time is real means: all that is real is real in a present moment which is one
in a succession of moments (12:10)..." This would mean that to the extent that the future is real, it can only be real in a present moment. Yes!.. But he goes on to say that rules, and laws can legitimately refer to past, present, and future, for reasons which remain unclear to me. My 8-ball grows dark. Did you already comment on that marcus?
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[skydivephil]

You (meaning marcus): "...dug...deeper than I..."

"
i don't see Darwin here, at all. Darwinian logic is a little circular. The animal survives to replicate because it's fit. It's fit because it survived. It doesn't explain anything, or predict anything. In that sense Darwinian evolutionary theory is not even a scientific theory at all, because you can't make any predictions from it. At least no one has yet. It's little more than a comfortable way to review history. Regarding Darwin i quote Mata Hari on Lancelot Link, "They got pies too, Lance!""
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I know this isn’t the right forum for this topic but since you raised I can't let it go.
What you have said is not correct at all. Survival of the fittest is not a phrase that Darwin even used. Darwin tells us that species evolve over time, creating a nested heriarchy of common descent, and that the reason for this include natural and sexual selection. His theory makes many predictions, possibly more than LCDM makes. .
Perhaps you might read some literature on the subject. Below is an example on human genomic evolution to get you started.
https://www.amazon.com/dp/1591025648/?tag=pfamazon01-20
. if you don’t want to buy a book,, here are 29 individual falsifiable predictions made by Darwinian theory:
http://www.talkorigins.org/faqs/comdesc/
and there are more predictions in the book above. . How many do we have for LCDM?
To quote the chimp genome draft published by Nature, a joint pAper by most of the leading genomic institutions in the world.
“More than a century ago Darwin1 and Huxley2 posited that humans share recent common ancestors with the African great apes. Modern molecular studies have spectacularly confirmed this prediction”
http://www.nature.com/nature/journal/v437/n7055/full/nature04072.html

Smolins theory of CNS is not as similar to Darwinian theory as some may believe, In biological evolution things are driven by a lack of resources, hard to see how that applies if Smolin's CNS is true.

 

[Adrian07]

negativzero you seem to be nearly as interested in time as me, shame the forum rules do not permit a proper discussion on the subject, I think we could have one serious discussion on the subject. I cannot believe time was relegated to such minor position. I find smolin neither radical or controversial but basic. Lectures seemed like a man stumbling in the dark looking for a door he knows is there somewhere. I admit my abilities are limited mathematically but time is not about the universe you can see but about the one you cannot see so thought experiments are far more useful. Whether my ideas are right or wrong time will tell. Be interested to see where this so called "radical" idea goes and if he can get it from controversial to revolutionary.

I agree this is not he thread for a discussion on evolution but I see it simply as simple systems interacting to form more complex ones, although complexity seems to lead to instability

 

[negativzero]

skydivephil,
Thanks for your response!
i didn't bring up Darwin, my fellow poster.
However:
http://www.literature.org/authors/darwin-charles/the-origin-of-species-6th-edition/
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Notice the title of chapter four, "Natural Selection: Or the Survival of the Fittest."
Darwin's words, not mine. Now one can argue about what he meant or why he wrote it, but it was writ by him.
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And i looked at:
http://www.talkorigins.org/faqs/comdesc/
and found not one single prediction that has been verified.
Did you read the works your source cited?
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Darwin said a lot of things besides this much repeated and hallowed phrase, but when people speak of "Darwinian Evolution," especially people in other fields, they mean survival of the fittest.
As an incorrigible speaker and reader of English i don't think i need sourcing here, however:
http://medical-dictionary.thefreedictionary.com/darwinian+evolution
and, http://www.merriam-webster.com/dictionary/darwinian
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i don't think i have to cite more iterations of the common meaning. On a physics forum i doubt that references to him are about "...creating a nested hierarchy of common descent..."
Seriously, give this objective question to a hundred posters on this forum, to wit:

"A. Darwinism refers to natural selection by survival of the fittest; or
"B. Darwinism refers to species evolving over time, creating a nested heriarchy of common descent."

We are both pretty sure how a majority of posters would answer. "A" is the common parlance, and "A" would be the most common answer. We are talking about usage here.
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Darwin is fine with me, i just don't get any predictions out of him, except perhaps that new species may develop from old ones as in the past, and that most species have gone extinct, so it's likely ours will too. The problem is that these are not specific predictions in form or time.
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But i see what you are saying, i think. Perhaps physical models could evolve as an analogy to the evolution of species. Looking around, as an observer of science i think maybe ideas do evolve sometimes. They also devolve. This discussion reminds me of the word "progress." Do we progress, or do we just change technologies? "Evolution" often implies some kind progress, especially when it refers to human endeavors.
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Yeah, i hope his theories get bigger and better, and when those ideas die, hopefully their progeny will live on to enlighten mankind even when mankind has evolved into a species populated soley by Nobel Laureates.

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[negativzero]

Adrian07,
Hey! i appreciate your post.
Smolin is on your side!
He starts with sequential momentum. Sequentiality is time. Given his rules (algebra) he gets a nice flat space/time, with a distinct past and present, and particles! The particles here are massless, but they have paths.
i think he agrees with you that cosmology without time (and he would say energy too) is avoiding the question of why things happen the way they do. To say the universe was just a fortituous initial condition of fundamental values given a spacetime and some quantum mechanics, does not satisfy him. He thinks it's a process; the universe is an emerging process.
If you asked him, does he begin with energy in time? i think he might agree without reservation. But i shouldn't put words in his mouth. Maybe someone could persuade him to post his theory here in 50 words or less.
As for evolution, Smolin brings up the concept himself. i'd say that makes the evolution topic semi-legit unless we start debating Lamarck.
Yes, his lectures are kind of odd. If you close your eyes, he sounds like Woody Allen.
Take care of yourself Adrian07
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[negativzero]

Adrian07 [in part]: "...Lectures seemed like a man stumbling in the dark looking for a door he knows is there somewhere..."
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i'm trying to imagine the spot he's in. He's actively trying to describe a new way of quantizing the universe. It's about cosmolgy for sure. It also has to be about time, energy, space, generally, and more specifically he wants a strong theory which will predict and explain a lot of specific questions that he thinks are important for a cosmology to answer. i.e. Is the present thick or thin; is every present event related to lots of other present events or is each event just the result of 1 previous event---that's just one question.
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On top of this, the lecture is polemic. He has to to dissuade folks from their previous assumptions for at least two reasons: 1. Their wrong-headedness is the MOTIVATION for his novel cosmology; 2. When he says words like, "Universe, event, Lagrange, constraint, or time," in order to understand him, they have to give up their old notions and open their minds. So he has to judge just how much his audience needs to be re-oriented. After all, how many people fret over whether Noether's theorem is appropriate?
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So he's telling us a bunch questions he wants to be able to answer, and physical situations he wants to describe, but with a new set of mental tools. He might have a very organized way of looking at this approach himself, but he still has to imagine just how disorganized other people's thinking is, in order to communicate.
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And i agree with you that he is all over the place!
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[skydivephil]

This willl be my last post about evolution as its too off topic. If you stand by your claims and want to continue to talk about it, please start another thread in the biologiy section and Pm me

I will offer a correction to a minor point, I should have said “survival of the fittest is not a phrase Darwin originally used , nor is it a phrase relevant to evolutionary theory today.”
If you read the wiki page:
http://en.wikipedia.org/wiki/Survival_of_the_fittest

Herbert Spencer first used the phrase – after reading Charles Darwin's On the Origin of Species – in his Principles of Biology (1864), in which he drew parallels between his own economic theories and Darwin's biological ones, writing…Darwin first used Spencer's new phrase "survival of the fittest" as a synonym for natural selection in the fifth edition of On the Origin of Species, published in 1869.[2][3] Darwin meant it as a metaphor for "better adapted for immediate, local environment", not the common inference of "in the best physical shape".[4] Hence, it is not a scientific description.[5]
The phrase "survival of the fittest" is not generally used by modern biologists as the term does not accurately convey the meaning of natural selection, the term biologist’s use and prefer. Natural selection refers to differential reproduction as a function of traits that have a genetic basis. "Survival of the fittest" is inaccurate for two important reasons. First, survival is merely a normal prerequisite to reproduction. Second, fitness has specialized meaning in biology different from how the word is used in popular culture. In population genetics, fitness refers to differential reproduction. "Fitness" does not refer to whether an individual is "physically fit" – bigger, faster or stronger – or "better" in any subjective sense. It refers to a difference in reproductive rate from one generation to the next.[6]
Your point relies on “fitness” being used in a way that is not consistent with current science, you are not fit because you survive, and fitness is about reproduction in this context.

We can think about this related to CNS, a universe that is fit in this case, is one that makes black holes, not one that lives for some extended amount of time.

Your point about common usage is irrelevant. There are plenty of people that make mistakes about modern cosmology, For example that the big bang started from a point in space or that the entire universe (rather than the entire observable universe) was once smaller than an atom or that the big bang proves there was no space or time before the big bang. All of these are commonly held misconceptions, should cosmologists defend them or correct them?

I have no idea how you can say there are no predictions made by evolution, this is ridiculous statement. Here is a simple prediction; you won’t find a rabbit in pre Cambrian strata. It’s falsifiable too.
A more sophisticated prediction, discussed in the talk origins document. Humans and chimps will share more common pseudo genes than humans and mice. This is found. Again Ill quote you the Nature document you conveniently ignored. Again Ill remind you, its co authored by a large number of the leading genomics institute in the world:
“More than a century ago Darwin1 and Huxley2 posited that humans share recent common ancestors with the African great apes. Modern molecular studies have spectacularly confirmed this prediction”
http://www.nature.com/nature/journal...ture04072.html

Another piece that is in PNAs and nature:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC52649/

“We conclude that the locus cloned in cosmids c8.1 and c29B is the relic of an ancient telomere-telomere fusion and marks the point at which two ancestral ape chromosomes fused to give rise to human chromosome 2.”

Also echoed in the Nature paper:

http://www.nature.com/nature/journal/v434/n7034/full/nature03466.html

Human chromosome 2 is unique to the human lineage in being the product of a head-to-head fusion of two intermediate-sized ancestral chromosomes.

 

[Adrian07]

negativzero due to rules can't go to far in saying where I think smolin needs to go but the door I think he is looking for is always behind him and can only be found and opened through power of thought. Any more than this I might get away with a private message to you, leave you to OK or not.

 

[inflector]

skydivephil asked:

I haven't had a chance to watch the video yet, but it seems that Smolin is saying the opposite to Barbour who argues time is an illusion. Is that correct?

and Marcus responded:

I don't really know enough to speculate properly but the way it could turn out to more of a semantic difference is that both are talking about change as being fundamental. That is, no "block universe". So there is no "fourth dimension". In that sense Barbour might say that "time" the fourth dimension does not exist. There is the world, and it changes, and Barbour in a purely classical non-quantum way can show you how, by watching dynamical systems change, you can see time being measured out by change.

Smolin is certainly more ambitious in that he wants physical law to emerge and quantum probabilities, he wants the whole business to arise from very simple primitives: a set of primitive events that keeps on growing as existing events cause the next generation of events.

But it seems that for him also there is no block, there is no fourth dimension, there is only a world that keeps changing. So change is the real thing for him (just as I think it may be for Barbour) the difference could be, primarily, that Smolin calls this process of change "time" and Barbour does not call it "time". A basically semantic difference not a deep philosophical opposition, IOW.

Barbour's view of time has been one of my core interests for the last three or four years.

My take is that as Marcus surmises, this is indeed a semantic difference rather than an underlying conflict in meaning.

Barbour says that time—as this objective linearly progressing fourth dimension—does not exist, indeed, that what is fundamental is the flow of change, not the concept we think of as time post-Einstein and post-Minkowski.

Smolin is using "time" as a word to represent the directional flow of change. And he's saying that the directional flow of change is fundamental. And more, of course...

Barbour would support these ideas of Smolin's with respect to time, even if he and Smolin use different definitions of time in this instance. Barbour's time is the more restricted linear flow that shows up in repeating clocks which he defines as oscillators with periodicity, a time that can be represented mathematically as a negative fourth spatial dimension. And Barbour says that is not fundamental, and so in that sense is an illusion, but that this more limited concept of time is an emergent phenomenon that develops from the more base flow of change through the system.

And Smolin would support Barbour's notion of directional causal flow being fundamental rather than a fourth-dimension of time.

 

[negativzero]

marcus was correct in discussing the notion of "evolution."
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Smolin brings up the term more than once, and he's not just talking about "evolving" his own ideations.
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Quoting Smolin, circa 14:20 thru 15: 50 in the video: "...what is this thing which is supposed to be a law of physics which does not have any evolution in time, doesn't have any physical properties, but acts at every moment telling things what to do? How do electrons and quarks know which equations to follow?..."
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It doesn't get more polemic than this. Here he is raging against the storm of wrong thinking!
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It's unequivocally clear from the above comment that one of Smolin's critiques of modern cosmology is that the rules DON'T evolve! At least not properly. And notice how Smolin gnashes his teeth threateningly. Such passion!
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Creds again to marcus. This time for understanding. It's a good thing to be wise.
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But there should also be room in the world for pedantic dogmatic pigeon holers. Mostly because they are here already.
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[TrickyDicky]

Barbour's view of time has been one of my core interests for the last three or four years.

My take is that as Marcus surmises, this is indeed a semantic difference rather than an underlying conflict in meaning.

Barbour says that time—as this objective linearly progressing fourth dimension—does not exist, indeed, that what is fundamental is the flow of change, not the concept we think of as time post-Einstein and post-Minkowski.

Smolin is using "time" as a word to represent the directional flow of change. And he's saying that the directional flow of change is fundamental. And more, of course...

Barbour would support these ideas of Smolin's with respect to time, even if he and Smolin use different definitions of time in this instance. Barbour's time is the more restricted linear flow that shows up in repeating clocks which he defines as oscillators with periodicity, a time that can be represented mathematically as a negative fourth spatial dimension. And Barbour says that is not fundamental, and so in that sense is an illusion, but that this more limited concept of time is an emergent phenomenon that develops from the more base flow of change through the system.

And Smolin would support Barbour's notion of directional causal flow being fundamental rather than a fourth-dimension of time.

Certainly both Barbour and Smoling ideas on time are interesting, suggesting, important, etc.. but I must confess that after reflecting a bit on their conclusions they don't seem to really lead to a progress in our understanding beyond ideas that are many, many years old, going from the Einstein comments about time as illusion(the famous Einstein quote comes to mind:"People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion.") I mean the remark that in relativity the important thing is not time by itself (or space by itself, either, let's remember Minkowski's words in his legendary 1908 speech "Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.") but the "flow of change" is very old (and still illuminating of course), and I'm not sure Barbour/Smolin are ultimately saying anything beyond this, which I'd say it is important to be said or remembered, I'm not critizicing them, yes it is profound and suggesting, but I miss the practical side. In other words I'd say the points Inflector remarks above where Barbour and Smolin agree, that the fundamental is the flow of change, is already implemented in GR as we know it.
Maybe it's me but if there is more to Barbour/Smolin ideas on time different than what Minkowski and Einstein were saying I'd like to be enlightened.