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

[Chalnoth]

Chalnoth, are you not using mathematics to prove one possible view of reality, but that view might yet still not be the truth of our reality?

I don't think there's any question that General Relativity accurately describes the large-scale behavior of our universe. It's just too well-tested for that. There's no question that the theory breaks down at very strong space-time curvature, or that it has to be modified to take into account quantum mechanics. But there's also good reason to be extremely confident that it has the general, large-scale picture correct.

Sure we can write down a coordinate as consisting of three spatial numbers and a temporal one and then we can think that this unique 4D point really does exist forever

I think the problem here is that you're thinking of some sort of "super time" that exists outside of the time we experience. This isn't the case: there's just time. A point in the past doesn't "always" exist. It exists in the past. The past is perhaps best understood as another location, separated from us in a direction we can't actually point.

There may be good reasons why time machines are impossible, but this isn't one of them.

 

[Tanelorn]

I am still trying to find the right words to describe what I meant and the closest metaphor I can find is the way that a computer generates a 3D world in a 3D game. Each moment is calculated on the moment that came immediately before, and when the calculation is complete, the moment and information is lost or discarded. Reality in this model is therefore a succession of moments and the past is gone. Can such a view be disproved?

 

[Chalnoth]

I am still trying to find the right words to describe what I meant and the closest metaphor I can find is the way that a computer generates a 3D world in a 3D game. Each moment is calculatated on the moment the one that came immediately before it and when the calculation is complete the moment and information is lost or discarded. Reality in this model is a succession of moments.

Right. I know what you're trying to say. I don't think it is a workable model, however. The problem is that another viewer might see a different slice in time.

The way I like to understand the way this works instead is that the physical laws provide a system of constraints. If you were to take the entire wavefunction of the universe at one particular time-slicing, you could, had you a powerful enough computer, compute the precise wavefunction of the universe for every other time-slicing. No time-slicing is more or less real than any other, and there isn't a sense in which one time slicing ceases to exist as another comes into existence: that view can't work in light of the fact that different observers see intersecting time slices.

The really interesting bits are in how we can translate from this "bird's eye" view of the universe to our own view.

 

[negativzero]

Sequentiality is a timelike feature of the pointlike perspective. i don't see how that makes it's timeline false or that sequentiality from another point of view is necessarily contradictory. Not that anyone said that, but i hold out hope that there will be a picture of time in physics that includes time as fundamental, and doesn't deny the human perspective.
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Smolin is trying to build a quantum picture of what is going on, and that, to a large extent, is going to be about particles. Particles are pretty pointlike. He begins with conservation of momentum which drives the process to the next event, in a series of events.
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His models require event generators, which are laws which constrain the propagation
of momenta in the creation of new events. So you have a bunch of [particles] interacting, momenta constrained in a series of events, and then he defines past as having a sufficient number of daughter events (at least 2) and the present as having an insufficient number of daughter events (1 or none) to pass the test of a past event.
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Notice he's not just taking the point of view of one event, or one series of conserved momenta. He's looking at the whole crowd of events and picking which constitute past and which constitute present.
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Pretty nifty really. Omniscient?
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[i should say he's not advocating this theory, it's just one of the models he's been thinking about.]

 

[Tanelorn]

Due to the nature of time, our reality can only ever exist in the ever moving Planck time slice of the present and can only be dependent on the particle interactions from the immediately preceding Planck time slice.

None of the other past time slices interact physically on the present time slice any more than those of the future do, and so from our point of view they no longer exist.

 

[Chalnoth]

Due to the nature of time, our reality can only ever exist in the ever moving Planck time slice of the present and can only be dependent on the particle interactions from the immediately preceding Planck time slice.

None of the other past time slices interact physically on the present time slice any more than those of the future do, and so from our point of view they no longer exist.

By that definition, there are no interactions at all.

 

[Tanelorn]

I am saying that only what is going on in the immediately preceding time slice has an effect on the new present time slice.

 

[Chalnoth]

I am saying that only what is going on in the immediately preceding time slice has an effect on the new present time slice.

Well, no. If you have all of the information of the immediately-following slice, you can also compute the full configuration of the current slice. For that matter, if you have any time slice at all, you can (with enough processing power), compute any other slice. So there's no way in which the immediately-preceding slice is unique in this regard.

 

[Tanelorn]

Well, no. If you have all of the information of the immediately-following slice, you can also compute the full configuration of the current slice. For that matter, if you have any time slice at all, you can (with enough processing power), compute any other slice. So there's no way in which the immediately-preceding slice is unique in this regard.

Yes, but the only time slice needed to determine the next time slice is the one immediately before. None of the other time slices are required, or have any effect on the present time slice, and therefore they are no longer real. Only the ever moving present time slice is real.

It all depends on how time outside of the present time slice works and whether time is perpetual or as I describing an ever moving very thin slice of present time. A perpetual model of time would require the storage of at least 10^44 copies of the entire universe per second. Since our movement through time cannot ever be broken anyway, perpetual time seems wasteful and nature does not like waste. So I now question HG Wells model of time.

 

[Chalnoth]

Yes, but the only time slice needed to determine the next time slice is the one immediately before. None of the other time slices are required,

What do you mean by, "required?" Any time slice is sufficient. Doesn't matter which one. You don't need the immediately-preceding one. You can pick any time slice you want.

or have any effect on the present time slice, and therefore they are no longer real. Only the ever moving present time slice is real.

So, according to you, a different observer moving relative to me who sees a different time slicing interprets most of my present time slice as being not real.

How does that make any sense?

Furthermore, this definition of reality includes parts of the universe that always have been and always will be causally disconnected from an observer.

 

[Tanelorn]

Chalnoth, sorry I think I am just repeating myself so perhaps I don't make any sense. If I may, just one last time:

Consider the video game analogy, all that is required to compute iteration n is iteration n-1. It is not necessary to store iteration n-2, or any older iteration data, so in an efficient system any data older than iteration n-1 would be discarded as unnecessary and therefore no longer exist.

General relativity, special relativity, and frames of reference effects not withstanding, I am suggesting that only particle interaction data in time slice n-1 are required to be able to compute or create time slice n, nothing more than this.

From this perspective we would literally have to reverse the direction of time (equivalent to the computer clock, which unfortunately can only be positive!) for the entire universe to be able take the present time slice backwards in time and we have no control over the direction of the arrow of time at least from inside our Universe. The past is therefore gone and the only way of recreating a past iteration would be to start the whole thing over again from time slice or iteration 0.

The Universe in this model resembles a massively parallel computer and perhaps the finite speed of light and other properties of the Universe are due to the equivalent of computer hardware limitations. Or perhaps the finite speed of light is just necessary just to prevent everything in the whole universe interacting simultaneously with everything else. Cause and effect could potentially become completely unstable if the speed of light were not finite.

I saw an episode of wormhole recently where they proposed another "computer" metaphor like this, and they mentioned how particle interactions, or was it diffraction patterns, become more precise depending on how closely they are being observed. i.e. the "computer" appears to calculate particle data more precisely depending on whether or not a more exact measurement is being required.

 

[negativzero]

The time as a film analogy suggests that since a film may be run backward, time could somehow run backward too. A universe where time ran backward like a film would presume that the forward version had already been made, or it couldn't be reversed. That would require a deterministic universe and would throw the uncertainty principle out the window.
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Any picture of time reversal from a piont-like perspective is going to require that you [AND I MEAN YOU SIR!] stop every single particle and reverse it's direction back to precisely the position that it occupied at the time you want to go back to, and then...then...you will have to start everything back up again in the propah directioines senior!
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No one has evah proved that quantum reality is randomized, and they may not ever prove it {because after all, the sense of randomness might just be some cosmological dirty trick}, but i can't prove it is not randomized. Seems to be experimentally confirmed to an extent--Tomas Erber, Boston College. decay of single mercury atom ions. It looks to me like trying to run time back and forth in an attempt to repeat outcomes is futile at the atomic level. Running the film backward will not be exact, then running it forward will not be exact...Heisenberg. We can't suspend all the rules of physics to nurture our wish for time travel...'What's your name?..."Weena!"';
--H.G.Wells.
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Show me the past! If it exists, show it. Same with the future bud. I'm from Missourri on this one.
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Any version of the future that i have ever heard of is right here and now in the present. All there really is of the future, is predictions. And I've been looking too.
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Once the wave form has collapsed, it's history. Von Neumann and Feynman would agree with me. We are talking particles here, not relativity.
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It doesn't matter what perspective one takes, one can't change the outcome. Collapse means, "It's ovah BAby!"
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But that's all me. Smolin i think is taking a more fundamental and less didactic view than myself. Regardless of any GR, he takes the sequential world path seriously. {By the way, the sequential world path is personal. It's yours and mine.} He suggests that one can build a two a dimensional reality from a whole bunch of 1 dimensional sequential life paths, and put together a possible template for a quantum 2-D space evolving or emerging as a result. He even leaves "u" as a possible bump out of 2-D into 3-D, but he says u is not working real well, so far.
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[Tanelorn]

negativzero, thanks, I think what you are saying is similar to what I was saying. I made one mistake though, you cannot recreate the exact same Universe again just by starting over, because it will be a totally unique and random Universe each time, even if all the laws are the same.

The alternative to this instantaneous present time slice model is the one where every piece of data for every particle is stored at 10^44 frames per second for the entire Universe. Then the data can be retrieved and a past reality recreated which then produces an effect similar to time travel, although it is not really an accurate description. Perhaps whoever is in charge is using data compression techniques and recording specific data for further offline analysis!


What could the purpose of such a Universe be? recreational perhaps? I hope I am just joking.."He even leaves "u" as a possible bump out of 2-D into 3-D, but he says u is not working real well, so far."
btw is u me, or the Universe, or something else?

 

[negativzero]

Tanelorn, my friends call me "minus,"

In the well known documentary, Star Trek, when folks get caught in a "time loop," they experience deja vu.
Somehow, the human mind transcends the physical limits of time keeping [note, the crew's wrist watches don't "ping" when time reverses].
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After playing exactly 10^44 do-overs in videogames, i can see why the intrepid crew would want some do-overs themselves. With enough opportunities, perhaps we can finally or perhaps perpetually get THIS UNVERSE right! i'd like to see my neighbors backyard cleaned up, for instance.
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If it's any consolation, judging by the rate of the wind thru my hair, we do seem to be "traveling" thru time but can't quite get out of first gear.
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Unfortunately, the only way to adjust time rate seems to be by changing relative acceleration or gravity wells.
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i'm already running as fast as i can, and I'm not in the market for a new gravity well right now.
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At any rate, since Smolin believes the universe is unique and emerging, i'd bet that he doesn't, "...tolerate do-ovahs 'roun' heah!"
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[negativzero]

Tanelorn: "...Yes, but the only time slice needed to determine the next time slice is the one immediately before. None of the other time slices are required..."
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Back to metaphors between computation and the universe itself, one of my calculus teachers used to tell me, that Alonso Church lectured him, i think it was at UCLA.
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Church would write a line of math, erase it, write the next line, erase that, and so on writing in one chalky spot on the blackboard, eraser in one hand, chalk in the other.
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Smolin wants physics where all particles in the universe have a shared past, with some kind of recordation of it, he called it "memory." Laws evolve as the result of memory of physical events. In some important way, something about the past is not "erased." [That part, i would call, "the present," but it's not about me.] This is not so different really from the oft repeated assertion that the current state of cosmological events is the result purely of initial conditions given the nature of space. The difference is really that the second view is from outside the system and the first view, Smolin's, is by the participant observer, trying to put it together from inside the system. While in one sense he is walking from GR, in the other, stuff is still relative in his inquiry; he keeps some rules of GR.
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The inside-out view allows for an evolutionary assumption. i personally am very reluctant to accept any "other universes" idea, as the experimental data is not there. However he mentioned recently at SETI, if it can be shown that the 30 parameters of the standard model are finely tweaked to maximize black hole production, not HUMAN production, but black holes, then his theory has credibility. And that would strongly imply NOT infinite parallel universes, but a kind of meta-time, which would connect a multitude of universes in a self replicating process, where each universe would be only a little different than it's mother. The meta-time would be the sequentiality of mother and daughter universes.
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[Chalnoth]

Consider the video game analogy, all that is required to compute iteration n is iteration n-1. It is not necessary to store iteration n-2, or any older iteration data, so in an efficient system any data older than iteration n-1 would be discarded as unnecessary and therefore no longer exist.

Right, but if I store iteration n-2, then I don't have to store iteration n-1, I can compute iteration n directly from iteration n-2. In fact, computer games generally have to be designed to accept different time durations between the iterations, because the amount of time used to compute the next frame can vary significantly both between computers, and between frames.

In principle, it would be entirely possible to design an animation where the computer only stores the initial conditions, and every new iteration it computes the current iteration from those initial conditions directly, instead of doing it based upon the previous iteration. In practice this isn't done because computer programs use a number of approximations that would make such large time deltas unworkable.

 

[negativzero]

If Smolin's theory of generation of universes by black holes is correct, it would EXPLAIN why the physical constants are what they are to a degree. It's conceivable that other combinations of tweaked constants could also evolve on a slightly different basis. He's saying that the parameters are tweaked locally. When he examines them, he doesn't vary their values greatly. He says that would be too difficult. He said that at SETI.
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More accurately, he said about 12 parameters were already "tweaked" and the rest seemed to be neutral.
That, to me, suggests that a variety of universes might evolve with 18 very different parameters, but which still maximize black hole generation! His number is 30 total parameters.
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[Tanelorn]

I want to thank everyone for thoughtful discussion. I will probably continue to think about this whilst traveling over the next 2 weeks vacation.

Chalnoth, I wouldn't use iteration 0 or n to compute iteration n+(10^44)*billions of years. I would instead use the most recent possible iteration to reduce required processing. However perhaps processing time is not an issue if each iteration is calculated outside of our observed time flow. However again, since particle interaction has many random qualities, you could not use older time slice iterations because they would yield different results for iterations that have already happened.Neg, my view would be that the Universe exists to create the most complex mass energy interactions, processes and structures possible, which probably are the mental processes of living things. I suspect that black holes are very simple in structure and carry no DNA for producing a Universe based on, except better than, the parent Universe. However it is interesting to consider a Universe which can evolve through Black Hole production might also be the same one that can produce the most complex mass energy interactions, processes and structures possible.

Minus, I am probably a futurist because of ST. It was a lot of fantasy and also in some cases future reality, but still fun. :) The above would be a new take on the Ultimate Computer!

 

[negativzero]

Smolin mentioned that his calculation is that to maximize black hole production a limit on masses of neutron stars would be right about 2 solar masses.
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i'm wondering if he just chose the least feasible mass to construct black holes with. It would seem like the least mass necessary would maximize black holes. Since the remnants of super novas by core collapse can include either neutron stars or holes but not both at the same time, a lower limit on black hole production would produce a correspondingly lower upper limit for neutron stars.
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Just speculation.
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[negativzero]

Smolin's take on Gödel's incompleteness theorem was very interesting. After all, cosmologies are theories of everything.
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Smolin's cosmology calls for a finite universe, thus the contradictions which issue from admission of infinities into the Godel's math are avoided. Gödel is insignificant.
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i probably shouldn't pile on Gödel here but, I've often wondered whether the presumption of existence of a counting number which can't be counted might not have some subtle logical inconsistencies from the outset. And inconsistencies in a physical sense.
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If number is part of the universe, that is, if math itself has a wholly physical existence that is not outside the universe, and further, the universe itself is finite, and space/time/and energy are a finite number of quantum bits, it's hard to see how one could apply the concept of infinity to any situation. The math concept "infinity" would be a contradiction and physical impossibility. Non-computability is another issue, as it itself is not a number. Maybe there is something out there in information theory that could deal with the symbolic technology on this one.
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The concept of a continuous function is essential to many parts of math, notably calculus. I'm sure new calculus can be invented as needed, so that's not a big problem. The definition of limit would have to change. That's already been done in my memory. But this is one more nibble at the heels of continuity.
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Entanglement too, requires a new look at continuity at the infinitesimal level. To me, it looks like entangled particles haven't completely disconnected until one or the other of them interacts with another particle. As long as particles are interacting at a rapid rate, and in close proximity, this looks like "classic" continuity, but when, as in experiments, the particles are widely separated in space and time, it doesn't look like Grampa's continuity at all!
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When someone shows me infinity, or an infinitesimal, i may change my opinion and turn Platonic, but until then, I'm an obdurate hick.
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[Chalnoth]

I want to thank everyone for thoughtful discussion. I will probably continue to think about this whilst traveling over the next 2 weeks vacation.

Chalnoth, I wouldn't use iteration 0 or n to compute iteration n+(10^44)*billions of years.

You might not. But you could. And if you were to do the exact calculation, the computing time required would be exactly the same.

I would instead use the most recent possible iteration to reduce required processing.

The processing is only reduced for short time scales because approximations that are only valid on short time scales are used. The real universe doesn't have this luxury. When doing the exact calculation, there just isn't any difference. The time delta is just a parameter, and its magnitude is irrelevant to the exact result.

 

[Chalnoth]

If Smolin's theory of generation of universes by black holes is correct, it would EXPLAIN why the physical constants are what they are to a degree.

I am in general quite skeptical of this theory. I'd be willing to bet that when examined carefully, the actual maximum black hole production level occurs with a set of low-energy physics quite different from our own.

 

[negativzero]

i appreciate your comment Chalnoth. i am not a true believer, but i like the fact that Smolin himself is a center of skepticism re existing standard cosmology and quantum theory. Just listen to the questions from the audience at SETI. People hope he has what just about everyone is always looking for...something new.
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Looking for something new at CERN, folks found Higgs. But no new physics. Smolin has sex appeal. He has something new.
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Like you, i have my doubts. Taking Smolin's comments as correct, that somehow 12 parameters LOOK AS THOUGH they have been finely tuned by evolution of universes to achieve this universe which maximizes black hole production, maybe there are alternate explanations for such parameters.
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i struggle with his theory in other ways. Do we really have so many black holes? He says a "billion billion." The universe is over 13 billion years old and we only have a billion billion so far. i can't measure my cosmic impatience.
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Did he "peek" at the data on neutron star masses and the come up with a theory that required that special mass to maximize black holes? ---that would basically be close to cheating, i mean, explaining is not predicting. It's evil of me to be suspicious.
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Does black hole maximization result from some necessary aspect of the initial conditions other than evolutionary process? If so, how would you weight that fact?
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And why black holes? Protons are also a feature of this universe. If it turns out that 12 or so parameters are finely tweaked to produce these protons with incredibly long decay times, does that imply that the universe has evolved to maximize the lifespan of protons? i guess that would be amended to say, "...evolved to maximize proton half life, AND black holes?" The accumulation of protons can, in part, lead to black holes, so i guess that wouldn't contradict his theory. It would just explain the mass of protons too. {Which are not fundamental, as we all know.}
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Then, of course, the questions that everyone is going ask..."What happens when i toss an empty beer can into this newly formed universe?" Or when black holes collide? The lack of answers doesn't deny the theory but as we look at our own universe i see no evidence of infalling beer cans. i.e. no evidence of infall into our little black hole universe, assuming we are one. ---i'm betting there is some dual relativist answer why 13 billion years from the inside of the hole will translate to some distorted time outside. Why does each generation of universes only change a little in physics from it's mother? Why not change on a random basis?
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How can you verify that any specific black hole has created anything at all?
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Other things bother me which are more difficult to nail down. Lots of questions.
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On the other hand i can't think of a single other cosmologist [or person] who has a semi-decent theory of why even one physical constant has the value it does. If true, it might be the most amazing result since the atomic theory. If not true, it opens ones mind to find out why not.
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Gotta give the guy his creds.
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[Tanelorn]

You might not. But you could. And if you were to do the exact calculation, the computing time required would be exactly the same.The processing is only reduced for short time scales because approximations that are only valid on short time scales are used. The real universe doesn't have this luxury. When doing the exact calculation, there just isn't any difference. The time delta is just a parameter, and its magnitude is irrelevant to the exact result.

Chalnoth, since particle interactions have many random qualities, you could not use older time slice iterations when trying to compute a future iteration, because they would very likely yield different results for iterations that have already happened in between.

 

[Tanelorn]

negativ, another alternative: Perhaps the Universe is fine tuned through evolution for something on MUCH larger size scales. Think about the ratio of the smallest particle to the size of the observable universe and then think about a ratio approaching that for something much larger and also with higher complexity. The potential for complexity is the thing which needs to be passed on to the next Universe whereas Black holes are probably relatively simple and also may not create new Universes. They may just be matter which is sufficiently dense so as to not allow light to leave, and nothing more.

 

[Chalnoth]

Chalnoth, since particle interactions have many random qualities, you could not use older time slice iterations when trying to compute a future iteration, because they would very likely yield different results for iterations that have already happened in between.

This isn't true, whether you're talking about quantum mechanics, classical mechanics, or General Relativity. In quantum mechanics, time evolution is simply governed by the Hamiltonian operator:

H|\psi\rangle = i \hbar {\partial \over \partial t}|\psi\rangle

No randomness involved. The randomness comes in either as an approximation (in statistical mechanics, for example), or because our future observations will be limited to a single branch of the full wavefunction. But when we're talking about something like the nature of time, these concerns are irrelevant.

 

[negativzero]

Chalnoth perhaps you can help me hone in on some of the slipperier issues with Smolin's approach.
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Smolin seems to lapse into a Newtonian picture or at least a non-relativistic picture for several parts of his theory, but the theory itself comes out of his use of GR, notably that GR doesn't require conservation of mass energy in black hole collapse. Never-the-less, time is given a direction, and the universe is placed in a mitotic colony of sequential universes. And particles, or events, or something, has memory, and the memory itself is apparently the enforcer of physical law. Not a force, just an enforcer. That's not even Newtonian. Where does he get that? Depending on the intransient reactionary reluctance of particles to change behavior is treating them like psychological entities, moreover it requires some kind of group memory. Now it's not only evolution it's ethnography. Or, [being less satirical] perhaps a shared feature of the state of every particle in a particular universe. That would require that each universe, being unique, would have it's own esprit de memoire. As if the all the particles in that universe are connected or entangled until a few of the them clot together into a black hole and disconnect in a collapse event vaguely analogous to wave collapse. It reminds me of the universe as a particle picture. It suggests a new kind of "Feynman diagram" for universes.
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He's throwing a lot of stuff together and i don't have a sense yet for why he picks one path over another. How do we know when to think in universal or "real time" vs the time we have gotten used to?
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It's the wobbling in and out of GR that i don't get. When does he decide to embrace and when does he slip out the back, jack?
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Tanelorn, my friend, perhaps you can see that, after reading your post, it influenced the note above to Chalnoth. You have contaminated my grey matter budro! GEt outta my HeAd! Seriously, i can't figure just when or why Smolin went down the logical paths he did, except that he has had a sense of where he wanted to wind up.
Have fun on your vacation.
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[Tanelorn]

thanks neg, at the airport now! (just trying to help :) )

 

[Tanelorn]

This isn't true, whether you're talking about quantum mechanics, classical mechanics, or General Relativity. In quantum mechanics, time evolution is simply governed by the Hamiltonian operator:

H|\psi\rangle = i \hbar {\partial \over \partial t}|\psi\rangle

No randomness involved. The randomness comes in either as an approximation (in statistical mechanics, for example), or because our future observations will be limited to a single branch of the full wavefunction. But when we're talking about something like the nature of time, these concerns are irrelevant.

Chalnoth, sitting at JFK trying to understand the implications of what you said.
Does this mean that the Universe could start over with the big bang and all that follows, and each time it did so I would be sat here typing this? I really didn't expect this, are you sure?

 

[WannabeNewton]

In general relativity if you specify an initial data space-like Cauchy hypersurface then the Einstein equations determine a unique evolution of this surface for all time, for as long as the equations remain well behaved.