Greetings from Norway, where we’re about to embark on what is surely the most logistically elaborate conference I’ve ever attended. Setting Time Aright starts here in Norway, where we hop on a boat and cross the North Sea to Copenhagen. The get-together is sponsored by the Foundational Questions Institute, although it came together in an unusual way; I was part of a group that was organizing a conference, and we applied to FQXi for funding, at which point they mentioned they were planning almost exactly the same conference at the same time. So we joined forces, and here we are. Unity ’11!
The topic, if you haven’t guessed, is time. That’s a big subject, one that can hardly be done justice by sprawling books with hundreds of (admittedly quite charming) footnotes. You can see why the conference has to spread over two countries. We’re trying an experiment in interdisciplinarity: while the conference is a serious event meant for researchers, we have a wide variety of specialties represented, including biologists, computer scientists, philosophers, and neuroscientists, as well as the inevitable physicists and cosmologists. (There is also a public event, for those of you who find yourselves in Copenhagen next week.) I can’t wait to hear some of these talks, it should be a blast.
My job is to open the conference with an introductory talk that hits on some of the big questions. Here are the slides, at least as they are right now; last-minute editing is always a possibility. I think I put enough in there to provoke almost everyone at the conference one way or another.
Dissipative structures far from thermodynamic equilibrium. Accept no substitutes.
Time does not have a “direction”: This is a complex illusion created by the human mind’s propensity for linear perception. Time simply *is*, now and forever, much in the same way Vonnegut described it. To say that it has any sort of “direction” is erroneous, however. Rather, it is human perception that does, being made up out of matter that decays thermodynamically along a single “straight line”.
Space is emergent but time isn’t. I’ve heard that before, and frankly I can’t imagine ‘no time’, but my guess is that nature doesn’t care. Also, this would imply a Lorentz violation and the possibilities of that seem unlikely.
1)”what is time?”
For most practical purpose time is just an independent variable.
2)”why does time have direction?”
3)”how does complexity evolve?”
question 3 is same as question 2 , I mean if time didn’t have direction how is it possible for anything to evolve…..or is it possible for time to flow but no evolution of complexity?? if yes then how can you tell them apart??
This is very beautiful – The Symphony of Time – a kind of symphonic rap on time.
http://www.youtube.com/watch?v=6AuQPqJPSKE
from the upcoming Science and Nonduality conference.
http://www.scienceandnonduality.com/
Time is, like, wow, man.
In this idea of the future reaching back to affect the past (Paul Davies is at the FQXi conference):
http://fqxi.org/community/articles/display/156
Is this an alternative to a multiverse (I thought Paul Davies’ idea is that it is – don’t think he likes the multiverse) where this article implies a self-sustaining universe, just one universe – I don’t know. Or are universes within the multiverse self-sustaining (all of them), or just ours for some reason?
Does the multiverse “select out” self-sustaining universes (and why)? Perhaps this way is there compatability between the two ideas?
My impression is that the multiverse is really necessary but is Davies right as well?
Just interested to known if anyone is thinking (with physics!) along these lines.
Good to bring people together.
Okay, how do you measure complexity of a system? Isn’t it a little arbitrary. You’re example shows two systems in equilibrium, which evolves into one system in equilibrium. So are you saying that complexity is a measure of distance from equilibrium?
Macroscopically you might think its not complex, but microscopically its horribly complex, not to mention there is a loss of knowledge about how long ago the system was in its initial state.
Wow, small universe. Earlier in the summer I was scheduled to be in Bergen myself this very week. Priorities changed and I had to cancel, but were I there, I’d have invited you to a dinner of lutefisk.
Why is this considered a mystery? The Universe starts out at maximum entropy, as you would expect; and then the entropy increases, as it must. this is possible because the Universe is expanding.
In more detail, shortly after the Big Bang, the Universe was in a maximum entropy configuration, with massive and massless particles in a uniform equilibrium soup.
As the Universe expanded, the maximum possible entropy increased (more volume means more possible states), and the actual entropy increases along with it, until the temperature drops to the point where the massive particles fall out of equilibrium with the radiation. (Stable massive particles like protons and electrons stick around even though the temperature is well below the particle mass because there aren’t anti-particles to annihilate with.)
At that point, the actual entropy falls behind the maximum possible entropy. The actual entropy is the entropy of the cosmic background radiation, plus the entropy of the massive particles. The cosmic background radiation is at maximum entropy for its energy density (i.e. it is in a uniform thermal blackbody distribution).
The particles are also in a uniform thermal distribution. However, massive particles in a uniform thermal distribution is not a maximum entropy or equilibrium state. Under the influence of gravity, any density fluctuations will start to collapse until the adiabatic compression heats it up until it is supported against gravity.
A gravitating gas system like one of these clumps has a negative heat capacity. The more thermal energy it loses, the hotter it gets as it contracts adiabatically. So two such systems in thermal contact (e.g. by radiation) will diverge in temperature and you will get dense hot objects and diffuse cool gas.
After a bit more evolution (dense hot objects starting to burn by fusion etc.) we get to the Universe we have today.
Alan (#7), thanks for the FQXi link. Just last week I asked in this forum if there were any experimental evidence for or against this interpretation of quantum phenomena.
{Hmm … perhaps today’s blog influenced me to ask last week’s question? 🙂 }
Sean, how do you think the cosmological entropic claims of 1108.3080 fit into all this? Does it solve/address the fundamental issues?
Good set of slides, should provoke interesting discussions! Nice to see Boltzmann covered, too.
(Hmm, it’s 2am with a hurricane coming this way?… Goodbye!)
Time only exists as a concept; it is an abstraction; a manmade system of measurement much like the metric system; it is simply a method of comparison. We are conditioned to believe it exists because of incorrect deductions based on our experience of life/the universe – our ability to remember our experiences (“the past”) and our cognitive ability to project potential experiences (“the future”); both of which are only conceptual constructs.
Time isn’t a property of the universe – well, no moreso than a unicorn is a property of the universe. That doesn’t mean however that we cannot retain it as what it actually is i.e. a system of measurement and comparison.
How about time dilation of relativity roosh..
Time dilation is based on the assumption that a clock measures the [non-conceptual] property called time. It doesn’t however, a clock is simply a standard unit of comparison against which change is compared.
I’m not familiar with all of the time dilation experiments; but I’m not sure how the more famous ones – atomic clocks in the concords (was it concords used?) and the decaying process of muon that is accelerated to a certain speed – show anything other than the physical effects of either gravity or motion (or perhaps both) on the relevant particles – the assumption, that these physical processes are a measure of the [non-conceptual] property called time, violates occams razor.
just to clarify though, that doesn’t mean that the results of the time dilation experiments are rendered inaccurate, simply that the assumption as to what they prove needs to be examined.
Occam’s razor is not a law, it’s maybe just a guide when we have many explanations to the same result… and thats not the case. Those experiments as far as we know are very well established, and many other tests were made. Unless a new theory appears, it’s the best we have today to explain how time works. We already use relativity predictions in many real-life applications, such as GPS for example.
I know Occams Razor is not a law, but that is just a way of expressing the fact that the assumption, that the aforementioned physical processes measure the [non-conceptual] property called time, is unjustified.
Again, the issue isn’t that the well established experiments are inaccurate, simply that the interpretation of the results needs to be examined; the assumption that they prove the existence of time is incorrect, because it can be more accurately said that they demonstrate the effect of motion and/or gravity on the specific physical processes.
No new theory is needed to challenge the assumptions upon which the current theory is based; indeed, a new theory may emerge or be developed if those in the field challenge the assumptions of the existing theory.
The only thing that’s “real” in the second slide (intuitive time) is the present hypersurface for the stick figure that maybe should be drawn as something much more microscopic, like an electron. The past is just as conjectural as the future – our memories are terribly unreliable and our records are highly incomplete. The local availability of information required to predict the generalized elsewhere diminishes with distance in all four dimensions, and the reliability of those predictions almost certainly decreases much faster.
Suppose, arguendo, that we actually do remember the future almost exactly as well as we remember the past, but that for whatever reason that memory isn’t available to what we think of as our conscious self. The reason we can catch a ball, or the reason that a parrot can catch an insect is not because the brains involved are especially good calculators that learn an effective theory of ballistics through practice, but because they have access to unreliable memory of their respective bundles of worldlines, where memory retrieval improves with practice. Just because humans don’t admit to having reasonable memories of the future doesn’t necessarily mean they don’t actually have them; it might just be that we can’t “visualize” future memories as clearly as past ones.
Perhaps an intelligent species which perceives little difference between prediction and retrodiction might think we’re a little odd in how we perceive time. Why did you catch the ball? Because you did. Why will you catch the ball? Because you did. Why can’t I remember both those events? Maybe because the parts of your brain that let you *realize* that you remember the future just as well as the past are vestigial because it consumed more food energy than it helped your ancestors acquire through hunting and gathering. (But don’t worry, your descendants may construct an analogue. :-)) Why do I give more weight to my memory of the past rather than my imagining of memory of the future? Again, perhaps something in the human brain shapes what one considers evidence independent of cultural influences (which again is probably related to something in the human brain).
Most of us likely would rely more upon 20th century records than 20th century speculative fiction, but perhaps that’s just because of biases that emerge from the structure of our brains. We also probably rely more upon recent records than ancient ones, and probably would agree that recent hard science fiction describing the near future is more likely to be right than hard science fiction from fifty years ago describing the distant future. We also probably prefer authors writing in our languages and if we’re American, we might prefer an American writer speculating about a future America over a British one doing the same. In other words, do we rely more on data and arguments compiled and made nearer to us in all four dimensions? Do we also give extrapolations they made greater weight when they attempt to predict events nearer to the authors in all four dimensions?
In other words, is there a relativity of knowledge?
Slide 6: is it quantum harmonic oscillators that underlie the assumption that time is somehow more real than a coordinate? Otherwise, is there some mechanism that generates “holes” as in the hole argument?
Pity. You’re a week early for the Skeptics in the Pub meeting. They’re even early due to football.
DMPalmer #10,
You wrote: “As the Universe expanded, the maximum possible entropy increased (more volume means more possible states), and the actual entropy increases along with it…”
You should read Roger Penrose’s ‘The Road to Reality’ to better understand the true mystery. In particular, chapter 27 on page 701 which he writes:
“There is a common view that the entropy increase in the second law is somehow just a necessary consequence of the expansion of the universe. This opinion seems to based on the misunderstanding that there are comparatively few degrees of freedom available to the universe when it is ‘small’, providing some kind of low ‘ceiling’ to the possible entropy values …”
“This cannot be the correct explanation for the entropy increase; for the degrees of freedom that are available to the universe are described by the phase space P_U.”
“This phase space is just ‘there’, and it does not in any sense ‘grow with time’, time not being a part of P_U.”
IOW the phase space describes the totality of all possible universes, incorporating their evolution wrt the laws of dynamics. This phase space is independent of time. So the mystery is why is our universe a “Big Bang” universe rather than a vastly more likely universe in near equilibrium.
Penrose proposes a “solution” to this mystery in his Conformal Cyclic Cosmology by positing that the final state and the initial state of the universe are indistinguishable, therefore leading to a eternal series of big bangs, referred to by Penrose as “Eons”.
Sean correctly concludes in his book “From Eternity to Here” that this doesn’t really solve the mystery, as he puts it :”Why our universe is so atypical is, of course, at the heart of the mystery.”
IOW the CCC is just as atypical as a Big Bang universe.
Dan
Dan said: “IOW the phase space describes the totality of all possible universes, incorporating their evolution wrt the laws of dynamics. This phase space is independent of time. So the mystery is why is our universe a “Big Bang” universe rather than a vastly more likely universe in near equilibrium.”
The Universe does spend just about all its time in the vastly more likely universe in near equilibrium. It spends all but the first googol years or so in that state. It’s only the small fraction of time that it is out of equilibrium that is inhabited by people who look around and wonder why. Only when the Universe is small.
So the ‘mystery’ is, why is there a time when the Universe is small? In other words, why did the Universe start with a Big Bang. To me the idea of a Universe starting at a point seems more likely than the Universe starting simultaneously over an extended volume googols of light-years across in a spatially uniform thermal state.
DMPalmer,
As Sean wrote in “From Eternity to Here” that the mystery is not that there are fluctuations away from equilibrium, but rather the enormity of the magnitude of the fluctuation in order to create a Big Bang is so immensely unlikely. He also writes that we could invoke the anthropic principle (AP), except that “Our actual universe seems to be an enormously more dramatic departure from emptiness than would be required by any anthropic criterion.” (FHtoE pg.312)
It seems that you are invoking the AP without stating it explicitly when you wrote: “It’s only the small fraction of time that it is out of equilibrium that is inhabited by people who look around and wonder why.”
I guess if you have a eternity of existence, a universe will eventually form that is immensely unlikely, even if the probability of its beginning state is on the order of one in 10^10^88. The problem arises as to why the entropy of the initial state was one in 10^10^88, when it could have been in any of the 10^10^120 possible states, which represents the max entropy of the observable universe.
So Sean (and his contemporaries) doesn’t give much credence to this argument since he writes: “The conclusion is perfectly clear: The state of the early universe was not chosen randomly among all possible states. Everyone in the world who has thought about the problem agrees with that. What they don’t agree on is why the early universe was so special – what is the mechanism that put it in that state?” (see FHtoE pg. 301)
Dan
Be careful, because another example of irreversible T-odd process is: crackpots never become good theorists, while some theorists go crackpot.