Hello Rodolfo,
Thanks for the paper!
Your abstract begins with:
"In quantum gravity there is no notion of absolute time."
Would it not be more proper to write, "In our universe there is no absolute notion of quantum gravity." By that I mean there is no experimental nor theoretical evidence for quantum gravity. Gravitons have never been seen, and gravity has never been quantized in any respected, accepted manner in any theory, nor in any finite manner, for that matter.
Might it not be dangerous to let something that does not exist--quantum gravity--inspire and/or dictate our contemplations on time? I mean theoretical physics is hard enough, even when it is built on reality. But to build theoretical physics upon the unreal--is this not the very "Trouble With Physics" Lee Smolin writes about, which is better suited to building sociological movements, even when begun with the best intentions?
Do we have to quantize gravity? Could it be that nature is as it is, and that God or the Prime Mover/Creator came up with both QM and GR, which seem to coexist perfectly well in their current forms? For instance, this laptop computer is powered by quantum phenonema, and too, it is held on my lap by gravity. Each one has a role, and each seems perfectly content to play it. Perhaps both mathematical predictions and the experimental search for gravitons has fallen short because gravitons do not exist. Now this is no reason to stop looking, but too, it is not exactly a reason to keep looking, and it is certainly not a reason to get rid of time, which does seem to exist, as my laptop's clock tells me I am running late, yet again. :)
A book you would enjoy is Freeman Dyson's THE SCIENTIST AS REBEL. On page 219 Freeman Dyson writes,
"(Brian) Greene takes it for granted, and here the great majority of physicists agree with him, that the division of physics into seperate theories for large and small objects is unacceptable. General relativity is based on the idea that space-time is a flexible structure pulled and pushed by material objects. Quantum mechanics is based on the idea that space-time is a rigid framework within which observations are made. Greene believes there is an urgent need to find a theory of quantum gravity that works for large and small objects alike. . . As a conservative, I do not agree that a division of physics into separate theories for large and small is unacceptable. I am happy with the situation in which we have lived for the last eighty years . . . The question I am asking is if there is conceivable way we could detect the existence of individual gravitons. I propose as an hypothesis that it is impossible in principle to observe the existence of individual gravitons." --Freeman Dyson, THE SCIENTIST AS REBEL, pp 219-220
Perhaps we should found our contemplations on time not upon the unreality of quantum gravity, but on the reality of *physical* theories represnting *physical* phenomenon.
Instead of being built on the unreal, my simple theory--Moving Dimensions Theory--is built upon the rock-solid empirical evidence supporting widely-accepted theories of relativity, quantum mechanics, and statistical mechanics.
And MDT tells us a lot about time and its arrows across all realms, showing that they are phenomena that emerge from a common, deeper principle--a fundamental universal invariant--dx4/dt=ic.
MDT views time as a phenomenon that naturally emerges because the fourth dimension is expanding relative to the three spatial dimenions at the rate of c. Change is fundamentally woven into the fabric of spacetime via dx4/dt = ic, which makes sense, because change is fundamentally woven into our everyday existence, empirical observations, and all branches of physics! Indeed--it would not be possible to make a measurement without change! A great thing about MDT is that it allows us to keep all of relativity while unfreezing time and liberating us from the block universe, which is yet a meaningful artefact that arises from certain interpretations of relativity. And who knows, perhaps MDT will tell us something about quantum time, which will tell us something about quantum gravity. For MDT also provides a *physical* framework for quantum entanglement and nonlocality, and thus it provides a *physical* model underlying qm's inherent nonlocal, probabilistic nature.
Think about MDT as a simple *physical* unification of relativity and QM--both entanglement and nonlocality can be accounted for via the same principle--the same hitherto unsung univeral invariant of dx4/dt=ic--that ensures a photon does not age, no matter how far it travels. A photon's timelessness, implied by relativity, represents a nonlocality in time. Both quantum entanglement and the agelessness of a photon descend from a common principle--a fundamenatl, universal invarinat: dx4/dt = ic. A photon is matter that "surfs" the fourth expanding dimension, and thus it remains in one place in the fourth dimension, while traveling through the three spatial dimensions at c. Ergo the fourth dimension is expanding relative to the three spatial dimensions. Perhaps this is MDT's simplest proof: The only way to remain stationary in the fourth dimension is to move at c through the three spatial dimensions: egro, the fourth dimension is expanding relative to the three spatial dimensions.
And a great thing about MDT is that it also presents a *physical* model for entropy, as briefly elaborated on in my paper:
http://fqxi.org/community/forum/topic/238
MDT represents the kind of theory we have not seen for awhile--a simple postulate and a simple equation that present a novel, hitherto unsung aspect of the universe--the fourth dimension is expanding relative to the three spatial dimension: dx4/dt=ic. This fundamental invariance underlies the invariance of the speed of light--both the constant velocity of c meausred by all inertial observers and, the constancy of c that is independent of the source. MDT also underlies relativity's two postulates, and all of relativity may be derived from MDT's simple principle of a fourth expanding dimension.
When we look at Einstein's 1912 Manuscript, we see that time plays a different role from position. x1, x2, x3 represent the three spatial dimensions, which we generally use to demarcate position. And then along comes x4, which Einstein equates with ict. So as t progresses on our watches, x4 must progress. Time is very, very different from the three spatial dimensions! Perhaps it is not a dimension after all, but a parameter that emerges because the fourth dimension is expanding relative to the three spatial dimensions, as suggested by x4=ict.
MDT and dx4/dt=ic also underly time's thermodynamic arrow, and in my paper I account for and unify all of time's arrows and assymetries with MDT's simple postulate and equation. And in addition to this, all of relativity may be derived from MDT, while qm's entanglement and nonlocality are explained with a *physical* model, along with entropy.
Thanks for the paper! I just think it would be prudent to wait for a consistent theory of quantum gravity, or some experimental evidence, before using quantum gravity as a tool to probe time's great and vast mystery. It would be like hanging something on a sky hook, or shifting smoke with a left-handed smoke shifter.
http://www.urbandictionary.com/define.php?term=left%20handed%20smoke%20shifter
As a new boy scout on my first campout back in sixth grade, I was sent forth to other campsites to go find a left-handed smoke shifter (to shift the smoke from the breakfast campfire) and a sky hook. Of course, this is a big inside joke to everyone but the youngest scouts, so people at the next campsite always smile and nod and say, "We just lent our sky hooks and left-handed smoke shifters to that troop down yonder." And so it would go, as we ran from campsite, to campsite, to campsite, looking for that which did not exist.
This pretty much sums up postmodern academia, where a postdoc might be sent from campus, to campus, to campus, looking for things that do not exist, as the elders get a good laugh. All the postdoc can really hope is that someday they'll be allowed to fund others to seek out their left-handed smoke shifters, to keep the cash flowing.
The big difference is that the joke only lasted a couple hours in boy scouts. When you returned to the campsite after running a few miles, scouting all the neighboring campsites for the left-handed smokeshifter, you were let in on it, and then taken on a snipe hunt that same night:
http://en.wikipedia.org/wiki/Snipe_hunt
It was all good fun, but in academia we are talking about entire careers and hundreds of millions of taxpayer dollars, so all this snipe hunting kindof loses its humor after a day or two.
Best,
Dr. E (The Real McCoy)