Clock Ambiguity and Physical Laws

[DrRocket]

http://arxiv.org/PS_cache/arxiv/pdf/0708/0708.2743v2.pdf

http://arxiv.org/PS_cache/arxiv/pdf/0805/0805.4452v1.pdf

These two papers are the subject of an essay in the most recent (13 September 2008) issue of Science News. They deal with some work involving fundamental re-thinking of the notion of time and how it is reflected in physical laws.

I have not read and digested them yet, so I have no comments or opinions to offer at this juncture, but I thought others might be interested in this work. Enjoy.

[Ken G]

The technical details are way above me, but on the surface, I'm unconvinced. The whole affair is an effort to understand, even predict, why the laws of physics are the way they are. That is indeed a very deep and important question, but it seems to me like the modern metaphysical equivalent of the philosophical proofs of God found in past centuries. Ultimately, when you look closely enough, you find that embedded in the reasoning is precisely the conclusion that is intended to emerge as a consequence.

I have the sense that the same holds here, and if we looked underneath the assumptions that go into devising a quantum field theory, we would see it as a significantly more technically sophisticated effort to attempt the very same type of circular argument. Personally, I think there is something scientifically impossible about knowing why science derives the laws it does-- the same process used to find what works cannot be used to find why it works, because we would need to know why science itself works, but that's just an embedded assumption of science that can only be tested by experiment.

[DrRocket]

The technical details are way above me, but on the surface, I'm unconvinced. The whole affair is an effort to understand, even predict, why the laws of physics are the way they are. That is indeed a very deep and important question, but it seems to me like the modern metaphysical equivalent of the philosophical proofs of God found in past centuries. Ultimately, when you look closely enough, you find that embedded in the reasoning is precisely the conclusion that is intended to emerge as a consequence.

I have the sense that the same holds here, and if we looked underneath the assumptions that go into devising a quantum field theory, we would see it as a significantly more technically sophisticated effort to attempt the very same type of circular argument. Personally, I think there is something scientifically impossible about knowing why science derives the laws it does-- the same process used to find what works cannot be used to find why it works, because we would need to know why science itself works, but that's just an embedded assumption of science that can only be tested by experiment.

I have now had a little time to scan through the two papers, and I share your skepticism, but perhaps for different reasons. It seems to me that rather than attempting to understanding, on some metaphysical level, why the laws of physics are what we see, they are simply trying to find a framework in which one might construct a theory that includes both gravity and quantum theory. Their approach seems to be to construct a space in which all possibilities live and then try to sort things out from there, the key being how one handles time. That idea might have some merit.

But the basic construction, and their conclusions, baffle me. It appears to me that they are saying that by choosing a suitable basis for "clock space" they can interpret the evolution of any dynamical system, with a fixed Hamiltonian, to proceed in any pre-specified manner whatever -- basiclly saying that any two Hamiltonians can be made indistinguishable by a suitable choice of basis for the "clock space".

If I sound a bit confused, it is because I am indeed confused by the paper. Their logic proceeds by decomposing a "superspace" which they assume to be finite, into a tensor product of a "clock space" and a "rest space", each of which are subspaces of the finite superspace. I am having more than a little bit of trouble figuring out how they do this in a meaningful way. If everything in sight is finite, then I am not sure what they mean by a subspace. Presumably there is some sort of an implied module structure, perhaps even a vector space, here. Along with that, if things are finite there must be a finite ring, perhaps a finite field. But they are quite silent as to what that might be, and they speak as though they are dealing with an ordinary real or complex vector space, which most certainly would not be finite. In addition there is this clock space, which I would assume must be one-dimensional if it somehow corresponds to what we normally think of as time, at least locally. But if clock space is one dimensional, then the tensor product of clock space with rest space ought to have the same dimension as rest space, and since everything is finite, hence finite dimensional, rest space would have the dimension of the full superspace, hence would be the whole thing, unless the module structures result in algebraic collapsing, in which case the tensor product might even be zero.

They refer to their argumens as heuristic, and perhaps that is where some of my confusion lies. I may be trying to interpret what they say using rigorous mathematics in a situation that is not quite mature enough to be doing that. Or I may just be missing the boat.

I think the Science News essay was more intriguing than the research on which it is based. I don't think this is likely to produce any near-term revolution that will produce a theory of quantum gravity. But I would like to be wrong.

[Drunk Vegan]

If you ask me, the laws of physics are a no-brainer.

Of * course * we have set laws of physics.

If we didn't, the universe would not exist. Constantly changing laws would not allow for a stable universe.

The universe would long ago been disintegrated by violent, unnaturally (to us) energetic matter-antimatter collisions.

Or gravity would have become so weak that every atom in the universe would be many light years apart.

Or gravity would have become so strong that the whole universe would have collapsed into a black hole.

Or whatever else - if the laws of physics are randomized the only possible outcome is a destroyed universe.

If they are set, the result is a stable universe.

We're still here.

Hence, the laws of physics are set and have been for a long time. Simple.

[Ken G]

DrRocket delves into the mathematical details I have not attempted to follow, I'm just trying to track their basic logic. Basically, it is another attempt, like "the landscape" of multiverses, to use what is essentially an anthropic principle to find some kind of "reason" why the laws are what they are. At the core of their idea is what they (and no one else, yet) calls the "clock ambiguity". That appears to mean that by programming a clock to read time in some arbitrary way, you could alter the laws of physics that would work when parametrized by such a clock into any laws you want.

But I don't see the problem with that, frankly-- it doesn't really surprise me that by remapping the independent variables you can get any response from the dependent variables that you like. I see the remapping as the subterfuge, the sleight of hand that will be used to ultimately conceal where the assumption of what is to be proved is made.

Their key connection with the application of an anthropic principle is that the universe must exhibit "quasiseparability" to be conducive to scientific inquiry about said universe. Quasiseparability is the requirement that beings and entities must maintain a separate existence for a long enough time to think deep thoughts and carry out scientific experiments-- if the universe killed scientists off in 100 seconds instead of 100 years, we would never have gotten to the point of asking these questions at all.

This is a reasonable idea, just as the anthropic principle is itself a reasonable idea. But where's the connection with the clock ambiguity? That's the part where I smell a circular argument-- something along the lines of, we conceive time the way we do because that is necessary to compose scientific thoughts, and only universes that play along with such thoughts could house scientists, so that's the reason that scientists break the clock ambiguity with this particular choice of what time means, which in turn gives us the laws we use instead of some other arbitary set of laws-- ergo the non-arbitrariness of the laws stem entirely from the non-arbitrariness (anthropically speaking) of our concept of time. I see that as a circular argument, because it merely assumes its most crucial requirement: that the universe obeys the laws it does because our concept of time must obey the laws it does, rather than the converse possibility. If the converse is instead true, what step in their argument would lead to a contradiction?

To me, it may be a useful insight that we could have chosen arbitrary meanings for the fundamental parametrization on which the laws are built (time). But what does it tell us about the laws themselves? It only tells us that the laws are connected to how we conceive time, but that doesn't surprise me-- they could both come from the same underlying structure, and still be connected to each other. Finding that they are connected does not tell us what is that underlying structure-- we get to know neither why the laws come from the way we conceive time, nor why the laws specify the way we will conceive time. So what is the article really telling us?

[mike alexander]

I first remember seeing something akin to this thirty years ago. I believe it was a paper from Wheeler in the Einstein Centennary volume Some Strangeness in the Proportion. If my memory is correct he was saying that time doesn't exist outside of a framework to measure it.

But it's been quite a while.

[Ken G]

Right, time doesn't exist outside a framework to measure it. But is that telling us something about time, or something about science? I say the latter-- we choose science, and we get time, so it is circular to then conclude that it is because time works the way it does that can explain why physics works the way it does, which seems to be their conclusion. Where's the metaphysical meat of this argument, hiding beneath the mathematical sleight of hand?