Does anyone know how well-accepted this timeless physics is within the scientific community?
Julian Barbour is the original author and apparently the only person who published refereed papers on the subject. His most recent preprint on the topic ("time is derived from change", whatever that means) has a few citations, though mostly reviews or peripheral mentions. Admittedly, I did not do a very thorough search.
As far as I can tell, the timeless model failed to generate any excitement among the experts in the field because it does not give a compelling answer to the standard question asked of any new research, "so what?" or, more bluntly, "why should anyone care?". Specifically, it does not make new interesting predictions, simplify any existing models or open any new promising avenues of research.
Such diverse people as Lee Smolin and Lubos Motl think it's an interesting idea (and having those two agree the sky is blue would be remarkable), but that just puts it as "fringe" rather than "crank". And you could say about the same about string theory.
it's an interesting idea
Absolutely. Unfortunately, this is just not enough in order to become a viable model.
that just puts it as "fringe" rather than "crank".
I don't think that anyone asserted that timeless physics is a crank idea, since there is no contradiction to the established science. Fringe is indeed a good description, due to the reasons I mentioned.
And you could say about the same about string theory.
I wish I could. String theory, while being an out-of-proportion popular piece of math which took over high-energy physics, has a few things going for it, despite getting its every testable prediction wrong.
It offers tantalizing hints of new perspectives on high-energy physics research, such as the duality between strong- and week-coupling models, the holographic principle, new unexpected yet elegant symmetries, and even useful calculational techniques for quark-gluon plasma analysis. Of course, it would probably not have gotten nearly as popular if Ed Witten didn't take up the cause.
It has testable predictions it got wrong? As I understood it, its predictions were untestable without radically more powerful accelerators.
I'm only half a layman, but I know that Brian Green (maybe others?), have put forward the idea that 11 dimensions do exist, it's only that they are "curled up" and so small that we can't (yet) observe them, analogues to how a wire might appear form afar, flat, but as you move close you see it's actually a cylinder, Greens own example.
And why did they propose it, other than to explain why these extra dimensions are not observed in nature, thus patching up a model with a falsified prediction?
One could argue that time as classically understood, simply doesn't pay rent, and exhort us into stating that there might be universes that exist were time flows backwards and the likes.
The concept of classical time pays rent quite handsomely, all of modern physics is based on it. "Time flows backwards" still implies a flow of time, not timelessness.
"Time flows backwards" still implies a flow of time, not timelessness.
I don't know if I misunderstand you, or if you misunderstood me, but I meant "Time flows backwards" is nonsensical concept, the perception of an arrow of time comes from how states relate to each other not because there is some there is this global now progressing. But I guess you now more about the concept of timelessness than I.
The concept of classical time pays rent quite handsomely, all of modern physics is based on it.
But is classical physics incompatible with timelessness?
signing up for cryonics, being vitrified in liquid nitrogen when you die, and having your brain nanotechnologically reconstructed fifty years later, is actually less of a change than going to sleep, dreaming, and forgetting your dreams when you wake up.
I don't think this counts as a "practical application" of EY's understanding of physics, but only as a basic example of instrumentalism, provided the reconstruction is faithful enough.
Today's post, Timeless Identity was originally published on 03 June 2008. A summary (taken from the LW wiki):
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