Starting with the expansion of universe theory, physicists suspect that the universe that existed before is not known and this creates illusions to what is.
This might mean that aspects of what we observe are not uniquelly determined by what the laws of nature are but by which solution to the equation of nature happens to be relevant
I. E we dont have the ultimate laws yet but the quantum. State of the region we exist solutions to the ultimate laws
Our laws, Witten says, might be the solutions to quantum state adopted or relevant to a region in space.
There's no such notion as ``our region of the universe''. That it isn't possible, by definition, to know what happens beyond any singularity (the Big Bang singularity is an example thereof) shouldn't be surprising.
On a curved background quantum states can't be unambiguously defined-that's not new, either.
Laws aren't ``adapted'' to states, whether in quantum or classical mechanics-it's the other way around.
Ιt is a big research topic on how quantum states can/can't be defined on curved spacetimes. But Hawking, Hurtle and others tackled it and worked it out some how, of course in narrow circumstances or aspects
Eddyboy now reached the ground state. only some vacuum fluctuations left.
Mr Nicolis,
Curved spacetime is a GR notation. You cannot let a notation from one theory, even if it is the established in the domain i.e cosmology, to prevent orvargue against the validity of using another (QM) or another theory that is not fully compatible with it to make inferences
Spacetime curvature isn't a convention in general relativity-which describes, also, cosmology. That's the only statement that makes sense-and it's wrong: Spacetime curvature isn't a coordinate artifact. It can't be eliminated by a general coordinate transformation. It would be useful to actually study general relativity and quantum mechanics, before just using words at random.
If two theories aren't compatible it doesn't make sense discussing them together. However GR and QM are, in fact, compatible enough for discussing certain common issues; just not those that have been attributed-wrongly-to Witten.
Mr Nicolis,
Οf course there is the strong evidence of non 180 degrees in triangles of light days near black holes that makes curved spacetime not "just a model" and the issue of compatibility of quantum states with curved spacetime a very real one.
But for the sake of theorizing one can forget it and see what the unbounded thoughts bring to existence..
From what I understand, Witten's idea of "our region of the universe" stems from the realization that due to expansion of the universe, some parts that were vidible to earth before humanity evolves scientific all are not vidible now.. Hence "our region".
Now the "wavefunction of our region" is a conceptual reversal to trash isotropic universe and propose anidomorphic universality wavefunction development or static one.
Some insights of strong theorists led to that but these ideas were never for all developped. The only similar is Smolin's, another former string theorist, who suggestested the even more harsh conceptual Reversal of changing physical laws or cosmological dsrvinisn
{Witten's claim documented}
This claim is about new approaches to the fne-tuning problem such as the relaxion or “Nnaturalness.
Unfortunately, it has been very hard to fnd a conventional natural explanation of the dark energy and hierarchy problems. Reluctantly, I think we have to take seriously the anthropic alternative, according to which we live in a universe that has a “landscape”of possibilities, which are realised in diferent regions of space or maybe in diferent portions of the quantum mechanical wavefunction, and we inevitably live where we can. I have no idea if this interpretation is correct, but it provides a yardstick against which to measure other proposals. Twenty years ago, I used to fnd the anthropic interpretation of the universe upsetting, in part because of the difculty it might present in understanding physics. Over the years I have mellowed. I suppose I reluctantly came to accept that the universe was not created for our convenience in understanding it.
https://www.ias.edu/sites/default/files/Witten%20reflects%20%E2%80%93%20CERN%20Courier.pdf
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