Conservation laws, like spacetime, apply within – immanent to – the (this) universe. Mass-energy belongs to the (this) universe which is not "eternal" (except in Einstein's time-reversible equations). IMO, the only 'physical' candidates which might be "eternal" are the true vacuum or the bulk encompassing (our) spacetime. — 180 Proof

:up:

From an astronomer-physicist's point of view, the Big Bang is when their equations break down and become meaningless. It's as if current cutting-edge science (paradigms + tools) hits a wall they can't penetrate/scale. We could cheat, but I haven't the foggiest what that would look like. Any ideas?

In QG, the planck era ("BB") occurred at the planck scale for which classical metrics (e.g. distance, interval, causality) do not apply. This is why the attempt to reconcile GR and QFT in a "ToE" is so intractably difficult.

In QG, the planck era ("BB") occurred at the planck scale for which classical metrics (e.g. distance, interval, causality) do not apply. This is why the attempt to reconcile GR and QFT in a "ToE" is so intractably difficult. — 180 Proof

I see. :up: We've arrived at a place beyond which what you'll say further on will go over my head. Au revoir.

Just as mathematics is the language of the quantum world, it's probably the language of any sort of world beyond the Big Bang, or the ends of time, and it's a language that evolves. It may be a hopeless task to try to gain philosophical knowledge that interprets these worlds in the contexts of our reality.

:up:

I think Roger Penrose suggested a cyclic universe of multiple big bangs? Was that chaos theory? Perhaps there can be multiple definitions of time or different levels as there are of Infinity within mathematics?

I was told that gravity slows time down and hence the acolytes of Einstein claim that frequent flyers live longer than their twins/birthday cohorts (by a few nanoseconds) :snicker: With the entire mass of the cosmos compressed into the singularity of the Big Bang, time didn't flow/pass i.e. time didn't exist before the Big Bang. So yeah @180 Proof there is "no north of the North Pole".

:chin:

The physicists who developed the interpretations of QM certainly didn't see their work as philosophy of science. There is a vast number of discoveries in physics that were thought up long before there was a means to test them. Indeed, some were thought up when it was believed it was impossible to test the theories, that the new particles dreamed up would be necessarily unobservable. And now these are part of the bedrock of physics.

Point being, falsifiability is a poor criteria for what makes science "science." The "presuppositions and implications," of science often end up being important, and trying to kick them out to philosophy is a fool's errand. You don't end up with a science free of such theorizing, you end up with implicit theorizing that clouds judgement and cuts down on new ideas while remaining unexamined in the background.

Some interpretations of QM have led to testable hypotheses (versions objective collapse). Other versions may be testable in the near future.

Trying to draw a hard line between what is science and what is philosophy spawned Copenhagen and what you got wasn't actually science separate from philosophy, but instead science taking on unexamined elements of logical positivism that have stuck around long after positivism died. Given the history of the field in the 20th century, where talking about so many things that turned out to be of scientific interest was handwaved away as "meaningless," I wouldn't be so dismissive about theorizing about events "before" the Big Bang.

Bell was on the short list for a Nobel Prize in physics at the time of his untimely death for work in an area that has previously been described as meaningless. Now his work is central to applied science re: quantum encryption (already in limited use) and quantum computing (in R&D and picking up speed). Mach rejected atoms as meaningless because it was thought that observing them was impossible, etc.

https://aeon.co/essays/a-fetish-for-falsification-and-observation-holds-back-science



Not on an intimate level, well enough I suppose. In terms of plausibility, I think it is more plausible than it seems at first glance.

Imagine we do not find a good way to use observations to determine whether the Big Bang is unique or if it is just the inside view of a black hole (it's debatable if we're currently in this situation, but let's just assume it for now). What then is more likely? That the start of our universe was something wholly unique, or that it is the result of a phenomena that we now know is incredibly common?

There is no good answer there because there is no good metric for comparison. I think it just points out how, if you have two theories that might explain your data, you often default to the one that's been around longer, even if the new one might be more plausible on a common sense basis (allowing that common sense is normally bad grounds for science). Old paradigms tend to stick around by being first, not necessarily the most coherent.

But of course there is a difference as respects the question in the OP. If the Big Bang was a black hole then it might make plenty of sense to talk of time before the Big Bang. It could conceivably be a common textbook fact that we talk of something casually prior to that event, it just depends on what we find and how we come to think of it.

I think Roger Penrose suggested a cyclic universe of multiple big bangs? Was that chaos theory? — TiredThinker

No. Chaos theory is a mathematical subject in dynamical systems in which slight variations at the beginning of a specified time period produce chaotic or unpredictable results.

But of course there is a difference as respects the question in the OP. If the Big Bang was a black hole then it might make plenty of sense to talk of time before the Big Bang. It could conceivably be a common textbook fact that we talk of something casually prior to that event, it just depends on what we find and how we come to think of it. — Count Timothy von Icarus

Say the black hole in the middle of the Milky Way is a baby universe and there are people in there. Is their time separate from ours somehow? Or how does that work?

My mistake. Conformal cyclic cosmology

It seems indeterminate. One way a professor recommended us to think of relativity is with distance as an X axis and time as a Y axis. You can move "faster" through one, but only by reducing your value on the other axis. At the maximum far end of the distance axis is the speed of light. Photons move the maximum amount through space and do not experience time at all. From the perspective of the photon, photons move instantly between interactions*.

With a black hole, the amount of information that is stored in one point in space exceeds the maximum possible without the creation of a black hole. Gravity warps space-time to such an extent that light can no longer escape. You appear to get a singularity and the destruction of said information.

However there is a lot of resistance to this arbitrary destruction of information in black holes, and an opposing concept has been advanced, that of black hole complementarity. The idea here is that all information going into the black hole is radiated (very slowly) back into space AND still goes through the event horizon, into the black hole.

This would seem to duplicate information and violate the no-cloning theorem, right? Potentially, but not so if no observers can ever see both versions of the information. Enter a (perhaps ad hoc) wall of fire that burns up observers at the event horizon so that they can not observe violations of the laws of physics.

We base our current concept of time on:
1. The direction of the trend from low entropy to high entropy.
2. The number of predictable cycles of a phenomena completed.

Our observers inside the black hole's sense of time will be dependent on if all black holes result in low entropy initial conditions for the universes they spawn and if the laws of physics work the same way for the new universes. If these two hold, the observers should have a time that is quite similar to our own. However, it still might be quite impossible to do an apples to apples comparison of the two times if no observers can see both universes. Comparisons would be fairly meaningless.

But that wouldn't mean that "nothing comes before the Big Bang," even if the Big Bang was the result of a black hole in a larger universe. If that premise finds support it would mean our concept of time is parochial and needs expansion. And for myriad other reasons plenty of physicists have already come out and said there appear to be deep problems with our current space-time and that it may need to be overthrown. Like I said in my other post, plenty of now foundational discoveries in physics have previously been written off as "meaningless" or worse still "metaphysics," so our ability to conceive of such changes now doesn't mean that much.





(*Even this example is somewhat fraught because we know that it's probably incorrect to talk about photon X moving between Y and Z interactions as if photon X has its own identity and we also know the photon itself only exists under specific circumstances of interaction, with a light wave existing otherwise.)

But that wouldn't mean that "nothing comes before the Big Bang," even if the Big Bang was the result of a black hole in a larger universe. If that premise finds support it would mean our concept of time is parochial and needs expansion. And for myriad other reasons plenty of physicists have already come out and said there appear to be deep problems with our current space-time and that it may need to be overthrown. Like I said in my other post, plenty of now foundational discoveries in physics have previously been written off as "meaningless" or worse still "metaphysics," so our ability to conceive of such changes now doesn't mean that much. — Count Timothy von Icarus

I see. Thank you!