But consider falling into a supermassive black hole in a quiescent state, one which doesn’t have massive radiation due to mass accretion and whose gravitational gradient at the event horizon is small enough that you survive the entry.
What happens then? No one knows, but extrapolating from the Einstein field equations the only way they make sense any more is if time and space exchange places. Your attraction to the singularity is not actually gravitational any more, but chronological. It’s your inevitable future. It’s why it’s impossible to escape from a black hole – because you cannot travel into what has now become “the past”.
Our brains are part of our bodies. And equally affected by our physical nature.
That certainly doesn’t mean that we can’t think of anything new – lots of evidence shows that we can. But we can only do so with the physical brains that we’ve got. We can possibly make other brains that can think otherwise – but if they can understand something our brains can’t understand, they won’t be able to explain it to us.
Isn’t time only measurable when there is change happening? If there’s nothing, it’s not that there is no time, it’s that there is no way to mark time. Which adds up to the same thing in real terms, but isn’t an absence of time itself.
Yes, I think that’s basically true. Some argue that time is not a real entity but a way to measure the changes that occur within the universe. Without the universe and the changes within it, there would be no time. However, I don’t think it’s incorrect to say the there was a time (not time) before the Big Bang (if that’s when the universe began).
At the onset of the theoretical Big Bang, the universe would have been something akin to a singularity, which means that time itself would have been a space-like dimension which somehow transitioned to a time-like dimension in the cataclysm (or all the dimensions were time-like and some of them became space-like). In the early part of the cataclysm, time dilation would have been so extreme that picoseconds would have been equivalent to contemporary millenia, and time gradually curved down into what we are currently experiencing. Where we are now is commonly described as long after the Big Bang, but the reality of it may be that the expansion of the universe is just us experiencing the ongoing cataclysm in a frame of reference that makes it appear to us that it is over.
But what is the definition of “What”? And what’s the definition of “How”?
That’s the problem with discussions such as this… answering questions with more questions results in infinite regress, and we end up being more confused & perplexed vs. when we started. (I am not picking on you. I am making a general statement, and am guilty of the same.)
That’s basically a pre-relativity viewpoint, however; in the modern era time is known to be an actual physical thing, a component of spacetime. I mean, we can detect gravity and acceleration distorting time with sensitive enough instruments.
It seems the more we discover, the more “weird” everything is, the more difficult it is to understand, and the more questions we have. It is the opposite of what’s desired in science. Might we reach a point where the simplest explanation is that we live in a simulation, and hence this hypothesis is likely to be correct according to Occam’s razor?
It’s possible, assuming the creators of the simulation don’t care about us figuring it out. Heck, at the extreme someday glowing words could appear in the sky announcing “Earth 1.0 Simulation shutting down due to budget cuts, thank you for your participation”.
If they do care about us finding out then we’ll never do so, since any evidence could be outright edited out of our minds or perception.
The concept of “imaginary time” in the Hartle-Hawking model of the universe makes the argument that time as we perceive it is an artificial construct. Furthermore, extrapolating the Einstein field equations for the geometry of a black hole suggests that time may become a spatial dimension beyond the event horizon. Meanwhile the radial dimension from the singularity to the outside world becomes timelike.
Inasmuch as the Big Bang represents the beginning of time, t=0, applying the term “before” to the Big Bang is meaningless.
More “unknowable”, at least from our present understanding. The Big Bang may have been when our universe started, but that doesn’t mean there was nothing before it. And some scientific theories do postulate an existence before our t=0; for example, one idea is that new universes “bud” from pre-existing universes.
I wouldn’t call those “theories” so much as wild hypotheses. The problem is that when we speak of anything “before” the Big Bang, or what might have “caused” the Big Bang, or imagining the Big Bang as occurring in preexisting empty space, we’re invoking common everyday intuitive notions that are extremely misleading, to say the least.
Nothing wrong with some wild hypotheses, as long as we’re not dealing with an area that has more established hypotheses or theories, which in this case there aren’t any. I personally find comfort in the idea that our universe is a white hole that appears as a black hole in some other universe, and that the ordinary matter it sucks up in that other universe becomes dark energy in ours, causing the expansion of our universe.