Beginning already implies temporality, so time can’t begin. There is either time, or there is no time.
It’s kind of like asking what’s north of the North Pole or is Alpha Centauri to the left or to the right of Earth.
Dynamic, no doubt.
Time is relative, recall. It stops at the speed of light, and ends in black holes. In fundamental stuff (quantum foam?) time is eternal and enables things to fluctuate, such as the density of energy. When the energy is dense enough, it becomes matter (the big bang), and that’s the beginning of spacetime.
Not quite. Cosmological time is still coordinate time, and no coordinate system foliates all spacetime events, so coordinate time is simply not an option. Perhaps it’s better to day I ground time in itself in spacetime, but that’s circular. Still, the two (time and space) are different aspects of the same thing, so in what might I ground spacetime besides perhaps mathematics?
I would have used ‘determines’ more than ‘generates’, the latter implying some sort of engine driving the evolution, or driving the mathematics, or however you look at it.
Yes, this might be wandering a bit off topic, especially in a naive topic such as this one.
Energy, like most physical values, seems meaningless in the absence of time.
I can think of numerous counterexamples, one being the set of all legal chess states. A temporal relation between states is emergent, albeit a discreet one.
It’s a common pop-sci myth that time stops at the speed of light.
As for it being relative, there are ways that I could agree to that.
Yes, but what we perceive as motion is always relative too, relative to fixed position. We can’t have one without the other, and where we have either one, we have both.
Things don’t just move, they move from this (fixed position) to that (fixed position). We wouldn’t notice motion if all was merely motion (nor would motion be motion, if all were simply motion). Just like things come to be things, absent the motion whereby they come to be at all.
Observation only begins by setting or finding stillness. If you observe anything, you mark fixed things, especially if you observe motion. (If you bumped into the fixed center of the universe and observed a motionless monolith - you would have to spin it through time with your watch and balance the universe in motion around it, to even say “it is motionless”. Motion and stillness are ubiquitous and entail each other. Tension, a dynamic force, is all that is observed, if you ask me.
I don’t understand what you are trying to say!
If time and space are aspects of the same thing — could that thing be: to exist is to make a difference?
Not even ‘determines’ but ‘prior to mathematics’?
Yes — mutual constitution and infinite regress are the same structure seen from different directions. Neither terminates.
Tension between what?
Time comes into existence only when it is measured, read or talked about by someone on the earth.
Indeed. Before spacetime emerges with the big bang, there is time in the more specific sense of eternally fluctuating particles, and possibly an energy reaching a high enough density to become mass, big bang, and spacetime.
I should’ve added tachyons existing backwards in time 
The point is that in one and the same universe, time can exist in different ways. It can begin (as spacetime) and end (as in a black hole), and possibly be eternal (as in fluctuating virtual particles).
Tension between what?
Legitimate question.
Tension, like war, entails opposing things or forces. If you see tension, you see tension between two things, so you already see two, in tension with each other. So the answer to “tension between what?” depends on what tension, or whatever thing, you are observing.
Any individual thing is a tension, arising at the boundary between the nature of the thing, and everything else, or the nature of the thing, and it’s becoming.
This is all basically what I’m talking about in the “what is a thing” thread.
No idea what you mean here. It seems you’re suggesting that spacetime is the same thing as a definition of ‘to exist’.
As for the definition itself, make a difference to what?
Whatever spacetime actually is, I suspect what it is doesn’t depend on it being designated as existing or not.
Again, this seems not to parse. I cannot substitute the phrase where ‘determines’ was and maintain coherent syntax.
And perhaps you imply that mathematics supervenes on the universe instead of the other way around, but I see no evidence of anything like that.
This from someone who just said:
OK, so now you’re idealistic (and incredibly anthropocentric) about the existence of time. Is this a general stance on existence, or is there anything (mind say) that doesn’t come into existence only when it is measured, read or talked about by someone on the earth?
You say ‘indeed’, but then contradict yourself, referencing energy (and ‘fuctuating’, ‘reaching’) in the absence of time, all quite self contradictory.
The universe has no total energy, and that energy isn’t conserved. That only works locally.
Another common pop-sci myth. A tachyon (were one to exist) exists on a spacelike worldline, and hence has no invariant speed or even direction that it’s going.
The point is that in one and the same universe, time can exist in different ways. It can begin (as spacetime) and end (as in a black hole)
Per relativity theory, time is indeed bounded by bangs, white and black holes, etc. In a view with a preferred moment in time, (anything but a block view), time is not bounded in any of these singularities, so it being bounded is interpretation dependent.
It is not a general stance on existence. It is a conclusion of the perceptual observation on time.
The “indeed” refers to your statement that energy seems meaningless in the absence of time. But I don’t reference any absence of time. On the contrary, which is open to read.
OK, you’re right about that. What you reference is another kind of time that isn’t spacetime:
Here we still have one kind of time where all those words are meaningful, but then it gives rise to spacetime, one dimension of which is a second kind of time where all those words are meaningful to us. Also a reference to a pre-space space since density is mentioned outside of the context of spacetime.
I read somewhere that energy can exist without being extended in space. If true, then it seems reasonable to assume energy of some density prior the big bang. When dense enough, the energy becomes mass, which in turn does extend and by doing so it creates space. Pure speculation, of course, but I’m curious and don’t know enough math to do the physics
That’s it exactly.
The boundary with everything else is the spatial aspect.
The boundary with its becoming is the temporal aspect.
You didn’t separate them.
So a thing isn’t in space and time. A thing is spatio-temporal tension. Space and time are what that tension is made of.
Which means “the beginning” of time isn’t a moment before which there was nothing. It’s the “first” boundary. The “first” act of exclusion that makes anything a thing at all. Not “first in time”, first in the order of what has to be true for time to be possible.
Prior as in: what has to be true before mathematics has anything to work with.
To make a difference to anything distinguishable from it.
If spacetime doesn’t depend on being designated as existing then it depends on making a difference. Designation is itself an act of distinction.
Solipsists who claim that nothing exists beyond one’s personal experience, and that everything beyond it is a “fiction” or “imaginary”, are tiresome.
@Corvus, do you honestly believe that the entire universe exists in your head, with nothing existing outside it, whether before you were born or after you die? If you were born after I was born (I’m not going to give out my birthdate, so let’s speak hypothetically) was I “fictional” before you were born? If I die after you die, do I become “imaginary” with your death?
My point was nothing to do with solipsism. You are barking at the wrong tree with misunderstanding on something.
It was about how much you can perceive time in the real world. And that is not just for you or me, but everyone living at present on the earth.
If you think more clearly about it, it is you who are thinking about time on the basis of imaginary position. You keep believing on the existence of time even when you are not perceiving anything at all. It based on your belief and imagination.
Whereas my account is more realistic in saying that everyone has the same limitation on the perception of time. Time exists when they measure, read, and record the reading with the events and movements observed.
It is in some respect like language. Language only exists when someone starts speaking or writing about something, or having conversation with others.
If you die, the moment of your death will end your time. Everyone has their own time. We are looking at time from objective paradigm while alive. It doesn’t mean you have full access to time which is tangible and physical. It is your illusion, if you think you do.
Anyhow, it is not about solipsism.
It implies solipsism, though, because it indicates that everything before you were born existed ‘outside of time’ and likewise everything that will exist after you die will likewise somehow exist ‘outside of time’, and how can anything exist ‘outside of time’? That leaves the only possibility as that nothing existed before you were born and nothing will exist after you die, and you seemed to agree with this assessment with your use of words like “fiction”.