It depends on the meaning of “are”.
There are infinite things that do not exist.
There is (has been?) an infinitude of virtual particles.
Where did I read that time is that what happens when nothing else happens?
No I haven’t.
Now you automatically gainsay what I’ve said, and we continue the cycle from there.
I can give you a theory where time is limited in the future, but you’re right that it’s not necessary. All that’s necessary is that for any given ‘metainstant’ the entire instantiated timeline is finite.
There are two ways your timeline could be:
- Bounded and fixed. We’re traveling from the past towards the future, and when we reach the end we’ll stop.
- Bounded and growing. (This requires metatime, and is required for the nonsense type of free will.) In this one the future is undefined, and is written as we go. The instantiated past of our universe (as in, between the bang and now) is always finite, and the future doesn’t exist until it happens.
In both cases the timeline is finite, but in the latter case it gets longer as we go.
I thought that there was a lower limit to the amount of energy something could posses because the smaller the amount of energy a photon has, the longer its wavelength; and eventually your photon would have such low energy that its wavelength would be larger than the observable universe
I think you are trying to present ad-hoc theories, but I don’t think these have any predictive value so I’m comfortable rejecting them out of hand.
As I said before, I believe that the conclusion (time has no future bound; time is infinite) follows from a fundamental premise (time always advances).
~Max
Do we actually know that time always advances? I mean, it has so far, but what’s to say it’ll keep advancing tomorrow?
That is a philosophical question. I suggest that the assumption is fundamental within the field of science.
~Max
Is it demonstrated by science, or is it assumed by science?
Assumed.
~Max
This sounds like a description of a black hole, doesn’t it? No edge, no size, effectively bounded but infinite on the inside. Or would that not be considered “in the universe” for our purposes.
Then you are comfortably rejecting the possibility that time will eventually end based on the fact that you find assuming that it might be otherwise to be uncomfortable.
Which is a fine way to go through life, I suppose, though if I rejected things that didn’t fit my assumed norm I’d still be saying that there couldn’t be turtles all the way down.
From a scientific viewpoint, I am very comfortable assuming time will never end. I think it is inconcievable for any formulation of science to avoid this assumption, because one of the basic tenets of a scientific theory is that it has predictive value. If time does not always advance, there is no predictive value; prediction operates on the assumption that there will be a future.
~Max
I thought black holes had an edge, if a fuzzy one. For example, there are black holes in the universe, but I’m not currently in any of them. (And hope to keep it that way.)
As for how infinite they are on the inside, I personally don’t have enough certainty to say whether they are, or whether the properties of things that end up in them just get really weird (but finite at any given moment).
Er, science always has an implied “presuming our assumptions hold” attached, doesn’t it? Science can perfectly predict the arc of a thrown baseball, but if it hits a bird en route then the prediction will necessarily be off. So if your thrown ball prediction also assumes that there will be a time t+5 (which it does assume) and that turns out to be incorrect, science will just shrug and say that its predictions come with a limited warranty. Won’t it?
Correct. I am saying one of those assumptions is that time always advances. The logical implication is that time is infinite. This is a direct answer to the OP, which was framed as a scientific and not epistimological prompt.
ETA: The difference with the assumption about a bird not interfering versus time always advancing is that it is impossible to present a scientific theory without assuming time always advances; it is quite possible to present a scientific theory that accounts for a stray bird.
~Max
As far as I understand it, space-time has perfect symmetry everywhere we’ve looked so far, with a few edge cases which we THINK are more to do with us not understanding the physics fully than a true asymmetry. That means that the same way your equation to calculate the path of a cannonball works whether you shoot it east or west, the equations also allow you to flip the time axis, and follow the cannonball from where it landed back to being launched.
If that’s the case, all we know is that WE experience time in a single direction; but all points on the time axis are equally real as well. So time doesn’t have an arrow; our perception of it does; and it is safe to say we will continue perceiving it that same way because our perception of time is governed by the physical laws that allow our consciousness to arise, and physical laws don’t just change randomly according to our models. They might in the future, in which case our models will need adjustment, but we have no reason to expect this to happen.
Forgive me if I butchered that argument, this stuff is very complicated and my understanding barely scratches the surface. But I always love to be corrected!
I believe the arrow of time is a different concept than the question of whether future time is bounded or unbounded. Even if the arrow of time was to reverse (as it can when no work is performed), you would still step through a process by incrementing t.
~Max
That depends entirely on what time is. If, as some have proposed, Time is the direction of entropy - IE forward in time is always an increase in entropy, even if locally entropy decreases (like a living thing imposing organization upon the local chemical soup) this comes at the cost of an overall decrease in entropy (life uses up energy faster than nonlinear processes).
If that’s how you choose to define time, then there was no time before the big bang (because entropy was at a uniform minimum throughout the point-like “universe”) and time will eventually end (when the heat death of the universe brings entropy to a maximum). And while time = decrease of entropy isn’t a perfect definition, I challenge you to come up with a better one, from a scientific point of view.
Regardless, that’s a scientific theory that does not assume time advances forever. Even if it is wrong, it shows that it is not impossible to present a scientific theory that accounts for time not advancing.
Sure, but you’re incrementing T back to where it already was, so the range of possible Ts is not infinite.
This makes no sense to me. How can increments go backwards? The state of the system might revert, it might loop, but (lowercase) t always advances.
~Max
What is lowercase t measuring if time is looping back? Some abstract hyperuniverse that exists outside our own may have some kind of hypertime (ht?) But by definition we would have no way of interacting with such a universe if one existed, and therefore any theories about it seem inherently untestable and unscientific to me.