I have no answer. I am interested in the topic tho. My thought is that there is a …
there isn’t a word that I know to describe what I’m thinking. “no time” or maybe “anti time” comes close.
I’m just a grade 12 graduate that has done manual labor all my life. About 40 years of labor so far.
After I leave this mortal coil, time will end.
If you ask me any math on this, I wouldn’t be able to say shit. But I do keep up with scientific stuff from time to time, and AFAIK this all is the most accepted stuff in scientific community.
This is 3 different theories? At least that is how I’m interpreting it.
Yes
Those were 3 proposed ones for the long term future of Universe after big bang. As I said previously, our observations and experimental data tells us that only accelerating expansion is the correct one.
We don’t know why it keeps accelerating, but we do know it does.
Your experienced perception will end sure, that doesn’t mean time will end. Unless we all are just NPCs and you’re playing one helluva detailed VR game 
Yes, or a simulation.
I believe quantum mechanics and the general theory of relativity not playing along means we don’t nearly have the picture we thought we did.
From what I know, quantum mechanics don’t disprove spacetime. I’ll need to dig in on this more. My quantum mechanics knowledge is the worst from all physics.
About the simulation. It’s virtually impossible to prove we’re in one, safe the creators of it tell us. So we can just skip this imo. Either it’s real one or virtual doesn’t matter, coz we play by those rules anyways.
Agreed, hence the blur.
@Eden @zavar @anotherriddle
I was gonna build up to this, but the gek called me out.
Your definition/interpretation of time all comes from the theory of general relativity, which I believe is wrong, and the answer to our reality lie with quantum mechanics, because it seems inherently more fundamental.
[Ben Shapiro Voice] And the idea that this [General Relativity] is wildly accepted within the world of physicist, simply isn’t true.
Okay, everyone strap in, here we go!
Please, for the text that follows keep in mind that I choose my words very deliberately and carefully. One inherent flaw of everyday language is that you can not be very precise with it, this is why we have mathematics where we use a reduced set of words with very precise defined meaning. The nature of logic is, that if we deduce from false premise we end up with false conclusions.
Opinions and commentary on the articles
"The Illusion of Time: What’s Real?" and
Digital Presentism: D-Theory of Time (The Origins of Us, Part II)
https://www.space.com/29859-the-illusion-of-time.html
I will skip the speculation to the part where statements and claims are made.
Huw Price, professor of philosophy at Cambridge University, claims that the three basic properties of time come not from the physical world but from our mental states: A present moment that is special; some kind of flow or passage; and an absolute direction. [emphasis mine]
Take note, that Huw Price uses a very different definition of time than I am using and that is used in physics. It might be closer to what the majority of people think of when they say “time” but it is very different from what physics uses. In physics we do not make assumptions that time has"A present moment that is special;" and “an absolute direction.”. Do not take my word for it, take a look yourself:
Please keep in mind that it is really hard to boil everything down to individual quotes that explain and not rely too heavily on mathematics.
Read either the full chapter or read the problem of “simultaneity” in the context of the requirement that causality needs to be conserved.
https://einsteinpapers.press.princeton.edu/vol6-trans/16
Here are the equations, take special note of equation (III)
https://einsteinpapers.press.princeton.edu/vol6-trans/20
And finally the use of “eigen-time” in general relativity, specifically the relativity of time (§2):
https://einsteinpapers.press.princeton.edu/vol6-trans/44
You see, the only real assumption made, regarding time, is causality.
As this part is only referencing the theory of space-time I will save the discussion on quantum physics for later. (Please remind me if I forget, it’s getting hard to keep track of everything.
“What physics gives us,” Price said, “is the so-called ‘block universe,’ where time is just part of a four-dimensional space-time … and space-time itself is not fundamental but emerges out of some deeper structure.”
This is an assumption, a possible interpretation and not a truth. The theory of general relativity, itself does not make any statements about a “deeper structure” . (See Sources above, here is a table of contents.)
Time is tenseless, all points equally “real,” so that future and past are no less real than the present.
“Tenseless” in this case is not consistent to the earlier stated definition of time and the interpretation used in physics. It is more used in a sense that a hypothetical observer outside of spacetime could “view” the whole of spacetime at once and it would appear as unchanging. The problem is, this is a thought experiment and one that implies a deterministic universe. It is a nice idea to think about but it does not mean that the fact that our (perceived or otherwise) experience of time comes form the fact that we are inside this system.
What follows are further analogies for the same concept.
“Time is out there,” said Andreas Albrecht, a theoretical cosmologist at the University of California, Davis. "It’s called an external parameter — the independent parameter in the [classic] equation of motion. So, time — the time we know since we learned to tell time on a clock — seems to disappear when you study physics, until you get to relativity.
You can interpret this statement several ways, but it does not say time is not real in our current understanding of the laws of nature. (personal opinion: It is more of a poetic take anyway.)
“The essence of relativity is that there is no absolute time, no absolute space. Everything is relative. When you try to discuss time in the context of the universe, you need the simple idea that you isolate part of the universe and call it your clock, and time evolution is only about the relationship between some parts of the universe and that thing you called your clock.” [5 of the Most Precise Clocks Ever Made]
Yes, a good summary of what is a clock in the context of general relativity.
Julian Barbour, a British physicist, describes time as “a succession of pictures, a succession of snapshots, changing continuously one into another. I’m looking at you; you’re nodding your head. Without that change, we wouldn’t have any notion of time.”
True. Isolating time from everything else does not make a lot of practical sense. The same is true of Gravity. You can use the field equations and apply them to a vacuum. The result is very boring, the same is true for time. Do not use this statement to conclude something does not exist on it’s own because you can’t observe it when you isolate it from everything else.
Time is a prime conflict between relativity and quantum mechanics, measured and malleable in relativity while assumed as background (and not an observable) in quantum mechanics. To many physicists, while we experience time as psychologically real, time is not fundamentally real. At the deepest foundations of nature, time is not a primitive, irreducible element or concept required to construct reality.
Yes, Quantum Mechanics and General Relativity are not compatible over large areas. Please note that the phrase “observable” has a very specific meaning in quantum physics and mathematics. It does not always mean that the variable can not be observed in the everyday language sense. Yes, it does describe a physical quantity that can be measured but measurability depends on other operators and commutativity.
https://en.wikipedia.org/wiki/Observable#Incompatibility_of_observables_in_quantum_mechanics
Opinion is divided, but many physicists and philosophers now suspect that time is not fundamental; rather, time emerges out of something more fundamental — something nontemporal, something altogether different (perhaps something discreet, quantized, not continuous, smooth).
Well, yes, maybe. In case time derives from some underlying effect it does not mean it is not real though. Atoms are build from protons, neutrons and electrons. Protons and neutrons are build from up and down quarks, this does not mean Atoms are not real. (At least in my interpretation of the word “real”) In my opinion the same is true for gravity and time and the electro-weak force …
https://www.ecstadelic.net/top-stories/digital-presentism-d-theory-of-time-the-origins-of-us-part-ii
This one will be short, because the first one already took a lot of time but it seems most of the arguments are made in this one
https://www.ecstadelic.net/top-stories/temporal-dynamics-seven-misconceptions-about-the-nature-of-time
and my arguments apply to most of the points made in my commentary on the first article.
Time is Universal
Actually, the past, present and future all exist simultaneously in the eternal NOW.
This uses the same interpretation as the first article and I already commented on that. Just let me add, the phrase of “now” here is used in a very different way than in everyday language and does not really relate to time.
Time Can Only Move Forward
Probabilistically, the time’s arrow reflects an observer effect — “crystallizing” of the classical present from the quantum past. But the opposite direction, anti-time, is just as valid and just as real.
Well, yes in a way. “Anti-time” might be valid on paper, however there are processes in physics that are non-time-reversible. This means the inverse of a process breaks time symmetry, you can not go back. See my earlier comment regarding time invariance and CPT symmetry.
This is simply not true. General relativity as well as quantum mechanics are both incredibly well tested theories. (I don’t really think you debate that, if you do, just say the word and I will provide links to papers) We do not agree on some interpretations because the equations allow for further phenomena that either cannot be observed or have not yet been observed. There is no doubt however that we still have a lot to learn and that a unified theory would be a great achievement. All this does not mean, however that time is not real.
Yes, you are right neither of both theories at the moment is in conflict with the other, we just don’t have a unified theory yet. Regarding the test for simulations: Interestingly there are tests that we can do to find out whether we are likely to be in a simulation. The problem is though that we can’t disprove it. (Also we have to make a couple of assumptions)
This question is likely impossible to answer as we expect the laws of physics, as we observe them, to change at these conditions. But there is a lot of speculation, nothing we will ever be able to prove though. Falsifiability is key for science.
Exactly! We need to find a good definition.
I still maintain that we have different working definitions here and that we all need to define the scope and meaning of the words we use better. @anon46267848 What I find interesting though is, that when I apply the same framework of definitions to Gravity as I do to time I end up with the result that either both are real or both are not. I would really like to know where our definition framework diverges.
After thinking a bit, I think the definition that makes the most sense to me is:
Time is a 4th dimension in a spacetime continuum. As such asking when something happened, is akin to asking where it did. As to why time dimension is limited to going only “forward”/one way is not clear.
I particularly enjoy world spacetime diagrams, all be it I only seen simplified 2D (1 space D + 1 time D) ones.
It’s particularly interesting to me, that when we’re talking about event horizons of black holes, after crossing it, it’s as if time and space flip on the diagrams. Since now you can only move in 1 spatial direction, towards the singularity. Space behaves like time in black holes.
Speculation:
Maybe it’s so that the spacetime itself has an inertia that propels everything in the 4th dimension (time) forward. 
The heat death of the universe? I would say no at that point. There ceases to be change, and nothing to observe it so everything has stopped, time, heat, all thing in the universe at final rest.
Again I think it’s important to differ what’s in spacetime, and spacetime itself.
While everything inside it will cease changing, that is not to say that spacetime itself will. From all we know it’ll keep on accelerating.
Is spacetime free if the need for energy? I assume that the heat death leads to the stop of all vibration and energy. So what furthers the expansion or acceleration?
Well that’s the question, lol. Does spacetime has intrinsic energy, and is it what we’re calling dark energy. We don’t know. But again, all the particles reside inside the spacetime. So even when all particles stop vibrating and reach 0 K, the spacetime doesn’t really “care” about that, AFAIK.
It is an interesting line of thinking but I feel we are getting off topic.
That is an interesting thought. I assume you don’t mean the same inertia we attribute to mass though. However, with current field equations we do not need to make this assumption. Maybe something like this will be necessary for a unified theory. I am not sure that we need a different concept of time, rather different field equations. This is not my field of expertise though.
I hope, it does not come across like that. I’m just very passionate about science.
It’s also useful for demonstrating how the speed of light is the speed of causality; to break that barrier would lead to reverse time travel.
