All of it. It's real yet unreal.

The past and future are real but they aren't here, nor are they all for there are other timelines, and other set of physics with infinite timelines each, and many more.

TIme is essentially change because things that do not change do not experience time.
Time is same as distance volume speed. Those values are simply numbers to measure something and thus they have to refer to something that they are measuring.

If we try to find how time works I think it is explained by well-known law that faster change requires more energy than slow change.

Good question.

I think many physicists would say that time is humans' perception of the constant increase in entropy within any given reference frame. It began (as far as the current real universe is concerned) when the increase in entropy began and the universe left its minimum-entropy initial state - in other words, at the Big Bang. Nothing "before" the Big Bang counts as existing, as far as science is concerned, because the Big Bang acts as a barrier preventing it from having any effect on everything that happened afterward. Time ends either when a singularity is reached (i.e. you reach the center of a black hole) or, if black holes conserve information, time never ends but rather extends infinitely into the future as a ray. That said, in most of the universe time will effectively stop existing when there is no matter or energy left in the nearby area, all of it having dispersed as the universe expanded.

>>6149

This theory has one problem as time has to exist for big bang to happen, as well as time has to exist even if good created universe simply because any action requires the concept of time. Nothing can happen without time.

Also, Blackhole does not preserve anything. If you fall inside you get ripped apart by the gravity differential before you even hit the ground.

>>6150 Oh, no worries, I well understand how inhospitable black holes are. A human's conscious perception of time would likely stop before even getting within spitting distance due to irradiation or just plain incineration (accretion disks get pretty hot). The debate among physicists these days is the "Firewall Paradox," in simple terms the contradiction between the laws of relativity and quantum mechanics as they apply to black holes. Do they destroy elementary particles as well, or simply trap them inside to be released later when the black hole eventually evaporates?

Regarding the big bang needing time to exist, time did exist right from square one, but didn't have to exist beforehand. Nothing needs time to have existed in the past for it to happen now - I can do anything I want now and not need to worry about whether time existed billions of years ago or even one second ago. Likewise, if time and space began simultaneously, neither needed to be sitting around forever ahead of time, which conveniently avoids chicken-and-egg problems (if space can't exist without time, and time can't exist without energy, and energy can't exist without space, then how do any of them exist in the first place?).

>>6155
You probably misunderstood something because I meant that time has to exist in philosophical terms as if the big bang "happened" it requires time to happen or if we have no time nothing can happen.
So the only reasonable hypothesis is that universe must be cyclic and time does exist before big bang as well


Black hole physic is a bit strange as well, as I do not understand how physicists do not see the problem that black hole breaks energy conservation law.
If anything falls into a black hole all energy of that object is released as radiation. so whatever falls inside should not exist already and if it gets to evaporate again you get double amount of energy than predicted by e=mc

>>6156
>So the only reasonable hypothesis is that universe must be cyclic and time does exist before big bang as well

I cannot begin to express how incorrect this is.