Time

[Silver]

I am not speaking of causality.

I am merely speaking of time.

[Alex K]

This is insanely fun - sorry if I'm being obtuse... Maybe I should study physics on my own... I'm not sure if I have the vocation to take up a course in physics at an university, so it would be better if I studied it in my own dilletante way. Do you guys have any good recommendations? The only books I ever read about physics, I think, are Krauss' A Universe from Nothing and Hawking's A Brief History of Time. I also watched a couple of documentary-Tv-Series, like Cosmos(the new version), a bit of the series behind that little youtube video presented earlier in the thread(certainly that, since I remember it so vividly), Through the Wormhole...

If you want to start getting into "real" physics textbooks, how about the Feynman lectures?

[Alex K]

I still don't have a simple coherent understandimg of how time works after 10 years of research in fundamental physics. Im quantum field theory, time is a continuous parameter like the three+ space directions, but distinguished from space via the metric tensor. Yet, time is not entirely separate from space because in relativity, which direction in the four dimensions one calls time is not uniquely defined.

The *direction* of time, i.e. the reason why past and future are so different, im classical physics seems to be a purely statistical phenomenon. A space like boundary of the 4D universe with low entropy is the past. But once I thought I got that a little bit, I got confused again because in quantum theory (at least in the usual picture) we have wave function collapse which fundamentally seems to distinguish past from future as well.

[robvalue]

I used to think of time as a parameter we invented to catalogue different three dimensional physical states. I'm sure that originally, that's exactly what it was. But it seems that what we are attempting to model with a simple parameter is much more complex than that. I haven't got my head around relativity yet.

[BrianSoddingBoru4]

Time is purely economic in nature. The Universe invented time so your boss could fire you for being late, or for taking 9 day week-ends.

Boru

[downbeatplumb]

Can anyone explain time to me? It never made sense to me that it's actually a real thing in physics, I always thought it was just another human peculiarity that makes no sense conceptually- just another fuck-up of linguistics.

Provide whatever explanation you like. Just please don't call me a moron - I already know that, sigh. 

Time is what stops everything happening at once.

[Excited Penguin]

Can anyone explain time to me? It never made sense to me that it's actually a real thing in physics, I always thought it was just another human peculiarity that makes no sense conceptually- just another fuck-up of linguistics.

Provide whatever explanation you like. Just please don't call me a moron - I already know that, sigh. 

Time is what stops everything happening at once.

Except that doesn't explain anything. It's like someone asking what is life and someone else answering it's that which stops you from being dead.

[Excited Penguin]

I personally, intuitively think that the universe is/might be far stranger than we perceive it and that time too is only something we made up in order to make sense of how everything "flows". Maybe once we'll get smarter or drastically extend our lifespans the notion of time will change for us too, or maybe even disappear altogether(who knows?).

Just like that with physics. I'm not saying the naturalist/scientific way of studying the cosmos isn't the best we have, I truly think it is, it's just that I'm extremely sceptical that it reveals anything of value to us about the universe. I think mankind is still far too biased by its own tools(e.g. language), let alone when comprehending its own discoveries. I'm not talking about an individual bias either, I'm talking more about an impossibly inherent one in all of us, one we can't even see yet. But that's just my philosophical nonsense - I might be wrong.

[IATIA]

... time too is only something we made up in order to make sense of how everything "flows".

Basically that is it. Time is 'convenient', not necessary. As far as the "strangeness" of the universe, yep! I make no claims on what the universe actually is, only what my "perception" of reality dictates to me. We cannot know more than what our brain "tells" us, because technically we are nothing more than a 'brain-in-a-vat'. We cannot know or prove that anything we perceive is really the way it is.

However, if time were to exist we have to deal with infinite regression. The only way out is for all 'realities' to exist, as the previous video shows (albeit, they could only show a simulated 3D representation of a 4D environment in 2D). In this scenario, there is another you with the same awareness asking the same questions. There is a past you, a present you and a future you. If I traveled to yesterday and engaged in this same discussion with you, it would still be 'you' in that 'reality' which is the same 'you' in this 'reality'. Each 'reality' is static. It is the change to the next that creates our perception of time and awareness.

Everything I have said to this point is possible under QM as we understand it today. Any particle can be anywhere at anytime.

[downbeatplumb]

Time is what stops everything happening at once.

Except that doesn't explain anything. It's like someone asking what is life and someone else answering it's that which stops you from being dead.

Ok then, time is a dimension in 4 dimensional space time down which we can only move one way.