Universal 'Now' at Time-Zero

[StringJunky]

When the universe was in the hot, dense state, was everything causally connected and the time, if it existed at that point, was the same everywhere until inhomogeneity occured i.e. space formed and photons/information could travel?

 

Edit: Might be in the the wrong forum; I just realised Relativity goes awry at time-zero.

Edited August 16, 2016 by StringJunky

[geordief]

The question (unanswerable I think ) may be of less consequence than the question as to how we could go about learning what was actually happening then.

 

If it is just a question of how close we can get to that moment then that is simply a quantitative improvement in our knowledge.

 

Is it possible that our scientific civilization could exist for millions of years and not come up with any answer or even a reasonable guess or could it be that someone will have a guess and it will make sense.

 

I mean is it possible that the scientific method will fail but that serendipity will pull us through ? (thanks Bob )

Edited August 16, 2016 by geordief

[StringJunky]

The question (unanswerable I think ) may be of less consequence than the question as to how we could go about learning what was actually happening then.

 

If it is just a question of how close we can get to that moment then that is simply a quantitative improvement in our knowledge.

 

Is it possible that our scientific civilization could exist for millions of years and not come up with any answer or even a reasonable guess or could it be that someone will have a guess and it will make sense.

 

I mean is it possible that the scientific method will fail but that serendipity will pull us through ? (thanks Bob )

My question really is: does it make sense that if everything is physically connected and homogenous, time doesn't exist because everything happens simultaneously everywhere in that state?

[michel123456]

My question really is: does it make sense that if everything is physically connected and homogenous, time doesn't exist because everything happens simultaneously everywhere in that state?

Do you mean something like my infamous pencil universe? (beware Martin - where is he?- didn't like it)

[tar]

String Junky,

 

Odd, but I was thinking about this, in a way, just now, considering the idea of the two nows I was arguing with Strange about, a while back. It seems that yes, if there was a time when the universe was very small, the effects of gravity, and any effects other than electromagnetic waves, which would have to wait until the place was transparent to photons, would, at the speed of light, or the speed of impulse, or however gravity is transmitted, have the time to reach from one end of the place to the other. Causally the place, in that one item, could "feel" all others, in a relatively short amount of time. It is still that way, that one item can feel all others, except there is a significant delay given the size of the place, from the event to the feeling of that event in a distant corner. However, in defense of the two senses of now idea, and to answer the thread question somewhat, we are just now "feeling" some of the universe for the first time, in terms of photon release, in the cosmic microwave background. So, we could have felt all of the place at one time through gravity, but as it got bigger and impulses took longer to get to us, the current arrangement of far away stuff became more and more delayed in terms of when we would feel it.

 

So we are not privy to the current arrangement of any of the universe, but are privy to the earlier arrangement of the place, immediately. That is, our now is composed of the before arrangement but not in any dual way, but in a smoothly digressing way where we feel the current arrangement in nanoseconds or minutes or hours or days or weeks or years or thousands or millions or billions of years, depending on the distance.

 

So, we see a star three light years away, as it was three years ago, but we were looking at it a million years ago, as well and kept our eye on it, for a million years, and watched it burn, real time, just will not see its current arrangement, for three more years.

 

But that star is well within our causal family. We have been sending photons and gravity toward it, and it to us for billions of years. Same with stuff we just now are seeing for the first time, in the cosmic microwave background. We have known it since before photons traveled, and it us through the effects of our masses on each other..

 

Regards, TAR

Edited August 16, 2016 by tar

[geordief]

My question really is: does it make sense that if everything is physically connected and homogenous, time doesn't exist because everything happens simultaneously everywhere in that state?

Yes I probably misunderstood you because I do find that whole area difficult to understand..

 

I have heard that "time doesn't exist " statement before . If I was to attempt to describe my reaction to it (account taken of my lack of research into the area ) I would probably start by saying that time requires a measurement and without that possibility it is meaningless to talk about time.

 

I don't know if that makes sense or is useful but it may be the best I can do....

[Strange]

When the universe was in the hot, dense state, was everything causally connected and the time, if it existed at that point, was the same everywhere until inhomogeneity occured i.e. space formed and photons/information could travel?

 

 

The evidence suggests that in the early, hot dense state everything was causally connected (hence the uniformity of the CMB, for example). That, and the resulting homogeneity, to my mind, implies that everything was in the same frame of reference - there were no gravitational gradients, for example.

[StringJunky]

 

 

The evidence suggests that in the early, hot dense state everything was causally connected (hence the uniformity of the CMB, for example). That, and the resulting homogeneity, to my mind, implies that everything was in the same frame of reference - there were no gravitational gradients, for example.

Yes. Cheers. If the universe was homogenous and, it seems to me, timeless as well, it makes no sense to talk about before the BB, does it?

 

When I look at it that way, Relativity hasn't broken down as a description; it's just that it can't describe what is outside of it's domain because those parameters (Itime and space) haven't yet emerged, beyond that zero point; You don't use the bus timetable to find out when the next plane is. Am I on the right track?

Edited August 16, 2016 by StringJunky

[tar]

Homogeneous does not imply timeless. If there was any distance between one part of the thing and another, then the two parts could not inform each other of their current status, instantaneously. As soon as there is distance and more than one arrangement, it seems to me, the timeless part is lost.

Edited August 16, 2016 by tar

[Strange]

Yes. Cheers. If the universe was homogenous and, it seems to me, timeless as well, it makes no sense to talk about before the BB, does it?

 

 

I wouldn't say it was timeless. It was expanding and cooling (very rapidly, if the inflationary hypothesis is correct).

 

And there is at least one attempt to add quantum effects to the early universe that ends up with an infinitely old universe.

[StringJunky]

Homogeneous does not imply timeless. If there was any distance between one part of the thing and another, then the two parts could not inform each other of their current status, instantaneously. As soon as there is distance and more than one arrangement, it seems to me, the timeless part is lost.

I am talking about the hot, dense state so everything is as one homogenous entity.

 

 

I wouldn't say it was timeless. It was expanding and cooling (very rapidly, if the inflationary hypothesis is correct).

 

And there is at least one attempt to add quantum effects to the early universe that ends up with an infinitely old universe.

At time zero I mean... the instant before inflation. I make no inference to whether universe started at that point. I think we have mentioned before the universe has likely always been around in some form/s.

Edited August 16, 2016 by StringJunky

[tar]

but does it have depth and width?

 

to what observer would it be one entity?

[Strange]

At time zero I mean... the instant before inflation.

 

 

We don't know anything about such a time. And there may not even have been such a time.

[tar]

String Junky,

 

The current universe is homogeneous on large scale, and to some godlike observer, not bound by the speed of light or gravity, the thing can be considered one entity. So when do you allow a distinction between one particle and another?

 

Regards, TAR

Edited August 16, 2016 by tar

[Strange]

The current universe is homogeneous on large scale, and to some godlike observer, not bound by the speed of light or gravity, the thing can be considered one entity.

 

 

There is not, and cannot be, any such observer. There are parts of the universe which are, therefore, not causally connected so claiming it is a single entity is dubious (without a very clear definition what you mean by "single entity").

I am talking about the hot, dense state so everything is as one homogenous entity.

At time zero I mean... the instant before inflation. I make no inference to whether universe started at that point. I think we have mentioned before the universe has likely always been around in some form/s.

 

http://phys.org/news/2015-02-big-quantum-equation-universe.html

 

This research produced some of the worst-ever science reporting. I think we should arrange for all the writers of totally misleading articles about this to be sent to Guantanamo Bay.

Edited August 16, 2016 by Strange

[tar]

Strange,

 

Granted.

 

But what is causally unconnected now, may have indeed been causally connected before. And if so, there is no part of the universe that at one time was not within reach of every other part.

 

Regards, TAR

[StringJunky]

 

 

We don't know anything about such a time. And there may not even have been such a time.

You'll have to expand

[tar]

and I might add, by logic, any part of the universe that is now within view has been within view for a very long time, right back to when the place was first transparent

[StringJunky]

String Junky,

 

The current universe is homogeneous on large scale, and to some godlike observer, not bound by the speed of light or gravity, the thing can be considered one entity. So when do you allow a distinction between one particle and another?

 

Regards, TAR

I'm not talking about the large scale. I don't use God-like observers anymore... they send you down rabbit-holes...YOU are IN the universe. I don't think you gain any extra understanding trying to stand 'outside' the universe; confounds more clarifies.

Edited August 16, 2016 by StringJunky

[Strange]

You'll have to expand

 

 

Well, inflation might not have happened, for example. Or the universe may be infinitely old (so there is no "time 0").

But what is causally unconnected now, may have indeed been causally connected before. And if so, there is no part of the universe that at one time was not within reach of every other part.

 

That is certainly what the inflationary model says.

[StringJunky]

 

 

Well, inflation might not have happened, for example. Or the universe may be infinitely old (so there is no "time 0").

You can have both, can't you? Time zero may just mark the beginning of a new epoch in its evolution. Let's assume inflation is true as that is the current consensus.

Edited August 16, 2016 by StringJunky

[tar]

Thread,

 

Let me correct what I said about being visible since the place was first transparent.

 

I am thinking about one observation post at the time of transparency. You could only see what was right in front of your nose. Then the sphere of visibility would have expanded at the speed of light, and the edge of this sphere is right now just getting to the area of space we see as CMB. So not everything has been in view since the transparency to photons occurred. But once we see a thing, we never lose contact with it...that is, it has been continually within view since first appearance. So to speak, since one area of space can evolve and change character over billions of years.

 

Regards, TAR

[Strange]

But once we see a thing, we never lose contact with it...that is, it has been continually within view since first appearance.

 

 

I don't think that is necessarily true. It depends how the Hubble constant (rate of expansion) has changed over time.

[tar]

But back to hot dense. If it was no longer a singularity, it was something with distinctions. And this something that had this area that later became the Milky Way, and that area that later became some area of space we are currently seeing as cosmic background radiation, was "small" enough so that the one area could feel the other over a relatively short period of time, even before there was photon travel. I would guess.

[StringJunky]

But back to hot dense. If it was no longer a singularity, it was something with distinctions. ...

It never was a singularity... it was hot and dense.