Understanding the 4th dimension and higher..

[Cras]

Oh, I'm not saying anything of the sort. If relativity is correct, then even time is a product of our universe. It does open the big question of what was before the universe, but I'm a firm believer that we can only physically explain the universe itself, and nothing outside it. Because if we could, that would kind of make it part of our universe by definition.

So if time itself is a product of the big bang, there doesn't really need to be any perfect order before it. The big bang is nothing but the first increase in entropy, and it has been growing ever since.

Ah hell, now I'm really starting to talk philosophy in a science thread. I should really stop now before I make an ass of myself... :facepalm:

I am of the similar belief that time was kick started by the big bang. Of course, the big bang theory then is not the start of anything but of Time (as we know it), and our expanded three spacial dimensions. But it only kicked them into the form we know of, it did not create anything. There is another "realm", what ever you want to call it, that has to exist for this bang to occur in. There are possibilities that we can detect certain interactions with entities outside our universe. If we will ever be able to actually do the measurements or have the energy required to probe matter down to the distances required (such as to find out if gravity really is as weak as we perceive it to be) is another matter.

Gravity does help in establishing the pre-big bang environment as being one of enormous order, but in short, we are not there yet. We still have work to do to figure out the big bang, and how it relates to time's arrow, and what space is actually made of.

While pondering time's arrow may seem to be fruitless, or utterly pointless at times (but it is still a subject that interests me a great deal), the fabric of space is still a very pertinent subject, since we have a geometric model of spacetime and its role with gravity, it is quite the reasonable question to ask "What is bent and warped anyway?" when we talk about General Relativity.

---------- Post added at 03:48 PM ---------- Previous post was at 03:46 PM ----------

Time travel is not possible unless you are willing to accept the universe follows a fixed path that was pre-defined and infinite amount of time ago. Just trust me on that, I've done the mental legwork. Of course, that doesn't stop relativity and causality preventing it as well, it just adds to the mix. It boils down to:
If the universe is not fixed:
You can't go to the future because it isn't determined yet, and you can't go to the past, because you'll be coming from an undefined future, and the rest is paradoxes. If needs be I'll try and compress my full logic into readable form later.

No need to worry, the physical laws we have and understand are quite clear that time travel is not possible, so the while the thought experiments are often a fun thing to do, especially when time travel is the subject, they are not required in preventing the horrors that time travel presents.

 

[jangofett287]

The way I (Think) I understand it, is that time is simply the product of the stretching of Space by mass and/or gravity.

 

[Jarvitä]

It does open the big question of what was before the universe.

No, it really doesn't. If time is a product of our universe coming into existence, "before the universe" is an absurd, meaningless phrase, just like "north of the north pole".

 

[Cras]

The way I (Think) I understand it, is that time is simply the product of the stretching of Space by mass and/or gravity.

Again, it is a bit more complicated. There have been whole books dedicated to the subject, some more technical than others, but they always seem to end in the same manner, "Time? We just don't know."

You really have to sit down and think about what time is. How it is experienced, and what changes when time is warped. Then you look at the equations that dictate those things, and when they lack an arrow, things get interesting, so you have to dig deeper, and as things tend to go in the cutting edge of quantum physics, you are bound to find many more questions before you find an answer.

But time as a product of space being stretched? not quite. Time is indeed far more influenced by gravity than space is. When you see those pictures of the giant circle in the warped field, when people try to describe general relativity, that is more like what time looks like. Time is far more warped by gravity than space is.

But this does not give time an arrow. It does give gravity its appearence of being an attractive force, as things want to be at the point in space where time is the slowest. An interesting idea, is it not?

 

[Linguofreak]

Time travel is not possible unless you are willing to accept the universe follows a fixed path that was pre-defined and infinite amount of time ago.

Relativity actually posits just about exactly this (except for the infinite time part. Relativity (plus the observation that the universe is expanding) tell us that the universe, including time itself, has only existed for a finite amount of time. But the universe follows a fixed path that was set when it began (or, if the universe was created by something outside it (for instance, God, as I believe to be the case), it's better to say that the universe follows a fixed, externally defined path. In either case, however, the point is that the future and past are well defined.

Relativity also posits mechanisms for time travel, although it's unclear if the things needed to create them actually exist (or even can). But time travel as the general public imagines it is impossible: Time machines in relativity are, so to speak, roads rather than vehicles: You can't travel back to a time before your time machine existed, or forward past the time when it will be destroyed.

 

[jedidia]

No, it really doesn't. If time is a product of our universe coming into existence, "before the universe" is an absurd, meaningless phrase, just like "north of the north pole".

Then let me rephrase: it opens the question of why the big bang happened in the first place

 

[Linguofreak]

No, it really doesn't. If time is a product of our universe coming into existence, "before the universe" is an absurd, meaningless phrase, just like "north of the north pole".

As far as time goes, yes. As far as causality goes, not so much. It would be better to phrase it, though, as "what caused the universe to exist" (or better yet, to make it more time-neutral, as time is part of the universe, "what causes the universe to exist").

 

[N_Molson]

Then let me rephrase: it opens the question of why the big bang happened in the first place

Because the Probe decided it was time (well, the Probe is in fact well above puny concepts like time). Simple. :yes:

 

[Linguofreak]

Ah hell, now I'm really starting to talk philosophy in a science thread. I should really stop now before I make an ass of myself... :facepalm:

I'm not sure this quite qualifies as a "science" thread.

 

[Jarvitä]

Then let me rephrase: it opens the question of why the big bang happened in the first place

As far as time goes, yes. As far as causality goes, not so much. It would be better to phrase it, though, as "what caused the universe to exist" (or better yet, to make it more time-neutral, as time is part of the universe, "what causes the universe to exist").

What if causality is just another by-product of the big bang as well? It's logical traps like this that give the MWI and past eternal proponents (a surprisingly large overlap there) what little credibility they have.

 

[Linguofreak]

No need to worry, the physical laws we have and understand are quite clear that time travel is not possible,

Actually not. They are quite clear that *arbitrary* time travel is not possible, and that things that we have not yet observed to exist (but that our current understanding of physics does not completely rule out) are required for time travel, but they do leave the possibility of limited time travel open.

 

[Cras]

Actually not. They are quite clear that *arbitrary* time travel is not possible, and that things that we have not yet observed to exist (but that our current understanding of physics does not completely rule out) are required for time travel, but they do leave the possibility of limited time travel open.

What? The worm hole thing? Most people who look at that conclude that the thing explodes before it becomes a time machine. And of course, worm holes have to exist first.

---------- Post added at 05:26 PM ---------- Previous post was at 05:19 PM ----------

Then let me rephrase: it opens the question of why the big bang happened in the first place

There are some very good sound theories for this. Look up Inflationary Theory and read up. That is a good one.

Others are more exotic, as it were, and involve more of the more cutting edge aspects of M-theory, mainly branes.

And while I do not know if Jarvita is being intentionally dense and/or confrontational, or something is being lost in translation, but the idea being talked about here is time as we know it coming into existance via the big bang, much in the same way the three spacial dimensions were via the big bang. That is not saying they were created, in fact I thought I was quite clear that the big bang did not create these things. Time plays a part some way some form in the pre big bang universe. If you do not see things this way, it becomes quite difficult to place the inflaton, or what ever your mechanism you are using to explain the big bang.

And I will state that what point of this is making this not a science thread? Is it because I and others refrain from talking in mathematics? The same arguments being written out here in words and paragrahs have already been made via mathematics. This is not a philosophical excercise, Cosmology is not pseudo science only the plaything of the fringe and weird. While some may be pulling things out of thin air, the majority of the stuff here is sound in the terms of what is being done on the cutting edge of Cosmology.

Of course, none of this is really much on topic with the OP, but whatever.

 

[Fizyk]

the idea being talked about here is time as we know it coming into existance via the big bang, much in the same way the three spacial dimensions were via the big bang. That is not saying they were created, in fact I thought I was quite clear that the big bang did not create these things. Time plays a part some way some form in the pre big bang universe. If you do not see things this way, it becomes quite difficult to place the inflaton, or what ever your mechanism you are using to explain the big bang.

What you get from general relativity is an event, beyond which you cannot go further back in time. If you choose a particle and start following its history, assuming we ignore quantum effects like particle decay etc., you will arrive at one point, regardless of which particle you have chosen - namely at the Big Bang singularity. There is nowhere to go from there.

In this sense there is no "before the Big Bang". There is no such direction as "past" at the Big Bang, just as there is no north at the north pole. That's also what Jarvita has already said.

Also, inflation does not explain the Big Bang and it doesn't even attempt to do so. It is used to explain some things such as apparent homogeneity and flatness of the Universe by saying that shortly after the Big Bang the size of the Universe increased at a ridiculous rate for a short time.

 

[Cras]

Also, inflation does not explain the Big Bang and it doesn't even attempt to do so. It is used to explain some things such as apparent homogeneity and flatness of the Universe by saying that shortly after the Big Bang the size of the Universe increased at a ridiculous rate for a short time.

I have seen inflation taken beyond the start of the big bang, so to say it doesnt even attempt to explain the Big bang is not something I would agree with at this point. Its original purpose certainly was not to explain that, but do just as you said, but with use of Higgs fields I have seen inflation used to describe a pre big bang environment which can lead to ours and a multitude of other universe.

And let us be fair, when talking about Cosmology, using General Relativity is not going to take you very far. Not to the point where you can get to the real interesting questions.

 

[Linguofreak]

What? The worm hole thing? Most people who look at that conclude that the thing explodes before it becomes a time machine. And of course, worm holes have to exist first.

Relativity does not rule out time machines, but it doesn't guarantee them either. There are possible quantum effects that could destroy wormholes (or other ways of creating time machines) before they became time machines, but it's not proven yet. And yes, stable wormholes have to exist first to use a wormhole as a time machine, which is by no means guaranteed (or ruled out) by current physics. (And the same things needed for stable wormholes to exist are also needed for most/all useful time machine solutions apart from wormholes).

 

[Fizyk]

I have seen inflation taken beyond the start of the big bang, so to say it doesnt even attempt to explain the Big bang is not something I would agree with at this point.

I didn't, but I'm nowhere near an expert in that field, so it is quite possible that there are things I haven't seen yet I can't imagine how that would work, though.

And let us be fair, when talking about Cosmology, using General Relativity is not going to take you very far. Not to the point where you can get to the real interesting questions.

General relativity is the basis for the whole cosmology, so you can't really talk about cosmology without referring to general relativity

 

[Cras]

General relativity is the basis for the whole cosmology, so you can't really talk about cosmology without referring to general relativity

That is a great point. I only said that because it doesnt take you all the way to time zero as it were (not to say that the things that do are on the same firm ground as general relativity) . And all of the things I was referring to are from Superstring theory.

Now I understand if people want to leave that as its own thing, and not want to put it on the same footing as the stuff we have learned from general relativity, since String Theory is not even close to be confirmed, and I may be more of the foolish optomist for taking all that I have seen reported on M-theory research and hold it up as if it were built from a more well proven theory, but this was a topic that I dove deep into a few months back, something I stumbled on when looking at the various multi-verse ideas that have been thrown about the past few years. And when you start to look at multi-verse theories, you start to see ideas and concepts for which could have occured prior to the big bang, and see the big bang as not the beginning of anything, but more of this transformative event.

I lack the ability which you have already demonstrated here before in being able to lay all this stuff out in a coherent statement that fuses a written explanation and a mathematical proof. If I would attempt such a thing, it would come across as a run on mess, and doubt anyone would be able to follow what would be represent a rambling incoherent TL;DR.

 

[RisingFury]

You know what I find the most sad about this thread?

The people who study Physics admit to not knowing and not being sure, while the people who don't have a clue are absolutely sure about their answers.

 

[Hlynkacg]

Turning and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.

Surely some revelation is at hand;
Surely the Second Coming is at hand.
The Second Coming! Hardly are those words out
When a vast image out of Spiritus Mundi
Troubles my sight: somewhere in sands of the desert
A shape with lion body and the head of a man,
A gaze blank and pitiless as the sun,
Is moving its slow thighs, while all about it
Reel shadows of the indignant desert birds.
The darkness drops again; but now I know
That twenty centuries of stony sleep
Were vexed to nightmare by a rocking cradle,
And what rough beast, its hour come round at last,
Slouches towards Bethlehem to be born?

 

[jedidia]

What if causality is just another by-product of the big bang as well?

Since causality and entropy are linked, that would actually make sense... I never saw it that way.

You know what I find the most sad about this thread?

The people who study Physics admit to not knowing and not being sure, while the people who don't have a clue are absolutely sure about their answers.

Isn't it always like that, though? the more you know about a subject, the more you become aware how little you know...