Observable Universe vs Entire Universe

[SimonWers]

Hey everyone, I just registered, this looks like a very cool forum. I was just on a site called Scale of the Universe, it's very cool, it lets you zoom in and out from an atom to the universe. If you zoom all the way out it says the observable universe is 140 Ym but the whole universe is estimated to be 930 Ym across. If the observable universe is based on the light leaving that point at the start of time and only reaching us now, how can anything beyond that point (anything in the non observable universe) have got there from the point of the big bang? Wouldnt it have to have travelled there faster than the speed of light?

 

Hope you can help! Thanks.

[Sisyphus]

That site seems like a big oversimplification. The big bang is not a traditional explosion. It did not take place at a single point and throw stuff outwards. In fact, there is no "outwards" - by current models, the universe has no center and no edges, and may or may not actually be infinite. I don't know why that site chose to represent it the way it does.

 

The big bang took place everywhere at once, so the size of the universe is not limited by how far stuff can travel from "there." The "expansion of space" does not mean objects traveling away from each other - in fact, it's a lot more literal than that. "Space itself" is expanding, so that, for example, every light year of distance actually grows by X inches per year. A consequence of that the distances between all objects on a large enough scale are increasing without them moving, and the rate of this increase is proportional to their distance. (If every light year grows by X inches per year, then an object Y lightyears away is getting farther away at a rate of X*Y inches.)

[michel123456]

Hey everyone, I just registered, this looks like a very cool forum. I was just on a site called Scale of the Universe, it's very cool, it lets you zoom in and out from an atom to the universe. If you zoom all the way out it says the observable universe is 140 Ym but the whole universe is estimated to be 930 Ym across. If the observable universe is based on the light leaving that point at the start of time and only reaching us now, how can anything beyond that point (anything in the non observable universe) have got there from the point of the big bang? Wouldnt it have to have travelled there faster than the speed of light?

 

Hope you can help! Thanks.

 

There is no need to go that far.

You yourself existed yesterday, as part of the Universe.

And you, yesterday, are not observable.

[peadmore]

That site seems like a big oversimplification. The big bang is not a traditional explosion. It did not take place at a single point and throw stuff outwards. In fact, there is no "outwards" - by current models, the universe has no center and no edges, and may or may not actually be infinite. I don't know why that site chose to represent it the way it does.

 

The big bang took place everywhere at once, so the size of the universe is not limited by how far stuff can travel from "there." The "expansion of space" does not mean objects traveling away from each other - in fact, it's a lot more literal than that. "Space itself" is expanding, so that, for example, every light year of distance actually grows by X inches per year. A consequence of that the distances between all objects on a large enough scale are increasing without them moving, and the rate of this increase is proportional to their distance. (If every light year grows by X inches per year, then an object Y lightyears away is getting farther away at a rate of X*Y inches.)

 

 

I would actually be very interested in your reply if I knew what it was you were talking about. It seems very much like another example of we don't actually know what happened so we'll fudge it.

 

I have never heard a good explanation for why the big bang happened at all and there are other very good explanations for the evidence that is interpreted as the big bang. Have you ever thought of exploring these.

 

Since Hubble nobody has seriously studied alternative explanations for the red shift, of which there are quite a few, and all have jumped on the big bang band wagon with religious like fervour.

 

There are far too many problems arising out of this theory and throwing dark matter and energy in to patch up the holes doesn't help matters much either. Neither does it help to say that space is expanding and yet things are not moving away from each other; it is just an increase in the size of a light year. That is just semantics and means absolurtely nothing.

[Sisyphus]

I would actually be very interested in your reply if I knew what it was you were talking about. It seems very much like another example of we don't actually know what happened so we'll fudge it.

 

So you don't know what I'm talking about, but you've decided it's without merit anyway?

 

I have never heard a good explanation for why the big bang happened at all and there are other very good explanations for the evidence that is interpreted as the big bang. Have you ever thought of exploring these.

 

Since Hubble nobody has seriously studied alternative explanations for the red shift, of which there are quite a few, and all have jumped on the big bang band wagon with religious like fervour.

 

That's absolutely not true that nobody has studied alternatives. There have been lots of alternatives studied. In fact, the term "big bang" was originally a joke term making fun of inflation theory. However, currently the only viable models that have not been falsified in some way involve inflation. So no, there are not "other very good explanations," though there were candidates in the past, and there may be in the future.

 

There are far too many problems arising out of this theory and throwing dark matter and energy in to patch up the holes doesn't help matters much either.

 

Being incomplete is not a problem, else no science would ever be valid. What matters is contrary evidence.

 

Neither does it help to say that space is expanding and yet things are not moving away from each other; it is just an increase in the size of a light year. That is just semantics and means absolurtely nothing.

 

What do you mean? Of course it means something. It's predicted by theory, fits all new observations, and is fully describable mathematically. Perhaps you mean it's counterintuitive?

[cypress]

It seems very much like another example of we don't actually know what happened so we'll fudge it.

 

Not too a bad summary of the situation that faces many of the historical sciences. As is often the case, these ideas include portions that are difficult to verify because the concepts lack causal adequacy. They make citations to processes that are not observed in current operation and are thus notional. In the case of sisyphus' description both inflation and the mode of expansion generally don't seem to have analogs in current reality and don't have a basis in any known physical laws. It would be interesting for the key aspects of these ideas if anybody could describe the observed process and the physical laws that allow for inflation and uniform expansion of 3 dimensional shape space. We of course know that mathematics can model many aspects of the but models are not necessarily reality. We all know the term garbage in, garbage out.

 

In this sense they are speculative just as you indicate, though "fudging" implies shifting it from some known reality which also is not quite right either.

[FakerBaker]

Hey everyone, I just registered, this looks like a very cool forum. I was just on a site called Scale of the Universe, it's very cool, it lets you zoom in and out from an atom to the universe. If you zoom all the way out it says the observable universe is 140 Ym but the whole universe is estimated to be 930 Ym across. If the observable universe is based on the light leaving that point at the start of time and only reaching us now, how can anything beyond that point (anything in the non observable universe) have got there from the point of the big bang? Wouldnt it have to have travelled there faster than the speed of light?

 

Hope you can help! Thanks.

 

 

http://wapedia.mobi/en/Observable_universe

 

This explains it nicely. See "The Universe versus the observable universe" Section.

[Mr Skeptic]

If the observable universe is based on the light leaving that point at the start of time and only reaching us now, how can anything beyond that point (anything in the non observable universe) have got there from the point of the big bang? Wouldnt it have to have travelled there faster than the speed of light?

 

You mean other than already starting off there as the Big Bang theory states? Many people don't realize that the Big Bang occurred throughout spacetime, not at one specific point in spacetime, since the latter would make no sense (as you seem to have noticed).

[Martin]

Hey everyone...

If the observable universe is based on the light leaving that point at the start of time and only reaching us now, how can anything beyond that point (anything in the non observable universe) have got there from the point of the big bang? Wouldnt it have to have travelled there faster than the speed of light?

...

 

Simon, welcome. Sisyphus and Mr.Skeptic are explaining things in words but you might also need to get some mental imagery. So I suggest you google

"wright balloon analogy" and watch it for 3 or 4 minutes as the two 2D universe expands

 

Then type a number 2 into the URL and get the second version "Balloon2", that has light in it. Little wigglers representing photons, that move across the 2D surface while it is expanding.

 

 

Also you mentioned the special relativity (1905) speed limit. That does not govern the rate that distances can expand in the improved (1915) theory called general relativity.

 

They do you a real disservice in school or in popular science books when they give you the impression that everything (including rates of largescale distance increase) is governed by the 1905 speed limit.

 

General Rel says you can't TRAVEL faster than light. You can't catch up to and pass a photon. You can't approach some destination faster than the standard rate c.

But it does not say that distances between galaxies cannot increase faster than c. Even when the galaxies are essentially standing still in their surrounding space.

You can even see that happening in the small movies I mentioned, if you are observant.

 

when you type 2 into the URL you will get

http://www.astro.ucla.edu/~wright/Balloon2.html

 

Watch it. The galaxies are all standing still (constant longitude latitude in the 2D spherical surface which is their universe) and the wigglers are all traveling at constant speed across the surface I would say about 3 millimeters per second, based on the scale of my computer screen. But there are photons heading in the direction of some galaxy which never get there, in fact get dragged back farther and farther away from their aimed-for destination, by the expansion of distance. And you may see photons whose distance from their point of departure is increasing much faster than the 3 mm/second rate they crawl through their local neighborhood.

 

Special Rel (1905) applies to NON-EXPANDING SPACE. What it tells you is only approximately right because our local small-scale space is approximately not expanding.

Only thing to do is watch the movie and get some new mental imagery. Words by themselves often do not work for people.

Edited December 9, 2010 by Martin

[michel123456]

You mean other than already starting off there as the Big Bang theory states? Many people don't realize that the Big Bang occurred throughout spacetime, not at one specific point in spacetime, since the latter would make no sense (as you seem to have noticed).

(emphasis mine)

That is the point.

All imagery of the Big Bang represent a starting point.

Only by words you can state that "the Big Bang happened everywhere".

IMHO once a layman understands that current Theory states that the entire Universe puffed into existence roughly in place where it exists now, it can only but raise astonishment and profound doubt.

Edited December 10, 2010 by michel123456

[Spyman]

IMHO once a layman understands that current Theory states that the entire Universe puffed into existence roughly in place where it exists now, it can only but raise astonishment and profound doubt.

Well, if we assume that the Universe suddenly "puffed into existence" then why is it so strange that it puffed in where it exists now as opposed to somewhere else?

 

One common misconception by laymens about the Big Bang theory is that it deals with how the Universe 'Banged' into existence. But how the Universe got into existence is NOT covered by the Big Bang theory and however the Universe managed to suddenly exist or from what it came, it must still have been in some cind of state afterwards.

 

IMHO I think the "puffed into existence" is of much more worrying concern than the resulting condition.

 

Anyhow the Big Bang theory starts out with the primeval state the Universe is in after the entrance to existance and is about the following evolution from there.

 

Without any evidence associated with the earliest instant of the expansion, the Big Bang theory cannot and does not provide any explanation for such an initial condition; rather, it describes and explains the general evolution of the universe since that instant.

http://en.wikipedia.org/wiki/Big_Bang

 

Another commonly wrong version amongst laymens of the Big Bang theory is that it is about an explosion in space, sending matter and energy outwards from a central point. But the Big Bang theory doesn't have any gunpowder explosion despite its 'Banging' name.

 

In the Big Bang theory the Universe was very dense in its primeval state after it came into existense and then it expanded, which it still continues to do.

 

The Big Bang is not an explosion of matter moving outward to fill an empty universe. Instead, space itself expands with time everywhere and increases the physical distance between two comoving points.

http://en.wikipedia.org/wiki/Big_Bang

 

 

Only by words you can state that "the Big Bang happened everywhere".

Lets make two different examples:

 

¤ 1) Suppose we have 1 million balls in a huge concentration and then a central explosion flings them away. Every observer on all of the large amount of balls would be able to discern his own position, speed and direction relative the other balls and the centre of the explosion.

 

¤ 2) Lets start out equally but instead of using explosives we instead expand the distance equally between every single ball simultaneously. Observers on these balls would not be able to discern their location, speed and direction relative the others nor would they be able to find a center.

 

In the first example the 'Bang' happened at a certain location but in the second example the 'Bang' happened everywhere at once. When we look up into the sky to observe other objects in the Universe then we are not able to measure our position, speed and direction as if there was an explosion but by observation it appears as if everything is separating from everything equally, just like if "the Big Bang happened everywhere".

Edited December 10, 2010 by Spyman

[michel123456]

Well, if we assume that the Universe suddenly "puffed into existence" then why is it so strange that it puffed in where it exists now as opposed to somewhere else?

(...)

 

If we believe in Harry Potter, nothing is strange. I don't believe in HP. So to me it is strange right from the beginning. I cannot swallow that the Universe puffed into existence: it looks too medieval.

 

2) Lets start out equally but instead of using explosives we instead expand the distance equally between every single ball simultaneously. Observers on these balls would not be able to discern their location, speed and direction relative the others nor would they be able to find a center.

 

Well, maybe it is putting this thread out of track, but:

 

the programmers of Autocad (which is an extremely evolved vectorized mathematical program) were not able to conceive the analog command ("Scale") without the input of a base point.

 

Commands go like that:

Command: scale

_select objects

_specify base point

_specify scale factor

[enter]

 

And indeed, without the base point, how could the program execute the scale factor? Scaling cannot be done with multiple base points.

[Sisyphus]

 

 

Well, maybe it is putting this thread out of track, but:

 

the programmers of Autocad (which is an extremely evolved vectorized mathematical program) were not able to conceive the analog command ("Scale") without the input of a base point.

 

Commands go like that:

Command: scale

_select objects

_specify base point

_specify scale factor

[enter]

 

And indeed, without the base point, how could the program execute the scale factor? Scaling cannot be done with multiple base points.

 

Indeed, what we observe can't be rendered in simple Euclidean space, such as is depicted in autocad. That's one reason for the common misconceptions, since people are used to thinking that way.

[pioneer]

If we compare a contracted space-time reference to an expanded space-time reference, side-by-side, time moves faster in the expanded reference. What that means is the entropy of the universe should be accelerating over time.

 

As an analogy, consider two identical factories, one in expanded reference and the other in contracted reference. Both produce 1 defect per hour in our reference. In a side-by side comparison, since time in the expanded reference is moving faster, its side-by-side rate of defects or entropy will be higher. In the contracted reference these happen slower. If we continue to expand the space-time reference of our factory the defects will appear faster and faster relative to any observation point.

 

Since entropy increase needs energy, that means the amount of energy in the universe that is going into entropy is doing so at an accelerating rate. This might explain where the energy difference within an original energy quanta, and its red shifted daughter photon, goes.

 

However, with space cooling, and entropy continuing to accelerate, where is the accelerating energy requirement coming from? All the hottest energy from the beginning is hardly worth anything, being in the microwave level. An acceleration of entropy needs more and more energy. Maybe one good place is from the energy output of stars and fusion. But with space-time expanding coming first, does that mean that the expansion of space-time is defining gravity to create the needed accelerating energy? Or if gravity comes first, is the output of energy created by gravity, such as the induced, stella fusion, the energy output needed to define the increasing entropy, so space-time is able to expand?

 

I am not adding dark energy and matter to the energy balance since this is theory not proof. But say we assume this exists is this red shifting at an accelerating rate to be able to meet the accelerating energy requirement?

Edited December 10, 2010 by pioneer

[michel123456]

Indeed, what we observe can't be rendered in simple Euclidean space, such as is depicted in autocad. That's one reason for the common misconceptions, since people are used to thinking that way.

 

I am not sure it is specific to Euclidian space.

If you try to execute scaling from let's say 2 origin points, you will get conflict. And I know no way to execute scaling without any base point at all.

[Spyman]

the programmers of Autocad (which is an extremely evolved vectorized mathematical program) were not able to conceive the analog command ("Scale") without the input of a base point.

All that tells us that it might be harder to simulate reality than what it first seems, but I am confident that cosmologists have more advanced simulators than Autocad and are able to model the expansion of the Universe.

 

 

And indeed, without the base point, how could the program execute the scale factor? Scaling cannot be done with multiple base points.

If you try to execute scaling from let's say 2 origin points, you will get conflict. And I know no way to execute scaling without any base point at all.

According to theory of Relativity the observer is his own base point as each observer has his own frame of reference.

 

If two observers are under equal conditions but at different locations then it doesn't matter which observer are used as base point when rescaling the distance between them, they will both agree on the change in distance.

Edited December 13, 2010 by Spyman

[michel123456]

All that tells us that it might be harder to simulate reality than what it first seems, but I am confident that cosmologists have more advanced simulators than Autocad and are able to model the expansion of the Universe.

 

 

 

 

According to theory of Relativity the observer is his own base point as each observer has his own frame of reference.

 

If two observers are under equal conditions but at different locations then it doesn't matter which observer are used as base point when rescaling the distance between them, they will both agree on the change in distance.

 

Correct. It doesn't matter. But there is need for a base point. You can choose any random point, but you need this point in order to execute the scale factor.

And you cannot use multiple base points. Scaling works only with one. Maybe I need a sketch for that.

Edited December 13, 2010 by michel123456

[Spyman]

And you cannot use multiple base points.

I don't understand your argument, I never claimed multiple base points.