Imagining The Expanding Universe

[RickyMason]

I was recently reading about this topic, and they described the expanding universe in a way that I never really thought about.

 

You see, I always imagined the big bang at the center, and the universe radiating away from it, but the example I read was a little different. It explained it by describing dots on a balloon. As you blow the balloon up, the dots spread apart.

 

While its a great example, it doesn't do that well of a job of describing a 3d universe, so i took it to myself to imagine what is actually happening.

 

I came up with something like this:

 

 

I took a look at the wikipedia article found here:http://en.wikipedia.org/wiki/Metric_expansion_of_space

 

It seems the picture I had is the reverse idea of the 'raisin bread' example. Whereas theoretically, the solid pieces of mass don't necessarily have to move to get further apart.

 

Many questions arose:

 

Firstly, Is this the correct way to picture it? LoL!

 

If it is, then it leads to more questions

 

1) Could space be fixed? and matter shrinking?

2) Is matter in a fixed place, whereas the distance between points simply expands?

3) Going real far out there, in regards to the theory of relativity, can space 'stretch'? When an object disrupts spaces curvature, it just kind of makes sense that what it is indeed doing is pulling 'new space' out of 'nowhere' and sticking it in between us an everything around us.

 

Just some crazy out there theories. If someone is able to go into more detail about it, or direct me to some interesting reads, i'd be happy to look into it.

[Lancewen]

 

1) Could space be fixed? and matter shrinking?

2) Is matter in a fixed place, whereas the distance between points simply expands?

3) Going real far out there, in regards to the theory of relativity, can space 'stretch'? When an object disrupts spaces curvature, it just kind of makes sense that what it is indeed doing is pulling 'new space' out of 'nowhere' and sticking it in between us an everything around us.

 

Just some crazy out there theories. If someone is able to go into more detail about it, or direct me to some interesting reads, i'd be happy to look into it.

 

1) Not likely.

2) All matter is in motion, moving through space, but that does not mean the space between galaxy clusters is not expanding.

3) I never think of warped space as being stretched or new space being pulled out of nowhere.

 

Generally the theories about the expanding universe are based on the redshifting of light coming from distant galaxies. Not everyone believes all the bases have been covered with the reasons for the red shift we are seeing. If you search on "redshift" you will find all the reading you could possibly want.

[JMJones0424]

I agree, a lot of the common language used in describing the big bang, beginning with the word "bang" itself, is highly misleading and an obstacle to understanding. I'm glad you've been able to get over the hurdle of thinking of the big bang as an explosion of matter from a point in space. Your illustration appropriately represents three dimensional objects spreading out in one dimension. A larger, though possibly more cluttered and less understandable, illustration showing expansion in all three directions might be even better.

 

Also note that while your image illustrates expansion, the scale is tremendously off. The Hubble constant is currently measured to be about 73 km/s per Megaparsec. In other words, a galaxy 3.26 million light years away from us (1 Megaparsec) is receding from us at about 73 km/s. Objects that are merely 100 light years apart would not experience space-time expansion relative to themselves, as they are close enough for gravity to overcome space-time expansion.

 

Could space be fixed? and matter shrinking?

 

As arKane has said, expansion of space-time is the standard explanation for the observation that apparent velocities of far galaxies, or their red shift, is relatively well correlated with their distance from us. Shrinking matter does not fix this observation. First of all, if matter where shrinking, given our current understanding of gravity, the distance between the center of gravity of objects would remain the same. Even if it weren't, and somehow galaxies were shrinking, it would not explain our observations of redshift as the far side of a distant galaxy would be approaching us as the near side recedes.

Edited September 18, 2012 by JMJones0424

[Buffy]

Item 1) would make Mark McCutcheon's head, er, implode....

 

Once you can accept the universe as matter expanding into nothing that is something, wearing stripes with plaid comes easy, :phones:

Buffy

[modest]

I was recently reading about this topic, and they described the expanding universe in a way that I never really thought about.

 

You see, I always imagined the big bang at the center, and the universe radiating away from it, but the example I read was a little different. It explained it by describing dots on a balloon. As you blow the balloon up, the dots spread apart.

 

While its a great example, it doesn't do that well of a job of describing a 3d universe, so i took it to myself to imagine what is actually happening.

 

I came up with something like this:

 

 

I took a look at the wikipedia article found here:http://en.wikipedia.org/wiki/Metric_expansion_of_space

 

It seems the picture I had is the reverse idea of the 'raisin bread' example. Whereas theoretically, the solid pieces of mass don't necessarily have to move to get further apart.

 

Many questions arose:

 

Firstly, Is this the correct way to picture it? LoL!

 

You are quite correct, Ricky. Very good observation.

 

Eddington, as far as I know, was the first to publish this idea that shrinking matter is another way of looking at the expansion of the universe.

 

When we assert that the universe expands, what is our

standard of constancy ? There is no particular subtlety about

the answer; the expansion is relative to the standards that

we ordinarily employ. It is relative to the standard metre

bar, for example, or to the wave-length of cadmium light

which is often suggested as a more ideal standard, or to any

of the linear dimensions associated with atoms, electrons, etc.

which are regarded as "natural constants" in atomic physics.

But if the universe is expanding relatively to these standards,

all these standards are shrinking relatively to the universe.

The theory of the expanding universe is also the theory of the

shrinking atom. Thus we cannot detach the theory of the

universe from the theory of the atom. We must not think

of the cosmical constant as an agent which manifests itself

only in the super-system of the galaxies and is insignificant

in the atom and other small-scale systems. It manifests itself

in a relation (of size) between the super-system of the

galaxies and small-scale systems, and it is no more a charac-

teristic of one end of the relation than of the other. Thus we

ought to be able to approach the cosmical constant through

the theory of the atom (or more explicitly through those

equations of quantum theory which determine the extension

of small-scale systems) as well as through the theory of the

universe.

 

According to the principle of relativity we can only

observe and have knowledge of the relations of things. So

when we refer to the properties of any object we must always

have a comparison object in mind. If we speak of its velocity,

we mean its velocity relative to some comparison object or

set of landmarks. If we speak of its size we must have some

standard extension to compare it with. Imagine yourself to

be quite alone in the universe so that there is nothing to

compare yourself with and then try to tell me how large

 

 

 

224 NEW PATHWAYS IN SCIENCE

 

you are. You cannot. You have no size unless something

else exists for you to be larger or smaller than.

 

SIR ARTHUR EDDINGTON — 1935 — NEW PATHWAYS IN SCIENCE, X The Expanding Universe 223

 

Expanding distances such as cosmology proposes are expanding relative to local rulers and clocks. Cosmic distances increase relative to local measuring devices and local measuring devices shrink relative to cosmic distances.

 

Einstein himself made a similar analogy. He imagined a hotplate that was unevenly heated. If you put measuring rods on the hotplate some of them would expand more than others depending on how hot that area of the surface was. The 'flat' surface would be measured as non-Euclidean (or curved) by the measuring rods, and if all of our measurements were limited to those rods then it would be just as correct to say the surface curves and the rods stay a fixed size as saying the surface is flat and the rods change size. That was how he explained the non-Euclidean nature of General Relativity (on which big bang cosmology is based).

 

In other words, relativity describes curved spacetime. Another way of looking at curved spacetime is to say that identical clocks and rulers change size and duration.