Expansion of Universe - Red Shift

[eclecticcowboy]

This is something that is starting to rankle my little Newtonian mind. If the universe is expanding in all directions at once like the surface of a balloon shouldn't everything in the universe be expanding as well? Therefore as the distance between stars, galaxies etc. becomes greater the stars and galaxies themselves (as well as atoms, electrons and photons inside them) become larger as well so proportionality is maintained and there is no Doppler effect? Or is it like tracing your hand, because everything expands at the same rate proportion is distorted? In other words because the distance between the stars and galaxies is so large the expansion between the objects in the universe is much greater, proportionally, than the expansion of the objects themselves? I have a headache.

[cypress]

Indeed. There are a number of serious problems with the expansion model. You have identified one of them.

 

Here is a summary of the issues with various models of Big Bang cosmology including the inflationary model you mention.

 

Big Bang Cosmology Summary of Issues

[DJBruce]

If i remember correctly on small scales the expansion of space is overcame by the objects gravity. This means that the objects themselves do not expand.

[Cap'n Refsmmat]

And fundamental particles are point-like and do not expand.

[timo]

If i remember correctly on small scales the expansion of space is overcame by the objects gravity. This means that the objects themselves do not expand.

That's correct. And on even smaller scales it is overcome by the chemical bindings, the electromagnetic interaction, the nuclear forces, the fact that points stay points (for e.g. molecules, atoms, nuclei, elementary particles). Gravity is only a special case of a force countering the expansion. It can be considered special because it is the largest-scale effect and it interestingly comes from the same theory that predicts the expansion in the first place.

[Spyman]

This is something that is starting to rankle my little Newtonian mind. If the universe is expanding in all directions at once like the surface of a balloon shouldn't everything in the universe be expanding as well? Therefore as the distance between stars, galaxies etc. becomes greater the stars and galaxies themselves (as well as atoms, electrons and photons inside them) become larger as well so proportionality is maintained and there is no Doppler effect? Or is it like tracing your hand, because everything expands at the same rate proportion is distorted? In other words because the distance between the stars and galaxies is so large the expansion between the objects in the universe is much greater, proportionally, than the expansion of the objects themselves? I have a headache.

Galaxies, stars systems and large bodies are held together by gravity. Tiny bodies, atoms and molecules are held together by nuclear forces. In a Newtonian view of space expansion, I think there has to be something that brings the objects apart and this something will have to struggle with the forces holding things together. The force that seems to expand space gets stronger with greater distance, while gravity gets weaker when the distance increases and on very small scales the nuclear forces are dominant.

 

With the understanding that Earths gravity is not able to continue to shrink the Earth because of the dominant nuclear forces on small scales, it is very reasonable to conclude that the expanding force is not able to swell the Earth either because on this scale it is also countered by their stronger forces and gravity on top of that as well.

 

 

On very very large scales even gravity gets so weak that the force expanding space gets the upper hand and can start to inrease the size between galaxies. But on the scales of galaxies and down to nuclear particles the expanding force are dominated by the other forces. This does not mean that small objects don't swell due to expansion, I think that it is considered that they do, but the measurable expansion in space takes place over tremendous vast distances while the distances on atomic level is infinitesimal puny.

 

The force expanding space should of course be acting inside matter too, slightly increasing the distance between particles, but on this scale the nuclear forces are large compared to the expanding force which is dwindling down to a vanishingly tiny level. The particles are held inside matter at a certain distance due to balance of forces and when adding the expanding force, it is offsetting this distance a tiny bit, this offset only causes the nuclear forces between the particles to rebalance with a slightly larger distance.

 

Bound systems only expands until they reach a slightly larger size where the forces that holds them together counter and stop the expansion. So bound systems don't continue to expand but they are a tiny bit larger due to the expanding force, this tiny bit is so teeny-weeny that it is not measureable and esteemed unimportant.

 

"A cosmological constant has the effect of a repulsive force between objects which is proportional (not inversely proportional) to distance. Unlike inertia it actively "pulls" on objects which have clumped together under the influence of gravity, and even on individual atoms. However this does not cause the objects to grow steadily or to disintegrate; unless they are very weakly bound, they will simply settle into an equilibrium state which is slightly (undetectably) larger than it would otherwise have been."

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

 

 

Here is a good link I think you should read: MISCONCEPTIONS ABOUT THE BIG BANG

[cypress]

That's correct. And on even smaller scales it is overcome by the chemical bindings, the electromagnetic interaction, the nuclear forces, the fact that points stay points (for e.g. molecules, atoms, nuclei, elementary particles). Gravity is only a special case of a force countering the expansion. It can be considered special because it is the largest-scale effect and it interestingly comes from the same theory that predicts the expansion in the first place.

 

Actually the fact that we don't observe that short distances (for example distances in our solar system and galaxy) don't seem to expand is a problem for Inflationary cosmology. It is an inconsistency that advocates attempt to answer by citing gravity, but the inconsistency remains. This current expansion model and these peculiar inconsistencies arise from the assumptions that go into the model in the first place which is to account for the observation that our universe seems to have been almost perfectly uniform very near the beginning. In addition, our universe is very nearly flat with respect to gravitational collapse and eternal expansion due to the apparent near perfect balance between actual and critical mass density. To explain the fine tuning of these two characteristics, modern day cosmologists have proposed inflationary models that don't require the initial configuration of the universe in its singularity to be so precisely assembled. However, this model also requires causal systems and one of them is the need for inflationary fields.

 

Inflationary fields are proposed to explain the homogeneity and flatness problems, but we don't know if they exist and there is reason to be suspicious because they don't seem to explain the features of the universe very well at all. This is because one must make elaborate and gratuitous assumptions about the initial configuration of the singularity as well. Roger Penrose in his book "The Road to Reality, A Complete Guide to the Laws of the Universe" has discussed these issues and has noted that inflation alone does not solve these problems but rely on many additional assumptions. In addition and here is the part that is relevant to this discussion, Stephen Hawking and Don Page have both noted that it is not currently possible to explain why inflation fields and gravitational fields should work together to produce the homogeneity of the background radiation and flatness of our observable universe. When the fields are linked there is nothing to guarantee that inflation will take place as they point out in "How Probable is Inflation?"

 

There is also a problem with causal adequacy. Inflationary cosmology relies on entirely unknown entities for its causal powers and it does so to explain mysterious effects for metaphysical reasons.

 

This model also has a major problem in explaining the origin of information necessary to produce the hypothetical inflationary fields and the numerous fields to which it must be coupled in order to produce a universe such as ours. The mechanism required to shut off inflation at just the right time, itself must have been fine tuned to between one part in 10⁵³ and 10¹²³ and this is just one example. Inflation makes the already acute fine tuning problem with entropy exponentially worse according to Penrose. Thus it is hardly any better to propose inflationary cosmology than to accept that the universe was precisely configured to begin with.

Edited July 19, 2010 by cypress

[Cap'n Refsmmat]

Actually the fact that we don't observe that short distances (for example distances in our solar system and galaxy) don't seem to expand is a problem for Inflationary cosmology. It is an inconsistency that advocates attempt to answer by citing gravity, but the inconsistency remains.

What, exactly, is inconsistent, when gravity is cited as a solution? You haven't explained, but rather gone into detail about other problems with inflationary cosmology.

[cypress]

I provided an example in the observed distances within for example galaxies don't seem to be expanding as should be the case under a inflationary expansion model. I find the other issues more significant.

[Spyman]

IMHO, I don't think that eclecticcowboy is asking for different problems or other issues with Big Bang, the OP seems very specific and clearly asks for a scientific explanation why objects or bound systems like galaxies don't expand like space do, in accepted scientific cosmology.

[IM Egdall]

This is my first post. I hope it helps.

As I understand it, if every single thing in the universe is expanding together, including the space between galaxies, galaxies themselves, and everything inside these galaxies, then we couldn't tell that there is an expansion! Think about it. If you went to sleep tonight, and woke up in the morning with everything in the universe double in size, how could you tell?

However, it is only the space between galaxies which is expanding. The galaxies themselves (and things inside the galaxies) are not expanding. In the famous balloon analogy, we are told to imagine a bunch of coins attached to the surface of a balloon. (Here the surface of the balloon represents space and the balloons represent galaxies.) As the balloon expands, the space between the coins increases, but the coins remain the same size.

Imagine you are a pixie on one of the coins. To you, as the balloon expands, it appears that all the other coins are moving away from you. In fact, if you calculate how much, you find that the coins further away appear to be moving away from you at faster speeds. The speed of each coin is proportional to its distance from you. Similarly, a galaxy twice as far away from us appears to be moving away twice as fast. A galaxy three times as far away from us appears to be moving away at three times the speed, etc. This is the essence of Hubble's Law (non-relativistic).

Now say there is another pixie on one of the other coins. To that pixie, it appears that she is stationary and all the other coins are moving away from her. The point here is that no matter what galaxy you are in, it appears to you that your galaxy is stationary and the rest of the universe is expanding around you.

To be more precise, the expansion of the universe does have a slight effect on things inside a galaxy. but the effect is overcome and stopped by gravity. So all things inside our galaxy are very slightly further apart due to the expansion of space, but are held at these distances by gravity. It is a kind of equilibrium state.

Oh, and it now appears that the expansion rate of our universe is increasing. and that this rate of expansion has been increasing for the last 5 to 7 billion years. What causes this increased rate of expansion? No one knows. Physcists generally call this unknown form of repulsive energy "dark energy". And if this increase in the expansion rate continues, at some time way in the future, the force of this expansion will become strong enough to overcome gravity, and eventually overcome atomic and nuclear forces as well. Galaxies will be ripped apart, then stars and planets, then all molecules and atoms, then the nuclei of atoms.

I think I got all this right. If you have any issues, please let me know