Science a GoGo's Home Page Forums General Discussion Physics Forum Light From Distant Galaxies.

I still don't see any disagreement. If the galaxies are moving apart as a result of an expansion of the intervening space (ergo they are not static in a static space) then that void must have some form of material substance resulting in a physical reaction pushing against thus forcing the galaxies to move away from each other.

I realize that the analogy may be getting a bit strained, but let's go back to the dots on the balloon analogy for the expansion of space. As the balloon inflates the dots move apart from each other. But there is no more balloon between the dots than there was before the balloon was inflated. Space works the same way. There is no reason to postulate the creation of more matter to fill the intervals. In fact that idea was the center of the steady state hypothesis that was overthrown by the discovery of the cosmic background radiation.

Bill Gill

Bill, I'm not sure which viewpoint the balloon analogy supports. No doubt Bill6 will point out that unless the balloon was made of solid material it would not cause the dots to move apart.

Tackling the question as to whether space works the same way is something we probably need to come back to when this particular issue is resolved.

I'm going to give it some thought, and see if I can come up with something devastating.

Bill S, you might want to keep in mind that space is definitely not solid. Remember that it stretches wherever there is mass. Remember black holes? They cause a huge distortion of space. So it has a lot of give to it and can easily be stretched by whatever it is that is causing it to expand. So there is no reason to assume that there is anything being added to cause the expansion of the universe. It is just space stretching, like the balloon in the analogy.

Bill Gill

I couldn’t think of anything devastating, so let’s try it this way.

The location of an object in space has relevance only in relation space. This may seem tautologous, but what I am really saying is that there is no reference point, outside space, relative to which an object can be stationary, or in motion. If an object is in space, and space moves, the object must move with it in order to remain in the same place. It isn’t a question of space needing to be tangible in order to move the object; the object does not move, it remains in the same place in space. The fact that one part of space has moved relative to another is irrelevant, the object is still in the same place.

A reference point relative to which a galaxy can be stationary or in motion is an adjacent galaxy.


Space does not move!


A specific galaxy may be said to retain its location but according to the expanding universe concept all (most of) the other galaxies are moving away from it.

According to Newton's first law of motion - force is required to make an object move and on the basis that 'space' is a total absence of matter it has no physical effect on any object no matter how much it stretches; ten times nothing is still nothing.

In accordance with the expanding universe concept - most of the galaxies are moving away from us and from each other and for any object to be made to move it must be subjected to some form of force however 'expanding space' is not 'a force'.


I, for one, am not talking about one part of space moving relative to another but am referring to other galaxies moving relative to each other.

The fact that 'the object' (a galaxy) may still be in the same place regardless of the 'stretching' of space is not the critical factor which is the then resultant location of other galaxies.

We could perhaps insist that whilst all the other galaxies are moving ours remains in the same place however this contradicts the observed CMBR frequency shifts.

Since the "adjacent galaxy" is also in space, my point still stands.



There are well accepted theories that would not agree with this.

If space is expanding (BB), every part of space is moving relative to every other part.
If space can be distorted (GR), parts of space move relative to other parts.



If a specific galaxy may be said to retain its location, every galaxy may be said to retain its location in space. If space is expanding, every galaxy must move away from every other in order to remain in the same location in space.

It has been determined that the Milky Way is hurtling toward the Virgo galaxy at around 640k-s. The Virgo galaxy is a reference point relative to which the Milky Way's location and rate of travel can be determined.


You may have noticed that I make every effort to directly respond to each and every one of your comments; a reciprocal attitude would be appreciated - space is a total absence of matter. Apart from what some well accepted theories have to say - what are your thoughts in this respect?

Perhaps you could cite one or more of those theories?


I believe that the expression is not that space is expanding but that the universe is expanding.


On that basis - every part of space (more specifically a galaxy that it contains) provides a reference point relative to which another galaxy can be stationary or in motion.


I do not accept that space can be distorted. I am of the opinion that 'a curvature of space time' is nothing more than a fancy name for a gravitational field.

Neither 'space' nor 'time' possess any physical substance thus cannot be bent.

A total absence of matter cannot move relative to any total absence of matter.


The 'specific galaxy' to which I refer is one that is in my reference frame ergo its location remains unchanged whilst that of the other galaxies does not.

Your efforts in this respect are neither unnoticed, nor unappreciated. You are one of a few who do that. I try to do the same, but unfortunately time is often short and frequently I have to divide responses between posts. It was my intention to return to your previous post to address a couple of other points including the "absence of matter".

It is now 2.40am, so I shall postpone further comments until a more civilised hour.

To some extent I am playing “Devil’s Advocate” in an attempt to clarify my own ideas, so please be patient, don’t hesitate to tell me if I slip into semantic nit-picking.

“…'space' is a total absence of matter…”. Agreed. Presumably, this includes an absence of energy?


“…it has no physical effect on any object…”. It would be extremely difficult to argue that a total lack of matter and energy could have a physical effect on anything. However, position in space seems to have some significance, even if only in terms of the argument that a force is required to move an object from one point in space to another.

“…no matter how much it stretches; ten times nothing is still nothing.” Multiplying nothing by any number may be an acceptable concept in mathematics, but in the real world it has no practical application. This leaves us with the idea of stretching nothing: I’m not very happy with that idea, but this brings us to another of your points:



If space is not moving, which must be the case if it is nothing, then as the Universe expands, the galaxies are moving through space, which scientists assure us that they are not doing.

There has to be a lot more to discuss here, but duty calls, so perhaps we can deal with one bit at a time.

Hi gentlemen.

You might like to read through this:

"Wilczek explains properties of space"

at:

http://thedartmouth.com/2010/05/07/news/space

Now if I just understood what Wilczek was talking about. I read the article, but didn't understand half of what it said. That may be because it was written by a reporter. Unfortunately reporters don't have a great record of explaining what scientists had to say. Any way I have no idea what he means by the material grid. Does any body have a link to an explanation of it?

Bill Gill

Thanks Rede, all contributions gratefully received!

My understanding is that what purports to be a description of space is actually a description of what space contains.

If, as the report suggests, all this stuff in space is able to exert pressure that could be what moves the galaxies, but at this point I don't find that very convincing.

Marcus Chown (Afterglow of Creation) says:

"...in Einstein's theory......space is malleable, it can be warped or curved in the presence of matter."

I think I need to know if you are saying that Einstein was wrong, or that the current interpretation of GR is wrong, or whether I have missed your point completely.

Your having sent three posts has complicated the procedure however I feel that I have said all I have to say on the subject of the claimed expansion of the universe preferring instead to accept the Occam's razor/Einstein's simplicity complying concept of the tired light theory which in my opinion, although obviously unacceptable by a vast majority of physicists, has never been disproved.

Space is a void that, however, contains random items of matter resulting in a medium of minimal density thought to average one atom of matter in a matchbox sized area of deep space however there would be a lot of free atoms in a distance of several million light years whereby light from distant galaxies would be absorbed/emitted by that 'medium'.

The greater the distance of those galaxies from us the greater the number of atoms - ergo the greater the redshift.

*********

I made no suggestion that Einstein, having referred to the concept of 'curved spacetime', was wrong.

I believe that the phrase is merely an extravagant description of a gravitational field employed in order to impress us commoners ergo a contradiction of his suggestion that we should keep things as simple as possible.

Thanks, Bill6.

I like the idea that 'curved spacetime' might be an extravagant description of a gravitational field.

I have not given as much attention to the concept of tired light as perhaps I should. I shall leave you in peace while I do that, and mull over the contents of this thread. No doubt I shall be back with more naive questions later.

One of the problems with saying that is that when Einstein developed the idea of curved spacetime he also adapted some very good math that fully described it. GR and the math that describe it have been tested over and over ever since he presented the General theory of Relativity (GR). The theory just keeps passing those tests. Since the math and the tests all depend on curved spacetime I don't think that it is just intended to "impress us commoners", it is a very real description of how the universe works.

As far as light being absorbed and re-emitted by matter in between the source and our instruments. Well, that is a well understood phenomenon, and is used to determine the composition and quantity of matter in the way. However, the red shift of the light from distant galaxies is a completely different thing. The characteristics are much different. Absorption/emission causes discrete shifts in wavelength of light. Red shift causes all wavelengths of light to shift in the same manner. It does not cause different wavelengths to shift in different ways. So absorption/emission does not explain the galactic red shift.

Bill Gill

The one thing that seems to be missing from this description is an explanation of the force that must, surely, be needed to cause and maintain that curvature.

Even the "duality" idea doesn't really solve this, because, in the same way that you cannot observe a quantum object as a particle and a wave at the same time, presumably, you cannot treat gravity as a force and a curvature of spacetime at the same time.

You have one of the major questions that a lot of people have about science. WHY? Unfortunately there is no good answer. A lot of times it is claimed that science is the quest for why things are the way they are. That is not strictly true. Science cannot answer the question "Why is it this way?". What science can do is to describe how the universe works. Let's take a quick example of Newton's law of gravity. His answer to why the planets move the way they do is that gravity directs their motion. But when it came right down to it he couldn't say what gravity was, it is just a force that works according to his law. Then Einstein came along and extended his work with GR. So now gravity is the result of warped spacetime. But we still don't know WHY spacetime is warped.

You are wondering what force caused spacetime to warp. But there is no force causing the warp. The warp just is. When we get right down to it, at the most fundamental level science can only say "That's the way it is just because that's the way it is". You are wondering about what warps spacetime. Well, if you think about the electromagnetic force there is no explanation of why the electric charge exists. Another case where science can understand the interactions between particles, but why the interactions exist is beyond the capabilities of science.

Bill Gill

Bill, it's not so much a question of "why", as a question of "how".
The whys can often resolve themselves into philosophical questions, rather than scientific ones.

I'm going to go through this and a couple of other threads, put the results together with my past notes and see what emerges in the way of silly questions.