[common_sense_seeker (OP)]

From the TV, I have learnt that in order to explain the formation of galaxies the concept of 'dark matter' was invented. I propose that galaxies were formed before the big bang, meaning that the concept of dark matter is no longer necessary.

Do you think that it's possible?

AL

[Bored chemist]

No.

[common_sense_seeker (OP)]

I wasn't expecting such a deeply considered argument. Well done.

[Don_1]

No.

Don't beat about the bush, just say what you really mean.

I think the universe has always existed. ("Always"..... a difficult concept to get your head around!!!)

When the current universe has finished expanding, it will begin to collapse on itself to form one hyper-body of such unimaginable size and mass that it would be impossible to put into words. It's hyper-gravity will cause it to compress to a point where it will be under more stress than the gravitational pull can hold together, it will explode and the whole process begins again.

Just about everything else goes in cycles, so why shouldn't the universe?

Dark matter = God
God = anything we can't otherwise explain.

Q. Where does the Sun go at night?                   A. God takes it.
Q. Where does rain come from?                         A. God makes it.
Q. Why does the mountain sometimes explode?    A. God breaks it.
Q. What was that noise last night?                     A. Mrs God faking it!!!       

No offence intended.

[Bored chemist]

I wasn't expecting such a deeply considered argument. Well done.

OK a slightly more involved version. The galaxies need the dark matter to stop them spinning apart.If there were no dark matter they would have fallen apart since the big bang.
Happy?

[pagheca]

From the TV, I have learnt that in order to explain the formation of galaxies the concept of 'dark matter' was invented. I propose that galaxies were formed before the big bang, meaning that the concept of dark matter is no longer necessary.

Do you think that it's possible?

AL

No, because structures like galaxies (or stars, or molecules or atoms or barions - any kind of structure) could not survive to the environmental characteristics (temperature and density) of the big bang. Passing through the big bang intact would be like to pass a car within a press and pretend it starts up.

[common_sense_seeker (OP)]

Bored chemist, surely it could be ordinary matter which simply doesn't shine?

[rich42]

For such a large amount of matter to not emit em radiation it must be very weakly interacting with the electromagnetic force. This rules out conventional baryonic matter as the dominant component and pushes us to postulate the existence of more exotic particles to make it up. Any large amount of matter will have a lot of photons incident on it, so will 'shine' by absorbing and re-emitting these photons.
One observation which leads us to postulate the existence of dark matter is gravitational lensing, the process by which a galaxy acts as a lens for EM radiation originating from a system further away. From the angle of the lensing effect (where we observe the images of the far-away object on the sky) we can infer the mass present in the lensing galaxy, which is usually a lot greater than we estimate from its luminosity. If there were a halo of normal baryonic matter, we would observe light reprocessed through it (by the presence of emission lines). The fact that we don't see this means that whatever is there doesn't interact with the EM force. 

[common_sense_seeker (OP)]

rich42, thanks for the intellectual response. Do you think it possible that a stack of proto-galaxies could be created before the big bang i.e. that there was a start to the universe and a build-up of pressure before the big bang?

AL

[rich42]

No problem...
There is a problem with the phrase 'before the Big Bang', as that implies that the Big Bang happened at a particular point in spacetime. At the moment of the Big Bang, the 4-dimensional universe (3 space and 1 time dimension) was a singularity. The time dimension we measure started at the Big Bang, and the concept of anything happening 'before' that has no meaning with relevance to our concept of time.
With that said, everything, every bit of mass and energy in the entire Universe was concentrated in that single point and spacetime expanded from that single point.

The standard analogy used for this Universal expansion is that of the expanding balloon with points marked on it representing galaxies. As you blow up the balloon, the points move further away from each other. Is this because they are moving into extra space which was there all the time? No, the size of the 2 dimensions on the surface of the balloon has increased so the space between all objects, all places on the balloon has increased.

OK, this has turned into a bit of a ramble, so to summarize: don't think of the Big Bang as an explosion in a room with a clock in it. Think of it as an explosion which creates an ever expanding room (with its own clock), before which you have no idea what a room or a clock are. 

[common_sense_seeker (OP)]

Hi Richard, I'm fairly familiar with the standard explanation. What I'm doing is trying to suggest a subtle alternative. For someone who is deeply involved in the subject, it might be too difficult to do. It's a good idea if you think outside the box a little.

AL

[rich42]

As I pieced together from some of your other threads (correct me if I'm wrong), your model has a static universe in place with protogalaxies already formed when the Big Bang explodes and expands into it, with no physical boundaries between the space with the protogalaxies in it and the Big Bang expanding 'shell'.
A couple of problems exist with this model: from our observations and inferred observations, the extent of the physical universe looks the same from every vantage point. I'm not sure if this still applies in this case, as the Universe would have a defined centre compared to the space in which we find the protogalaxies. More importantly, the particle horizon beyond which we are unable to see (because light from that point hasn't reached us yet) would lie outside the 'edge' of this expanding universe, so we should be able to see a point beyond this and a visible change in properties. 
I also do not think that a protogalaxy would be able to survive an explosion the size of the Big Bang expanding into it. The disruption from shocks and movement of mass through it at relativistic speeds should tear it apart. Unless you have a model by which they can survive this, this is a serious problem.
Just a first thought on the problem...I know you are looking for a simple and elegant explanation of the Universe, but this would turn out even more complicated than the model we have at the moment!

[common_sense_seeker (OP)]

As I pieced together from some of your other threads (correct me if I'm wrong),

You haven't got it right. I'm thinking in geometric terms. My 'big bang' is the outburst of the collapse of two opposing proto-galaxy stacks. I'm supposing that a 3-dimensional bubble appears in a 4th-dimensional space and is then 'injected' with spinning energy (i.e matter). It can be all pictorially represented, although I'm less keen to show such 'secrets' I've been working on for so long. Unless it's the right person of course.

AL