Brits seek missing WIMPs of universe

[Az]

Well, what they tell you on these popular science programs on TV isn't true. Partilce, anti-particle pairs do not just spontaneously appear out of the a vacuum. There has to be something there for them to come. You kind of implicitly know this since you said 'from energy' - energy has to be in some form, eg. as a photon.

That's what I meant by energy.

Thanks for the explanation about the photon, and I am too young for the Higgs Boson.

[Rogan Josh]

Originally posted by Azazel
WAIT A SEC.......STOP!!!!!!!


faster than light?

Yep!

There is no problem with the universe itself expanding at faster than the speed of light. The problem is only with exchanging information at the speed of light. Since everything is moving with the space-time expansion, you still can't send information faster than the speed of light so it is OK.

[Dauphin]

Originally posted by Rogan Josh


That's not true either. If the universe had expanded at the speed of light after the Big Bang then there would be no stars 14 billion light years away because we would see the Big Bang singularity itself 14 billion light years away (in all directions). Then, what you just said would be true - everyone, everywhere would have the same horizon, bounded by the Big bang singularity.

I have trouble conceptualising that scenario, unless you are saying that the universe would be a closed space of 14 billion l.y diameter. For you are effectively saying that everyone is at the 'centre' of a finite universe.

I'm not saying that this is not the case, I'm just saying we can't discount the alternatives as BG was.

[Lancer]

"Brits seek missing WIMPS of universe"

Tell em to look across the channel.

[Rogan Josh]

Originally posted by Big Crunch
I have trouble conceptualising that scenario, unless you are saying that the universe would be a closed space of 14 billion l.y diameter. For you are effectively saying that everyone is at the 'centre' of a finite universe.

I get into difficulties with relativity here. What do we really mean by 'now'? As I am sure you know, the light which we see coming from stars in the sky is billions of years old, so we are seeing the star as it was billions of years ago. If you regard the 'universe' as being what lies along our past light cone, then yes it is a closed space of 14 billion years diameter- and you are sitting at the centre (since it is your light cone).

I would tend to think of the universe in a wider sense though.

[Dauphin]

Originally posted by Rogan Josh


I get into difficulties with relativity here. What do we really mean by 'now'? As I am sure you know, the light which we see coming from stars in the sky is billions of years old, so we are seeing the star as it was billions of years ago. If you regard the 'universe' as being what lies along our past light cone, then yes it is a closed space of 14 billion years diameter- and you are sitting at the centre (since it is your light cone).

I would tend to think of the universe in a wider sense though.

In this instance I am refering to the totality. If you could freeze the universe in space and time what would a map of it look like when all parts are the same age (or rather same stage of development).

[Az]

Yep!

There is no problem with the universe itself expanding at faster than the speed of light. The problem is only with exchanging information at the speed of light. Since everything is moving with the space-time expansion, you still can't send information faster than the speed of light so it is OK.

Oh, I got it, the space itself was expanding, and so was the matter in that space, and on agreggate the speed was faster than light.

My question is, if space/time itself was expanding, what point of reference can one have?

[Dauphin]

RJ, let me clarrify my thinking for you, so you can correct me if I'm missing stuff.

If you consider an explosion from a point in flat or open space there will always be parts that are at the edge of the matter conglomerate, and bits left in the middle. They will all have different perspectives

In a closed space explosion you can have all particles touching another particle from the explosion. They all have the same view.



I don't *know* if that is true, but that is my visual aide, and fits in with what I remember from maths classes.

[Rogan Josh]

Yes BC, that seems right to me.

Sorry Azazel - I don't understand your question.

[Az]

well, if Space/time itself expands, what does it expand over?

If space time expands, a meter in a certain direction becomes longer as time passes by. correct? But if a meter becomes longer with time, what stays the same?

[Rogan Josh]

Originally posted by Azazel
well, if Space/time itself expands, what does it expand over?

If space time expands, a meter in a certain direction becomes longer as time passes by. correct? But if a meter becomes longer with time, what stays the same?

That is a very good question. I actually asked this very question myself to about 10 different cosmologists before I could find one who even understood my question.

The answer (as I understand it - I am not a cosmologist) is that the expansion is only occuring at large scales. So you are not getting any bigger. It is only the measure of distances at large scales (like Earth to the Orion nebula) which are expanding. To make a bad analogy, imagine an explosion which send lumps of rock flying in all directions - the distance between the rocks grows but the rocks themselves don't.

[Az]

So let me get this straight, while, say a human being grows say, 2% in length, a planet grows 10%? No, this can't be right. you probably mean that the change is only noticeable on extremely large scales. Also, as I understand OBJECTS don't grow, it's the space that does?

generally, something smells fishy in this. I understand that we're pretty much at the frontiers of human understanding of the universe, right?


I feel missing out, that I didn't go studying in that direction in Uni. Cosmology always fascinated me as a kid. ( But who wasn't fascinated by cosmology as a kid, right? )

[The diplomat]

Does the universe have an edge? If so, then what happens when light reaches the edge of the universe? It can't cross the boundary since there is nothing on the other side, and it can't simply dissapear because that would be a violation of the law of conservation of energy. It seems to me that the only possibility is that the light would reflect off of the boundary and come back towards us. But if this is the case, then it would mean we are essentially surrounded by a cosmic mirror in all directions. In such a case, everything would be reflected ad infinitum, and it would mean that most of the galaxies we see are actually just multiple reflections of closer ones.

[Az]

The universe doesn't have an edge, as apparently ( ), if you go one way real far, you'll come out of the other end.

[Japher]

Scientists around the world are racing to be the first to discover the truth about Dark Matter, which cannot be seen because it does not emit light. They believe it makes up the vast majority of the universe.

I don't get this. Not everything that can be seen emits light, a lot/most of it reflects light, right? What the heck are they saying dark matter is? Mini Black holes?

well, if Space/time itself expands, what does it expand over?

I like to think that it is not expanding over something, but into something. That something is something like a Bizarro universe where everything is opposite of what it is here. This could explain a lot, and I am to lazy to explain it. Has something to do with matter/anti-matter relations and entropy. Kind of like a magnetic spring/coil expanding from the big bang, it will eventually reach its full potential energy, at which time all real entropy will be disipated, but concurently bizzaro entropy will be at it's max... and BANG!

Then again, it could just be expanding over a banana