Where does the dark energy / matter come from?

Asked by: Chuang Wei Hsun

Answer

If our galaxy (for example) consisted of just the stuff we can see or otherwise observe/measure - stuff you could call 'light matter' - it's thought it would not stay together; the stars would drift off because the mass that we are aware of only accounts for perhaps a tenth of the gravity needed to bind things where they are.

'Dark matter' is the term we apply to objects that we have been so far unable to detect, but that we still reckon exist, because it would account for certain phenomena that we have observed, such as the fact that stars do tend to cluster into galaxies.

We don't know what form this dark matter takes, what kinds of particles it consists of. We don't know the precise location of any. That, unfortunately, is the whole point about it being 'dark'. We don't even for certain that it is there at all. I suppose it's always possible that there could be some hereto undiscovered force or forces at work in our universe somehow supplementing the effect that gravity has. So I think it may be a little optimistic at this stage to try and explain where it comes from.. However, there are no shortage of theories about dark matter...

More info on dark matter:

• Dark Matter
  from UC Berkeley
• Dark Matter in the Universe
  Article by Scientific American
• Dark Matter Mystery
  from Chandra X-ray observatory

Answered by: Antony Bartlett, B.S., Reading, UK