What is the evidence that most of the mass in our Galaxy lies in some as-yet-undetected form?

Answer 1

The orbital speed of stars orbiting our galaxy's core can be calculated based on the doppler shift of the radiation we observe from them. The physical dimensions of the galaxy are calculated by a variety of complex methods including triangulation and the intensity of light from stars of theoretically known output. Given these two factors, we can calculate the mass needed in the galactic centre to produce the observed orbital speed and dimension. But that mass far exceeds the estimated mass of the visible stars in our galaxy. Therefor it is assumed that a considerable amount of our galaxy's mass is not currently observable.

Answer 2

As well as the high speeds of the orbiting stars, they should be following a Keplerian decay, i.e. the further they are from the centre the slower they're moving. Problem is, they don't - the curve flattens out, which can be explained by the presence of dark matter.

Another piece of evidence is ionised gas in galaxy clusters - it's gravitationaly bound to the clusters, but we can't see enough matter to keep it there. It seems there must be at least 4 times as much dark matter as ordinary matter otherwise the gas would escape.

Answer 3

It is very possible that there could exist at the center of the Universe which would be the centerline where the Universe started, a mass which is not visible by telescope or radio astronomy where all Galaxies interact with.
Unfortunately there are limitations to Human observations.
So far science has postulated black holes but no one has seen one YET.

Answer 4

For the other galaxies, we can observe the rotational speeds of galaxies and orbital velocities of galaxies in clusters, gravitational lensing of background objects by galaxy clusters such as the Bullet cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies. And just in case you think of it, modifications to gravity theory to account for these observations would have to be very complex, while the dark matter theory is much simpler.

For the Milky Way, we can see the orbital velocity of the observable stars or gas clouds in orbit around the galactic core. Again, the data is best explained by the presence of dark matter.

Answer 5

Dark matter was invented in order to 'make the equations work' forthe Big Bang hypothesis. There 'must' be more matter than we can see to hold the galaxies together.

However there is no direct obervational evdence for it.

http://www.googlesyndicatedsearch.com/u/creationontheweb?q=dark+matter&hl=en&lr=

Answer 6

It's just a scientific term mean 'I don't know'

Answer 7

There really is none.