Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: guissepe on 18/01/2010 22:34:36

Title: What is the evidence for dark matter?
Post by: guissepe on 18/01/2010 22:34:36

Theory of the dark matter should explain the phenomena that all stars move the same speed no matter how far from the center of galaxy they are, what is not too much according the newtons laws.
I think that the matter as we know it doesnt need to have the same properties all over the galaxy. We know that weight of an atom is number of protons multiplied 2, but what if this doesnt need to be a rule, maybe it just some sign of our conditions. I want to say that there can be something what makes the atoms havier dependent how far from the center of galaxy they are just by increasing the number of neutrons in its cores. 


[MOD EDIT - THREAD TITLE CHANGED TO A QUESTION, IN LINE WITH FORUM POLICY. CHRIS]

Title: Re: What is the evidence for dark matter?
Post by: yor_on on 19/01/2010 00:51:05

As far as i know stars move at different speeds?

The velocity is revealed by the Doppler effect and measures the stars proper motion, distance and radial velocity.

Do you have proof of it being otherwise?

Title: Re: What is the evidence for dark matter?
Post by: guissepe on 19/01/2010 00:55:00

I am gonna try to explain what is dark matter... when two objects attract each other by gravity how is it possible that they dont crash one another. It is because they move, they circulate in acurate speed so the centrifuge force has the same value as the gravity force but opposit direction. If they move faster they would get lost If they move (circulate) more slow than needed they would crash.

Then we know that the longer is distance betwen them the smaller is gravity force, the less centrifuge force is needed, the slower is circulation. That is how it works in solar system but in galaxy are all stars moving more or less the same speed round the core almost independent on the distence from it. In galaxy gravity dontwork like we are used to so we came up with a theory of some matter that afects world by its gravity but we cant identify it. And it is dark matter. And I wanna say that maybe there is no dark matter but just somewhere is the classical matter havier than somewhere else.

Title: Re: What is the evidence for dark matter?
Post by: yor_on on 19/01/2010 01:06:38

Stars and speeds (http://www.astronomycafe.net/qadir/q181.html)
As for clusters, they move at the same speed, maybe it was this you meant?

Title: Re: What is the evidence for dark matter?
Post by: guissepe on 19/01/2010 01:41:41

the graphs should look similar for similar gravitaty..but they just dont

Title: Re: What is the evidence for dark matter?
Post by: guissepe on 19/01/2010 01:42:58

sorry for my english