A couple of weeks ago, there was a Ph.D. thesis defence in Sharif University of Technology by Hossein Haghi **,***under supervision of Dr. Sohrab Rahvar/He is my supervisor too!:)/, in physics department with the title of MOND* in ... : Modified Newtonian Dynamics.
What is it about?and what is the story of modification...
During last century, in physics history usually we observed new phenomenas in experiments which could not be described by approved and used models and physical laws of the day.So what happened? Immediately the situation is divided in two ways
1)In the same frame of our known laws and models, we defined new physical entities to describe the experiment. or
2)We concluded that we do not know the laws well, and we start to change and modify them.
This scenario was happened several times, as a famous example is the problem of missing mass in beta decay in late 20's and beginning of 30's ,as I mentioned there were two solution 1)The law of conservation of energy is not correct or
2)there is a new mysterious unseen particle that we do not know about it and can not detect in experiment.
The history in this case shows that the second solution, the famous Neutrino predicted by Pauli was the right answer.
Now we have such a situation in galactic scale cosmology too.
The rotation curves of stars rotating in galaxy contradict with the prediction of Newtonian Mechanic, and we get flat rotational curves.
Immediately there is two solutions to the problem
1)Modifying the Newtonian law:Which means we do not understand it well,or there is more complete theory standing there.MOND as an example.
2)There is a new mysterious,only gravitationally interacting particle which named DARK MATTER ,which is responsible for this new missing mass in galaxy.
Finally what I want to mention is about the always existing two perspectives as a solution of the problem.
1)Modifying the laws or 2)Introducing New physical entity, are always teasing physicists minds.
But which one is seems more plausible is not yet well established but it will be fair to mention that the DARK MATTER campaign is so large /because of its success in cosmological model for structure formation models as CDM and there is a huge Hope to find light supersymmetric particles (LSP) in LHC arXiv:0807.2244 as a candidate for this entities as DARK MATTER.
But the story is not happy ended yet .Anyhow let us see what experiments unreveal for us.
*Nice web site about MOND related papers: http://www.astro.umd.edu/~ssm/mond/
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