A Conversation for Dark Matter

Is DM everywhere?

Post 1


If dark matter is holding our galaxy etc together, does that mean that it is everywhere? Does it permeate real matter? Am I composed of 90% DM? If the only way we can detect it is through gravity, does that imply that there are other fundamental forces we don't know about that apply to different types of matter?


p.s. matter matter matter

Is DM everywhere?

Post 2

Mammuthus Primigenius

Dark matter - according to the the WIMP hypothesis - consists of a cloud of particles gravitationally bound to the galaxy. Apart from gravity they interact through the weak nuclear force which has a very low interaction rate. Therefore WIMPs don't clump together or exert any noticeable effect on ordinary matter although billions pass through you every second. However the interaction rate is not zero, just very very small. Very occasionally a WIMP will hit an atom and scatter off it, this is what underground search experiments are hoping to detect.

Until they do, the WIMP theory remains just a hypothesis. There are other theories which are not so popular with most physicists, some suggesting the existance of a 'shaddow universe' with dark stars and planets which only interacts with our universe through gravity. Some eccentrics have even proposed the Tunguska incident was caused by a dark object hitting the Earth. No reputable scientist believes this, but until we have a confirmed WIMP sighting, we can't disprove it.

Is DM everywhere?

Post 3

Researcher 204763

If you are talking about branes and the M-theory, you'd be surprised how popular the theory is now. It explains many of the problems the Big Band theory has, and it is almost, as one NASA astrophysicst puts it, mainstream now.

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