(May 9, 2009 at 12:52 pm)g-mark Wrote: Does electromagnetic radiation travel through us?Again with the irrelevant questions?
Yes or no, it is frequency dependant. In the visible range, there is mostly reflection or absorption. For higher energies there's a probabilty for a photon interaction whilst it's inside you, by photoelectric effect or compton scattering but mainly yes it does "go through you"
(May 9, 2009 at 12:52 pm)g-mark Wrote:lilphil Wrote:This is an absolutely baseless statement
How so?
We know that a certain mass density (which may be a fuction of position) of dark matter is required to explain galactic orbits.
This means there is a certain number density required. But since it's unknown what the mass of an individual dark matter "particle" is (since we don't even know what it is!), it is impossible to say what this number density should be, and your quote suggests it's billions, even though this cannot be known.
Galileo was a man of science oppressed by the irrational and superstitious. Today, he is used by the irrational and superstitious who claim they are being oppressed by science - Mark Crislip
