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Name: David
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1999

What is the (theorized) nature of dark matter? How can we tell that it exists? Where in the universe is it thought to exist, in our galaxy, or our solar system?

Matter that emits light or radio waves or other EM radiation is called non-dark matter. When we estimate the amount of mass represented by the non-dark matter, there does not seem to be enough matter to "close" the universe, that is, to have the expansion of the universe sometime slow down and have the universe start to collapse. Most scientists would expect that the universe is closed or slightly open, but not as open as the estimate of the mass from visible matter. Thus, dark matter was invented to be the unseen mass that would close the universe. Some theories had it be neutrinos with mass (experiments seems to show that the neutrino mass is too small). Some theories have suggested that it is made up of neutron stars and the most recent measurements of gamma ray bursters suggests that the dark matter might be white dwarfs that are all around. This is an exciting area and no one knows the answer. I don't know if you can understand all of my answer. If not, please ask again.

Sam B

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