Wed Feb 27, 2013, 09:16 AM
hue (4,444 posts)
Will we ever… understand what dark matter is made from?
Perhaps the biggest secret in the Universe is the mysterious substance that makes up most of its mass. If dark matter does exist, asks Matthew Francis, what exactly is it?
Beautiful as it is, the Universe hides a great deal of its secrets from us. All the stars, galaxies, and other objects we see mask the presence of another substance that comprises 84% of all the mass in the cosmos. That substance, which in our ignorance we call dark matter, has proven annoyingly elusive for the better part of a century.
Detecting dark matter directly has proved to be tricky, but there is strong evidence for its existence, and it comes from a variety of sources. The first hint of dark matter's existence came in 1933, when Swiss astronomer Fritz Zwicky calculated that the Virgo Cluster of galaxies didn't have enough visible matter in the form of gas and stars to hold it together. It must be embedded in a halo of something invisible, or else it would fly apart. In the early 1970s, American astronomer Vera Rubin demonstrated the magnitude of the missing mass problem when she showed that the outer regions of spiral galaxies rotated far too quickly unless the galaxies contained a lot more mass than could be seen.
In the intervening decades, the evidence for dark matter has only grown stronger. Galaxy clusters—including the iconic "Bullet Cluster" discovered in 2006 – clearly contain far more mass than is visible in stars and gas. On even larger scales, galaxies collect into clumps and long filaments, rather than falling into random configurations, and surround regions largely devoid of matter.
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Will we ever… understand what dark matter is made from? (Original post)
|Uncle Joe||Feb 2013||#1|
Response to hue (Original post)
Wed Feb 27, 2013, 03:47 PM
TrogL (31,696 posts)
2. It's likely going to be difficult to get your head around
It's like realizing that you can't talk about before the beginning of the universe and even talking about the beginning of the universe is shaky ground due to observer problems.
If you want to give yourself a sleepless night, apply string theory to Genesis 1:1.