Dark Matter

[degree451]

Whenscientists say that 90% percent of the matter in the universe cannot be seen,have they factored in black holes? Even if we have to guess at the # of blackholes and the mass they contain on average, surely that’s been calculated somewhereright? Any links to articles with these calcs would be awesome.

 

[baric]

Whenscientists say that 90% percent of the matter in the universe cannot be seen,have they factored in black holes? Even if we have to guess at the # of blackholes and the mass they contain on average, surely that's been calculated somewhereright? Any links to articles with these calcs would be awesome.

 

Dark matter is only detected by its gravitational effect, so black holes that are not currently "feeding" would fit into this category.

 

However, the mechanism by which black holes are understood to form would be difficult to reconcile that with 90% of the mass of the universe.

[DrRocket]

Whenscientists say that 90% percent of the matter in the universe cannot be seen,have they factored in black holes? Even if we have to guess at the # of blackholes and the mass they contain on average, surely that's been calculated somewhereright? Any links to articles with these calcs would be awesome.

 

 

The lion's share of that 90% is taken to be "dark energy" which produces a repulsive effect accelerating the expansion of space. Black holes produce only a conventional gravitational attraction.

[Airbrush]

Whenscientists say that 90% percent of the matter in the universe cannot be seen,have they factored in black holes?

 

Dark matter is believed to be mostly nonbaryonic matter, which excludes black holes, since black holes are believed to be baryonic (ordinary) matter. I don't know a link to this but try wikipedia on "dark matter".

 

Wikipedia: "...dark matter constitutes [approx] 83% of the matter in the universe, whereas ordinary matter makes up only 17%."

 

http://en.wikipedia.org/wiki/Dark_matter

 

"Massive astrophysical compact halo object, or MACHO, is a general name for any kind of astronomical body that might explain the apparent presence of dark matter in galaxy halos. A MACHO is a body composed of normal baryonic matter, which emits little or no radiation and drifts through interstellar space unassociated with any solar system. Since MACHOs would not emit any light of their own, they would be very hard to detect. MACHOs may sometimes be black holes or neutron stars as well as brown dwarfs or unassociated planets. White dwarfs and very faint red dwarfs have also been proposed as candidate MACHOs. The term was chosen whimsically by contrast with WIMP, another proposed form of dark matter."

Edited October 10, 2011 by Airbrush

[Arch2008]

Here’s a program that calculates DM:

 

http://users.telenet.be/nicvroom/program2.htm

 

When scientists observed a galaxy rotate and then added up an approximation of the mass of the visible matter they were surprised. According to general relativity, the galaxy should have spun itself apart. The galaxy would need an additional 5 times the observed mass for it to match the observations. This has since been proved with the WMAP:

 

http://map.gsfc.nasa.gov/

 

So, the mass of the universe is 4.6% baryonic matter, 23.3% non-baryonic (dark) matter and 72.1% dark energy. However, the matter in the universe is one sixth baryonic and five sixths dark matter.

 

In the ‘90’s, two ideas competed for the dark matter crown. Weakly Interactive Massive ParticleS (WIMPS) and MAssive Compact Halo ObjectS (MACHOS). It seems that WIMPS more closely match the observations. So uncounted black holes with five sixths of all the matter in the universe aren’t as feasible as a cloud of sub-atomic particles that clump together by gravity but don’t form visible matter.

[Genius13]

maibe dark matter is some form of matter that interacts only with the Higgs boson so it only has a gravitational influence

[Realitycheck]

...

Edited October 17, 2011 by Realitycheck

[Bart]

Here's a program that calculates DM:

 

http://users.telenet...om/program2.htm

 

When scientists observed a galaxy rotate and then added up an approximation of the mass of the visible matter they were surprised. According to general relativity, the galaxy should have spun itself apart. The galaxy would need an additional 5 times the observed mass for it to match the observations. This has since been proved with the WMAP:

 

http://map.gsfc.nasa.gov/

 

So, the mass of the universe is 4.6% baryonic matter, 23.3% non-baryonic (dark) matter and 72.1% dark energy. However, the matter in the universe is one sixth baryonic and five sixths dark matter.

 

In the '90's, two ideas competed for the dark matter crown. Weakly Interactive Massive ParticleS (WIMPS) and MAssive Compact Halo ObjectS (MACHOS). It seems that WIMPS more closely match the observations. So uncounted black holes with five sixths of all the matter in the universe aren't as feasible as a cloud of sub-atomic particles that clump together by gravity but don't form visible matter.

 

Very readable and easy to use a program included on the link: http://dl.dropbox.com/u/26262175/SagitariusBRprogramDescription.pdf , convincingly proves that the observed rotation speed of stars in galaxies, is the result of natural distribution of baryonic mass in the galaxy and this has nothing to do with dark matter.

The program is very ingenious and inventive, and can cause a lot of satisfaction to the user. I checked it out!