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Q & A: Black holes, dark matter and dark energy

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Most recent answer: 07/16/2009
Q:
Sorry, this is a several part question. What happens to matter that enters a Black hole? Since Dark matter and Dark energy seem to be furthest from black holes and have significant gravity, can there be some sort of correlation between them? For instance, can the dark matter be normal matter obliterated by the gravity of a black hole? Then since it has no where to go, can it potentially be pushed through space to pop out where there is the least amount of Gravity? Could the gravity from Dark energy exist because the Dark matter is still in a different state from being pushed through space yet it still has significant mass from the forces of the black hole? I might not check for my answer soon, \
- Brian C (age 32)
Crest Hill, IL USA
A:
First, the experimental facts:
1.  The existence of dark matter was first proposed in 1933 by the Swiss astronomer Fritz Zwicky in order to explain some peculiar kinematic properties of galaxies.  Astronomical and astrophysical measurements ever since have confirmed Zwicky's hypothesis. 
See:   http://en.wikipedia.org/wiki/Dark_matter for details. 
2.  The fact that the universe is expanding has been known since 1929 when the astronomer Edwin Hubble discovered that the red-shift, or receding velocity of far away galaxies, was proportional to their distance from us.  See:   http://en.wikipedia.org/wiki/Edwin_Hubble
3. The new wrinkle is the recent measurements in 1998 and later, seem to indicate that not only is the universe expanding, it is expanding at an ever increasing rate.     
See http://en.wikipedia.org/wiki/Accelerating_universe

Those are the facts.   Now comes the tough part.  How do you make theories to explain all of these facts.    Fact #1 can be plausibly  explained by postulating a fundamental particle, as yet undetected , that contributes to the total mass of the universe but only interacts weakly with ordinary matter; only through gravity. No problem.
There is nothing strange about fact #2 within the framework of general relativity.   
Scientists are still digesting the consequences of fact #3.   Theories are a dime a dozen.  There are vigorous arguments going on within the physics and astronomy communities about this.   One of these theories postulates the existence of "Dark Energy", a mythical property of a "Scalar Field".   Other theories simply add an additional term to the Einstein equations of general relativity, a so-called cosmological constant.  (This was actually considered and rejected by Einstein)

So the answer is;  we don't know.  

Now to answer your questions:  
Black holes are well understood within the framework of general relativity.  They are known to exist, we have a big fat one in the center of the Milky Way.   They eat ordinary mater for breakfast and would be happy to swallow any dark matter that comes their way for lunch.
As for correlations between dark matter and dark energy...   who knows?  Could be.  As I said before, theories are a dime a dozen.   Experimental facts are harder to come by.

Best regards,
LeeH


(published on 07/16/2009)

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