About Jayendra Upadhye Expertise 1 - General questions on most astronomy topics such as:-
Solar system, Cosmology, Black holes, Quasars, Dark matter etc.
2 - General questions about the geologies of planets.
3 - General questions about Orbits and laws governing them.
4 - General questions about rockets / spaceships
5 - General questions about stellar interiors and supernovas.
Experience I was an askme.com expert rated no#1 for quite some time - and was top ten there by the time it closed - in Astronomy and general science categories.
Education/Credentials Bachelor of Engg. (Electrical engg), Maharaja Sayajirao university of Baroda, Gujarat, India.
Awards and Honors None to write about except the askme rating if it is any worth!
Question Hi, I asked a question about black holes a bit agao and I just would like to clear something up. I've read the laws of physics break down at the black hole's singularity. What laws of physics break down? Time and space are bending and slowing, so what laws are being violated? Also, I understand that mass is a controling factor, therefore, if a black hole were to meet a star with a smaller mass the black hole would consume the star, but, I want to clarrify; if a object, say a galaxy had a larger mass than a black hole and met a black hole, would the galaxy therefore consume the black hole, and, what would that entail? THank you for answering these issues, Marc
Answer Hi Marc,
The beauty of physics and maths is that we can break down the larger issues into the smaller ones.
Then look at the soultions of the smaller ones and let those guide us.
case 1:-
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Breaking down of the laws of physics at the singularity.
Let alone the singularity, we dont even know what happens inside the event horizon which is a fairly large spherical volume of 3d space, that marks the swarzchild radius of the singularity.
Consider it as a black box.
we "dont know" what happens inside the box, but we do know that the weak force gravity extends from all the way in its center, to the farthest corners of the universe, and that it does follows the inverse square law.
The laws of physics break down because space is impossibly warped there in the vicinity of the singularity.
All objects in space occupy volume if they have mass. This basic law is violated at the singularity.
A black hole HAS mass, but NO VOLUME. IT is a dimensionless entity, a point, with no length, breadth nor hieght.
in such a place where no physical dimensions apply, which other law can hold?
THAT is the argument.
Gravity remains as it is a warp in the very fabric of space-time, caused by the mass.
If the black hole is a bullet breaching 4d space time, its gravity is the bullet mark!
case 2:-
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Here is how we break down and understand things one piece at a time.
1 - A black hole has a finite mass.
2 - As long as this mass is constant, the inverse square relation ship holds.
3 - So provided you have sufficient distance from the event horizon, you would be experiencing just the normal pull of gravity as from the sun or any planet.
Only in the accretion disk very near to the event horizon, is the rate of change of gravitational intensity great enough to cause individual particles of a body to accelerate away from each other with such a large differential that the body experiences "tides" and is shredded by that differential across its very physical dimensions.
The tidal locking of the moon is caused by a similar but weak tide caused by the earth. And the solar and lunar tides we see in the oceans are so natural for us.
The tides of the black hole are titanic to say the least.
But if the sun were to be a black hole tomorrow, it would have no ill effect on the earth, as the sun's mass would continue to be the same.
Extending this small piece of knowledge, A black hole would consume a star only as lomh as the star's surface was so close to it that the tides lifted matter off the star and onto the hole.
Cygnus X-1 was such a candisate. It is believed that a black hole is orbiting a red giant star and siphoning away matter into an accretion disk.
Galaxies gobbling black holes...why not, a galaxy has a mass a 100,000,000,000 solar masses!
Black holes a million solar masses routinely reside in the hubs of spiral galaxies. Ours has one known as sagittarius A. It is 4.31 million solar masses!
And yet the galaxy and us have survived unhurt for the last 4.5 billion years.
And the galaxy is older than the sun!
refer:- http://en.wikipedia.org/wiki/Sagittarius_A*
So there you have your answer.
regards
Jayen
