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Subject: 
Re: Black Holes
Newsgroups: 
lugnet.off-topic.geek
Date: 
Fri, 15 Aug 2003 15:41:32 GMT
Viewed: 
385 times
  
In lugnet.off-topic.geek, Stefan Garcia wrote:
   A Black Hole is supposed to be a collapsed neutron (type?) star, right? So then, why is a Black Hole always depicted as an infinite toilet-flush? I can understand that the “matter disc” forms into a disc because of gravity, like the rings of a planet, but shouldn’t the actual whatever-is-at-the-heart-of-a-black-hole be an infinitely small pinpoint?

I’d attribute this to popular myth, except that even NASA seems to show the “infinite toilet-flush” as the shape of a black hole.


“infinite toilet flush” as you call it is using a three dimensional model to describe 4 dimensional spacetime. In the typical diagram, the x and y axis describe area, while the z axis (up and down) describes graviational warping of spacetime.

like in this pic here:



since a black hole has super massive graviatational effect, the lines that converge on it sink straight down. whereas in a ‘normal’ object, the gravitational warping isn’t so severe, and wouldn’t decend infinitely, like this:



a black hole is a point in space that is infinitely dense (meaning finite amount of matter squeezed into zero space).

NASA shows the 3D map because it is the best analogy to help people understand the super-complicated concept of 4 dimensional space-time.

I can’t find it at the moment, but I had this website that contained flash movies that really helped drive home an understanding of warping spacetime. It showed what the sky would look like while moving over surfaces of different mass densities. It showed on earth, on the sun, and on a neutron star. On earth the stars moved hardly at all. On the sun they moved in a slightly eratic pattern, and on the neutron star they went crazy, moving up around and then over.

If you’re more interested, email me and I’ve got some cool websites that help explain it better.

Of course, I also recommend Stephen Hawking’s books “Brief History of Time” and “Universe in a Nutshell”

-Jr.Marshal Hoffman




Message is in Reply To:
  Black Holes
 
A Black Hole is supposed to be a collapsed neutron (type?) star, right? So then, why is a Black Hole always depicted as an infinite toilet-flush? I can understand that the "matter disc" forms into a disc because of gravity, like the rings of a (...) (21 years ago, 11-Aug-03, to lugnet.off-topic.geek, lugnet.space)

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