How to define a black hole?

Dividing by zero is fine under many conditions. Of course, you don't really get the full picture in high school algebra. 0/0 is undefined but since the mass is positive and you would be approaching zero volume from the positive side, "divide mass by zero volume to get infinite density" is well-defined.



Let's not jump to conclusions =P Originally Posted by reciprocity

In that case you are speaking of a limit but not actually dividing by zero because it is always undefined or dne-does not exist. I took linear algebra in college right before differential equations, you know?

Geez...I was told there would be NO Math!

Camille,
Smart AND beautiful ...... what a combo!!!!!

abdclub Originally Posted by abdclub

ABD, oh I dunno...more like PWI lol.
I've been celebrating a birthday for about 3 days straight now and am on intravenous coffee at this point. I could babble about the extrusion and thermoforming properties of high impact polystyrene to show I can grasp some degree of technical knowledge of an industry..but I warn ya, it would be just that...babble.
Back to the topic in hand...my head feels like the black hole today.
Enter at your own peril...

C xxxx

You were more tolerable when you looked like Johnny Depp Originally Posted by heidilynnla

See, the handsome guys get away with more shit.

Reciprocity, I see that we are on the same page here.

http://mathforum.org/library/drmath/view/55795.html
"Some people say that 1/0 is infinity as a kind of short hand for what
happens to 1/x as x approaches 0. Note that if x approaches 0 from
the right, 1/x becomes larger and larger; often we say that 1/x
approaches infinity. Note also that 1/x becomes smaller and smaller
as x approaches 0 from the left, so that 1/x approaches negative
infinity."

EXPANDING HOLE..KINDA LIKE BIRTH.. lol annie

Reciprocity, I see that we are on the same page here.

http://mathforum.org/library/drmath/view/55795.html
"Some people say that 1/0 is infinity as a kind of short hand for what
happens to 1/x as x approaches 0. Note that if x approaches 0 from
the right, 1/x becomes larger and larger; often we say that 1/x
approaches infinity. Note also that 1/x becomes smaller and smaller
as x approaches 0 from the left, so that 1/x approaches negative
infinity." Originally Posted by Can I Play Too???

I'm glad we agree now. Rest assured that I have the qualifications to speak on this subject.

I don't plan on "hobbying" as you guys say - I'm only here because I'm sort of bored with my two regular forums (one is my favorite author's official site and the other is a PhD job market forum - both are a bit inactive now). I found this site after reading an article in The Economist about the escort business.

What a conversation that must have been.
But how lucky it is to be in a word that is torn by strife and such that we can come together on such a vast subject that at the end of it we are bound to walk away and know almost nothing of it.
We are really dealing with the subject of truth and truth by definition is exclusive. So when looking at the scientific theory of Black Holes you really don’t get exclusivity.
What an interesting subject and one that would require at least a case of wine to dive into.

Well instead of defining a black hole, I can give an example: One of our "No piece of ass is worth $XXX" threads.

A Supermassive Black Hole

SOURCE:NASA IOTD. In a single exposure, astronomers were able to confirm the existence of a supermassive black hole in the center of galaxy M84. They did this by using the Hubble Space Telescope's more powerful spectrograph to map the rapid rotation of gas at the galaxy's center. The colorful zigzag provides the evidence. If no black hole were present, the line would be nearly vertical. The Space Telescope Imaging Spectrograph measured a velocity of 880,000 mph within 26 light-years of the galaxy's center. This measurement allowed astronomers to calculate that the black hole contains at least 300 million solar masses. M84 is located in the Virgo Cluster of galaxies, 50 million light-years from Earth, and a nearby neighbor to the more massive M87 galaxy, which also contains an extremely massive black hole. The image on the left shows the galaxy's center in visible light. This image was originally released May 12, 1997. Image Credit: NASA, Gary Bower, Richard Green (NOAO), the STIS Instrument Definition Team For credit and copyright guidance, please visit image webpage.

http://www.nasa.gov/multimedia/image...ture_1846.html

Wowza. Thanks Lauren.

50 million light-years from Earth

That would be a road trip...