black hole question

[blackhole123]

I have a question about black holes. I dont know much about them but I was thinking about it the other day and couldnt figure something out.

 

From what I understand, black holes are stars that have collapsed on themselves and now have gravity so powerful that light cannot even escape it. My question is this. When the star collapses all it does is become more dense (or so i would assume from the word "collapse"). So that means the original star had the same amount of mass as the black hole. So then why wouldnt the original star have the same amount of gravity that the black hole has? Why wouldnt regular stars trap light?

[tejaswini]

well i think in normal stars the gravitational pull {inwards} and the pressure pulling out perfectly balance each other, but when the nuclear fuel is exhausted the gravity gets the upper hand and the star starts to collapse under it's own gravity.the more denser it becomes . the gravitational pull reaches it's maximum in case of a black hole.now ur question was why stars and black holes even though have same mass show differences in light trapping capacities. well now a black hole can trap light because of the immense gravitational pull.nothing to do with mass. it curves the straight path of the light and traps it .but an oridnary star does not have same gravity because the forces balance each other and hence the gravity cannot dominate.so it cannot trap light.

physics is not my thing . so excuse me.but this is what i think.

[AweBurn]

From my limited reading on the topic, I understood that gravity is dependant on both mass and distance from the center of the mass in question. That being said, its much easier to get to the center of the star when the mass has become much more dense.

The event horizon is the point at which light can not escape the gravitational pull of the blackhole and in a live star this imaginary line would probably be well within the star meaning you would also negate the influence of any mass above that point. The event horizon of a blackhole may be 100 miles away from the center for its mass but at that level on an equally heavy live star that would be buried deep inside and consequently not be an event horizon at all.

 

Please correct me if I am wrong, im simply an enthusiast.

 

-AweBurn

 

edit: Spelling. Rush rush rush.

[JustStuit]

It is actually dependent on energy. Mass can be converted to terms of energy for computations. For most situtations newtonian gravity works but at speed of light or near black holes it doesn't.(general relativity)

 

Our sun's event horizen if compressed would be 3.33 km, 100 miles seems pretty large. I just went to a lecture which dealt with some of this from a professor from FIU. It was pretty interesting.

[Quantoman]

I had speculated that Black Holes are inverted light

but i guess i was wrong.

 

 

It looks like in 2007 at the CERN Large Hadron Collider

there will be an experiment conducted to attemp a

recreation of a Black Hole.

 

 

They plan to blast two PROTONS together with enough

energy to make them rip apart the fabric of spacetime.

 

 

Until then i guess we can still SPECULATE if Black Holes

exist....

[insane_alien]

the black hole has exactly the same gravitational pull as the star. its just more concentrated because it is far far far far more dense than an atomic nucleus. and since gravity works on a 1/r^2 relationship and the event horizon(for all intents and purposes the surface of the black hole) is really small the light can close enough where the force of gravity is HUGE.

[anglepose]

Black holes are where space time cotinuem collapses in on itself due to overwelhming density at the poit of collapse the singularity becomes frozen

its gravitational force becomes equal to the star it came from yet smaller and more conncentrated you are unlikely to detect a balck hole for a few milion years until it gathers enough mass to make a mark.