Answers to Readers' Questions on Black Holes - Astronomy. Also refer to Physics, Physical Science, stars, planets, sun, speed of light, escape velocity, mass, gravity, event horizon, Schwarzschild, thermonuclear, Ron Kurtus, School for Champions. Copyright © Restrictions
Answers to Readers' Questions on Black Holes
The following 12 questions have been answered. They are listed according to date.
List of first 10 items
- Observations and comments about black holes
- What if something fell into a Black Hole?
- Confused about the equation x = v^2 / 2g
- Why would object that fell into black hole look red?
- What is a Black Hole made of?
- Does every black hole have the same mass?
- What if Black Holes collided?
- Can nothing escape a black hole?
- Can Black Hole turn objects into Carbon?
- Horizon of the black hole
Observations and comments about black holes
Question
November 10, 2009
Now, I am no university professor but in the section about black holes it says that they "gain energy" but i have also heard there is gamma radiation emitted from black holes when it devours matter (named Hawking radiation)this emitted gamma is greater or less than the devoured energy (or relative energy) depending on the mass of said black hole. So, in theory black holes have the ability to either continuously gain in mass or slowly evaporate to a lesser mass until the gravity is at a state in which is does not have a escape velocity = to c (speed of light) so i don't know the calculations but this process would probably take a massive time period, but once a black hole has "evaporated" you would be able to see it and it would no longer be "black" this would probably be classified as a neutron star.
This text - property of Michael Diaz, Grade 9 Student
Michael - Canada
18646
Answer
Thanks for your observations and comments.
The original, simple theories about black holes said they had such high gravity that not even light could escape. If that was the case, then they would be continually absorbing incoming radiation and thus gaining energy. I didn't get into this in my lesson, but perhaps I should.
But continually gaining energy--even a small amount--can bring up a number of problems, as you point out. The way the Hawking radiation works in theory is that quantum tunneling effects occur near the event horizon of the black hole. These effects bypass the gravitational requirements. This also reduces the mass of the black hole, ultimately causing the black hole to change its form.
What is amazing is that Hawkins made many of his discoveries through "mind experiments". Of course, he isn't the only scientist who contributed to theories about black holes.
What if something fell into a Black Hole?
Question
May 14, 2009
what would happen if something fell into a black hole? would it come out on the other side? or would it disappear for forever?
Julie - USA
17739
Answer
A Black Hole is a star, sun or even planet that has so much gravity that even light cannot escape it. Thus if some object got too close, it would be sucked in by the gravity and probably be crushed into a small clump. Nothing escapes a Black Hole, except for a stream of gas at its top or bottom due to its spin.
Confused about the equation x = v^2 / 2g
Question
December 4, 2008
I am confused about the equation x = v^2 / 2g
You said v was the velocity, but what velocity is that exactly? Average, initial, final? Also, you said the gravitational acceleration is 9.8m/s^2, but if the ball is going up, wouldn't the acceleration be negative?
Just a couple questions to clear up my understanding of the equation. :) Any help would be appreciated. Thanks!
Kristin - USA
16904
Answer
See the lesson "Gravity Equations for Upward Motion" at:
http://www.school-for-champions.com/science/gravity_equations_upward.htm
v is the initial velocity that the object is propelled upward. x is the maximum height the object will reach, if it starts at velocity v. The equation is the opposite of the distance a falling object goes to reach v. Thus, the negative signs cancel out.
Why would object that fell into black hole look red?
Question
November 4, 2007
Why would an object that fell into a black hole have its color turn to a rusty red once it has passed the event horizion? Does this have something to do with the time dilation... The light shifting to the red end of the spectrum or something? Thank you!
Maria - USA
14702
Answer
When objects that give off light, such as a star or sun, are moving away from us, their light becomes more red. This is called the red-shift. Thus, as such an object started to speed toward the black hole, it would appear to us to be more red than yellow.
Anything inside the event horizon of a black hole will not escape, including light. That is why is it called a black hole. You would not be able to see light from an object within the event horizon.
What is a Black Hole made of?
Question
August 5, 2007
what is the black hole made of?
stephanie - Australia
14163
Answer
Black Holes are suns or stars that have collapsed on themselves. Their force of gravity is so great that their light cannot escape.
Does every black hole have the same mass?
Question
December 29, 2006
i remember hearing that the center of a black hole has infinite mass. but each black hole has a different size. does every black hole have the same mass?
- USA
12712
Answer
Actually a black hole is a star that has collapsed on itself. It does not have infinite mass, but its density is extremely large. It is as if our Sun had collapsed to the size of a golf ball. Since different stars have different masses, the various black holes also have different masses and different densities.
What if Black Holes collided?
Question
August 20, 2006
can black holes be destroyed? if they can't be destroyed, wouldn't our universe one day become one giant black hole? and also don't black holes have infinite mass? if one huge black hole and a black hole ten times smaller than that one meet, wouldn't the small black hole not be able to be sucked in by the huge black hole because they have the same density?
Vince - USA
11737
Answer
As a star gains more and more matter, its gravity increases. At a certain critical point, the gravity becomes so great that it compresses the matter into a small volume. Since the force of gravity is reduced as the square of the distance from the center, this gravity is much greater than that of the normal sized star and prevents light from escaping.
If two Black Holes would collide, the result would be the same as if two normal stars collided. The collision could either combine both into a stronger Black Hole or it might jar the contents apart and spread the material such that it became several normal stars.
Can nothing escape a black hole?
Question
June 3, 2006
nothing can escape a black hole. am i correct?
- USA
11266
Answer
The gravity is so strong that even light cannot escape. But new theories state that there is a vortex in the center that shoots out material. So, it is black everywhere except the vortex.
Can Black Hole turn objects into Carbon?
Question
May 31, 2006
how is a black hole able turn any object into a carbon atom? where the the object go, and where is the carbon atom-sized object stored? the incoming object has to go somewhere. it can't just dissapear,
- USA
11238
Answer
A Black Hole is a star with so much gravity that it will not let light escape. It has nothing to do with Carbon. Incoming objects just make the star bigger. Since light can't escape, the objects can't either.
See the lesson on Black Holes at:
http://www.school-for-champions.com/science/blackholes.htm
Horizon of the black hole
Question
April 15, 2005
In the mini-quiz, how can question 3 be "a.The horizon of the black hole" if can escape the horizon of the black hole.
- USA
6675
Answer
At some distance from the center of a black hole, the gravity is not strong enough to keep light from escaping. Anything inside that "horizon" gets sucked in and outside that boundary can escape.
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Answers to Readers' Questions on Black Holes