Which of the following statements about black holes is false?

Question

If the Sun magically disappeared and was replaced by a black hole of the same mass, the Earth would soon be sucked into the black hole.

If you were falling into a black hole, you would see more and more pronounced distortion in the pattern of the constellations.

If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls nearer to the event horizon of a black hole.

If you were fall into a black hole, you would experience time to be running normally, i.e., you would be aging at the same rate as if you were far from a black hole.

If you watch someone else fall into a black hole, you will never see her cross the event horizon. However, she will fade from view, as the light she emits becomes more and more redshifted.

Answer 1

1: False. If the mass and the distance remain the same then the gradational forces will also remain the same.

2. Unknowable. If you were to fall into a black hole, before your speed was anywhere need high enough to distort your view of the universe, you would be killed by tidal forces.

3. True. As the clock falls faster and fast, time dilation would make it appear to run slower to an observer not falling.

From Stephen Hawking's "A Briefer History of Time"

Suppose an intrepid astronaut is on the surface of a collapsing star and stays on the surface as it collapses inward. At some time on his watch—say, 1 1:00—the star would shrink below the critical radius at which the gravitational field becomes so strong that nothing can escape. Now suppose his instructions are to send a signal every second, according to his watch, to a spaceship above, which orbits at some fixed distance from the center of the star. He begins transmitting at 10:59:58, that is, two seconds before 11:00. What will his companions on the spaceship record?

We learned from our earlier thought experiment aboard the rocket ship that gravity slows time, and the stronger the gravity, the greater the effect. The astronaut on the star is in a stronger gravitational field than his companions in orbit, so what to him is one second will be more than one second on their clocks. And as he rides the star's collapse inward, the field he experiences will grow stronger and stronger, so the interval between his signals will appear successively longer to those on the spaceship. This stretching of time would be very small before 10:59:59, so the orbiting astronauts would have to wait only very slightly more than a second between the astronaut's 10:59:58 signal and the one that he sent when his watch read 10:59:59. But they would have to wait forever for the 11:00 signal.

4. Unknowable. See answer 2

5. True. You would see her (why a her, why not a him) moving faster and faster until, eventually her speed would be so great that the light form her would be out of the visible light range.
And, from the excerpt from A Briefer History of Time quoted above, you will see that the final second will last for infinity for an observer outside the effect.

For the unknowables.

As you fall into a gravity well so deep that escape velocity is =>c, then you will experience tidal forces so intense that the force on your feet is markly greater than the force on your head. This force will stretch you out and tear you apart long before you actually reach the event horizon, and the effect on the observable universe would not really be noticeable by your senses until you reach a large fraction of the speed of light.

But, let’s suppose that you could survive all this somehow and still retain your senses. That would change the anwers,

2. If the constellations were directly ahead, or directly behind you, you would only see the colors changing, the ones ahead would blue shift, and the ones behind would red shift (eventually the light from the ones ahead would shift so much they would be gamma rays that would also kill you, but we will forget about that). The position of these stars would not distort.

But the ones to the side, these would. They would first seem to compress until you actually pass them, the they would seem to expand back to normal.

4. Time, to you, would flow normally. See answer #3.

Answer 2

"...If the Sun magically disappeared and was replaced by a black hole of the same mass, the Earth would soon be sucked into the black hole..."

The above is false. Mass is mass is mass is mass, therefore gravity is gravity is gravity -- no matter the volume that mass occupies. Were the sun to 'magically' disappear and be replaced by a black hole it would suddenly be very dark and Earth would be bathed in massive waves of lethal radiation.

Another respondent to your question said that this statement is false ==> "...If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls nearer to the event horizon of a black hole..." This is actually TRUE and is due to relativistic time dilation effects.

Answer 3

Part A is false.

Gravitational force is only a result of Mass and Distance. A black hole would not be massive enough to form if it had just the mass of the Sun as it is now. And if the Sun were to be replaced by a Black Hole of the same Mass, it would continue orbiting at the same rate, since the Earth would still be the same distance from the center of mass of the black hole, and it would have the same mass, so overall the force of gravity wouldn't be any different.

Fg=G*M*m/(R^2)

Nothing in this equation would change, so nothing would change with the Earth's Orbit.

Answer 4

If the Sun magically disappeared and was replaced by a black hole of the same mass, the Earth would soon be sucked into the black hole.

Answer 5

The first one is definitely false. I guarantee it. I just took a semester long course on general relativity. The first one is wrong because the any object with the same mass of the sun will cause the same gravitational forces on the planets. Therefore nothing about the motions of the planets will change.

Two is right because the intense curve of space near the black hole would cause light bending.

Three is right because the curve of space causes time to slow down the closer you get to the black hole.

Four is right because you would experience the proper time in your frame of reference so time would tick at the same speed for you.

The last one is right because gravity redshifts light, and it would take forever from your point of view because time would appear to slow down for the person falling in from your point of view. I forget the equations to prove it exactly, but I'm sure.

Answer 6

If we watch a clock fall toward a black hole, we will see it tick slower and slower as it falls nearer to the event horizon of a black hole.

False.

Answer 7

The answer is
E. All of the above.
Black holes don't exist except in man's imagination.

Answer 8

I ate 15 burritos last night and now my black hole is badly distorted. Also, the gaseous emissions are much like this very question.

Answer 9

surer i have a black hole in my yard yep 2 meters down and 13 inches wide

Answer 10

The third and fourth statement is false