Star Lifespan Near Black Hole: Time Dilation & Energy

In summary: So the star would appear to be outputting less energy than it actually is. This would be a paradox in mass energy conversion, but it would still be true that the star is really there and is emitting energy.
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neh4pres
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I would like to know, how much a stars life would appear to lengthen relativisticly as observed from earth, if the star was in a close orbit around a supermasive black hole. If the stars lifespan is longer from our perspective than a star of its size should be, would it also appear to be outputting less energy than it actually is in its own reference frame?
If time dilation does not make the star dimmer from a far away reference frame, would that not be a paradox in mass energy conversion? Where a far away observer sees more energy output over the stars life than was actually produced?

The question comes from a twist on the scene in interstellar, where I'm replacing people, or the planet with a star, if that helps to understand the question.
 
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  • #2
neh4pres said:
I would like to know, how much a stars life would appear to lengthen relativisticly as observed from earth, if the star was in a close orbit around a supermasive black hole.

It depends on the black hole and how close the orbit is. In the movie Interstellar, which you reference, the supermassive black hole is rotating rapidly and the orbit is about as close as it's possible to have an orbit without falling into the hole. Kip Thorne (the physicist who was asked to provide the actual parameters for the scenario in the movie) chose this situation because it gives pretty much the maximum possible time dilation for an object in a stable orbit. That time dilation is the same regardless of what kind of object is orbiting--planet, star, whatever.

neh4pres said:
If the stars lifespan is longer from our perspective than a star of its size should be, would it also appear to be outputting less energy than it actually is in its own reference frame?

Yes, because the light we see from the star will be strongly redshifted, as compared to the light that would be seen by someone orbiting close to the star and at rest relative to it.
 
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1. What is time dilation near a black hole?

Time dilation near a black hole is a phenomenon where time appears to slow down for an observer outside the black hole. This is due to the intense gravitational pull of the black hole, which warps space-time and causes time to pass at a slower rate.

2. How does time dilation affect the lifespan of a star near a black hole?

Time dilation near a black hole can significantly affect the lifespan of a star. As the star gets closer to the black hole, time will appear to slow down for the star, causing it to age at a slower rate. This means that the star's lifespan will be extended compared to a star that is not near a black hole.

3. Can a star survive near a black hole for an extended period of time?

It is possible for a star to survive near a black hole for an extended period of time, depending on its distance from the black hole and its size. If the star is far enough away from the black hole and has enough energy to counteract the gravitational pull, it can survive for a longer period of time.

4. How does time dilation near a black hole affect the energy output of a star?

Time dilation near a black hole can cause the energy output of a star to appear dimmer to an outside observer. This is because the time dilation effect causes the light from the star to appear to slow down, making it appear to have a lower frequency and therefore lower energy.

5. Can a star's energy be completely absorbed by a black hole?

Yes, a black hole can absorb all of the energy from a star that gets too close to it. This is known as an "accretion disk" and is a result of the intense gravitational pull of the black hole. The energy from the star is converted into heat and radiation as it is pulled into the black hole.

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