Star Lifespan Near Black Hole: Time Dilation & Energy

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SUMMARY

The discussion centers on the relativistic effects of time dilation experienced by a star in close orbit around a supermassive black hole, as illustrated in the film "Interstellar." It is established that the lifespan of the star appears lengthened from Earth's perspective due to significant time dilation, which is maximized in a stable orbit close to the black hole. Additionally, the star's energy output appears diminished to distant observers because the emitted light is strongly redshifted compared to what would be observed by an observer at rest relative to the star. This creates a scenario where the energy output observed from afar does not match the energy produced in the star's own reference frame.

PREREQUISITES
  • Understanding of general relativity and time dilation
  • Familiarity with the concept of redshift in astrophysics
  • Knowledge of supermassive black holes and their properties
  • Basic principles of mass-energy equivalence
NEXT STEPS
  • Research the effects of gravitational time dilation near black holes
  • Study the principles of redshift and its implications in astrophysics
  • Explore the characteristics of supermassive black holes and their formation
  • Investigate Kip Thorne's contributions to the physics of "Interstellar"
USEFUL FOR

Astronomers, astrophysicists, and science enthusiasts interested in the effects of relativity on celestial objects, particularly those studying the dynamics of stars near supermassive black holes.

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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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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