Light Taking U-Turn: Transformation of Star to Black Hole

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In summary, light traveling away from a mega sized star at the time of its transformation into a black hole will trace its path back after a U-turn.
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shivakumar
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sir , i always taught what would happen to light traveling away from the mega sized star at the time of transformation of this star into a black hole? will it trace back its path after it taking a u - turn?
 
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The event horizon forms within the star as it undergoes the final stages of collapse, and expands out to its final size. Light that is outside the horizon escapes. Light that is at the horizon can, in theory, remain there forever. Light inside the horizon ends up in the singularity, but this does not involve a u-turn. The singularity inside a black hole is more like a moment in time than a place in space, and there isn't really an "inwards" and "outwards" direction - the topology of the space inside the black hole is not the same as it was before the black hole formed.

Black holes spacetimes can be surprisingly complicated even for fairly simple idealised situations.
 
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shivakumar said:
sir
Did you just assume our genders?
 
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I meant respect to more learned person, madam
 
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shivakumar said:
sir , i always taught what would happen to light traveling away from the mega sized star at the time of transformation of this star into a black hole? will it trace back its path after it taking a u - turn?
I don’t think that there is any need to restrict yourself to the time of collapse. For a formed black hole light is trapped at the horizon, it orbits at the photon sphere, and it is deflected at larger distances. So a U turn is just a large deflection, but less than an orbit. That means that at some distance above the photon sphere you should be able to make a null U turn for a stable black hole
 
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Dale said:
So a U turn is just a large deflection, but less than an orbit.
I think we may need to ask @shivakumar for clarification of what "U turn" means in this context. You seem to be imagining light falling from infinity and doing a half orbit. I was imagining light coming up from the star, turning back and falling on to the star/black hole again. Your scenario is possible, mine isn't (hence my longer explanation).
 
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Ibix said:
You seem to be imagining light falling from infinity and doing a half orbit. I was imagining light coming up from the star, turning back and falling on to the star/black hole again. Your scenario is possible, mine isn't (hence my longer explanation).
Good point. Yes, that is what I was considering.
 
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malawi_glenn said:
Did you just assume our genders?
Please not also on PF...:rolleyes:
 
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FAQ: Light Taking U-Turn: Transformation of Star to Black Hole

1. What is a "Light Taking U-Turn" in the context of a star transforming into a black hole?

A "Light Taking U-Turn" refers to the phenomenon where light emitted from a star is bent back towards the star due to the intense gravitational pull of the star as it collapses into a black hole. This can be observed as a sudden increase in brightness before the star disappears from view.

2. How does a star transform into a black hole?

A star transforms into a black hole when it runs out of fuel and can no longer sustain the nuclear fusion reactions that keep it stable. Without this outward pressure, the star collapses under its own gravity, becoming denser and denser until it reaches a point of infinite density known as the singularity, which is surrounded by the event horizon - the point of no return for anything, including light.

3. Can we observe the transformation of a star into a black hole?

Yes, we can observe the transformation of a star into a black hole through various methods, such as detecting gravitational waves, observing changes in the star's brightness and spectrum, and studying the effects of the star's intense gravitational pull on its surroundings.

4. How long does it take for a star to transform into a black hole?

The time it takes for a star to transform into a black hole depends on the size and mass of the star. Generally, more massive stars will collapse faster, while smaller stars may take longer. This process can take anywhere from a few milliseconds to millions of years.

5. What happens to the light that gets trapped within a black hole?

Light that gets trapped within a black hole cannot escape, as it is unable to travel faster than the speed of light. This is why we cannot observe anything beyond the event horizon of a black hole. The light is essentially stuck inside the black hole, adding to its mass and energy.

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