Metric for an observer in free fall two schwarzchild radii from black hole.

In summary, the speaker is asking for help with finding the metric for an observer in free fall near a black hole. They are wondering if they can substitute values into the usual metric and if this counts as a radial trajectory. They apologize for posting in the wrong place.
  • #1
Sae_Phys
2
0
Hi all,

I have a GR exam on tuesday and getting a bit confused as to how to find the metric for an observer in free fall a distance two schwarzchild radii from a black hole.

I know this is a bit of a basic question but I am just wondering if I am correct to substitute r=2rs and dt=d(tau) into the usual metric and simplify. Also does this class as a radial trajectory so can you set d(theta) and d(phi) =0 ... HELP!

Thanks :)
 
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  • #2
SorryI realize I have posted this in the wrong place (new to this forum).
 

1. What is the significance of being two Schwarzschild radii from a black hole?

At two Schwarzschild radii from a black hole, the gravitational pull of the black hole is so strong that it is impossible to escape. This is known as the event horizon, and it marks the point of no return for any objects or observers.

2. How does an observer in free fall experience time at this distance from a black hole?

An observer in free fall at two Schwarzschild radii from a black hole would experience time dilation, meaning time would appear to pass much slower for them compared to an observer far away from the black hole. This is due to the intense gravitational pull of the black hole.

3. Can an observer in free fall survive at this distance from a black hole?

No, an observer in free fall at two Schwarzschild radii from a black hole would not survive. The gravitational forces would be too strong and would result in the observer being stretched and torn apart in a process known as spaghettification.

4. How does the mass of the black hole affect the observer's experience at this distance?

The mass of the black hole has a direct impact on the gravitational forces experienced by an observer at this distance. The larger the mass of the black hole, the stronger the gravitational pull and the more extreme the effects on the observer.

5. Can any objects or signals escape from two Schwarzschild radii from a black hole?

No, nothing can escape from two Schwarzschild radii from a black hole. This is because the gravitational pull is too strong for anything to overcome, including light. This is why black holes are often referred to as "invisible" objects.

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