Is black hole existence relative to the reference system?

In summary, it is possible for a black hole to exist in a reference frame and not exist in another. However, one needs to distinguish between the horizon and the singularity.
  • #1
mihaiv
6
0
Is it possible for a black hole to exist in a reference frame and not exist in another?
I did some naive calculations and the result was that what are neutron stars in relation to Earth could be black holes in relation to a proton accelerated near the speed of light at LHC. That is because, relative to the proton the neutron star moves with near the speed of light, and its mass is much bigger than the rest mass. Also, there is some length contraction...
 
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  • #2
mihaiv said:
Is it possible for a black hole to exist in a reference frame and not exist in another?

No, it can't happen.
 
  • #3
Is it possible for an object to pass through the event horizon in one reference frame but not in another?
 
  • #4
Is it possible for an object to pass through the event horizon in one reference frame but not in another?

The general answer is "yes". But one needs to distinguish between the horizon and the singularity.

A stationary observer just outside a black hole horizon will be fried from thermal radiation emanting from the horizon; a free falling observer will never even detect a horizon...and will not observer that thermal radiation...
 
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  • #5
mihaiv said:
Is it possible for a black hole to exist in a reference frame and not exist in another?
I did some naive calculations and the result was that what are neutron stars in relation to Earth could be black holes in relation to a proton accelerated near the speed of light at LHC. That is because, relative to the proton the neutron star moves with near the speed of light, and its mass is much bigger than the rest mass. Also, there is some length contraction...


One man's black hole is another man's universe.
 
  • #6
mihaiv said:
Is it possible for a black hole to exist in a reference frame and not exist in another?

starthaus said:
No, it can't happen.

skeptic2 said:
Is it possible for an object to pass through the event horizon in one reference frame but not in another?

Naty1 said:
The general answer is "yes".

Granted the existence of a black hole and the passing of an object through the event horizon are not equivalent but nevertheless closely related. The dependence of one on the reference frame but not the other appears to be a contradiction. Would either of you care to clarify your answer?
 
  • #7
skeptic2 said:
Granted the existence of a black hole and the passing of an object through the event horizon are not equivalent but nevertheless closely related. The dependence of one on the reference frame but not the other appears to be a contradiction. Would either of you care to clarify your answer?

Sure, the easy way to prove this is by checking its properties. They are all frame-invariant. So, a black hole cannot be "black" in one frame and "pink" in another :-)
 
  • #8
starthaus said:
Sure, the easy way to prove this is by checking its properties. They are all frame-invariant. So, a black hole cannot be "black" in one frame and "pink" in another :-)

To a person in the black hole, they aren't in a black hole. They are just in the universe. However, in the time it takes them to blink an eye, billions of years go by in our frame. So that every star in our universe is dead within the first few seconds of the black holes existence from its perspective. by the time a few billion of black hole years have gone by, space will have expanded sufficiently such that the energy density is the same for the black hole as it is for us now and our universe will be a thin veneer trillions of years old.
 
  • #9
I edited my original post to distinguish between a black hole (singularity) and the horizon of a black hole. The original post is ambiguous because the singularity and the horizon are quite different...the former a physical entity, the latter a mathematical hypothesis...with some apparent physical properties.

In fact there are several types of black hole horizons..
One discussion of horizons is here:
http://en.wikipedia.org/wiki/Event_horizon#Interacting_with_an_event_horizon

In general, a stationary observer just outside an even horizon (say, hanging on a rope or accelerating in a spaceship) will observe a hot thermal bath...and be promptly fried to smithereens...the closer one gets the more energy is required approaching infinity...time slows to a stop at the horizon as viewed by a distant observer..

and yet a free falling (non accelerating in GR) observer passes the same horizon without incident, without being able to detect it...and passes on to the singularity as he/she it ripped apart by tidal forces...so its "relative" like space and time...to the observer...analogous to the cosmological horizon or Unruh type...

A great non mathematical book is Kip Thorne's BLACK HOLES AND TIME WARPS which I am starting the reread today...Leonard Susskind's THE BLACK HOLE WAR (between him and Stephen Hawking) is also very good perhaps more unique reflecting Susskind's views...
 

1. What is a black hole?

A black hole is a region in space where the gravitational pull is so strong that nothing, including light, can escape it. This occurs when a massive star collapses in on itself and becomes incredibly dense.

2. How does the existence of a black hole relate to the reference system?

The existence of a black hole is relative to the reference system because it is dependent on the observer's frame of reference. This means that the properties of a black hole, such as its size and gravitational pull, can appear different to different observers depending on their position and velocity.

3. How does the reference system affect the perception of a black hole's event horizon?

The reference system can affect the perception of a black hole's event horizon, which is the point of no return where the gravitational pull becomes too strong for anything to escape. For example, an observer moving towards a black hole will perceive the event horizon as closer than an observer who is stationary relative to the black hole.

4. Can the reference system affect the shape of a black hole?

Yes, the reference system can affect the perceived shape of a black hole. This is because the shape of a black hole is determined by its event horizon, and the event horizon can appear differently to different observers depending on their reference system.

5. How does the reference system impact the study and understanding of black holes?

The reference system is crucial in the study and understanding of black holes as it can affect the measurements and observations of these objects. It is important for scientists to take into account the reference system when studying black holes in order to accurately interpret their properties and behavior.

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