What happens when you enter a black hole

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Discussion Overview

The discussion revolves around the theoretical implications of entering a black hole, particularly in the context of relativistic travel and perception of mass. Participants explore various hypotheses about the nature of black holes, the effects of relativistic speeds, and the experiences of a traveler approaching and entering a black hole.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants propose that a traveler moving at relativistic speeds could be perceived as a black hole by an observer on Earth, while the traveler would see Earth as a black hole.
  • Others argue that this perception is flawed, stating that a black hole's existence is not relative and that one cannot be perceived as a black hole if they are not one in their own reference frame.
  • A participant suggests that if a traveler were to enter a black hole, they might not see a black hole behind them due to relativistic effects, implying a potential for exiting through the other side.
  • Another participant mentions the concept of Hawking radiation and its implications for someone approaching a black hole, discussing the paradox of radiation encountered by a falling observer.
  • Some participants challenge the idea that relativistic mass could lead to the formation of a black hole, emphasizing that rest mass is what contributes to gravitational fields.
  • A later reply questions the validity of earlier claims, suggesting that the gravitational effects and perceptions of mass are more complex than initially presented.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of black holes and the implications of relativistic travel. There is no consensus on the validity of the claims about perception and the experience of entering a black hole.

Contextual Notes

Limitations include the dependence on relativistic effects and the definitions of mass and black holes, which remain unresolved in the discussion.

  • #31
If the mass is the relativistic mass in dependent of the observer then for the moving observer he can continue to accelerate past c.
He can continue to accelerate. Of course, as he can always claim to be "at rest", so what should stop him? But his velocity relative to someone else will never be greater than c.
Although the one regarding my flawed interpretation of g equation in GR needs addressing.
I don't think it makes sense for you to delve into GR before getting the basics of SR.
 
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  • #32
While I was in the shower I was thinking. A stationary observer (A) see a moving observer (B) increase in mass by m = gamma*rest mass. the moving observer disagrees, he (B) says he is stationary and A is moving. So each observer sees a mass increase, they just disagree who ate all the pies. In this interpreation the mass increase in relative and still mean a velocities must be less than c.

Also given stevebd1 GR equation, would a volume of gas in a closed box at the temperature T1 and pressure P1 see an increase in the gravitational field it creates when the pressure and temperature are increased to T2 and P2? I would say not as the temperature and pressure are directly related to the K.E of each particle. As already discussed increases in K.E do not increase it gravitational field strength. Is this right? Am I getting there, where ever there is?
 
  • #33
bm0p700f said:
As already discussed increases in K.E do not increase it gravitational field strength. Is this right? Am I getting there, where ever there is?

KE confined in a frame would contribute to the gravity of an object. For example, for a rapidly rotating neutron star, pressure and rotational kinetic energy (K_{rot}=\frac{1}{2}I \omega^2) would contribute, both have a place in the stress energy tensor, but if the KE is not confined (such as in an object moving in one direction) then it's contribution is negligable. As stated in the wiki talk section, there may be some kind of effect where the gravity field becomes uneven, maybe there's an increase in the field to the front and a decrease at the back (the integral of which shows no increase in g as a whole). Based on the gravity field being uneven, you can also consider the zeroth law of black hole thermodynamics that for a black hole to exist, the surface gravity (κ) must be constant over the black holes event horizon.
 
  • #34
GoodPR said:
ZikZak the statements your making assume that you know what happens when you flash a light while your in a black hole, I find that hard to believe.

For any useful definition of the word "know," I absolutely do know what happens when I flash a light inside a black hole. The answer is given to me by the theory of General Relativity, the most well-supported theory in all of science.

Just because you see the light leaving your frame how can you say that another frame would see the same thing. You can't your just making predictions because you don't like this idea in general because it goes against your high school physics lessons. There is no math anywhere that states if you shine a light in your frame that it is visible in any other frame. Your just assuming that.

You misunderstand the role of math in science. There is nothing magical about math that makes things true. And in any case, there is certainly "math" that shows that no light flash in a black hole ever gets out. There is certainly "math" that shows that you do not become a black hole at high speeds. The "math" is called the Einstein Field Equations.

This is, of course, because the makers of General Relativity DID make an assumption. It's the radical, closed-minded assumption that there is an external reality on which all observers agree. In fact, ALL those crazy, closed-minded scientists seem to assume this. What the hell is up with that?? But the result of the assumption of external reality is: that if the photon gets out of the black hole, then it gets out of the black hole. It makes no difference what reference frame you are in.
 
  • #35
ZikZak said:
But the result of the assumption of external reality is: that if the photon gets out of the black hole, then it gets out of the black hole. It makes no difference what reference frame you are in.

Different ACCELERATED frames do not agree on the number of real (non-virtual) particles.
Virtual particle in one frame can become a real one in another accelerated frame and vs
AFAIK the Hawking radiation is based on that fact.
 
  • #36
bm0p700f said:
So for a moving observer there is a density increase. Density and the gravitational field strength that results are linked. So a black hole could form in that respect.
A http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_fast.html" . GoodPR has yet to provide any evidence, logic, or math in support of his position, instead relying entirely on stubborn determination to ignore and misunderstand everything anyone else says. It is simply wrong, it has been refuted by reputable sources, by theoretical considerations, and by experimental observation (high energy cosmic rays do not form black holes).
 
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  • #37
I just want to add to post #33 the following extracted from wiki talk-

'The only time kinetic energy shows up as increased gravitational field is when it's the kinetic energy in a SYSTEM where the sum of momenta is zero. Otherwise, kinetic energy shows up.. ..as increased momentum, but not as gravity.'

which I think shed more light on the subject of KE as gravity or momentum.

While it's already been proved that objects at high speed increase in mass/energy (as in the LHC, the sum mass of the particles produced is approx. equal to the KE + rest mass of the particles collided), it would be interesting to know how the gravitational field of these objects is affected at high speed.
 
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  • #38
 
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  • #39
Different ACCELERATED frames do not agree on the number of real (non-virtual) particles. Virtual particle in one frame can become a real one in another accelerated frame and vs AFAIK the Hawking radiation is based on that fact.

Virtual particles are not observeable to a stationary observer. A free falling observer will pass the horizon of a black hole as virtual particles invisibly flash in and out of momentary existence harmlessly around him; a stationary observer outside the black hole horizon will be fried by those former virtual particles that now appear as REAL particles exhibiting thermal energy.
 
  • #40
When you enter a black hole, you get ripped apart by the shear force of the gravitational field. Also, black holes could be considered not part of the rest of the universe because space-time is altered so much that time literary stops theoretically.

Here is an interesting point. Let's say you are just outside the black hole, before the event horizon so you don't get pulled in and you throw a rock into the black hole. What you will see is the rock heading towards the black hole then eventually slow down and come to a stop. You will see the rock just "floating" in the black hole. Because space-time is skewed so much, you will see the rock frozen in time while the rock is actually ripping apart in the black hole. Good old theory of relativity.
 
  • #41
dream431ca said:
When you enter a black hole, you get ripped apart by the shear force of the gravitational field. Also, black holes could be considered not part of the rest of the universe because space-time is altered so much that time literary stops theoretically.

What a nice collection of misconseptions about black holes!
Tidal forces are not infinite at the horizon. For very heavy black holes these forces can be quite small so humans can survive
Also, GR insists that BH *is* a part of our space time (and for that very re4ason it can calculate what is inside)
"times stops" is WRONG. I recommend checking space time diagrams to really understand what is inside.
 
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