To the person approaching the black hole, time (unfortunately) proceeds at a normal pace. To an outside observer, time slows down until it nearly stops just as the person hits the event horizon.
The speed of light may have been broken.
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To the person approaching the black hole, time (unfortunately) proceeds at a normal pace. To an outside observer, time slows down until it nearly stops just as the person hits the event horizon.
You hurry too hard and still not established dates.Yes. The clock that is moving runs slower than the clock that is stationary. The formula for this change in speed is:
Since the bottom term grows slowly until V is near C, the effect is only pronounced near the speed of light. But with accurate enough instruments it is measurable even at slower (i.e. jet aircraft) speeds.
Let's see what is the relative speed between two objects.
To understand have to introduce another reference system, for instance the ground.
Now we have two ships with speed V1 and V2. (relative to the ground)
To eliminate the ground we must calculate the relative speed between the two ships.
What methodology you use to find the relative speed between the two ships?
In the above equation, V is the observed difference in speeds between the two ships. It is not based on comparison to the ground (or any third inertial frame.)
So you say you can not calculate just observe?
Within SR as you approach c clocks slow until at c they stop.
Within GR as you move out of a gravity well your clock speeds up. So a clock in a satellite in orbit around the earth, speeds up some by moving out of the Earth's gravity well and slows down as a result of it's velocity, an effect of SR. For the earth/satellite the SR effect is orders of magnitude greater than the GR effect. The Earth's gravity is not large enough to compare with the SR effect.
Approaching a black hole you are moving into a massive gravity well. GR says that as you approach your clock will slow until at the event horizon it stops. So a clock at an event horizon stops just as a clock moving at c would.
An observer in either situation cannot see the time dilation. They slow down just as does their clock.
P.S. The formulas for time dilation due to velocity (SR) and gravity (GR) are not the same but in the case discussed the end result is the same.
So lets assume I can see the clocks one approaching the speed of light and the other one approaching the event horizon. Both of the clocks will be running slower than the clock I am holding in my hand. My question is why does time change with two very different events? Do they have something in common that I'm just not understanding?
This could get close to one of the SR paradoxical thought experiments but...
Yes they do have something in common but it may get a little tricky trying to explain it.
In a way it is tied up in the equivalence principle, or an extrapolation of it.
The equivalence principle says that if you are in a box with no window you cannot tell whether the box is at rest on earth or under a constant acceleration of 1 g in empty space. To know which you have to look outside the box to see if you are moving.
The equivalence principal connects gravitation to inertia in that what you feel as gravity when you are accelerating is your inertial resistance to the constant change in motion due to the constant acceleration.
Moving at the speed of light your inertial resistance reaches infinity and you can go no faster.
At the event horizon, or the exact point where the escape velocity is c, any attempt to move away from the BH is met with an infinite inertial resistance just as if you were traveling at c. In fact to just sit there you would have to be accelerating at c away from the BH just to keep from falling into it.
Both situations are indistinguishable. You could not tell if you were in a box at an event horizon or in a box moving at c.
The paradoxical aspect is that some would tell you that if you were in a space ship moving at c you could not tell it. Or that if you were in a spaceship at the event horizon you could not tell that. Everything inside the spaceship would seem normal. This is a trick of time dilation that does not account for the inertial aspects of the two situations.
If you are in a ship moving at c, you could not walk from the back of the ship to the front of the ship without exceeding c. Actually you could not move from back to front because your inertial resistance to motion in that direction would already be infinite.
O.K. So you are at the event horizon again, this time you are in a stable orbit. Experience says that you would feel weightless. You would be in free fall, a point where the fictitious centrifugal force and the gravitational pull of the BH balance one another. But this does not quite work either, because any attempt to even raise a hand is a motion away from the BH and there is already an infinite inertial resistance to any motion away from the BH. (beside the orbital velocity at the event horizon is likely close to if not at the speed of light and that alone would result in an infinite inertial resistance to any further motion in that direction, as in the previous example.)
It really is a good thing that time stops in both cases because that way if you are the observer you never have to know you are trapped.
I hate these things... They get too convoluted and full of well what if this or what if thats.
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All I can say to that is you are the first person even to try an explanation for the effect of those two things on time, and I actually understood what you said. But light itself does not experience inertial resistance does it? It has no mass and always travels at c in a vacuum. There is never any acceleration involved. So would a clock made out of photons act differently?
This thread has gotten very off topic of the original issue ...... and I did say I hate these things, did I not? Thought experiments involving time and space and light.... That said...
KilljoyKlown said:
Or does it?
Conventional wisdom says no. But conventional wisdom also says light is affected by gravity. Both by the curvature of space and in a redshift associated with light moving out of a gravity well. So if light is not immune to gravity and gravity is in some way associated with inertia, how can light not also be affected by inertia or some inertia like relationship with gravity. And where in the case of GR gravity is essentially an aspect of space.... It cannot end there but maybe that is enough of an answer...?
At least for a start...
As seen from your frame - yes.
Well, in the case of the moving spacecraft you're seeing time dilation due to relative motion. In that case you are considering two inertial frames, one moving faster than the other.
In the second case you are considering two frames - one inertial and one accelerating, and the difference in time is due to that difference. (Gravity is equivalent to an accelerating frame; same effect.) So two effects, same end result.
True. However that case isn't possible, since you can't move at C. You can, however, get very, very close to the speed of light. At that point time dilation would have slowed you down so immensely that you would take years to move an inch - and thus you would not violate the speed of light.
Agreed. However, there is a practical reason this cannot work. At those incredible gravity levels, the level at which you are in a truly stable orbit is nanometers across. If you are below that level you feel hundreds of G's pulling you down since you are closer to the gravity well of the black hole. If you are above that level you will feel hundreds of gravities in the other direction, since your motion is trying to pull you away from the black hole (and gravity is insufficient to cancel it out.) Thus you'd very quickly be torn into little pieces.
Just above the event horizon time dilation would again slow you down immensely, to the point that you were moving so slowly that you would not feel any difference. At the horizon itself you would again not notice any difference (if you could avoid being torn to bits by the tidal forces, of course) - your passage of time would seem to stop to an outside observer, but you would continue seeing time pass normally.
See I said I hated these for this exact reason. They lead into the paradox discussions with variables that have nothing to do with the question to be answered.
It was a hypothetical. And yes when you start trying to fit a hypothetical to the the exact nature of current theory, it becomes more and more complicated and untimely can be argued from many different models.
The question was, "... Why does time change with two very different events? Do thye have something in common...?"
All the hypothetical needs is sufficient information to address the question. I did that. More information than required almost always leads into these discussions of imagining what would or could happen and there are many different ideas on that...
I help you.
The speed is calculated by vector addition.
Now we have the relative speed between the two objects (and a component perpendicular to the velocity) and we can remove the ground.
You agree?
To see that you understand, a question:What is the relative velocity between an observer and a train (speed V), when it passes in front of the observer?
(direction between the observer and train is perpendicular to the vector speed of the train)
Or have you surrendered?
In Newtonian mechanics, that works. In frames moving quickly it does not, since velocity is distance over time, and time is no longer invariant in relative frames. Thus an observer on the ground, trying to calculate the differential speed of two objects, will see a different result if an observer on one of the objects tries to do the same thing.
However, for all intents and purposes, Newtonian mechanics works in our everyday life.
Motor Daddy
Valued Senior Member
Of course not, because no observer agrees with any other observer in SR. Everyone in SR will say they are at rest and it's really the other guy that's in motion. So everyone is at rest in SR and nothing is in motion. Just ask them, they'll tell you.
Barney: Hey Fred, Are you in motion?
Fred: No Barney, are you in motion?
Barney: No I'm not in motion.
Fred: Barney, you must be in motion because I am at rest and the distance between us is increasing.
Barney: No Fred, it's you that's really in motion, because I am at rest.
Wilma: You are both in motion, it's really me that's at rest.
Dino: rrrrr, rrrrr, I'm at rest and all of you are in motion.
Pebbles: I am at rest and you are all in motion.
Bam Bam: What I say goes, Bam, Bam, I am at rest, and all of you are in motion.
Just ask 'em, they'll tell ya, everyone is at rest.
The above is also true in Galilean relativity, dimwit.
Motor Daddy
Valued Senior Member
So, you aren't only denying special relativity, you are also denying Galilean relativity?
Motor Daddy
Valued Senior Member
Correct.
Motor Daddy
Valued Senior Member
I am trying to tell you what absolute motion is, and what the preferred frame is. You seem to have trouble listening. Why is that? Is it because you have previously held beliefs that you refuse to let go of? Sounds more like a religion.