The Paradoxical Nature of Black Holes

[Slinkey]

Well, most people at least expect the singularity inside the black hole to be eliminated.

 

I wasn't aware of that but I guess that would be the expectation. It is an infinity

 

Maybe the BH is denied by graviton resistence. Watch this space (no pun intended).

[antimatter]

The object becomes frozen right outside the event horizon because light can't 'refresh' the image. You already knows what happens to the object...

I'm not sure if red shift has anything to do with it, but it's mostly because of gravitational lensing

[iNow]

The object becomes frozen right outside the event horizon because light can't 'refresh' the image.

 

I think you alluded to this somewhat, but just to make it explicitly clear... The object only appears to freeze relative to an outside observer. The object itself carries along right into the blackhole and everything seems pretty normal from it's perspective.

 

So... Person looking at the object from outside: Object looks frozen (infinite redshift).

 

Object falling into blackhole: Doesn't notice the difference, and falls into it's coming death from tidal forces without noticing anything that much different. From it's perspective, it's not frozen at all, but still moving.

[antimatter]

You're right, I meant that in the eye of the beholder he stays frozen.

I still don't really understand how redshift applies to this

I understand what redshift is, it's just...well, you know.

[iNow]

You're right, I meant that in the eye of the beholder he stays frozen.

I still don't really understand how redshift applies to this

I understand what redshift is, it's just...well, you know.

 

Let's say a spaceship approaches a massive blackhole. There are two astronauts aboard, and they each set their clocks to be exactly synchronized with one another. One of the astronauts puts on his space gear and exits the spaceship. He puts a light beacon on his pack which flashes a light for each second which passes on his watch.

 

One second on the watch passes, the light flashes once. Another second on the watch passes, the light flashes again...

 

 

The traveller who exited the spacecraft goes toward the blackhole, and his companion remains in the spaceship recording the flashes from the beacon on the other astronaut's pack. He sees the same thing... one second on his watch, one flash of the light... since the watches are synchronized.

 

As the traveller outside the spacecraft gets closer to the blackhole, the flashes from his pack still go out one every second.

 

But, then, he crosses the event horizon, and while the traveller in space sees no change (he sees his light flash once for every second on his watch which passes), his friend on the spaceship notices something strange.

 

The guy on the spaceship now sees the light flash every 1.3 seconds (I just made this number up for the story... the point is, it now takes longer than one second on the spaceships watch for the light to flash).

 

As the traveller continues farther into the blackhole, the spaceship sees his flashing pack going even slower... it now only flashes every 3 seconds... then every 10 seconds.... then only once a minute... then only once an hour... and so on...

 

The information from the traveller off the ship is being redshifted.

 

However, the traveller who is actually falling into the hole doesn't notice anything different. As far as he's concerned, his light is flashed perfectly once every second... as measured on his watch.

 

But, to the guy on the spacehip, the light takes longer and longer between each flash as his buddy falls farther and farther into the blackhole.

 

Then... sooner or later, the guy on the spaceship doesn't see the light flashing anymore. His last measurement of a flash was 30 years ago according to ship time. The guy on the spaceship dies, and the universe progesses along and millenia pass... and that light on the travellers pack is so redshifted that it's frozen... it no longer flashes.

 

 

But to the traveller, it flashes right on time... once per second.

 

It's just that the light from his pack never escapes the event horizon, and the farther down the blackhole he falls, the more redshifted the flashes are (the time between the flashes grows relative to an outside observer)... Until the information (the flashes of light) is so redshifted that it's a flat line (remember, red is a longer wavelength than blue) and those outside of the hole see it as perfectly frozen.

 

 

 

The above is my attempt to repeat a story in Kip Thorne's book "Blackholes and Timewarps: Einstein's Outrageous Legacy." I apologize in advance if I screwed any of it up or left out any key parts. It's just that when I hear questions such as yours above, I immediately remember that book, and all that it taught me.

[antimatter]

Oh thank you!

I understand now, that was very very helpful.

So the time between the flashes gets redshifted until it just stops, but to the traveller (who'd most likely be dead, right?) it stays the same throughout?

[iNow]

That seems correct, yes.

 

Remember, though, I'm no expert, just an interested reader.

 

This site has some greatly useful images, animations, and links which you may find useful:

http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html

[antimatter]

Ah thanks, but I have one more question.

Would the traveller also stay there, frozen on the event horizon too, or just the flashing light?

[iNow]

Ah thanks, but I have one more question.

Would the traveller also stay there, frozen on the event horizon too, or just the flashing light?

 

Okay, now I think you're missing the point again.

 

The traveller only stays there (flashing light and all) according to those outside the blackhole.

 

According to the traveller, nothing has changed, and he keeps on moving just as if he were walking to the store on a sunny day.

[Mr Skeptic]

Just remember that it is near the event horizon that time nearly stops. If you actually go through the event horizon, nobody on the outside is going to see you, and also all bets are off (or theoretical).

[antimatter]

Right, I understand that.

I asked my science teacher about it today and he said it's not as much redshift, as it's a sort of loop in time. As soon as the observer leaves the image disappears.

[iNow]

Just remember that it is near the event horizon that time nearly stops. If you actually go through the event horizon, nobody on the outside is going to see you, and also all bets are off (or theoretical).

 

 

Thank you. You are correct and I mistated... The same idea applies, but the redshift happens on approach to the event horizon, and once past it, that's when the traveller appears to freeze (relative to an outside observer).

 

 

Apparently, blackhole cosmology and dirty martinis don't mix too well.

[antimatter]

I'm not entirely sure what you mean, if you go through the event horizon won't your image still stay there, but frozen in time?

[iNow]

I'm not entirely sure what you mean, if you go through the event horizon won't your image still stay there, but frozen in time?

 

Relative to whom?

[antimatter]

To an observer

[iNow]

To an observer

 

Based on the previous posts in this thread, what do YOU think, and why?

[antimatter]

I think that your image will stay there, but as long as the observer is there to see it.

It's just sort of a fold in time that causes that loop to freeze the person's image there.

Am I correct?

[Riogho]

It's like the Lorentz contraction doesn't actually make the volume of something contract when it is moving, it just APPEARS that way to an outside observer, because the object is in motion (or in a gravitational field) space-time is curved, therefore the objects you are using to measure (clocks, rules) are 'curved' (inaccurate) proportional to the space-time curvature.

[Slinkey]

It's like the Lorentz contraction doesn't actually make the volume of something contract when it is moving, it just APPEARS that way to an outside observer, because the object is in motion (or in a gravitational field) space-time is curved, therefore the objects you are using to measure (clocks, rules) are 'curved' (inaccurate) proportional to the space-time curvature.

 

Hmm, not sure Feynman and Michelson and Morley would agree with you there. If there is no contraction then we wouldn't get the null result from their experiment. Unless I am misunderstanding what he says in vol.1 chap. 15 of "The Feynman Lectures on Physics".

 

If any object hits the event horizon of a black hole , on a relativisyic basis its mass becomes infinite ( at c ) hence the energy release becomes infinite . Infinity is infinity so how come the universe is stll here ?

 

The set of all positive integers (P) is an infinitely long set. Agreed?

 

The set P can be sub-divided into the subsets:

1. the set of all positive even (Pe) integers. An infinitely long set.

2. the set of all positive odd (Po) integers. An infinitely long set.

 

All three sets are infintely long. Agreed?

 

Yet, the subsets must clearly be less than the the main set because

 

Pe + Po = P

 

Infinity isn't always infinity

[Slinkey]

It's like the Lorentz contraction doesn't actually make the volume of something contract when it is moving, it just APPEARS that way to an outside observer, because the object is in motion (or in a gravitational field) space-time is curved, therefore the objects you are using to measure (clocks, rules) are 'curved' (inaccurate) proportional to the space-time curvature.

 

Yes, the rule is shorter, but for the person in the curved spacetime (with the short rule) so are the distances he measures and he sees no change. As I say in another thread elsewhere on this forum - the speed of light is constant for all observers regardless of velocity. Relativity describes the universe with this single fact in mind and as a consequence it demands that the laws of mechanics must change. That is, when an object is moving relative to us it must be contracted in the direction of its movement.

[antimatter]

Yes, the rule is shorter, but for the person in the curved spacetime (with the short rule) so are the distances he measures and he sees no change. As I say in another thread elsewhere on this forum - the speed of light is constant for all observers regardless of velocity. Relativity describes the universe with this single fact in mind and as a consequence it demands that the laws of mechanics must change. That is, when an object is moving relative to us it must be contracted in the direction of its movement.

 

And the only person noticing VISUALLY the contraction is the observer

[Riogho]

Yes, the rule is shorter, but for the person in the curved spacetime (with the short rule) so are the distances he measures and he sees no change. As I say in another thread elsewhere on this forum - the speed of light is constant for all observers regardless of velocity. Relativity describes the universe with this single fact in mind and as a consequence it demands that the laws of mechanics must change. That is, when an object is moving relative to us it must be contracted in the direction of its movement.

 

Except that in it's own reference frame, it isn't contracted at all.

[Slinkey]

Except that in it's own reference frame, it isn't contracted at all.

 

Indeed. Hence the statement "for the person in the curved spacetime (with the short rule) so are the distances he measures and he sees no change."

[Zephir]

...therefore BHs can only evaporate and never gain mass...

Never say never...;-) You way of thinking is quite correct, but the large black holes can appear by gradual merging of smaller ones. Only tiny particles can evaporate (nearly) completelly during such merging (the lightest ones, like the neutrinos can still escape). But the true is, the probability of such merging is the lower, the more the Universe has expanded. Therefore we are facing the conceptual problem of the formation of the giant black holes at the centers of gallaxies by accretion, because the matter should evaporate even before reaching of event horizon into accretion radiation. The AWT is facing this problem by assumption, the matter of such gallaxies has evaporated from central white holes (so called the quasars) instead, but many other possible scenarios are possible here, too.

 

BTW The idea of yours isn't very new one, I explained it before years and it was even presented in mainstream press by Tanmay Vachaspati. Technically, whole the classical model of black holes, as follows from steady state Schwarzschild's solution is misleading, because the collapse of such BH into central singularity would require more time, then the Universe life time allows. Most probable solution is, every BH is containing many daughter singularities of different level of nested hiearchy, which will appear as a daughter black holes or Universe generations from internal perspective of such BH or like the nested foam from outer perspective.

[King, North TX]

Please forgive the intrusion, no derail intended, but I was hoping that someone could answer a question...

 

"What happens when two black holes meet...mathematically speaking?

Edited April 30, 2010 by King, North TX