Black holes in a Big Bang Universe?

[Rolando]

So it speeds up and slows down at the same time?

The slowing down is only observed from a distance.

[space noob]

The slowing down is only observed from a distance.

 

Please read this http://www.thebigview.com/spacetime/spacetime.html

Edited May 15, 2012 by space noob

[zapatos]

The slowing down is only observed from a distance.

So the guy falling into the black hole sees himself speeding up?

[space noob]

So the guy falling into the black hole sees himself speeding up?

 

I think maybe you two should restart or look over your conversation again because i'm sure Rowland thinks he is talking about something else and has forgotten what he said

[zapatos]

Please read this http://www.thebigview.com/spacetime/spacetime.html

From your link:

In fact, the distant observer would never see the hapless victim actually fall in. His or her time, as measured by the observer, would appear to stand still.

What would I see? Would I see an unmoving victim? Would I see him keep falling faster and faster until he suddenly stops just at the event horizon.

[space noob]

Rolando Sowi

[zapatos]

Rolando Sowi

?

 

BTW, I am the space newbie around here!

[space noob]

From your link:

 

What would I see? Would I see an unmoving victim? Would I see him keep falling faster and faster until he suddenly stops just at the event horizon.

 

I don't know -.- it sounded like he didn't understand time dilation

 

It would all happen slow to you I guess, the closer he got and the faster he got the slower he would appear to you? That just my opinion though i'm not using the link to aid my answer in this instance

I've previously started that i'm quite stupid

 

?

 

BTW, I am the space newbie around here!

I got his name wrong and said sorry but in a cutesy way, not appropriate given the place sorry

You can be a space newbie but I will always be the best space newbie

Edited May 15, 2012 by space noob

[zapatos]

I don't know -.- it sounded like he didn't understand time dilation

 

It would all happen slow to you I guess, the closer he got and the faster he got the slower he would appear to you? That just my opinion though i'm not using the link to aid my answer in this instance

I've previously started that i'm quite stupid

The problem I'm having with this is a couple of things.

 

First, if we see things basically stop before going in, shouldn't we see stars and the other things that have fed the black holes for millions of years, hanging around just outside the event horizon?

 

Second, I thought time dilation was the same whether it came from gravity of acceleration. If so, then wouldn't that mean that we would simultaneously see a space ship accelerating toward the speed of light both speed up (as it accelerates) and slow down (due to time dilation)?

 

Doesn't make sense to me. Thus my confusion.

 

I got his name wrong and said sorry but in a cutesy way

Oh, got it. Jeez, I am slow tonight.

Edited May 15, 2012 by zapatos

[space noob]

Wouldn't things shrink before entry, therefore we wouldn't see them anyway, maybe we don't have enough time in our life to observe the entry or enough visible black holes to see an object entering by chance

I'm a bit off myself tonight, long day

 

I have to ask why is it we know objects would be crushed by mass and yet we don't know if they even enter?

 

Another consideration is stretching

Edited May 15, 2012 by space noob

[zapatos]

Wouldn't things shrink before entry, therefore we wouldn't see them anyway, maybe we don't have enough time in our life to observe the entry or enough visible black holes to see an object entering by chance

I'm a bit off myself tonight, long day

 

I have to ask why is it we know objects would be crushed by mass and yet we don't know if they even enter?

 

Another consideration is stretching

I don't think it shrinks per se, I think it contracts parallel to the direction it is travelling, so theoretically we should still be able to observe it. Also, the object probably is not travelling close to the speed of light when entering the black hole so I guess that doesn't matter anyway.

Edited May 16, 2012 by zapatos

[space noob]

http://en.m.wikipedia.org/wiki/Ergosphere

ta-dah, good old reliable wiki

did I say close to light speed?

I can't be bothered re-reading everything, anyway this is from the article:

This is because the space here is being dragged at exactly the speed of light relative to the rest of space. Outside this limit space is still dragged, but at a rate less than the speed of light.

[zapatos]

http://en.m.wikipedia.org/wiki/Ergosphere

ta-dah, good old reliable wiki

did I say close to light speed?

I can't be bothered re-reading everything, anyway this is from the article:

This is because the space here is being dragged at exactly the speed of light relative to the rest of space. Outside this limit space is still dragged, but at a rate less than the speed of light.

Nope, I had assumed when you said objects might shrink before entering a black hole that you were talking about length contraction. My bad.

[space noob]

I'm so tired right now :'( by shrinking I was talking about being crushed by the black holes mass, if that's length contraction then sorry,

 

It's really strange, we know that travelling at the speed of light does not stop time but combining it with the black holes mass and the affect of it's movement, causes us to not see objects enter

 

Here's a question, the universe is 13.7 billion years old, being on the inside of our galaxy's spiral arm time travels for us faster than most places and much faster than the super massive black holes relativity at our centre, so if the black hole is at a different time speed wouldn't it be younger than everything else in the galaxy?

As in, billions of years have not passed since it's creation judging by it's relativity, in real time black holes could possibly even last a short amount of time before evaporating or not evaporating, depending on your views about black holes

Edited May 16, 2012 by space noob

[Bill Angel]

Here's a question, the universe is 13.7 billion years old, being on the inside of our galaxy's spiral arm time travels for us faster than most places and much faster than the super massive black holes relativity at our centre, so if the black hole is at a different time speed wouldn't it be younger than everything else in the galaxy?

As in, billions of years have not passed since it's creation judging by it's relativity, in real time black holes could possibly even last a short amount of time before evaporating or not evaporating, depending on your views about black holes

I think that's an interesting question. A book I'm reading, "once before time: a whole story of the universe" by martin bojowalk describes black holes as being "singularities in time" rather than in space. The author also states "The singularity appears entirely different from all other astrophysical objects, and not only because of its extremely high density. Its spacelike nature means that it forms only at the exact moment when an observer falls in!"

[imatfaal]

Zap - SpaceNewbie

 

The poor bugger falling into the BH does not notice the EH and falls inwards - we are not sure what happens within the event horizon, but as some point tidal forces will probably be high enough to rip apart to the atomic level. An observer in a stationary position (ie with a rocket ship stopping him falling into the BH) will see the faller slow down as he approaches the black hole. An outside observer will never see a faller cross the EH - he will only see the faller getting closer and closer at a slower and slower rate. The faller will continue to send out pulses of radiation saying "still here" - but over time the signal will be more and more red-shifted. As some point the signal will be so red-shifted as to be un-receivable by the watcher. What the watcher sees is the faller being spread out over the EH - as the light gets red shifted the precision drops and the faller seems to get smeared over the EH

[space noob]

This is a bit too complicated for my grasp :-\ I think I've got it sort of, so the observer would become part of the black holes disk? Would this inevitably lead to passing through the event horizon, like falling down a drain?

[imatfaal]

Spacenewbie - it all depends from whose perspective.

 

Assume that the watcher sends a continuous signal to the faller, and vice versa; and that they have high powered telescopes aimed at each other

1. Forget about accretion disks, angular momentum and orbits. They are very important in the real world - but the simplest scenario deals only with the time dilation effects of relativity.

2. From the fallers perspective, local time stays as normal, but when he looks at the watchers signal it is speeded up and the view is blue shifted. the faller does not notice the EH

3. From the watchers perspective, local time stays as normal, but when he looks at the fallers signal it is slowed down and the view is red shifted. The faller seems to be slowing down and getting spread out due to the time dilation and red-shift. The watcher will never observe the faller reach the EH - just get closer and closer, slower and slower.

[zapatos]

Spacenewbie - it all depends from whose perspective.

 

Assume that the watcher sends a continuous signal to the faller, and vice versa; and that they have high powered telescopes aimed at each other

1. Forget about accretion disks, angular momentum and orbits. They are very important in the real world - but the simplest scenario deals only with the time dilation effects of relativity.

2. From the fallers perspective, local time stays as normal, but when he looks at the watchers signal it is speeded up and the view is blue shifted. the faller does not notice the EH

3. From the watchers perspective, local time stays as normal, but when he looks at the fallers signal it is slowed down and the view is red shifted. The faller seems to be slowing down and getting spread out due to the time dilation and red-shift. The watcher will never observe the faller reach the EH - just get closer and closer, slower and slower.

So presumably the faller enters the black hole at the rate determined by free fall. If it looks like he is slowing down to us, is that because the signal is delayed getting to us? I assume he has been dead long before we see him spread out over the EH?

[imatfaal]

Zap - not it is not signal delay. The signal is EMR/light - it always travels at 3*10^8 m/s. The time of the faller is dilated compared to the watcher. It is the action of time dilation due to differences in gravitational potential - which is made completely bizare by the extreme conditions of the Black Hole. Simultaneity is completely screwed by the enormous differentials. Your "dead long before" question is almost meaningless because of this lack of simultaneity - I will see if I can dig out a nice reference, I hope physicsfaq has one.

[space noob]

Surely to the victim entering the event horizon, time would flow normal for him? The galaxy spiral arms around him would possibly move fast in his point of view looking out into the galaxy, all he would see providing he can be safe entering was himself moving faster and faster into the event horizon? Judging by the known forces and relativity

Edited May 16, 2012 by space noob

[zapatos]

Sorry if I'm bothering everyone with simple questions but I'm still having trouble with this.

 

As I observe a spacecraft with a person aboard approach a black hole, time dilation increases for that person. I took that to mean that the person would age slower than me, his clock would tick slower than mine, etc. But I did not take that to mean that his spacecraft would appear to me to decrease its velocity as it approached the black hole.

 

Does the spacecraft seem to me to decrease its velocity as it approaches the black hole?

 

If so, what is the mechanism? If the mechanism is time dilation, what physically is happening? For example, if the craft is moving at 100m/sec toward the black hole, if photons leave his craft toward my eye at all times, I should see photons when the craft is 100 meters away from the event horizon, then 50m from the event horizon, then 25, etc. The photons travel toward me at c, so there is no delay. So why does it appear to me to slow down?

[space noob]

Sorry if I'm bothering everyone with simple questions but I'm still having trouble with this.

 

As I observe a spacecraft with a person aboard approach a black hole, time dilation increases for that person. I took that to mean that the person would age slower than me, his clock would tick slower than mine, etc. But I did not take that to mean that his spacecraft would appear to me to decrease its velocity as it approached the black hole.

 

Does the spacecraft seem to me to decrease its velocity as it approaches the black hole?

 

If so, what is the mechanism? If the mechanism is time dilation, what physically is happening? For example, if the craft is moving at 100m/sec toward the black hole, if photons leave his craft toward my eye at all times, I should see photons when the craft is 100 meters away from the event horizon, then 50m from the event horizon, then 25, etc. The photons travel toward me at c, so there is no delay. So why does it appear to me to slow down?

 

just outside the black hole matter is being pulled it at just under light speed as compared to the black holes event horizon where it gets pulled i'm at light speed, when he gets closer the gravitational becomes stronger because he is travelling faster, the speed And being next to an object of super mass is what allows the time down, time is moving faster for you than it is for him from your view but his time is still normal, I think,

Also let's say this happens in the milky way, Andromeda could collide in the space of time it takes an object to fall in so what would happen in this instance? A black hole appears to have an affect on objects making them appear stationary, but the universe surrounding them continues to evolve if it takes too long for an object to fall in then things can change dramatically before that has a chance to happen

Edited May 16, 2012 by space noob

[MigL]

It is the same 'mechanism' for any gravitational time dilation. From the frame of a distant observer, clear of the gravity well, an object sinking into the gravity well experiences time dilation. Conversely an observer in a gravity well will observe a distant object's time appear to speed up. This gravitational time differential predicted by GR, verified experimentally and used in every GPS, is not encountered just in the vicinity of black holes, but also our sun and even between earth orbit and surface.

The only difference is that at a black hole's event horizon, a far observer will 'see' ( if he could see loonger and longer wavelengths approaching infinite, of light ) the infalling object time dilation approaches infinite, ie time appears to stop at the event horizon to a far observer. This is purely based on the chice of reference frame, however, since an infalling object or person, sees no slow-down in their subjective time. They see them selves continue through the event horizon with no slow down or stopping, just as we on the surface of the earth don't see a time slowdown compared to astronauts.

As has been mentioned before light always travels at c, and so light is not trapped inside the event horizon, unable to escape. Rather the infalling light ( or alternately any light emitted by the interior 'structure' of the event horizon ) is red shifted to infinitely long wavelength and so cannot be seen or detected. It is this absence of any visible emissions which give rise to the term black hole, its not really a hole in space.

Edited May 16, 2012 by MigL

[zapatos]

It is the same 'mechanism' for any gravitational time dilation. From the frame of a distant observer, clear of the gravity well, an object sinking into the gravity well experiences time dilation. Conversely an observer in a gravity well will observe a distant object's time appear to speed up. This gravitational time differential predicted by GR, verified experimentally and used in every GPS, is not encountered just in the vicinity of black holes, but also our sun and even between earth orbit and surface.

The only difference is that at a black hole's event horizon, a far observer will 'see' ( if he could see loonger and longer wavelengths approaching infinite, of light ) the infalling object time dilation approaches infinite, ie time appears to stop at the event horizon to a far observer.

Would we experience the same results if the time dilation was due to velocity?

 

For example, if a spacecraft was orbiting the earth and was accelerating toward c, would we on earth see the craft accelerate for a while, then appear to slow down as it reached a significant percentage of c? That is, would the craft seem to take 1 hour to orbit earth, then 30 minutes, then 1 minute, until as it reached a significant percentage of the speed of light where it would then appear to take 2 minutes, 30 minutes, etc., until at near the speed of light it would appear to be nearly motionless in the sky?