Black holes in a Big Bang Universe?

[MigL]

No, you're confusing speed with time. I you could see inside a spaceship moving at an appreciable fraction of c, you would see all motion inside the spaceship as well as their clocks slow down. The spaceship and anything moving along with it, is one frame, while you, stationary on the earth, are another frame.

[space noob]

No, you're confusing speed with time. I you could see inside a spaceship moving at an appreciable fraction of c, you would see all motion inside the spaceship as well as their clocks slow down. The spaceship and anything moving along with it, is one frame, while you, stationary on the earth, are another frame.

 

I thought speed, especially travelling at light speed like the matter entering the event horizon, would have a direct affect on time, ergo when you go faster the higher your mass, the higher the mass the slower time travels, but only from an afar distance away, by someone who is stationary, whilst the traveller would experience time as normal and to him the click would tick at the same rate it always has

[zapatos]

No, you're confusing speed with time. I you could see inside a spaceship moving at an appreciable fraction of c, you would see all motion inside the spaceship as well as their clocks slow down. The spaceship and anything moving along with it, is one frame, while you, stationary on the earth, are another frame.

Yes, I know I'm confusing something!

 

I would have been surprised to learn that it appeared to stop, motionless in the sky just because it seems so illogical. But I have the same problem with the craft crashing into the black hole. If velocity time dilation does not appear to make the spacecraft slow as time dilation increases, what makes gravitational time dilation different? Why does gravitational time dilation make the spacecraft appear to slow in velocity just before it hits the event horizon?

[space noob]

Yes, I know I'm confusing something!

 

I would have been surprised to learn that it appeared to stop, motionless in the sky just because it seems so illogical. But I have the same problem with the craft crashing into the black hole. If velocity time dilation does not appear to make the spacecraft slow as time dilation increases, what makes gravitational time dilation different? Why does gravitational time dilation make the spacecraft appear to slow in velocity just before it hits the event horizon?

 

http://www.thebigview.com/spacetime/spacetime.html

 

The black holes largest amount of mass centers in the event horizon, the close you get the slower time

travels

http://en.m.wikipedia.org/wiki/Time_dilation#section_3

Check the velocity time dilation

[zapatos]

http://www.thebigview.com/spacetime/spacetime.html

 

The black holes largest amount of mass centers in the event horizon, the close you get the slower time

travels

http://en.m.wikipedia.org/wiki/Time_dilation#section_3

Check the velocity time dilation

I don't think I'm making myself clear, or I missed it in your links.

 

Velocity time dilation as a spacecraft approaches c - Observer on earth sees clock in spacraft slow down, but sees spacecraft accelerating.

 

Velocity time dilation as a spacecraft approaches a black hole - Observer on earth sees clock in spacecraft slow down, and also sees spacecraft decelerating.

 

Why the two different results?

[space noob]

I don't think I'm making myself clear, or I missed it in your links.

 

Velocity time dilation as a spacecraft approaches c - Observer on earth sees clock in spacraft slow down, but sees spacecraft accelerating.

 

Velocity time dilation as a spacecraft approaches a black hole - Observer on earth sees clock in spacecraft slow down, and also sees spacecraft decelerating.

 

Why the two different results?

 

a combination of velocity and mass both slowing down time to create a dramatic decrease in the flow of time?

The way I see it, in some way moving at the speed of light close to the black hole must have some affect on time as well as the mass of the black hole

http://www.thenakedscientists.com/forum/index.php?topic=43495.0 imatfaal is on this one too

I think the relationship between velocity and gravitational time dilation is called dual dilation or something to that affect it is explained buy special relativity

 

If i'm entirely wrong just tell me straight

Edited May 17, 2012 by space noob

[MigL]

You would measure the speed of the spacecraft by measuring distance travelled per time interval. If you are using a time interval generated by the spacecraft approaching the black hole, the time intervals received by you, the far-off observer, will get progressively longer and approach infinite. Gravitational time dilation works by time shifting all signals, including light, rising out of the gravity well. Some of the other members of this board are much more knowledgeable of GR than I am; Elfmotat, AJB or the absent DrRocket come to mind.

Edited May 17, 2012 by MigL

[Spyman]

Velocity time dilation as a spacecraft approaches c - Observer on earth sees clock in spacraft slow down, but sees spacecraft accelerating.

 

Velocity time dilation as a spacecraft approaches a black hole - Observer on earth sees clock in spacecraft slow down, and also sees spacecraft decelerating.

 

Why the two different results?

As I understand it, it is because the spacecraft approaching a black hole are going through strongly warped space.

(Disclaimer: I am NOT an expert of relativity so I could be wrong, use your salt cellar as you please.)

 

If we say that we could place a long ruler across space and pin markers to the space 'fabric' for every meter, then we would see how space warps.

 

The spacecraft accelerating in flat space are passing meter markers faster and faster as the speed increases and our view of the spacecraft's progress through space agrees with the visible markers, from our distant view the markers appears to stay at a fixed distance of one meter.

 

The spacecraft accelerating towards a very compact and dense object are also passing meter markers faster when its speed increases but our view of the spacecraft's progress through space is now false, because space is warped causing the markers to get closer nearer the object.

 

Since we are not able to place true markers that shows how the space 'fabric' warps we can only from our distant view see that the spacecraft appears to slow down compared to the flat space metric we are observing in our frame of reference, but it is still passing through local space 'fabric' faster.

 

 

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According to my understanding, a black hole is defined as an object whose mass is hidden behind an event horizon. According to its definition, an event horizon represents a boundary from which it takes an infinite time for light to reach a distant observer. Thus, in the observer's frame of reference, event horizons are at an infinite distance in time.

 

 

Now, current doctrine teaches us that there are black holes in the Universe while it also teaches us that the Universe has existed for only a finite time. To me, it is obvious that these teachings contradict each other, yet I have seen them repeated over and over again also in the most prestigious publications. How can this be?

It's probably best that I add this Disclaimer once more: I am NOT an expert of relativity so I could be wrong, take it with a grain of salt.

 

AFAIK, the event horizon is not a physical object that needs to be manufactured under time restrictions, it is an inherent limit in the laws of nature that have been here as long as the Universe has. This limit determines when spacetime curvature is strong enough to prevent light from escaping.

 

The creation of an event horizon does not take place inside itself or another event horizon, it happens in 'normal' space when the conditions are right and exceeds the needed limit, as such the creation proccess takes place under reasonable time, well within the estimated age of the Universe.

 

When mass accumulates and reach the critical limit at its center, an event horizon will form instantly and then grow outward with the speed of light until it reaches its Swartzchild radius, which is determined by the amount of mass/energy it encapsulates.

 

EDIT: Separating posts a little for clarity.

Edited May 18, 2012 by Spyman

[MigL]

Maybe I wasn't clear enough in my post.

If you are looking at a spacecraft approaching an event horizon, you see it travelling progressively shorter distances according to your clock. But then you are mixing frames.

If you use a clock generated by the spacecraft, so that you are not mixing frames, then the intervals between clock pulses get progressively longer. in its own frame it is still travelling at its proper speed. The only time confusion arises is when frames are mixed.

 

As to the difference between time dilation due to gravity as opposed to speed, A spacecraft is a distinct well defined frame ( defined by the outer hull ) and its speed is measured against the background stars, which are in your ( the observer's ) frame. Gravitational time dilation doesn't have a well defined frame as it changes continuously with depth in the gravity well.

This is at the root of any observed differences.

[zapatos]

Thanks everyone. Nice answers!

[space noob]

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!"

 

So according to the book, the author would seem to believe that objects actually do end up falling into the event horizon?