Does Consciousness Create Time in a Timeless Space?

[PeterDonis]

How is it a moment in time but not a place?

This is really not a "B" level question (the "B" level response is what I already said), but I'll give a short answer here, and if you want more, please start a new thread.

The more technical way of saying "moment of time" in GR is "spacelike surface" (where "surface" can be a 1-dimensional, 2-dimensional, or 3-dimensional set of points, and "spacelike" means any two points in the set are spacelike separated from each other). The more technical way of saying "place" in GR is "timelike curve"--i.e., you have to be able to imagine some observer sitting at rest in the "place" in question, and the timelike curve describing the "place" is that observer's worldline.

The set of points with $r = 0$ in the Schwarzschild geometry is a spacelike line. So, using the above translation manual, it is a "moment of time", and not a "place".

 

[PeterDonis]

I do not recall the red shift situation for an observer who has freely fallen from infinity as he gazes back at the outside stars

The light he sees coming into him from the stars is more and more redshifted as he falls; the redshift factor is 2 at the horizon and increases without bound as the singularity is approached.

 

[BL4CKB0X97]

This is really not a "B" level question (the "B" level response is what I already said), but I'll give a short answer here, and if you want more, please start a new thread

I had no idea what the letters meant. What should I post it under. I have no aversion to complex mathematics, it will just give me something to work out. I learn better when given a sheet of maths I don't understand and need to find out what it means. I enjoy it.

Also, does anyone know of some reading material that I should read(related to this thread) GR and Schwarzschild is being mentioned but I leave that to the guys who have had an advanced education. i assume you'll know the best stuff to read.

 

[BL4CKB0X97]

Also, I found this in Roger Penrose's book The Road To Reality.

I apologise for the orientation. It replicates some of what you are all saying. But it poses another question, I assumed black holes where spherical,is this not the case or is it just to make it easier to understand?
http://imgur.com/RYzbg4c

 

[timmdeeg]

If quantum gravity effects are only significant near $r = 0$ (i.e., for values of $r$ much less than $2M$), then the center cannot be a place, because curves of constant $r$ inside the horizon are spacelike, not timelike, and only a timelike curve can describe a "place".

Thanks, good to know. So timelike and lightlike worldlines with decreasing $r$ are not sufficient to describe a "place". For this - if I understand it correctly now - any two points within a spacetime patch have to be separated timelike. Kindly correct if wrong.

Personal speculations are off topic here.

I am sorry, I should have remembered this.

 

[Nugatory]

I assumed black holes where spherical,is this not the case or is it just to make it easier to understand?

They are spherical (as long as they aren't rotating). That picture is a space-time diagram, a graph in which time is increasing towards the top of the page. Slice the shape from side to side and you'll get a cross section of the black hole at a particular moment in time. That cross section will be a circle, which is what you'd expect from a cross-section of a sphere. So the diagram shows the collapsing matter shrinking down to a point over time while the event horizon starts as a point and rapidly expands to its final size.

(Actually the idea of a "cross section" of a black hole is very problematic, but we can get it away with it if all we're doing is showing how that diagram shows a spherical black hole forming and expanding to its final size).

 

[BL4CKB0X97]

They are spherical (as long as they aren't rotating). That picture is a space-time diagram, a graph in which time is increasing towards the top of the page. Slice the shape from side to side and you'll get a cross section of the black hole at a particular moment in time. That cross section will be a circle, which is what you'd expect from a cross-section of a sphere. So the diagram shows the collapsing matter shrinking down to a point over time while the event horizon starts as a point and rapidly expands to its final size.

(Actually the idea of a "cross section" of a black hole is very problematic, but we can get it away with it if all we're doing is showing how that diagram shows a spherical black hole forming and expanding to its final size).

Thanks!

 

[PeterDonis]

I had no idea what the letters meant.

See here:

https://www.physicsforums.com/help/threadprefixes/

 

[PeterDonis]

does anyone know of some reading material that I should read(related to this thread) GR and Schwarzschild

I would recommend Sean Carroll's online lecture notes for a start:

https://arxiv.org/abs/gr-qc/9712019

 

[SlowThinker]

I would recommend Sean Carroll's online lecture notes for a start:

https://arxiv.org/abs/gr-qc/9712019

Good luck with that, Blackbox. I tried reading it.
First I got pretty confused with eq. 1.10 where he simply says

One simple variety are the translations, which merely shift the coordinates:
$$x^{\mu}\mapsto x^{\mu'}$$
(Notice that we put the prime on the index, not on the x.)

which does not make any sense at all.
Then I hit the wall at the introduction of cotangent bundle and dual spaces, on page 10 out of 231.
That was the point where I realized I need a better book, but haven't found one yet.

 

[PeterDonis]

I got pretty confused with eq. 1.10

Don't get bogged down in the notation. You could just as easily write $(x, y, z, t) \rightarrow (x', y', z', t')$; that's basically what Carroll means when he says he's putting the prime on the index.

Then I hit the wall at the introduction of cotangent bundle and dual spaces, on page 10 out of 231.

You can actually skim through a lot of the manifold and tensor stuff in chapter 1, just bear in mind that it's there for reference in case you need it while you read later chapters. But you can't expect to get very far in GR without using these tools, so time spent learning them will not be wasted.

That was the point where I realized I need a better book, but haven't found one yet.

If you really want as much of a non-geometric, non-tensor approach as is possible with GR, you could try Weinberg's textbook (it's listed in the Bibliography of Carroll's notes--which, btw, is worth looking through for other possible references in general). But I don't think most readers would say that made it easier.

 

[BL4CKB0X97]

Good luck with that, Blackbox. I tried reading it.
First I got pretty confused with eq. 1.10 where he simply says
which does not make any sense at all.
Then I hit the wall at the introduction of cotangent bundle and dual spaces, on page 10 out of 231.
That was the point where I realized I need a better book, but haven't found one yet.

Thanks for heads up. It's downloaded now I just need the time...

 

[eltodesukane]

I was thinking about being past an event horizon, and recalled that time stops in such a place and physics breaks down.
I am aware that no one would survive such conditions like an event horizon

Physics doesn't breaks down at or beyond the event horizon.
And time doesn't stop for an observer at or beyond the event horizon.
And we can survive at or beyond the event horizon, if the event horizon is large enough and not too much matter is falling through. According to General Relativity, there is nothing special at the event horizon.

 

[phinds]

Physics doesn't breaks down at or beyond the event horizon. And time doesn't stop for an observer at or beyond the event horizon.

Yes, exactly that was said in the second post in this thread. It's a good idea to read an entire thread before replying in it.

 

[BL4CKB0X97]

Physics doesn't breaks down at or beyond the event horizon.
And time doesn't stop for an observer at or beyond the event horizon.
And we can survive at or beyond the event horizon, if the event horizon is large enough and not too much matter is falling through. According to General Relativity, there is nothing special at the event horizon.

I have been informed... Thanks though

 

[jedishrfu]

Since this thread has run its course and the OP's question has been answered, we are closing it to avoid further digression.

Thanks to all who helped answer the OP's question.