Gravitational Singularity

[hazelm]

This from Wiki: 

Singularity - Wikipedia

https://en.wikipedia.org/wiki/Singularity

 

"Gravitational singularity, a region in spacetime in which tidal gravitational forces become infinite. Initial singularity, the gravitational singularity of infinite density before quantum fluctuations that caused the Big Bang and subsequent inflation that created the Universe."

 

If I am reading rightly, this has spacetime existing before the Big Bang and the initial singularity in existence before the Big Bang.  Then it has quantum fluctuations causing the Big Bang. 

 

Am I misinterpreting?  I thought we did not know of anything before the Big Bang.  I like the sound of it happening this way but do we really know this?

 

 

 

 

 

[TomKalbfus]

we know nothing directly about before the Big Bang, but we do have some theories based on our knowledge of Physics.

Edited October 3, 2017 by TomKalbfus

[hazelm]

So  it is a theory.  It is saying more to me than I can explain - more about how we are all held  together ( life and the universe).  I need to get the right words.  More reading needed.  Thank you for reply.

[exchemist]

So  it is a theory.  It is saying more to me than I can explain - more about how we are all held  together ( life and the universe).  I need to get the right words.  More reading needed.  Thank you for reply.

I would say a singularity is really a mathematical concept: a mathematical point (i.e. dimensionless) at which there are discontinuities or infinities in mathematical functions, in this case the way gravitation is expressed. It is worth bearing in mind that this hypothesised singularity is an extrapolation from the observations we can make about the red shift and the cosmic background radiation, but there is no direct evidence for it, so far as I am aware.

 

I struggle with the concept of anything "before" the Big Bang, since spacetime itself only started to expand from the hypothesised singularity then. So there could not be a "before", it seems to me. Equally, how could there be fluctuations in something with no spatial extent?  But I'm not a cosmologist so if someone can explain it, I'll be happy to listen. :) 

[hazelm]

I would say a singularity is really a mathematical concept: a mathematical point (i.e. dimensionless) at which there are discontinuities or infinities in mathematical functions, in this case the way gravitation is expressed. It is worth bearing in mind that this hypothesised singularity is an extrapolation from the observations we can make about the red shift and the cosmic background radiation, but there is no direct evidence for it, so far as I am aware.

 

I struggle with the concept of anything "before" the Big Bang, since spacetime itself only started to expand from the hypothesised singularity then. So there could not be a "before", it seems to me. Equally, how could there be fluctuations in something with no spatial extent?  But I'm not a cosmologist so if someone can explain it, I'll be happy to listen. :)

Something else strange.  In an article about all this (which is what sent me to Wiki), a star (one star) exploded and created the black hole which is at the center of our universe.  Only one star?  According to the article, our little universe came out of a larger four-dimensional universe.  Since there were no stars in ours (other than that one that exploded), it must have come from the four-dimensional universe.   One does wonder why only one star. 

 

But, like you (only much less-informed), I am not a cosmologist.  More over, if it involves math, I am "out of here". 

[exchemist]

Something else strange.  In an article about all this (which is what sent me to Wiki), a star (one star) exploded and created the black hole which is at the center of our universe.  Only one star?  According to the article, our little universe came out of a larger four-dimensional universe.  Since there were no stars in ours (other than that one that exploded), it must have come from the four-dimensional universe.   One does wonder why only one star. 

 

But, like you (only much less-informed), I am not a cosmologist.  More over, if it involves math, I am "out of here". 

There is definitely something fishy about that. For a start, there is no "centre" to our universe. But there is a centre to our galaxy. And there is a radio source almost at the mathenatical centre (of rotation), which is consistent with a black hole. Could that be what you read?

More here: https://en.wikipedia.org/wiki/Galactic_Center 

 

Or could it be that your source is a bit wacky? Do you have a reference we can check out?  

[hazelm]

There is definitely something fishy about that. For a start, there is no "centre" to our universe. But there is a centre to our galaxy. And there is a radio source almost at the mathenatical centre (of rotation), which is consistent with a black hole. Could that be what you read?

More here: https://en.wikipedia.org/wiki/Galactic_Center 

 

Or could it be that your source is a bit wacky? Do you have a reference we can check out?  

I plan to check it out again tonight.  it is a reprint from Scientific American to Scientific American collector's edition.  I'll see if it tell me anything helpful.  

[hazelm]

As I re-read, I think Exchemist has taken care of much of this.  I'll see what I can add.  First, the source:  a bookazine from Scientific American called Wonders of the Cosmos.  First section: How Did The Universe Begin?.  First chapter:  The Black Hole at the Beginning of Time.   If you want to find it, this is the Fall 2017 Special Collector's Edition. 

 

I could wish you had a copy because of what I must describe.  It is an illustration that requires your imagination otherwise.  You are familiar with the cone-shaped diagram that is often used to illustrate the early history of our universe.  We have a similar cone back up to it, small ends together.  This cone represents the imagined 4-D universe from which our universe came at the implosion of the two.  (speculation, of course).  It does actually show "Time at the 4-D cone with arrow pointing forward to the implosion point.  And I suppose, if you are going to imagine this 4-D universe, you have to give it Time, do you not?  And space?

 

The point where the two meet is called the Event Horizon.  Next section is described thus:  Most commonly known model:  big bang (white dot) followed by inflation (black curve).  Next is a small ring called Cosmic Microwave Background Horizon.  Then, of course, The Dark ages,  All this you know.  I just wanted to get across how they link the 4-D universe to our 3-D universe.  If you already also knew that, apologies.

 

The authors explain why they have done this investigation into the 4-D universe because of problems contemplating the 3-D universe.  The successes that scientists have had coming forward from the Big Bang "belie deep and complex mysteries that may lend themselves to a holographic explanation".  Problems:

 

1)  Not understanding the five parameters

2)  Not understanding inflation completely

3)  Not understanding how it all began.  

 

I rather thought that third one was good enough to imagine this idea which, of course is not a new idea, just an enriched one, I think. There is much, much more well-worth reading but i must not rewrite the book.

 

This black hole that they are "creating" is, by the way, three-dimensional, not two as are the rest of the black holes that we think we know exist.  I still must find the story of the one star exploding.  I never found it last night.  It may be in the next chapter:  "The First Starlight".    I know we need that clarified.  I'll look for it and be back -- if our threatening skies don't turn loose with the red rain of Pern.

[hazelm]

I have read and re-read but I do not find the original.  Nevertheless, here is a recap that accompanies the above-described illustration.  The laws of physics break down at the singularity of the Big Bang.  "The authors postulate that the universe began when a star in a four-dimensional universe collapsed to form a black hole.  Our universe would be protected from the singularity at the heart of at the heart of this black hole by a three-dimensional event horizon.

 

From there we follow the diagram we all know.  Anything else?  Comments appreciated.

[exchemist]

I have read and re-read but I do not find the original.  Nevertheless, here is a recap that accompanies the above-described illustration.  The laws of physics break down at the singularity of the Big Bang.  "The authors postulate that the universe began when a star in a four-dimensional universe collapsed to form a black hole.  Our universe would be protected from the singularity at the heart of at the heart of this black hole by a three-dimensional event horizon.

 

From there we follow the diagram we all know.  Anything else?  Comments appreciated.

I don't think I can help. This is the sort of cosmological speculation that I tend to give up on these days. As I understand it, the observational data justifies an extrapolation back to just after the hypothesised Big Bang. The data is consistent with ideas of cosmic expansion (of spacetime itself), as seen in the cosmological red shift, and of the start involving radiation, then matter in the form of plasma, then condensation into atoms, at which time space became transparent for the first time, creating the "surface of last scattering" that gave rise to the observed cosmic background radiation.

 

I can get my head around dark matter, since there is observational data for that: we know the rotational curves* of galaxies don't fit the mass of them, as estimated from the visible populations of stars in them, so it seems there must be more mass there that we can't see. But that's about where I stop, at the moment.  

 

Maybe someone more conversant with cosmology can comment.

 

 

* We can estimate their rates of rotation at various radii from their centres, due to the Doppler shift in their spectra on opposite sides.

Edited October 5, 2017 by exchemist

[TomKalbfus]

I would say a singularity is really a mathematical concept: a mathematical point (i.e. dimensionless) at which there are discontinuities or infinities in mathematical functions, in this case the way gravitation is expressed. It is worth bearing in mind that this hypothesised singularity is an extrapolation from the observations we can make about the red shift and the cosmic background radiation, but there is no direct evidence for it, so far as I am aware.

 

I struggle with the concept of anything "before" the Big Bang, since spacetime itself only started to expand from the hypothesised singularity then. So there could not be a "before", it seems to me. Equally, how could there be fluctuations in something with no spatial extent?  But I'm not a cosmologist so if someone can explain it, I'll be happy to listen. :)

Maybe time does not affect the Universe as a whole, but is only a dimension of the Universe. The Big Bang exists now, it is eternal and infinite as is the Universe. Our perception of time is a result of our traveling away from the Big Bang through the dimension of time. if the Universe was infinite, there could be no time as we think of it for the Universe as a whole. Every possibility is expressed in an infinite Universe, travel in one direction through time and the Universe, the part which we can see, appears to be expanding from an event we call the Big Bang. What we see happening depends on what part of the Infinite Universe we are in. We are currently in a part of the Universe where it is 13.7 billion years old, and as we travel along the fourth dimension within the three dimensions of space, we see the Universe getting older. But when we include time as a part of the Universe, every particle has a world line, it has a beginning and an end, its path through time-space depend on its interactions with other particles and energy fields until it is destroyed. Photons follow similar world times, except they are timeless, one end of their world line is where they are created through conversion of mass into energy, the other end is where their energy gets converted back into mass, that is the length of a photon in both time and space. The Universe is a timeless thing, but we move through it, and we cannot revisit the same part of time space that we've been to before. We could go back in time, say through a wormhole, but only to another part of the Universe that we hadn't been to before, and as the Universe is infinite, that is not really a problem.

[exchemist]

Maybe time does not affect the Universe as a whole, but is only a dimension of the Universe. The Big Bang exists now, it is eternal and infinite as is the Universe. Our perception of time is a result of our traveling away from the Big Bang through the dimension of time. if the Universe was infinite, there could be no time as we think of it for the Universe as a whole. Every possibility is expressed in an infinite Universe, travel in one direction through time and the Universe, the part which we can see, appears to be expanding from an event we call the Big Bang. What we see happening depends on what part of the Infinite Universe we are in. We are currently in a part of the Universe where it is 13.7 billion years old, and as we travel along the fourth dimension within the three dimensions of space, we see the Universe getting older. But when we include time as a part of the Universe, every particle has a world line, it has a beginning and an end, its path through time-space depend on its interactions with other particles and energy fields until it is destroyed. Photons follow similar world times, except they are timeless, one end of their world line is where they are created through conversion of mass into energy, the other end is where their energy gets converted back into mass, that is the length of a photon in both time and space. The Universe is a timeless thing, but we move through it, and we cannot revisit the same part of time space that we've been to before. We could go back in time, say through a wormhole, but only to another part of the Universe that we hadn't been to before, and as the Universe is infinite, that is not really a problem.

...or, on the other hand, maybe not.....

 

This is very creative, but it is an example of the sort of thing that strikes me as too metaphysical and arbitrary to get hold of.   

[hazelm]

I don't think I can help. This is the sort of cosmological speculation that I tend to give up on these days. As I understand it, the observational data justifies an extrapolation back to just after the hypothesised Big Bang. The data is consistent with ideas of cosmic expansion (of spacetime itself), as seen in the cosmological red shift, and of the start involving radiation, then matter in the form of plasma, then condensation into atoms, at which time space became transparent for the first time, creating the "surface of last scattering" that gave rise to the observed cosmic background radiation.

 

I can get my head around dark matter, since there is observational data for that: we know the rotational curves* of galaxies don't fit the mass of them, as estimated from the visible populations of stars in them, so it seems there must be more mass there that we can't see. But that's about where I stop, at the moment.  

 

Maybe someone more conversant with cosmology can comment.

 

 

* We can estimate their rates of rotation at various radii from their centres, due to the Doppler shift in their spectra on opposite sides.

I think I am going deeper into the enjoyment because I like the idea of a hyperspace.  All imagination but - I hope - fairly good reasons for dreaming it up.    When you said "I can get my head around dark matter,", you got my attention.  I have been wanting to ask "what does dark matter actually do?  Or, at least,, what do we think it does?  I know what we think it is but no hint of what it does other than act as a "place holder".  ["place holder" - the nemesis of math; never did like that term] 

[hazelm]

Maybe time does not affect the Universe as a whole, but is only a dimension of the Universe. The Big Bang exists now, it is eternal and infinite as is the Universe. Our perception of time is a result of our traveling away from the Big Bang through the dimension of time. if the Universe was infinite, there could be no time as we think of it for the Universe as a whole. Every possibility is expressed in an infinite Universe, travel in one direction through time and the Universe, the part which we can see, appears to be expanding from an event we call the Big Bang. What we see happening depends on what part of the Infinite Universe we are in. We are currently in a part of the Universe where it is 13.7 billion years old, and as we travel along the fourth dimension within the three dimensions of space, we see the Universe getting older. But when we include time as a part of the Universe, every particle has a world line, it has a beginning and an end, its path through time-space depend on its interactions with other particles and energy fields until it is destroyed. Photons follow similar world times, except they are timeless, one end of their world line is where they are created through conversion of mass into energy, the other end is where their energy gets converted back into mass, that is the length of a photon in both time and space. The Universe is a timeless thing, but we move through it, and we cannot revisit the same part of time space that we've been to before. We could go back in time, say through a wormhole, but only to another part of the Universe that we hadn't been to before, and as the Universe is infinite, that is not really a problem.

I must re-read and think.  You are - I think - saying what I'm thinking.  Some years ago, someone said (about the Big Bang) that it was not the beginning, only a happening along the way.  The main thing I came away with was his thought that the Universe - think Multi-verse - always was, that there was no beginning.  I wish I had stayed with that but it just didn't make sense then.  We learn in a world that says everything has a cause and a start.  Then we find out "not necessarily".  "The Universe is timeless".   It is fascinating.  Is this still going to hook into space and be called "spacetime"?  Does that fit in with your opening?   Anyway, thank you.  Your points make good sense to me  as far as my brain will carry them.

 

Your bit about the wormhole is coming up.  Scientific American ran an article about that and why traveling thousands of light years would not take as long as we think because we could use a black hole into a worm hole.  (It didn't have a good ending. :-(  )  That is coming up later in the collection I am reading. 

 

Thanks again.  I shall return. 

[hazelm]

...or, on the other hand, maybe not.....

 

This is very creative, but it is an example of the sort of thing that strikes me as too metaphysical and arbitrary to get hold of.   

Somebody said that it couldn’t be done,

    But, he with a chuckle replied

That "maybe it couldn’t," but he would be one

    Who wouldn’t say so till he’d tried.

So he buckled right in with the trace of a grin

    On his face. If he worried he hid it.

He started to sing as he tackled the thing

    That couldn’t be done, and he did it.

 

Forgive Edgar Guest and I for going poetic on you but I'll bet you can come up with a dozen instances of a new idea in science that "could not be".  Be a dreamer.   As for metaphysical, I can certainly see it going that way but we shall not. 

[exchemist]

I think I am going deeper into the enjoyment because I like the idea of a hyperspace.  All imagination but - I hope - fairly good reasons for dreaming it up.    When you said "I can get my head around dark matter,", you got my attention.  I have been wanting to ask "what does dark matter actually do?  Or, at least,, what do we think it does?  I know what we think it is but no hint of what it does other than act as a "place holder".  ["place holder" - the nemesis of math; never did like that term] 

I thought it was the other way round: we know what it does (exert gravitational attraction) but we don't know what it is, except that it does not seem to be ordinary baryonic matter, as that would interact with radiation and give some signature of its presence.  

[exchemist]

Somebody said that it couldn’t be done,

    But, he with a chuckle replied

That "maybe it couldn’t," but he would be one

    Who wouldn’t say so till he’d tried.

So he buckled right in with the trace of a grin

    On his face. If he worried he hid it.

He started to sing as he tackled the thing

    That couldn’t be done, and he did it.

 

Forgive Edgar Guest and I for going poetic on you but I'll bet you can come up with a dozen instances of a new idea in science that "could not be".  Be a dreamer.   As for metaphysical, I can certainly see it going that way but we shall not. 

Trouble is dreaming gets you nowhere in science until you work out how your dream could be put to the test by observation. Esoteric speculations by themselves are not science.

Edited October 5, 2017 by exchemist