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Sweeney
2008-Dec-28, 10:47 PM
Could Singularities, and Dark Energy have something in common? Could they be of the same stuff?

Perhaps as our universe expands, and galaxies get pulled along with it, the Black Holes that get carried along will leave a residual effect. For example, the tectonic plate being pulled over the volcanic plume we know as Yellowstone Park. The caldera has left a mark across the Pacific Northwest.

Isnít it possible that such an extreme occurrence like a Singularity might leave a rip in space-time? And if we could detect it, I would think that there would be some similarities with Dark Energy.

Tensor
2008-Dec-29, 12:07 AM
Could Singularities, and Dark Energy have something in common? Could they be of the same stuff?

No, they are not the same stuff. Mathematically, a singularity is simply a point, or locus of points, where the equations used to model the universe no longer work. In the case of the central singularity in a black hole. The radius has shrunk to zero. In the case of density, the radius is in the denomonator, which means you are dividing by zero, thus the equations are undefined. Other such cases show up in a black hole.

Dark energy enters into the Einstein Field Equations through lamda. It has nothing to do with singularities. Unless you want to count being part of the equations that end up no longer working.


snip....

Isnít it possible that such an extreme occurrence like a Singularity might leave a rip in space-time? And if we could detect it, I would think that there would be some similarities with Dark Energy.

While a singularity has been described as a "rip" in spacetime, that is simply an attempt to put into words, what the mathematical equations are describing. There really are no similarities between Dark Energy and Singularities.

Cougar
2008-Dec-29, 02:26 AM
Perhaps as our universe expands, and galaxies get pulled along with it, the Black Holes that get carried along will leave a residual effect.

Like the trail left behind by a snail? :lol::confused: No, the galaxies and black holes aren't moving through space (except for some limited, local motions). Besides, I'd imagine a black hole takes its spacetime along with it.

WayneFrancis
2008-Dec-29, 03:56 AM
Black holes do add to the "dark matter" of the universe though. They are one form of MACHOs (http://en.wikipedia.org/wiki/MACHO)

Sweeney
2008-Dec-29, 06:41 PM
When you say galaxies are not moving, what do you mean? Certainly the universe is expanding. The galaxies are all speeding along at an ever increasing speed.
Even raisins in the cooking bread (To steal a metaphor:)) move away from the original locals.

Sweeney
2008-Dec-29, 06:56 PM
There really are no similarities between Dark Energy and Singularities...

I was just wondering -

For the sake of this discussion, let's call the whatever existed before the Big Bang "The Stuff". As our universe, its' mass, space and energy, expands into the stuff, could there be any local way to see this stuff.

Since the universe's accelerating rate of expansion, and the speed of light barrier, will forever forbid our ability to see this stuff, maybe there's another way.

Maybe a singularity punches a hole in our universe. We'll never be able to see a singularity, but maybe we can see its' residue.

What do you think? Or am I really off the mark here?

Cougar
2008-Dec-29, 07:01 PM
Even raisins in the cooking bread (To steal a metaphor:)) move away from the original locals.

Yes, but they are not moving with respect to the rising dough around them... They're not moving through the dough. And yes, all the other raisins are apparently "moving away" from any chosen raisin, but they are not moving through the dough either. The apparent motion is due to the dough expanding between them.

I like the raisin bread analogy since it gives one an understandable model of the universe's dynamics... but note that astrophysicists are not (yet?) prepared to claim that space itself is "really" expanding like the bread/yeast mixture (as I've come to learn). The universe is expanding, yes, but apparently not enough is known about "space itself" to reach conclusions about its dynamical capabilities, if it has any... :think:

Sweeney
2008-Dec-29, 07:24 PM
Wow, I always just assumed that space, as we know it, is expanding into ‘the stuff’. I guess I’ve heard so many times, that before the Big Bang, there was no time. If space and time are so related, then I thought there was no space prior to the Big Bang.

I realize that this train of thought butts up against Michelson/Morley on at least a superficial basis. But didn’t their experiment do away with the ether only with respect to the speed of light?

Here’s a brain twister: Could there be a Michelson/Morley test for space with respect Time?

Hornblower
2008-Dec-29, 08:45 PM
Wow, I always just assumed that space, as we know it, is expanding into Ďthe stuffí. I guess Iíve heard so many times, that before the Big Bang, there was no time. If space and time are so related, then I thought there was no space prior to the Big Bang.For all we know there may be no such thing as "before the Big Bang". There may be no such thing as an absence of space/time.

As I see it, we do the best we can at developing a theory of cosmic evolution from observation. We back-extrapolate it just so far and run into the mathematical predicament of a singularity. We do not know what was happening before then, or whether or not it might be eternal.



I realize that this train of thought butts up against Michelson/Morley on at least a superficial basis. But didnít their experiment do away with the ether only with respect to the speed of light?

Hereís a brain twister: Could there be a Michelson/Morley test for space with respect Time?The Michelson/Morley test was an explicit test for the presence of a reputed inertial ether through which light propagated at constant speed, and through which we moved at varying speeds and directions.

For me, the brain twister is trying to figure what you mean by "space with respect Time". Please clarify.

Sweeney
2008-Dec-29, 10:03 PM
First, I meant with "...respect to Time." Sorry about the typo.
Nonetheless, in my mind (layperson), I think of Time and Space as one in the same. It is hard for me to get a grasp on it, but I try to take out the subjective perception of time and its' passage.
The "Arrow of Time", and its relation to the Laws of Thermodynamics are one thing when observed by a person with a finite perspective, and another when I consider it (or try to) objectively.
When I do, it reduces to a consideration of distances in space, a grid, or what have you.
I'm not sure I'm on the right track, but that's how I always thought that time, as we know it, expands or contracts (depending on the observer) when considered with speed.
So I was just wondering, since we were talking about Space, and the possibility of it expanding like raison bread after the Big Bang, was I bringing back the long dead ether argument.
I'm familiar with the Michelson/Morley test, so I'm not proposing anything like that. I was just wondering, however, we know we can bend space. We know that, even in what we call a vacuum, it teams with energy popping in and out of existence.
You have guys out there like Smolin, and the Loop Gravity folks, trying to quantize it (space).
So maybe it is the dough for raisons. And if so, with tongue in cheek, I wondered about the idea of Time and its passage, and that old test came to mind.
Did you know that that was the first Nobel for Physics given to someone from the US?

Tensor
2008-Dec-29, 10:17 PM
For all we know there may be no such thing as "before the Big Bang". There may be no such thing as an absence of space/time.

As I see it, we do the best we can at developing a theory of cosmic evolution from observation. We back-extrapolate it just so far and run into the mathematical predicament of a singularity. We do not know what was happening before then, or whether or not it might be eternal.


Hornblower, just for some update, Tim Thompson provided some papers in this (http://www.bautforum.com/astronomy/82269-big-bounce-post1397146.html#post1397146) post on possible ways around the singularity at the beginning of the universe.

Hornblower
2008-Dec-29, 11:39 PM
Hornblower, just for some update, Tim Thompson provided some papers in this (http://www.bautforum.com/astronomy/82269-big-bounce-post1397146.html#post1397146) post on possible ways around the singularity at the beginning of the universe.
Thanks for the references. I am here to learn as well as to comment.

Tensor
2008-Dec-29, 11:53 PM
Thanks for the references. I am here to learn as well as to comment.

You do both rather well, that's why I provided the references. Check the astronomy forum, Tim's got another post with references (along with a additional posters providing other references) about the expanding space/coodinate change discussion. The thread is called "Note on Expanding Space".

pzkpfw
2008-Dec-30, 12:17 AM
ATM bits (and their replies) moved here: http://www.bautforum.com/against-mainstream/82928-norths-claims-space-gravity.html

NO more here, please.

astromark
2008-Dec-30, 12:56 AM
Could Singularities, and Dark Energy have something in common? Could they be of the same stuff?

Perhaps as our universe expands, and galaxies get pulled along with it, the Black Holes that get carried along will leave a residual effect. For example, the tectonic plate being pulled over the volcanic plume we know as Yellowstone Park. The caldera has left a mark across the Pacific Northwest.

Isnít it possible that such an extreme occurrence like a Singularity might leave a rip in space-time? And if we could detect it, I would think that there would be some similarities with Dark Energy.

What is going on here ?

That looked like a question to me ?

Is ATM the right place to throw this...why did this happen ?

and the answer is NO.

Tensor
2008-Dec-30, 01:03 AM
What is going on here ?

That looked like a question to me ?

Is ATM the right place to throw this...why did this happen ?

and the answer is NO.

astromark, his question, and answers that are mainstream, are staying in Q and A. north's comments, some of them ATM, were what was moved to ATM.

Cougar
2008-Dec-30, 01:26 AM
If space and time are so related, then I thought there was no space prior to the Big Bang.

That's right - there wasn't. There was no 'stuff' either, or so goes our current, best theory: Everything in our universe, including space, came out of the "big bang." From my layman's perspective, some of the theory's practitioners1 are investigating possibilities that the beginning of our expanding universe may not have been the ultimate beginning of everything.

First we find there's nothing 'central' about our planet, or our sun, or our galaxy.... now it could be that even our entire universe is nothing special among a myriad of others. :eek:

____________________
1 Before the Beginning, Our Universe and Others [1997] -- Martin Rees
The Cosmic Landscape [2006] -- Leonard Susskind
Many Worlds in One [2006] -- Alex Vilenkin
Endless Universe, Beyond the Big Bang [2007] -- Paul Steinhardt and Neil Turok
The Trouble With Physics [2006] -- Lee Smolin

astromark
2008-Dec-30, 02:24 AM
This indeed is good news.
For humanity to except that we and the Galaxy we are in, and now the whole of this Universe might not be all of everything and that a before, or at least a other might just be plausible. That the great expansion may have been one of many is entirely reasonable. That there are not goblins and elves and fairies and that sadly Santa is not real.: All seems perfectly logical and scientific to me. Whew, maybe humanity does have a chance after all.
That we are not the reason for the existence of this universe is indeed a giant step forward. Acceptance of that small fact is perhaps the big step forward that could unify humanity into a tolerant understanding and forgiving culture. ya .. I know thats stretching it a bit.. Lol. But I make my point that we need to understand. It is not our universe. It might be the Universe., and there might be more.

WayneFrancis
2008-Dec-30, 04:08 AM
When you say galaxies are not moving, what do you mean? Certainly the universe is expanding. The galaxies are all speeding along at an ever increasing speed.
Even raisins in the cooking bread (To steal a metaphor:)) move away from the original locals.

It really isn't moving. It is apparent motion because of the expansion of space. The raisin bread metaphor breaks down because that bread is expanding in 3D space and the raisins all move to an external observer. With the universe the fabric of space/time is growing just like if you had a balloon with stars on it and blew it up the stars don't really move on the surface of the balloon. Galaxies don't move relative to the space/time they are in even though the amount of space between any 2 galaxies does increase.

70km/s/megaparsec it looks like we are moving. But if we look to our left and see a object 1 megaparsec away moving away at 70km/s then we could say that it is really moving away from us at that speed or we are moving away from them at that speed. When we look to our right and see another object 1 megaparsec away moving also 70km/s directly away from us then we have to start to question what is happening. It gets worse when we see almost everything is moving away from us at this speed. Either we are not moving and everything is moving away from us, and at a higher rate of speed the further away it is, or the better answer is is that nothing is actually moving and space everywhere is just expanding.

Sweeney
2009-Jan-01, 07:32 PM
Thanks - That's a lot of help.

So let me ask - Do Black Holes ever move? And if so, under what circumstances?

Because I'd really like to if they'd leave any "residue"?

Durakken
2009-Jan-01, 08:00 PM
galaxies move...black holes are in galaxies... blackholes must move.

Hornblower
2009-Jan-01, 08:15 PM
Thanks - That's a lot of help.

So let me ask - Do Black Holes ever move? And if so, under what circumstances?
A black hole can be in motion relative to nearby objects just as can any other body. Whether it is analyzed as being in motion or stationary depends on the frame of reference.

Because I'd really like to if they'd leave any "residue"?
When the Milky Way and M31 eventually collide, their central black holes likely will pass through interstellar gas and dust at high speed. There should be some accretion fireworks, and I would expect trails roughly analogous to those produced by meteors in our upper atmosphere.

pzkpfw
2009-Jan-01, 09:17 PM
It really isn't moving. It is apparent motion because of the expansion of space.


When the Milky Way and M31 eventually collide, ...

(My underlines.)

Contradiction? No. They are writing at different scales, or levels of detail.

WayneFrancis is writing about the overall "apparent motion" of the Galaxies that results from the expansion of the Universe.

Hornblower has an example of how "locally" Galaxies can be in motion.

(If Galaxies only appeared to move, away from each other, as a result of the expansion of the Universe, then the Milky way and M31 couldn't collide.

The coming collision between the Milky way and M31 is sometimes used (as an example) by people to argue against the expansion of the Universe, but it's a local Gravity-induced effect, no different to how space between the Earth and our Sun does not expand, as we are Gravitationally bound to the Sun.)

Cougar
2009-Jan-01, 09:25 PM
This indeed is good news.
For humanity to [ac]cept that we and the Galaxy we are in, and now the whole of this Universe might not be all of everything and that a before, or at least a other might just be plausible.

Well, it's not so much that it might be plausible, but rather that there is just no evidence either way. I should have added that Steinhardt and Turok oppose this view and posit that a single, expanding universe is the more rational position....

Sweeney
2009-Jan-02, 07:44 PM
Then let me resubmit:

Would the Black Hole's singularity leave any signature?

Hornblower
2009-Jan-02, 08:49 PM
Then let me resubmit:

Would the Black Hole's singularity leave any signature?
The singularity in question is the mathematical predicament we encounter when trying to describe the final state of the center of a black hole by means of general relativity. It is not necessarily an actual physical object.

A black hole is surrounded by a spherically symmetrical gravitational field (perhaps distorted if spinning). It should leave some sort of a trail if it whizzes through interstellar gas and dust at high speed, as I argued in my previous post. The characteristics of whatever is inside the event horizon will be immaterial for the purpose of analyzing this signature.

pzkpfw
2009-Jan-02, 09:19 PM
Sweeny, I have idea you feel there is some sort of base "fabric" of space time on which everything sits, and that a black hole will leave a rip on that fabric as it passes.

That implies there is some sort of unmoving reference frame to everything.

There isn't, so the only "signature" of the black hole will be what Hornblower has written in posts #22 and #26; i.e. the effetcs of the black hole on the other stuff around it.

Apology if I've mis-read you.

Sweeney
2009-Jan-03, 05:15 PM
Dark Energy intrigues and puzzles me. In an attempt to consider one possibility, I thought of the singularity.
First, I considered Dark Energy as a pre Big Bang state that is currently "outside" our universe driving the expansion.
Because we're expanding faster than light, I realized that we may never "see" Dark Energy.
So then I considered a more local phenomenon; the Singularity. Perhaps it punches through our universe, and perhaps would reveal Dark Energy, or its' properties.
Thanks everyone for your input. I'll keep thinking about it!