creation

[universe]

I am not an astronomer, or a cosmologist but it seems to me that if
all matter came into existence at one place and time that would be a
recipe for a black hole.

[cable]

On 2002-12-26 08:37, universe wrote:
I am not an astronomer, or a cosmologist but it seems to me that if
all matter came into existence at one place and time that would be a
recipe for a black hole.

Universe,
welcome on board.
Black Hole is there where our laws of physics won't work. BH is where our physics dies, ie. a limit to our present scientific knowledge.

[GrapesOfWrath]

On 2002-12-26 08:37, universe wrote:
I am not an astronomer, or a cosmologist but it seems to me that if
all matter came into existence at one place and time that would be a
recipe for a black hole.

I think of it more as a hardware algorithm, "recipe" seems kinda nutty, or cooked up. Anybody else hungry? Hey, universe, welcome to the BABB. We're all going down to Mickey D's for burgers, want to join us? I think we can fit you in...oops, where'd everybody go?

[irony]

On 2002-12-26 08:37, universe wrote:
I am not an astronomer, or a cosmologist but it seems to me that if
all matter came into existence at one place and time that would be a
recipe for a black hole.

My guess is it would depend on whether the outward force of whatever is causing the expansion is greater than the force of gravity trying to drag everything in.

[Aldrin]

On 2002-12-26 08:37, universe wrote:
I am not an astronomer, or a cosmologist but it seems to me that if
all matter came into existence at one place and time that would be a
recipe for a black hole.

Scientists Gung Ho Mission To Create A Black Hole in Lab...

http://www.sciforums.com/showthread.php?threadid=1197

[ljbrs]

Universe,
welcome on board.
Black Hole is there where our laws of physics won't work. BH is where our physics dies, ie. a limit to our present scientific knowledge.

Cable:

I have in front of me a heavy book (646 pages) by the famed S. Chandrasekhar entitled *The Mathematical Theory of Black Holes.* I believe that the late Nobel Physicist Chandra (as S. Chandrasekhar was affectionately called by many scientists) would have been surprised at your statement. Of course, the laws of physics are said to break down at a singularity, but that is a part of the theory. I do not think that this Oxford Science Publications book, full of calculus equations (646 pages) would agree with you on this. We need not understand everything to be able to make theories.

I think that we could say that our laws of physics don't work in many areas, but that is the way things are in science. There are many unfinished areas in physics (as well as in all science). Nothing gets set in stone... Not, at least, to my knowledge...

ljbrs [img]/phpBB/images/smiles/icon_biggrin.gif[/img] [img]/phpBB/images/smiles/icon_biggrin.gif[/img] [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

[cable]

There are many unfinished areas in physics (as well as in all science) ...

Ljbrs,

unfinished ?
I prefer rough approximation, false theory.
take Newton. nobody suspected it as unfinished untill Einstein. in fact Newton made false assumptions eg. mass= constant.

my opinion: comparing Newton to Einstein is like comparing Einstein to the REAL theory ( that we still didn't discover yet).

NOW with our "unfinished" laws of physics, astrophysicians are making projections/conjectures on the whole universe ... looks like a meteorologist making forcast for a remote planet (with atmosphere), while struggling to make it on earth for next 72 hours !!!
it's too pretentious.

[samsara15]

It WOULD have been a Black Hole, except space was expanding so fast it could not collapse.

[John Kierein]

So there couldn't be any black holes now because space expansion has accelerated since the big bang.

[carolyn]

Do the black holes know that? [img]/phpBB/images/smiles/icon_wink.gif[/img]

[Tom]

What if the black hole was universe-sized?

Would it have just fallen apart into miniscule stellar and planetary size pieces?

[img]/phpBB/images/smiles/icon_biggrin.gif[/img]

[irony]

On 2002-12-27 17:32, John Kierein wrote:
So there couldn't be any black holes now because space expansion has accelerated since the big bang.

No, after the inflationary period it slowed down, then gradually began to accelerate again. I don't understand this, either.

[samsara15]

No, Black Holes can exist now because the Expansion slowed down somewhat after the Inflationary Period.

[Rich]

On 2002-12-27 17:32, John Kierein wrote:
So there couldn't be any black holes now because space expansion has accelerated since the big bang.

But from inside the event horizon of the black hole how would any observer know that?

Maybe the Big Bang is just a singularity expanding inside at black hole. The mass never changes, so you'll still have the same event horizon, from the perspective of an outside observer. If this were true every black hole may contain a separate universe.

[John Kierein]

Greenspan says there is no inflation. The inflationary period is figment of your imagination.

[RickNZ]

Im with the author of this thread. Black holes are black because not even light escapes and since nuthing can travel faster than the speed of light and since the speed of the universes expansion is still accelerating...

Sounds like a recipe for a black hole to me too [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

[Tom]

It should actually be called an "invisible hole", because black is actually the absence of color (or composite of ALL color) in normal space. A "black hole" does not reflect light, and will bend light passing close to it's event horizon.

No one will ever see a black hole.

[GrapesOfWrath]

On 2002-12-31 13:00, Tom wrote:
black is actually the absence of color (or composite of ALL color)

well, which is it? [img]/phpBB/images/smiles/icon_smile.gif[/img]

[ToSeek]

On 2002-12-31 13:26, GrapesOfWrath wrote:

On 2002-12-31 13:00, Tom wrote:
black is actually the absence of color (or composite of ALL color)

well, which is it? [img]/phpBB/images/smiles/icon_smile.gif[/img]

It depends on whether you're looking at a monitor or a printer. [img]/phpBB/images/smiles/icon_wink.gif[/img]

[SeanF]

On 2002-12-31 13:38, ToSeek wrote:

On 2002-12-31 13:26, GrapesOfWrath wrote:

On 2002-12-31 13:00, Tom wrote:
black is actually the absence of color (or composite of ALL color)

well, which is it? [img]/phpBB/images/smiles/icon_smile.gif[/img]

It depends on whether you're looking at a monitor or a printer. [img]/phpBB/images/smiles/icon_wink.gif[/img]

Not really - the mixing of all the inks results in a removal of all reflected color. The black you see is still no color and not all color. [img]/phpBB/images/smiles/icon_smile.gif[/img]

[ljbrs]

my opinion: comparing Newton to Einstein is like comparing Einstein to the REAL theory ( that we still didn't discover yet).

NOW with our "unfinished" laws of physics, astrophysicians are making projections/conjectures on the whole universe ... looks like a meteorologist making forcast for a remote planet (with atmosphere), while struggling to make it on earth for next 72 hours !!!
it's too pretentious.

cable:

I will go with the astrophysics as it is and let the REAL astrophysicists make the changes in the theories. Conjectures are just that -- conjectures. I do not make more of the conjectures than they are. I shall let the scientists do the science.

Then again, there is no law against making conjectures, unless, of course, the conjectures involve selling bogus products and the like. People who do silly science get trounced roundly by the scientific community. Look at Cold Fusion for such an example.

ljbrs [img]/phpBB/images/smiles/icon_confused.gif[/img]

[Wiley]

On 2002-12-26 12:50, GrapesOfWrath wrote:
I think of it more as a hardware algorithm, "recipe" seems kinda nutty, or cooked up. Anybody else hungry? Hey, universe, welcome to the BABB. We're all going down to Mickey D's for burgers, want to join us? ...

Shouldn't we be goin' to the Big Bang Burger Bar? [img]/phpBB/images/smiles/icon_smile.gif[/img]

[SeanF]

On 2003-01-02 14:06, Wiley wrote:

On 2002-12-26 12:50, GrapesOfWrath wrote:
I think of it more as a hardware algorithm, "recipe" seems kinda nutty, or cooked up. Anybody else hungry? Hey, universe, welcome to the BABB. We're all going down to Mickey D's for burgers, want to join us? ...

Shouldn't we be goin' to the Big Bang Burger Bar? [img]/phpBB/images/smiles/icon_smile.gif[/img]

Nah, we're going to Milliways. Oh, wait, the subject of this thread is "creation," and Milliways is at the other end . . . [img]/phpBB/images/smiles/icon_smile.gif[/img]

[Wiley]

On 2002-12-27 10:18, cable wrote:

Ljbrs,

unfinished ?
I prefer rough approximation, false theory.
take Newton. nobody suspected it as unfinished untill Einstein. in fact Newton made false assumptions eg. mass= constant.

Cable,

I must disagree with your characterisation. Newtonion dynamics are an approximation of Einstein's relativity; however to say they are false is an exaggeration. "False" implies that Newton is wrong, and he is definitely not wrong. Ljbrs's term "unfinished" is more accurate.

Also most (pre-relativity) scientists supected Newtonian dynamics was unfinished. Gravity travels infinitely fast in a Newtonian world, and this "action at a distance" was distasteful to most scientists. In addition, Maxwell's theory of electromagnetics did not jive with Newtonian dynamics. One of them had to give.

And who said mass was not constant? [img]/phpBB/images/smiles/icon_smile.gif[/img]

[DStahl]

"...this 'action at a distance' was distasteful to most scientists..." Didn't even Newton find it unsatisfactory, prompting him to famously refuse to conjecture about how it worked--"Hypotheses non fingo," I frame no hypotheses.

As far as the collapse of the early universe into a black hole, during the inflationary epoch in the first milliseconds of the big bang the universe seems to have been in a physical state called "false vacuum." Physics predicts that in that state gravity becomes powerfully repulsive rather than attractive. I think no gravitational collapse would be possible for a universe in a false vacuum state--in fact, the exponential expansion of the inflationary epoch was driven by this repulsive gravity.

As I get older I find gravity more and more repulsive myself, especially when hiking up especially steep hills...

The false vacuum state was probably only metastable, and the universe soon underwent a phase transformation to something like its present state. Matter in the form of "hot quark soup" was produced as a consequence of the collapse of the false vacuum, and the immense kinetic energy of the period of repulsive-gravity-driven exponential expansion--the inflationary epoch--resulted in an expanding universe.

At least, that's my understanding of one version of the physics of the early universe. It should be noted that things like the physics describing a "false vacuum" are not drawn out of a hat but are mathematical consequences of what we know of physics--in fact, "false vacuum" was described in theory some time before Alan Guth and Andre Linde realized that it had any particular relevance to the cosmology of the big bang. And a period of exponential expansion driven by the physics of the false vacuum offers a single explanation for some observations about the universe: the extreme rarity (or absence) of magnetic monopoles; the closeness with which the term omega, loosely the ratio between gravitational self-attraction and kinetic energy of the universe, approaches one; the mechanism by which the early universe was able to achieve thermal equilibrium; and probably some others that I'm forgetting.

I seem to recall that P.J.E. Peebles, author of Principles of Physical Cosmology, wrote that he found it unfortunate that the big bang had no close rivals in cosmology, but no other theory explains as much about our observations of the universe. (Sorry, John Kieran, I know I'm spouting the party line here, but I think Peebles' opinion is worth noting...especially his wish for a strong alternative to the big bang.)

Anyways, there are a number of good layman's books--The Inflationary Universe, by Alan Guth, is one--which shed light on this subject. Nice discussion.



<font size=-1>[ This Message was edited by: DStahl on 2003-01-02 22:54 ]</font>

[GrapesOfWrath]

On 2003-01-02 14:31, Wiley wrote:
I must disagree with your characterisation. Newtonion dynamics are an approximation of Einstein's relativity; however to say they are false is an exaggeration. "False" implies that Newton is wrong, and he is definitely not wrong. Ljbrs's term "unfinished" is more accurate.

Depends upon your point of view, I guess. It seems to me that in order to accept that point of view, you also have to admit that Ptolemy was not wrong either. Is that so?

[DStahl]

Here's a link to a semi-technical essay on the false vacuum state and its physics: WAS COSMIC INFLATION THE 'BANG' OF THE BIG BANG? by Alan Guth, one of the originators of the theory. Very nicely written piece!

And here's a link to a story from the April 2002 issue of Discover Magazine which talks about Guth and his concept of an inflationary epoch in the early universe: Guth's Grand Guess.

And to round things out a bit, here's a link to an article published in Astronomy Magazine in September, 1999, written by Tom Yulsman: BEFORE THE BIG BANG.

Enjoy!

[Wiley]

On 2003-01-02 23:29, GrapesOfWrath wrote:

On 2003-01-02 14:31, Wiley wrote:
I must disagree with your characterisation. Newtonion dynamics are an approximation of Einstein's relativity; however to say they are false is an exaggeration. "False" implies that Newton is wrong, and he is definitely not wrong. Ljbrs's term "unfinished" is more accurate.

Depends upon your point of view, I guess. It seems to me that in order to accept that point of view, you also have to admit that Ptolemy was not wrong either. Is that so?

I don't think the cases are analogous. Nothing of Ptolemy's is used today. Kepler did not build on Ptolemy; he completely redid the fitting formulae. The chain starts at Kepler, not Ptolemy. Newton showed the physics behind Kepler's kinematic description; Einstein (in SR) kept the same dynamics but modified the kinematics.

But to answer your question, was Ptolemy wrong? If you mean did it or did it not accurately (for the time) predict the motion of the planets? You know the answer as well as I do. But is it's kinematical description useful as a stepping stone to an actual physical description? No, it's a scientific dead end.

[GrapesOfWrath]

On 2003-01-03 14:13, Wiley wrote:
I don't think the cases are analogous. Nothing of Ptolemy's is used today. Kepler did not build on Ptolemy; he completely redid the fitting formulae. The chain starts at Kepler, not Ptolemy. Newton showed the physics behind Kepler's kinematic description; Einstein (in SR) kept the same dynamics but modified the kinematics.

I think the cases are analogous. I notice that you ended that chain at Einstein's SR. GR starts a new chain almost as assuredly as Kepler's. That's the whole point--of a different perspective. You can look at it as a whole chain (Ptolemy, Kepler, Einstein) or you can look at it as distinct links. Kepler is as false to Einstein (GR) as Ptolemy was false to Kepler. Ptolemy was an approximation of Kepler, as Kepler was an approximation of Einstein (GR). Without appreciating that, we cannot advance to the next link.

But to answer your question, was Ptolemy wrong? If you mean did it or did it not accurately (for the time) predict the motion of the planets? You know the answer as well as I do.

Yes, the answer is yes, of course.

But is it's kinematical description useful as a stepping stone to an actual physical description? No, it's a scientific dead end.

And as others have pointed out, Newton's dynamics are definitely not a stepping stone to general relativity. There was no pressure within the paradigm to produce GR. Many people have said it--that without Einstein, GR would have never attained. No one else believed in it.

The analogy keeps working--as long as you take it all the way to GR.

[Wiley]

On 2003-01-03 14:53, GrapesOfWrath wrote:
I think the cases are analogous. I notice that you ended that chain at Einstein's SR. GR starts a new chain almost as assuredly as Kepler's. That's the whole point--of a different perspective. You can look at it as a whole chain (Ptolemy, Kepler, Einstein) or you can look at it as distinct links. Kepler is as false to Einstein (GR) as Ptolemy was false to Kepler. Ptolemy was an approximation of Kepler, as Kepler was an approximation of Einstein (GR). Without appreciating that, we cannot advance to the next link.

I stopped the chain at SR because I only wanted to write one sentence. The chain easily moves from SR to GR. Obviously the principle of relativity bind the two, but we have retained the concepts of force, momentum, and energy. Admittedly their definitions are modified for GR, but remember pre-Newton they were non defined at all.

I disagree the Ptolemy is an approximation of Kepler. From Newton, we can get Kepler. From Einstein, we can get Newton. However from Kepler, we can not get Ptolemy. Yes, they produce similar results, but the methods are completely different.

And as others have pointed out, Newton's dynamics are definitely not a stepping stone to general relativity. There was no pressure within the paradigm to produce GR.

First, this does not invalidate my argument. A causal connection from Newton->SR->GR is required, not from Newton->GR. Second, I would argue that Newtonian dynamics is a stepping stone to GR, if for no other reason we retain such Newtonian concepts as force and energy.