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Physics, Astronomy & Cosmology / Is Time and Change the same phenomenon?

« on: 06/06/2009 20:08:50 »

To me it seems impossible to have change without the concept of time and vice versa. If you had a volume of space in which nothing changed, would time still flow? If it did, it seems time would have no meaning. If time was still flowing at the normal rate, could we tell in which direction it was flowing (i.e. forward or backward)? I certainly cannot imagine change happening without time, could time flow without change? Can anyone offer a thought experiment that might shed some light on this question?

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Physics, Astronomy & Cosmology / Are We Living Inside of a Black Hole ?

« on: 07/04/2009 06:21:30 »

Below I have pasted the part of the article I found so interesting

this link has a good illustration to go with this and alot more additional info if anyones interested or can understand it 

http://members.cox.net/jhaldenwang/black_hole.htm


Spacetime Geometry Inside a Black Hole
by Jim Haldenwang
written  Nov. 12, 2004
revised  May 28, 2008

Life Inside the Black Hole
 
Some have speculated that our universe might exist inside a gigantic black hole.  Let’s explore this idea further, in order to gain more insight into what the interior of a black hole is really like (and for the fun of it).  If our universe is really inside a giant black hole, one might ask where the event horizon is.  Is there any path we can take that will bring us closer to the event horizon?  According to GRT, if our universe is inside a black hole, every point in our universe is moving closer to the center of this black hole, and away from the event horizon.  There is no (spatial) direction that will bring us closer to the event horizon.  As it is difficult to visualize a four-dimensional curved surface (one needs to think in five dimensions to be able to do this), subtracting a dimension or two makes it easier.  Imagine a giant sphere, and a point on the interior surface of this sphere. This point detaches from the inner surface and moves toward the center, at the same time expanding into a disk.  This expanding disk represents our universe expanding in space as it moves through time.  In this model let's suppose that our universe formed on the event horizon of the giant black hole, represented by the surface of the sphere.  We suppose that the Big Bang occurred at the event horizon of the black hole.  See figure 5.  The expanding disk is a two-dimensional representation of the three spatial dimensions of our universe.  (We could label these spatial dimensions q, j and t.  Note that the disk represents an unimaginable curved 3-D hypersurface.)  Every point in our universe (the disk) is moving away from the inner surface of the sphere (the event horizon) toward the center of the sphere (the singularity of the giant black hole).  The dimension through which this disk is moving is a timelike dimension (let’s label it r).  For every point on the disk (our universe at a point in time), the event horizon lies in the past and the singularity of the black hole lies, unseen, in the future.  All timelike and lightlike world lines in our universe lead from the event horizon to the singularity of the black hole.  To travel to the event horizon would be to travel backward in time.  Therefore, there is no path we can take that will bring us closer to the event horizon.

In this imaginary model, the only point of the spacetime of our universe that is connected to the event horizon of the giant black hole is the point in space and time at which the Big Bang occurred.  With a powerful enough telescope, one can, in theory, look in any direction and see the Big Bang (or at least 380,000 years after the Big Bang, when the universe became transparent).  One can look around in any direction and see the Big Bang, yet one cannot travel toward it, because it lies in the past.  This is the way of things inside any black hole.  Even a super-powerful rocket cannot prevail against the gentle timelike acceleration toward the singularity at the center of a black hole.

Could we detect the presence of this gigantic black hole?  If we had sensitive enough instruments, it should be possible to detect the tidal acceleration gradient, at least over astronomical distances.  This might be mistaken for a slight variation in the strength of gravity over very large distances.  Also, the expansion of the universe should eventually slow down and reverse, as the universe moves closer to the central singularity of the black hole.  In this model, our universe would eventually shrink down to a single point (the Big Crunch).

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Physics, Astronomy & Cosmology / Are We Living Inside of a Black Hole ?

« on: 07/04/2009 04:26:18 »

Thanks Yor_On for the links, but alas I've seen this kind of info before.

you and some others I've seen post here obviously know more (much more)about physics than I and hoped for some informed opinion.

below I've included a link to a site I though was interesting.

couldn't understand all (OK most) of the math but the lower section on life in a black hole was interesting

http://members.cox.net/jhaldenwang/black_hole.htm

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Physics, Astronomy & Cosmology / Are We Living Inside of a Black Hole ?

« on: 07/04/2009 03:52:30 »

From what I've read it seems that if enough matter congregates in a small enough area or surpasses a certain threshold, a black hole must result. If this is true and we rewind the universe to its beginning, then all the matter and energy in the known universe were in a singular point, would this not be a black hole? Is it possible that inside this Singularity exist all that we have or need in this Universe,  i.e. energy/matter, space/time and allow for the expanion of space?

any information or opinions on this would be Greatly Appreciated 

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Physics, Astronomy & Cosmology / Are We Living Inside of a Black Hole ?

« on: 07/04/2009 03:25:37 »

Allthough I've read we know little about what goes on inside of black holes, is it possible that the Universe exists inside one? If we were, how might we know?

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Physics, Astronomy & Cosmology / Are Black Holes giant nuclear fusion reactors?

« on: 06/04/2009 23:23:54 »

Since atoms would likely be ripped apart to their subatomic building blocks (i.e. quarks),and possibly to their building blocks (if they exist), the journey of atoms to the center of black hole would likely be the opposite of fusion. The gravitational differences would become so large even on the tiniest scale, spaghettification would reduce all forms of matter to their lesser building blocks and perhaps into pure energy. Fusion probably does take place near the event horizon in the accretion disk that orbit a black hole where temperatures and pressures are like the ones found in the cores of stars. Since the matter making up the accretion disk is most likely to contain mostly hydrogen and helium, fusion would be the likely result. Since the temperatures and pressures might be much greater than in stellar cores, much heavier elements may be able to be fused here, before being ultimately ripped apart later on their journey

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Physics, Astronomy & Cosmology / Are Black Holes giant nuclear fusion reactors?

« on: 06/04/2009 22:56:58 »

I think what "lets split up" meant by a "negative universe" is what others might think of as a universe made up of antimatter. My (limited)understanding of string theory, M theory and other theories do not rule out other universe existing in these other universes/dimensions, nor do they rule out them consisting of antiparticles. However since all known antimatter seem to possess mass and light (photons) are essentially massless particles, they seem unlikely to have an anti- counterpart. If however they in deed had an antimatter equivalent, they would most likely self annihilate when they met their matter counterparts and produce energy/radiation along the electromagnetic spectrum, one of which would in fact be visible light. Sorry to give a long answer but cant help myself I agree with VERN when he answers simply NO