Is the universe inside a black hole?

[sepulchrave 721]

I'm not sure I am explaining myself properly, but I am suggesting our observations do not take place along 'radial lines' (as in spokes on a wheel - which is what I think you are implying?), but along spiralling paths.

That is a valid hypothesis, but even if the paths are spiralling, they should be originating from different points in space.

Depending on how ``tight'' the spiral is, the direction we observe as ``Universal up'' (in a radial line sense) might actually be a completely different direction, but there should still be some other direction that we would observe as ``Universal down''.

And I am suggesting that, due to the nature of the universe, space is stretched more in one direction (towards the black hole) than the other (which accounts for the r², unless I am mistaken - and I readily admit I may be).

A gravitational body shouldn't really stretch space, it should compress it.

But regardless, you have to admit that it would take a very peculiar combination of stretched/compressed space and spiralling geodesic paths to make the Universe look globally isotropic when in fact it has quite strong anisotropy.

Assuming the Einstein equations reasonably accurately define how mass/energy influences the curvature of space and vice versa, I don't think it is possible to produce the kind of space-time required for the ``seemingly-isotropic trumpet Universe'' to exist without a very specific and ``cosmological constant'' that depends on the specific time/space coordinates.

If I could ask a question, some of your discussion has been concerning the possible shape of the universe. Has it not been determined experimentally that space is flat? How would this affect possible shapes?

The experimentally determined shape of the Universe depends on the assumption that the Universe is homogeneous (on a large scale, galaxies are roughly evenly spread out) and isotropic (the Universe looks approximately the same in all directions).

These seem to be relatively good assumptions, but if they are not true than the findings that the Universe is flat are called into question.

For example, if the Universe follows the Godel metric that StarMountainKid alluded to above, then it is possible that when looking through a telescope into the distant Universe we are actually observing our own Milky Way at some point in the distant past.

Now this doesn't seem to be the case (for one thing, we don't see the same young-looking galaxy some great distance away when looking in every direction), but it is something to keep in mind; if some directions ``loop back'' to our own past then our assumptions of isotropy and homogeneity may need to be re-examined.

[Frank Merton 17,411]

I was always lead to believe that there were many 'Blackholes' within the known Universe & not the Universe inside a Blackhole?

There is nothing saying black holes can't be inside black holes.

[Frank Merton 17,411]

If I could ask a question, some of your discussion has been concerning the possible shape of the universe. Has it not been determined experimentally that space is flat? How would this affect possible shapes?

Well it is flat as far as we can tell, but our measurement is always limited and the curvature, if it exists, could be beyond our ability to detect it. Take the surface of the earth as a three two-dimensional curving within a third dimension comparison. We don't detect the curvature until we go quite a ways. If the earth were gazillions of times larger we would still not have detected it.

[spacecowboy342 2,327]

That is a valid hypothesis, but even if the paths are spiralling, they should be originating from different points in space.

Depending on how ``tight'' the spiral is, the direction we observe as ``Universal up'' (in a radial line sense) might actually be a completely different direction, but there should still be some other direction that we would observe as ``Universal down''.

A gravitational body shouldn't really stretch space, it should compress it.

But regardless, you have to admit that it would take a very peculiar combination of stretched/compressed space and spiralling geodesic paths to make the Universe look globally isotropic when in fact it has quite strong anisotropy.

Assuming the Einstein equations reasonably accurately define how mass/energy influences the curvature of space and vice versa, I don't think it is possible to produce the kind of space-time required for the ``seemingly-isotropic trumpet Universe'' to exist without a very specific and ``cosmological constant'' that depends on the specific time/space coordinates.

The experimentally determined shape of the Universe depends on the assumption that the Universe is homogeneous (on a large scale, galaxies are roughly evenly spread out) and isotropic (the Universe looks approximately the same in all directions).

These seem to be relatively good assumptions, but if they are not true than the findings that the Universe is flat are called into question.

For example, if the Universe follows the Godel metric that StarMountainKid alluded to above, then it is possible that when looking through a telescope into the distant Universe we are actually observing our own Milky Way at some point in the distant past.

Now this doesn't seem to be the case (for one thing, we don't see the same young-looking galaxy some great distance away when looking in every direction), but it is something to keep in mind; if some directions ``loop back'' to our own past then our assumptions of isotropy and homogeneity may need to be re-examined.

Yeah, that makes sense to me. I suppose the fact that we can only see back to the point where the universe cooled to the point where the temp dropped low enough for atoms to form a opposed to plasma would restrict our ability to see our early galaxy as you say.

[spacecowboy342 2,327]

Well it is flat as far as we can tell, but our measurement is always limited and the curvature, if it exists, could be beyond our ability to detect it. Take the surface of the earth as a three two-dimensional curving within a third dimension comparison. We don't detect the curvature until we go quite a ways. If the earth were gazillions of times larger we would still not have detected it.

Good point. I was watching a video and Dr. Michio Kaku said pretty much the same thing, that he thought the universe might well have a curvature that was too slight for us to detect. Lawrence Krauss, however seems to say that a flat universe is the only type with an overall energy content of 0, and the only type that would be stable enough to come into existence through quantum fluctuation and exist long enough for inflation to occur. I get most of my information on this stuff through you tube videos and programs on the science channel so my understanding of these things are somewhat limited but I am completely fascinated.

[Leonardo 10,412]

But regardless, you have to admit that it would take a very peculiar combination of stretched/compressed space and spiralling geodesic paths to make the Universe look globally isotropic when in fact it has quite strong anisotropy.

I agree it might seem improbable, but I'm throwing it out there to highlight that all we assume we know is based on our observations, and if those observations are not as we assume them to be then what we know also should be called into question.

While I don't disagree with orthodoxy, neither do I restrict myself to consider it the only possibility.

As for space compressing due to extreme gravitational force, I agree that would be the case if the measurement of space was done in a straight line towards the centre of gravity. If we throw rotation into the picture, however, space could become more stretched the closer it gets to the centre of rotation and this could outweigh the compression due to gravity. Similar to spaghettification.

[sepulchrave 721]

I agree it might seem improbable, but I'm throwing it out there to highlight that all we assume we know is based on our observations, and if those observations are not as we assume them to be then what we know also should be called into question.

While I don't disagree with orthodoxy, neither do I restrict myself to consider it the only possibility.

As for space compressing due to extreme gravitational force, I agree that would be the case if the measurement of space was done in a straight line towards the centre of gravity. If we throw rotation into the picture, however, space could become more stretched the closer it gets to the centre of rotation and this could outweigh the compression due to gravity. Similar to spaghettification.

Ok, I can accept that argument.

[spacecowboy342 2,327]

I agree it might seem improbable, but I'm throwing it out there to highlight that all we assume we know is based on our observations, and if those observations are not as we assume them to be then what we know also should be called into question.

While I don't disagree with orthodoxy, neither do I restrict myself to consider it the only possibility.

As for space compressing due to extreme gravitational force, I agree that would be the case if the measurement of space was done in a straight line towards the centre of gravity. If we throw rotation into the picture, however, space could become more stretched the closer it gets to the centre of rotation and this could outweigh the compression due to gravity. Similar to spaghettification.

If this rotation was happening would light not appear to bend away from the direction of rotation? I'm thinking like a ball thrown between two people on opposite sides of a rotating merry-go-round where the flight of the ball would appear to curve away though it was travelling straight as the observers moved, or am I missing something?

[Leonardo 10,412]

If this rotation was happening would light not appear to bend away from the direction of rotation? I'm thinking like a ball thrown between two people on opposite sides of a rotating merry-go-round where the flight of the ball would appear to curve away though it was travelling straight as the observers moved, or am I missing something?

Light emitted from a source would appear to us to be travelling in a straight line, but would actually be travelling a spiral path along with everything else in the universe. It's motion is the same as everything else with respect this rotation so we would (or should) not expect to see a deviation such as you describe. That only happens when an object leaves a rotating objects frame of reference, but in a rotating universe all frames of reference are rotating around the same common axis.

Edited October 12, 2013 by Leonardo

[spacecowboy342 2,327]

Light emitted from a source would appear to us to be travelling in a straight line, but would actually be travelling a spiral path along with everything else in the universe. It's motion is the same as everything else with respect this rotation so we would (or should) not expect to see a deviation such as you describe. That only happens when an object leaves a rotating objects frame of reference, but in a rotating universe all frames of reference are rotating around the same common axis.

OK. I was thinking in terms of, if light were a wave propagating through the ether as was first proposed it would behave that way but being particles traveling independently of the space it was traveling through would appear to bend, but you undoubtedly have a better understanding of this than I do. Obviously with everything in rotation around the same common axis as you say you wouldn't be able to see the rotation just like my people sitting across a merry-go-round from each other would appear stationary to each other. I still can't get the idea of the thrown ball curving away as it flies though. I know when light travels through space bent by intense gravitational fields it appears to bend though, at least as I understand it, it is actually traveling in a straight line through curved space Edited October 12, 2013 by spacecowboy342

[StarMountainKid 9,494]

If we look at spacecowboy342's merry go round from a stationary position above, and the ball is thrown from one side of the merry go round to the other, what do we see? Don't we see the ball traveling in a straight line, yet its trajectory from our point of view is following a curve or spiral in the same direction of the rotation of the merry go round?

If the MGR is rotating counter-clockwise, every foot the ball moves its position is shifted in the counter-clockwise direction so that it ultimately is caught by the receiver.

[onereaderone 93]

.... very cool stuff ....

[Pyridium 108]

What people are calling "black hole" is just a neutron star that has enough mass to generate a gravity enough to form an event horizon that extends beyond the surface of the neutron star. When a neutron acquires enough mass it switches from glowing white to black, not glowing at all. I believe all neutrons stars that we can see have an event horizon located between the surface and center core.

http://en.wikipedia.org/wiki/Neutron_star#Examples_of_neutron_stars

[spacecowboy342 2,327]

What people are calling "black hole" is just a neutron star that has enough mass to generate a gravity enough to form an event horizon that extends beyond the surface of the neutron star. When a neutron acquires enough mass it switches from glowing white to black, not glowing at all. I believe all neutrons stars that we can see have an event horizon located between the surface and center core.

http://en.wikipedia....f_neutron_stars

As I understand it, and I admit my understanding is limited, above 3 solar masses neutron degeneracy pressure is not enough to prevent the gravitational collapse of a star beyond the neutron star level and into singularity. This is determined by mathematics obviously and not by observation as no on can look inside to see what is happening. Do you have reason to doubt the validity of the math?

[sepulchrave 721]

As I understand it, and I admit my understanding is limited, above 3 solar masses neutron degeneracy pressure is not enough to prevent the gravitational collapse of a star beyond the neutron star level and into singularity. This is determined by mathematics obviously and not by observation as no on can look inside to see what is happening. Do you have reason to doubt the validity of the math?

You are talking about the Tolman-Oppenheimer-Volkoff limit. Above approximately 3 solar masses, the neutron degeneracy collapses as you say. The math is actually a bit vague, because the behaviour of the Pauli exclusion principle is pretty complicated for composite objects like neutrons (compared to simpler objects like electrons, for example).

Above the TOV limit it is still possible to avoid gravitational collapse if there is an even more degenerate form of matter. It is, for example, reasonable to expect that a quark star can exist, and these could be dense enough that they might generate event horizons (and therefore be indistinguishable from a black hole).

In fact, because there isn't a quantum theory of gravity, we can't really be sure whether the Pauli exclusion principle (singularities are impossible, there will always be some non-degenerate state of matter regardless of the gravitational force) or gravity (completely degenerate matter, i.e. a singularity, is possible) will win.

There are other considerations as well, for example if space is quantized into some form of discrete lattice then momentum is periodic; and it may be impossible for an object to actually reach a singularity (since the objects' momentum would increase until it hit the maximum limit, then increase further and end up going negative as it ``wrapped around''); consequently even gravity does beat the exclusion principle it might still be impossible to get all that matter into the same spot.

[Frank Merton 17,411]

There are other considerations as well, for example if space is quantized into some form of discrete lattice then momentum is periodic; and it may be impossible for an object to actually reach a singularity (since the objects' momentum would increase until it hit the maximum limit, then increase further and end up going negative as it ``wrapped around''); consequently even gravity does beat the exclusion principle it might still be impossible to get all that matter into the same spot.

Your last paragraph (above) puts me in mind of a speculation I heard a long time ago to the effect that if space/time is quantized then a singularity ought not be possible without breaking the quantum structure, which one presumes would destroy space/time. It makes sense to me but of course I'm just visualizing it all in gross terms.

[Leonardo 10,412]

Your last paragraph (above) puts me in mind of a speculation I heard a long time ago to the effect that if space/time is quantized then a singularity ought not be possible without breaking the quantum structure, which one presumes would destroy space/time. It makes sense to me but of course I'm just visualizing it all in gross terms.

Not necessarily true. In a quantised space-time a singularity can still exist and have zero-volume. It would simply have an apparent volume.

Although the problem sepulchrave set out regarding periodicity still might make a singularity impossible.

Edited October 18, 2013 by Leonardo

[spacecowboy342 2,327]

This is fascinating though i'm definitely going to have to let it soak in a while to really wrap my head around it. So singularity may or may not be possible. The quark star possibility is new to me, though it would seem to make sense.

[Pyridium 108]

OMG! Many of you are finally coming around to my way of thinking. If you think we have a "Black Hole" at the center of our galaxy, you may also believe that our universe is in a singularity within a singularity...infinity. When anyone says "black hole" it always assumes a singularity is fact. This is imagination taken as fact.

I posted a link above which shows the layers within a neutron star. The outer layer is the neutrons, each neutron has 3 quarks. During the super nova, the atoms that make up the neutron remnant are so packed that the electrons were forced to bond with each proton to produce individual neutrons without orbiting electrons. Deeper into the neutron star the quarks begin to break away from the neutron cluster. Deeper at the core is the energy and pressure break up quarks into its smaller component parts like gluons, muons, etc. At some point, the neutron star is a quark star. There are many layers and with all the energy focused toward the center, there must be a repelling force balanced against the push of the gravitational force.

Every neutron star has an Event Horizon. This is the spot where photons are forced back toward the core of the star, hence no light escapes from this horizon. When enough mass is accumulated, the neutron star will generate an Event Horizon that goes beyond the actual surface of the star. At this point, the neutron star turns ifs lights off. I predict one day we will see a bright shiny neutron star switch off, turn black.

So, we need to use more accurate terminology. Think of every black hole as nothing more than a neutron star. We can see the small young ones. This will allow the math to work. Math fails when talking about a singularity.