Every Black Hole Contains Another Universe?

[Cochise]

http://patdollard.com/wp-content/upl...tney_alone.jpg

LEAVE MAXX ALONE!

[pahnphoenix]

isn't the analogy more like ps2 not only being able to play ps1 games, but playing them via totally different mechanics? it's not like a ps2 with a ps1 inside of it.

also, while i don't know much about physics, being able to make analogues that produce "the same" results in newtonian physics as GR isn't what 'reducible' means. for example, biology is "reducible" to chemistry exactly if every notion of biology can be explained in the language of chemistry, and the results all line up. if a section of biology is "reducible" to chemistry, again, this is the case exactly if the notions involved in that section of biology can be restated in the language of chemistry, and the same (redescribed) results occur. you can't just have chem-entity-X "taking the place of" bio-entity-Y. that's not reducibility, that's analogy.

the chances of one theory/discipline reducing to another when one entails the other's falsehood are about 0. the chances of "this section of theory A where only X,Y,Z of its laws but not N,M,Q are necessary for its usual results," reducing to "some section of theory B" are a little bit better, but will probably drop back to 0 when you again consider entailment. for example, if GR thinks of spacetime in a different way than newtonian physics, there's probably something about each explanation that is going to make trouble for reducing any given part of GR to newtonian physics, if one is attempting to maintain consistent enough equivalency to be "reducing" in the first place. that trouble being made is probably why GR exists in the first place, even if GR gives occasionally gives results that look like newtonian physics.

p.s. the original version of this post contained a long section regarding the quus function, a la kripkenstein. excised for your pleasure.

[Max™]

isn't the analogy more like ps2 not only being able to play ps1 games, but playing them via totally different mechanics? it's not like a ps2 with a ps1 inside of it.

also, while i don't know much about physics, being able to make analogues that produce "the same" results in newtonian physics as GR isn't what 'reducible' means. for example, biology is "reducible" to chemistry exactly if every notion of biology can be explained in the language of chemistry, and the results all line up. if a section of biology is "reducible" to chemistry, again, this is the case exactly if the notions involved in that section of biology can be restated in the language of chemistry, and the same (redescribed) results occur. you can't just have chem-entity-X "taking the place of" bio-entity-Y. that's not reducibility, that's analogy.

the chances of one theory/discipline reducing to another when one entails the other's falsehood are about 0. the chances of "this section of theory A where only X,Y,Z of its laws but not N,M,Q are necessary for its usual results," reducing to "some section of theory B" are a little bit better, but will probably drop back to 0 when you again consider entailment. for example, if GR thinks of spacetime in a different way than newtonian physics, there's probably something about each explanation that is going to make trouble for reducing any given part of GR to newtonian physics, if one is attempting to maintain consistent enough equivalency to be "reducing" in the first place. that trouble being made is probably why GR exists in the first place, even if GR gives occasionally gives results that look like newtonian physics.

p.s. the original version of this post contained a long section regarding the quus function, a la kripkenstein. excised for your pleasure.

Well stated explanation.


I realized where the mix-up was coming from, I assumed it was obvious that I meant "if you calculate the motion of objects using Newtonian Mechanics in situations where Relativistic corrections are minor, i.e. nearly flat spacetimes, low gravity, low mass, low velocity, then the results from General Relativity will be virtually identical", apparently it was not.

Naturally there are deviations from the various factors which GR considers, though there are ways to achieve a closer fit to the Newtonian limit if you take c to be infinite, for example.



Why do exact EFE solutions matter, even if GR may not be the end all be all theory?

The black hole solutions told us we'd find shit like this:

http://www.weizmann.ac.il/home/tal/pp/GCOrbits2003.gif

That's the black hole at the center of the milky way, deflecting stars orbiting it in a manner which allows us to calculate it's mass using GR, and check how accurate the theory is.

It's pretty fucking accurate, and an exact solution, while not corresponding to reality perfectly (exact solutions are generally for specific states of spacetimes in particular situations, not the general state of an entire Universe full of gravitating masses), predicted that we would find that object there, doing that, and not emitting light.

Though it does periodically flare in infrared, which has been confirmed recently.

http://www.weizmann.ac.il/home/tal/pp/GC_flare_loop.gif


Now, how does this have anything to do with Newton?

Typical stars cannot approach the Galactic black hole as close as the emitting gas without being destroyed by the tidal field of the black hole. Thus, stars can mostly probe the weak-field limit of General relativity. Though less spectacular than the strong-field limit, stars orbiting a million solar mass class object at up to a few percents of the speed of light nevertheless probe a virtually unexplored regime of relativistic celestial mechanics. One effect that will be hopefully detected with continued monitoring is the slow-down of time near the black hole (gravitational redshift), as expressed by the Doppler shift of the stellar spectra. This effect is substantially larger at the orbits' point of closest approach than it is on the surface of a white dwarf. Another effect that may be eventually detected is the advancing rosette-like orbits that are predicted by General Relativity (Figure 7) as a consequence of the deviation from the Newtonian http://www.weizmann.ac.il/home/tal/pp/img9.png gravitational force law.

Spoiler: show

http://www.weizmann.ac.il/home/tal/pp/perishift.gif

A schematic comparison of a classical Newtonian orbit around a point central mass (red) and a General Relativistic one (blue). In Newtonian physics the gravitational force falls exactly as the distance squared, and the orbital ellipse closes on itself. Close enough to the central black hole General Relativistic effects deviating from Newton's law of gravitation cause the point of closest approach to advance, leading to a rosette-shaped orbit (blue).

http://www.weizmann.ac.il/home/tal/pp/pp.html


That's all...

[Kaylia]

What are you trying to say in your last post? That relativity is a better model than newton mechanics? You don't have to convince anyone...we all know this.


Also, your bolded argument goes against what you said.

"Now, how does this have anything to do with Newton?"
"Another effect that may be eventually detected is the advancing rosette-like orbits that are predicted by General Relativity (Figure 7) as a consequence of the deviation from the Newtonian gravitational force law. "

Please, do tell me how it has anything to do with Newton's law, since the part you bolded tell me clearly it has nothing to do with its law since it's deviate away from it.

[Max™]

>.<

I said it does not deviate much in the weak field situation, by Thor, I was illustrating cases where it does, like black holes, and noting where it doesn't.

If you drop an apple 3 feet and calculate how it will react using Newtonian Gravitation, and General Relativity, the results will differ by miniscule amounts. If you consider the GR case with the speed of light set as infinite, and use a minkowski spacetime (perfectly flat), you will get the same results.

Enough bitching about ridiculously overwrought points though, more pretty pictures about black holes:

http://www.nasa.gov/images/content/1...in_A400_lg.jpg

http://www.youtube.com/watch?v=GAwO1okR074

[Uzor]

Even the universe suggest white people give and black people steal.