Harlequin wrote:So black holes can themselves be full of smaller black holes?
If not, that proves that the universe isn't one, because we're pretty sure that the ones we see have event horizons. On the other hand, maybe event horizons do nest.
KlaxonCow wrote:Indeed, if it's right, then all those supermassive black holes at the centres of galaxies and black holes generally would very much feature heavily in the density calculations, I reckon.
Like, most of all the mass is there. Everything else is just the scale of a "rounding error" in comparison.
The mass of Sagittarius A* is much less than the mass of the Milky Way, maybe less than 1%? If dark matter is only black holes, it's a lot of them.
"My way is the way of not fighting":- the book of Enter the Dragon.
Our plot of all objects also seems to suggest that the Universe is a black hole. We explain how this depends on the unlikely assumption that our Universe is surrounded by zero density Minkowski space.
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It's very easy to see from galactic rotation that the percentage of mass at the centre of the galaxy is small. Indeed, that's what put us on to dark matter in the first place.
zip accident wrote:If gravity is the curvature of spacetime with respect to mass, why wouldn't the other physical forces be curvatures of spacetime as well?
Because gravity (defined as spacetime curvature) is gravity and the forces that are not gravity are not gravity?
I think Einstein did not consider gravity to be a force at all, hence it and the three "other" forces being termed 'interactions' these days (but then he did create quantum mechanics before refuting its findings). The quantum view of gravity may differ but QM and the Relativity theories have never played nicely together and are probably best kept apart in separate reality-modelling playgrounds.
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zip accident wrote:If gravity is the curvature of spacetime with respect to mass, why wouldn't the other physical forces be curvatures of spacetime as well?
Because gravity (defined as spacetime curvature) is gravity and the forces that are not gravity are not gravity?
The other force which is present on the macroscopic level is electro-magnetism, treating that as a curvature of spacetime with respect to electrons might explain the orbits of electrons around atoms, and the way fluctuations of the electro-magnetic field give rise to the movement of photons.
I think Einstein did not consider gravity to be a force at all, hence it and the three "other" forces being termed 'interactions' these days (but then he did create quantum mechanics before refuting its findings). The quantum view of gravity may differ but QM and the Relativity theories have never played nicely together and are probably best kept apart in separate reality-modelling playgrounds.
As per the thread title, it's a stupid question. However, I don't have enough maths to know it wouldn't work out, and if it did it might give enough of a different perspective (hah, geometry) on things to get some other new ideas going.
Dio wrote:The Dirac Equation would disagree.
With whom?
That is certainly something I don't remember, maybe I never knew it.
"My way is the way of not fighting":- the book of Enter the Dragon.
The Dirac Equation is the relativistic generalisation of the Schroedinger equation.
It was an essential extension to the Schroedinger equation to give accurate answers for electron wavefunctions, since the electrons in atoms "move" very close to the speed of light, and it's a fundamental cornerstone of all quantum theory since most interactions involve very high-speed particles - it predicted both electron half-spin and positrons.
So relativity has been very successfully mixed with quantum physics, to the point where the latter doesn't work without it. That quantum gravity hasn't been worked out is a completely separate thing.
Dio wrote:The Dirac Equation is the relativistic generalisation of the Schroedinger equation.
It was an essential extension to the Schroedinger equation to give accurate answers for electron wavefunctions, since the electrons in atoms "move" very close to the speed of light, and it's a fundamental cornerstone of all quantum theory since most interactions involve very high-speed particles - it predicted both electron half-spin and positrons.
So relativity has been very successfully mixed with quantum physics, to the point where the latter doesn't work without it. That quantum gravity hasn't been worked out is a completely separate thing.
I'm not suggesting any current equations that work will need to change, I'm suggesting maybe we can look at them in a different way.
I'm not talking about relativising quanta either, I'm talking about something different, in the same way Einstein's theory was different from Newton's without making Newton's general idea any more inaccurate than it already was.
A new Piltdown Man would do nobody any good, I'm not saying this is correct, I'm saying does this work?
If there are two different sorts of force, one a curve in spacetime, the other with multiple cases of fields that are attractive or repulsive, wouldn't it be simpler and more elegant to have only one sort of force, different variations on curves in spacetime.
"My way is the way of not fighting":- the book of Enter the Dragon.
Dio wrote:The Dirac Equation is the relativistic generalisation of the Schroedinger equation.
…
So relativity has been very successfully mixed with quantum physics, to the point where the latter doesn't work without it. That quantum gravity hasn't been worked out is a completely separate thing.
My understanding is that there are still compatibility problems between the quantum and Einsteinian models of gravity, though.
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Effectively there are no quantum models of gravity. The chattering typewriters of the string and quantum gravity theorist monkeys are completely ignore-able at this point, since you can basically suggest anything.
@z_a: I was merely replying to the statement that quantum mechanics and relativity have never been successfully conjoined and indeed are best kept apart. The Dirac equation absolutely requires both and is deeply insightful and a fundamental plank of all modern quantum theory.
But as to your theory, I'm not much of an expert but I would instinctively say that it's unlikely because of the way that gauge boson mass means that non-electromagnetic force strength over distance is dependent on different functions to a simple inverse-r (they have different ranges, basically). To simulate that with just a curvature model seems to mean that you'd need the, I dunno, "tension" of the space-time "sheet" to be locally varying dependent on the type of force and that seems quite silly. Or maybe multiple 'sheets' but then that's not "just spacetime".
Harlequin wrote:I think Einstein did not consider gravity to be a force at all, hence it and the three "other" forces being termed 'interactions' these days (but then he did create quantum mechanics before refuting its findings). The quantum view of gravity may differ but QM and the Relativity theories have never played nicely together and are probably best kept apart in separate reality-modelling playgrounds.
Dio wrote:@z_a: I was merely replying to the statement that quantum mechanics and relativity have never been successfully conjoined and indeed are best kept apart. The Dirac equation absolutely requires both and is deeply insightful and a fundamental plank of all modern quantum theory.
Oops! I see now that I entirely screwed up that sentence in my over-editing attempts to clarify other bits of the paragraph. I meant to refer only to different models of gravity; not to relativity and QM in general.
Dio wrote:But as to your theory, I'm not much of an expert but I would instinctively say that it's unlikely because of the way that gauge boson mass means that non-electromagnetic force strength over distance is dependent on different functions to a simple inverse-r (they have different ranges, basically). To simulate that with just a curvature model seems to mean that you'd need the, I dunno, "tension" of the space-time "sheet" to be locally varying dependent on the type of force and that seems quite silly. Or maybe multiple 'sheets' but then that's not "just spacetime".
Interesting. I was going to suggest that, if gravity is effectively just another name for spacetime curvature, zip's ideas might require either a different kind of curvature and/or a different kind of spacetime. I abandoned that because more ideas had been introduced to the thread by the time I had finished over-editing that reply.
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So, the idea is that, per Einstein's "moving clocks tick slower", time is actually moving slower inside galaxies than in the voids between them - because mass distorts spacetime and all that.
Therefore, the expansion of the universe is happening faster inside the vast voids between galaxies, than it is inside galaxies. They reckon there's a 38% discrepancy here, so it is significant enough to matter.
Therefore, distant galaxies look further away than theory predicts. Therefore, we assume that the expansion of the universe is accelerating - and there must be "dark energy" to power this acceleration - because of how it looks from our perspective.
But, so the paper suggests, the expansion is, in fact, constant and it's not accelerating - and there is no "dark energy" - but it's just that time ticks faster in the voids.
If this is correct, then not only does dark energy vanish, but we also have to call into question other age measurements, including the age of the universe, accounting for the fact that time is not, in fact, ticking by uniformly in the universe, and that galaxies are a "moving clock that ticks slower" in comparison to the voids between them.
(And another obvious thing to check is whether the distribution of mass inside galaxies has a similar effect - is "dark matter" also bollocks, because we've not been accounting for similar time dilation?)
This one is also worth paying attention to, because it's not some mad outlandish idea that calls on some new exotic concept, as is often the case with these new theories, but it's just, in a rather pedestrian way, asking whether we have been measuring this right all along. Like, were we simply being too "Newtonian" and forgot about the time in spacetime, and should have been looking at it in a more "Einsteinian" way all along?
Edit: Sabine Hossenfelder's thrown up her explanation, while we wait for Dr.Becky's Jan 16th video on it (which will probably be more considered, as she's an actual astrophysicist and is taking her time to get it right). But this'll do for now:
"Words ought to be a little wild - for they are assaults of thought on the unthinking."
- John Maynard Keynes
Although it sounds legit, it is suspiciously close to certain creationist lines of thought to make me just a little wary (they are desperate to find anything that might throw doubt on the idea that the universe is anything more than 6,000 years old after all... ). Its not so much that I doubt the thinking behind it but more I worry that creationists will do what they always do and wildly misinterpret the hypothesis for their own ends.
Time in the void is running 38% faster than in a typical galaxy.
That's nowhere near enough to turn billions of years into 6,000 years.
Also, I don't think it should be a concern. They deny evolutionary biology, what DNA says, geology, radiometric dating, etc. and implicitly are also denying the correlation between these quite independent methods all corresponding with each other to paint the exact same picture - so there's really no amount of evidence that'll ever change their minds.
As Jonathan Swift had it: "You cannot reason someone out of a position they did not reason themselves into”.
God is real because warm fuzzy feelings. No amount of evidence removes the warm fuzzy feelings.
Indeed, don't even bother with facts, until you've undermined "warm fuzzy feelings" with a few rounds of "the problem of evil" and why God not only tolerates but provides instructions for enslaving people, to soften them up from feeling quite so warm and fuzzy about their horridly unjust Cosmic Tyrant first.
"Words ought to be a little wild - for they are assaults of thought on the unthinking."
- John Maynard Keynes
