71–80 of 116 posts
What is going on with titles? Do physicists really put on boxing gloves hoping that physical violence will resolve a scientific argument? Is this a new widely accepted approach? I find this level of editorializing ridiculous to the point of insulting. I don’t need the imagery of violence to boost my curiosity about a new discovery.
Here's a question I'm not even remotely qualified to ask: could it be that supermassive black holes cause a contraction of local spacetime in a way that gives the impression that local space is static while distant space expands? I think this mechanism would be largely indistinguishable from classic hubble expansion, at least on local scales.
That's a good question and is not exactly easy to answer. The Einstein field equations of General Relativity are highly non-linear which makes it difficult to talk about superpositions of solutions to the equations and to compare local physics (at the level of black holes) to cosmological effects (e.g. the expansion of the universe) and transfer results and insights between them. Let me explain. When we talk about co…
Not in the standard black hole model with a singularity at the center, no. In the standard black hole model, the collapsing matter that formed the hole hits the singularity and is destroyed. The interior of the hole is vacuum, just like the exterior.
In the alternative "black hole" model being used in the proposed hypothesis for dark energy, no singularity is ever formed; instead, the collapsing matter undergoes a kind of phase transition (probably induced by quantum field effects of some sort) that changes its equation of state from that of normal matter to that of dark energy. This stops the collapse and creates an object that, at least on time scales much shorter than the Hawking evaporation time scale (since these objects will eventually evaporate by emitting Hawking radiation), looks from the outside like a standard black hole, though it isn't. The dark energy inside such objects, it is proposed, could drive accelerated expansion of the universe.
What is going on with titles? Do physicists really put on boxing gloves hoping that physical violence will resolve a scientific argument? Is this a new widely accepted approach? I find this level of editorializing ridiculous to the point of insulting. I don’t need the imagery of violence to boost my curiosity about a new discovery.
I think the title of fine.
Earlier quoted context omitted.
That's a good question and is not exactly easy to answer. The Einstein field equations of General Relativity are highly non-linear which makes it difficult to talk about superpositions of solutions to the equations and to compare local physics (at the level of black holes) to cosmological effects (e.g. the expansion of the universe) and transfer results and insights between them. Let me explain. When we talk about co…
> Outside a black hole there's vacuum, inside a black hole there is… Well, we don't really know but the mass from which it formed has gotta be somewhere, right? Not in the standard black hole model with a singularity at the center, no. In the standard black hole model, the collapsing matter that formed the hole hits the singularity and is destroyed. The interior of the hole is vacuum, just like the exterior. In the a…
If the interior of a black hole becomes a vaccume, what continues to assert the intense gravitational pull that the now destroyed matter once created?
Here's a question I'm not even remotely qualified to ask: could it be that supermassive black holes cause a contraction of local spacetime in a way that gives the impression that local space is static while distant space expands? I think this mechanism would be largely indistinguishable from classic hubble expansion, at least on local scales.
> could it be that supermassive black holes cause a contraction of local spacetime in a way that gives the impression that local space is static while distant space expands? No. That's not how the spacetime geometry around black holes works.
What is going on with titles? Do physicists really put on boxing gloves hoping that physical violence will resolve a scientific argument? Is this a new widely accepted approach? I find this level of editorializing ridiculous to the point of insulting. I don’t need the imagery of violence to boost my curiosity about a new discovery.
Some synonyms of spar are argue and quarrel. This isn't ridiculous editorializing.
Earlier quoted context omitted.
That's a good question and is not exactly easy to answer. The Einstein field equations of General Relativity are highly non-linear which makes it difficult to talk about superpositions of solutions to the equations and to compare local physics (at the level of black holes) to cosmological effects (e.g. the expansion of the universe) and transfer results and insights between them. Let me explain. When we talk about co…
> Outside a black hole there's vacuum, inside a black hole there is… Well, we don't really know but the mass from which it formed has gotta be somewhere, right? Not in the standard black hole model with a singularity at the center, no. In the standard black hole model, the collapsing matter that formed the hole hits the singularity and is destroyed. The interior of the hole is vacuum, just like the exterior. In the a…
Sure, but that's a model for which we don't have any observational evidence whatsoever since it's the black hole's interior. That's why I phrased it that way.
It doesn't matter, though, even if you say the matter inside the black hole no longer exists (and I'm very happy to entertain that thought): Any sensible definition of mass of the vacuum black hole (i.e. not necessarily the ADM mass since it's defined at infinity but e.g. some definition of quasi-local mass) will still give a non-zero contribution to the mass density.
Earlier quoted context omitted.
> Outside a black hole there's vacuum, inside a black hole there is… Well, we don't really know but the mass from which it formed has gotta be somewhere, right? Not in the standard black hole model with a singularity at the center, no. In the standard black hole model, the collapsing matter that formed the hole hits the singularity and is destroyed. The interior of the hole is vacuum, just like the exterior. In the a…
> Not in the standard black hole model with a singularity at the center, no. In the standard black hole model, the collapsing matter that formed the hole hits the singularity and is destroyed. The interior of the hole is vacuum, just like the exterior. If the interior of a black hole becomes a vaccume, what continues to assert the intense gravitational pull that the now destroyed matter once created?
[0]: https://news.ycombinator.com/item?id=34898647
[1]: https://en.wikipedia.org/wiki/Mass_in_general_relativity#ADM...
Earlier quoted context omitted.
These are the free parameters of the Standard Model https://en.m.wikipedia.org/wiki/Standard_Model#Construction_...
Every one of those parameters is associated with a field that does symmetry breaking. Every one of those fields has a particle associated. Every one of those particles has been observed, studied, and found to have properties in line with what would be required for the fields to have the values that we measure. So yes, that's a lot of free parameters. But they are intrinsic to the theory. And we have considerable expe…
I'm a layman, but I like this idea intuitively. It's not mentioned in the article, but this theory also necessitates that black holes aren't singularities, which gets rid of what always seemed to me like the biggest hack in physics.