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Apparently I am not watching enough PBS SpaceTime because I still do understand what a "gravitational atom" might be. They are not implying a particle that cau

by ck2 2y ago

Apparently I am not watching enough PBS SpaceTime because I still do understand what a "gravitational atom" might be. They are not implying a particle that causes gravity right? Because I thought it is pretty well accepted there isn't a "gravaton" like there are photons. They also don't mean atom-sized black-holes, so I still don't get it. Hoping Matt does an episode on this so I can grasp it. https://www.pbs.org/show/pbs-space-time/ https://www.pbs.org/show/pbs-space-time/

tectonic 2y ago
I think they are more drawing an analogy between the atom one or more black holes with a cloud of particles around them. Black holes are quantum mechanical and so the resulting system could behave much like an atom, including having things that look like energy levels. The universe rhymes.
pdonis 2y ago
> I still do understand what a "gravitational atom" might be. It's a vague gesture in the direction of a speculative theory of quantum gravity. It's not anything we have any actual evidence for.
pokeymcsnatch 2y ago
> I thought it is pretty well accepted there isn't a "gravaton" like there are photons. Different branch of physics that we can't quite mesh with GR yet. A graviton is the quantized "piece" of gravity, like phonon is for sound/mechanical waves, or photons for EM. It exists as much as a photon or any other "messenger particles" exists, in that it's a useful mathematical model. It's not something we have isolated/observed with equipment though.
andrewflnr 2y ago
As far as I know the existence of the graviton is 100% up in the air, not well accepted either way. But yeah, particles in energy levels gravitationally bound to a black hole in a similar way electrons are electrically bound to a nucleus.
gradientsrneat 2y ago
In an atom, the electrons orbiting the nucleus are only allowed to be at discrete energy levels (the energy levels are "quantized"). In a classical model of an orbit, the energy level of a spaceship orbiting a planet can be thought of as the speed it has that allows it to orbit at a certain altitude, assuming no friction or other effects. Velocity is energy in that case (E=m*v^2 in classical mechanics). Unlike electrons in an atom, the spaceship can be in any one of a continuous range of energy levels (up to escape velocity). The proposal in the article is (I think) that bosons orbit certain black holes in quantized energy states, like electrons would orbit an atomic nucleus.
vagab0nd 2y ago
Speaking of PBS SpaceTime, pretty much every one of their videos starts fine but always lose me around the half point. Anyone feel the same?

by ck2 2y ago

tectonic 2y ago

I think they are more drawing an analogy between the atom one or more black holes with a cloud of particles around them. Black holes are quantum mechanical and so the resulting system could behave much like an atom, including having things that look like energy levels. The universe rhymes.

pdonis 2y ago

> I still do understand what a "gravitational atom" might be. It's a vague gesture in the direction of a speculative theory of quantum gravity. It's not anything we have any actual evidence for.

pokeymcsnatch 2y ago

> I thought it is pretty well accepted there isn't a "gravaton" like there are photons. Different branch of physics that we can't quite mesh with GR yet. A graviton is the quantized "piece" of gravity, like phonon is for sound/mechanical waves, or photons for EM. It exists as much as a photon or any other "messenger particles" exists, in that it's a useful mathematical model. It's not something we have isolated/observed with equipment though.

andrewflnr 2y ago

As far as I know the existence of the graviton is 100% up in the air, not well accepted either way. But yeah, particles in energy levels gravitationally bound to a black hole in a similar way electrons are electrically bound to a nucleus.

gradientsrneat 2y ago

In an atom, the electrons orbiting the nucleus are only allowed to be at discrete energy levels (the energy levels are "quantized"). In a classical model of an orbit, the energy level of a spaceship orbiting a planet can be thought of as the speed it has that allows it to orbit at a certain altitude, assuming no friction or other effects. Velocity is energy in that case (E=m*v^2 in classical mechanics). Unlike electrons in an atom, the spaceship can be in any one of a continuous range of energy levels (up to escape velocity). The proposal in the article is (I think) that bosons orbit certain black holes in quantized energy states, like electrons would orbit an atomic nucleus.

vagab0nd 2y ago

Speaking of PBS SpaceTime, pretty much every one of their videos starts fine but always lose me around the half point. Anyone feel the same?