Science Confirms That Gravitational Waves Exist

[Sphere]

I'm a physics noob so this may sound stupid: This thought just occurred to me: If gravity propagates via waves (not sure if propagates is the correct term but i don't have a better one) and all waves have a speed does it mean there is a speed of gravity? And if not why not?

Iskar has it. But to add a little more history.

Newton was unsettled that his theory of gravity was instantaneous. Gravitational attraction between two objects was "spooky action at a distance".

Einsteins General relativity gets rid of this by having gravity as a field with a value at each location in space. Changes in this field could only occur at the speed of light. This gets rid of of spooky action at a distance.

Along comes quantum mechanics and quantum entanglement, which allows particles at enormous distances to somehow know what the other is doing instantaneously. Spooky action is back. Einstein did not like this and spent a good chunk of his later life trying to get rid of it by coming up with a better theory (to no avail).

[Mangalore]

Gravitational waves propagate at the speed of light. However, one needs to distinguish between gravitational waves, which are a disturbance of the geometry of spacetime caused by significant changes in the mass/energy distribution at some point in the universe, and the propagation of gravity itself as a force (analogue to photons transmitting the electromagnetic force). The hypothetical particle/wavelet-thingy for gravity, analogue to the photon, is the graviton, but as far as I know it has not been detected yet. It's detection would be a major step in understanding quantumgravity, i.e. how the usually large-scale theory of relativity works in the completely different setting of particle physics. One would expect the graviton to move at the speed of light, too, though.

Is the graviton still a thing given the discovery of the Higgs boson? In essence the Higgs field declares gravity to be a side effect of another force/field affecting the other fields creating elementary particles so (I'm not sure) but wouldn't this void the expectation that there is a graviton when there is already a Higgs particle aka wouldn't that be the graviton?

[Magister Militum Flavius Aetius]

The Higgs Boson simply confirms the standard model. Quantum Gravity and/or String Theory are a whole different thing.

[Iskar]

Is the graviton still a thing given the discovery of the Higgs boson? In essence the Higgs field declares gravity to be a side effect of another force/field affecting the other fields creating elementary particles so (I'm not sure) but wouldn't this void the expectation that there is a graviton when there is already a Higgs particle aka wouldn't that be the graviton?

The Higgs field (whose transmitting particle/wavelet is the Higgs boson recently detected by CERN) is a completely different thing from gravitation and the hypothetical graviton. While the gravitational field describes how masses/energy distributions affect each other (in Newtonian approximation: what forces they enact on each other), the Higgs field describes how matter attains mass as a property at all.

The point that is probably difficult to grasp at first here, is that one needs to get away from the everyday intuition that "matter" and "mass" are basically synonymous. In fact from the point of view of particle physics and its otherwise wide-reaching symmetries it is a priori astounding that some particles have mass, while others don't and that the masses of the particles are so different in scale. In a perfectly symmetric setting all particles would be massless, like the photon. Now the interaction with the Higgs field at least procedurally explains how "mass" as a property of matter (i.e. particles/wavelets) actually comes to be: The stronger a particle interacts with the Higgs field, the more mass it has. (Figuratively speaking, particles interacting more strongly with the Higgs field get impeded by the Higgs bosons interacting with them and become more inert.) So the beauty of the Higgs field is that it puts mass as "gravitational charge" on the same level as electric charge - a mere property of the underlying matter (well, almost, because photons do not have mass but are still affected by gravity, but that is basically the problem of making (algebraic) quantum theories compatible with the (geometric) theory of gravity in a nutshell.)

Now the theory of relativity describes (to be somewhat more precise) how a given mass-energy distribution (encoded in the energy-momentum tensor) relates to the geometry of space-time (encoded in the Einstein and metric tensors), so it assumes a priori that matter has mass and does not bother where that property came from. The graviton would be the hypothetical transmitting boson of the gravitational field (analogous to the photon for the electromagnetic field) if gravity was properly quantised.

(The main problem in doing so is that the theory of gravity uses a mathematical formulation that implies a smooth, continuous structure of space, while quantum theories require there to be some smallest units of everything, i.e. quanta. There has in fact been some astonishing work by mathematician Alain Connes in developing so-called non-commutative geometry that naturally produces something which behaves very much like one would like hypothetical "space quanta" to do. I can try to elaborate on all that, but maybe we'd be digressing too much here, so we might wish to adjourn to a separate thread. It might, depending on everyone's knowledge of mathematics/geometry also be necessary to give a short introduction into the geometrical "language" that the theory of relativity is formulated in.)

[Sphere]

Is the graviton still a thing given the discovery of the Higgs boson? In essence the Higgs field declares gravity to be a side effect of another force/field affecting the other fields creating elementary particles so (I'm not sure) but wouldn't this void the expectation that there is a graviton when there is already a Higgs particle aka wouldn't that be the graviton?

Nah mate. To compare it with electronmagnatism

Charge A <-Photon->Charge B
"Mass" A <-Gravitron->"Mass" B

There are several of things which go into the sum total of a particles mass/energy, the higgs mechanism is just one of them. The Gravitron, in theory, is still doing the work of carrying the force.

But it should be noted that the graviton has zero experimental evidence because gravity is so incredibly weak as to be undetectable on small scales. Also there is no real theoretical framework (i.e. equations) for quantum gravity. Just kinda a hand wavy "all the other forces of nature are this way so gravity probably is to". But in truth, we only have a real scientific/empirical understanding of gravity on large scales (i.e. General Relativity).