The Hypothesis is that the Graviton could be the force carrier for gravity. But with the knowledge of Einsteins theory of relativity which states that Gravity is NOT a Force, wouldn’t the Graviton disprove Relativity or at least some aspects of it?
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>wouldn’t the Graviton disprove Relativity
Without commenting on the rest, which I’ll leave to more informed commenters, I want to point out that this part of your objection isn’t a big deal. Relativity is a model. A professor of mine once said (quoting someone else, I’m sure) “All models are wrong, some are useful”. Newton’s classical mechanics are wrong. But they’re very, very useful, even today.
> wouldn’t the Graviton disprove Relativity or at least some aspects of it?
Welcome to science!
That’s literally the entire point of science you’ve just written there. Let’s run down the exactly three options here, though their likelihood will differ vastly from a precise 33/33/33 scenario. Either…
A- The particle doesn’t exist, and someone manages to prove it doesn’t exist. Einstein’s Theory of Relativity lives to see another challenger, unscathed.
B- The particle does exist, and some scientist in the near-ish future who found it gets to make new physics theories to accommodate for it, replacing Einstein’s Theory of Relitivity with a newer, more complete model.
C- The particle does exist, but it’s a resulting particle, not a causing particle, or more clearly, the bends in spacetime “create” gravitons, instead of the gravitons “creating” the bends in spacetime. This would be a bit like discovering neutrinos, when light is already a complete theory. This would essentially not cause much trouble for Einstein’s Theory of Relativity, it would just cause a few textbooks to need a re-write to include the graviton particle as part of the spacetime bends side-effects.
It’s a big deal when trying to unify relativity with quantum physics. A force-carrying particle would add a quantum value for gravity to the current quantum zoo of particles and give us a totally new way to model gravity, from the least possible unit to all of the universe. If it turns out gravity is a force we’d be able to seriously consider modeling the interiors of black holes. We could more precisely model orbits. We could directly hypothesize anti-gravity technology. We could build weapons that make nukes look like cat farts. Getting ahead of myself…
They do so because there must be a connection between QFT and ART.
Booth theories are well probed but we do still not have an idea how they are connected.
You can measure the effect gravitation has as an amount of energy and because of einstein energie is equivalent to a mass you can call it a (virtuell) particle and name it graviton.
The idea is that gravitation is somehow quanted like anything else.
This is an open question and the one who found the answer will get the nobel prize and come into the liga of einstein himself.
Einstein’s theory says gravity is not a force but the bending of space-time. However, in quantum mechanics, everything’s about particles and forces. Gravitons come in here, thought of as the ‘force carrier’ for gravity. The big problem? These two theories, Einstein’s relativity and quantum mechanics, don’t play nice. So, scientists are still figuring this stuff out. It’s like trying to merge chess and checkers into a single game. We ain’t there yet.
Force isn’t a good concept to use in modern time, at a technical level. You can use “force” colloquially to give names to something (e.g. force carrier), but it’s not a technical concept to quibble over on whether something is really a force or not.
When Einstein came up with General Relativity, the idea of gravity is not a force was based on Newtonian physics’d real force vs fictitious force. In Newtonian physics, A real force is a force that can be seen in the inertia frame, while a fictitious force is an (otherwise unexplained) acceleration of all objects in a frame accelerating compared to the inertia frame. If you change your reference frame so to “undo” that acceleration, you will eliminate the fictitious force.
Because gravity acts on everything the same way, Einstein posits that it should be like a fictitious force.
However, there is a crucial difference here. Unlike Newtonian physics, you can’t never eliminate gravity altogether just by changing the frame of reference. This is because of the curvature. You can eliminate gravity *locally* up to 1st order only by changing the frame of reference, but if you choose a frame of reference to eliminate gravity at one point, you will see even more gravity elsewhere. Thus, to describe gravity, Einstein needs a metric field, which basically describe which change of frame of reference needed to eliminate gravity at each point. The metric field, of course, can be perceived differently depends on the frame of reference (for example if you’re already at a frame of reference where gravity don’t exist at that point, then the metric you see would be the boring Minkowski metric), but the curvature cannot be eliminated.
From modern perspective, the “true” gravity force is the curvature itself. The metric field is not the source of gravity. (just to put in context, Einstein himself was struggling with philosophical issue regarding space with different metric but indistinguishable gravitational effect – this is the “hole argument”; from modern perspective, this is a meaningless distinction, the 2 spaces are the same, just described differently)
But this is extremely similar to the way other forces are already work in quantum physics. The fermions are described by fields, which does not have exact numerical values; rather, their “perceived” value depends on the frame of reference. The force carriers describes which frame of reference you need to change to to not see that force. Once again, you can eliminate the force at any points by choosing a new frame of reference, but you cannot eliminate it entirely. The curvature of the field is the real source of the force.
Of course, there is still the crucial different between gravity and other forces. Gravity acts the same on all kind of particles, while other forces having different effects. But here is where all sorts of hypothetical come in. For example, for many possible choice of frame of reference, gravity acts differently in different direction; but we only know that because we know how to change the frame of reference. Who is to say that it doesn’t happen for particles too? Perhaps all fermions are really the same thing, we just naturally see them as different because we look at them the wrong way, and once we pick the right frame of reference, other forces act the same on all particles. Perhaps all forces are part of the same whole, and the part that we see as gravity is just the part that act the same on everything.
Everything related to Quantum mechanics is highly debatable, with multiple perfectly working mechanics that are different from each other, all of which contains something that is technically impossible. Limitations of observation also mean it may be impossible to ever ascertain the actual truth of reality.
So while maybe it could change things, this wouldn’t be anything new to have controversial and contrary theories in the realm of QM.
Einstein himself disavowed most of them choosing to focus on relativity and gravity instead, because he was unhappy with the unreconcilable aspects of most QM models. Schrödinger came up with the cat example for the sake of showing how absurd he felt the Copenhagen model of quantum physics was (a cat obviously cannot actually be both dead and alive at the same time and indeed there is debate as to what wave function collapse actually mechanically is in actual reality).
Interestingly the mainstream QM model is the mainstream model partly for political reasons but mainly simply because it has the simplest and therefore most convenient to use formula. Bohmian is the next most likely format, essentially much closer to a classical physics approach that explains wave-like behavior of particles as the result of waves influencing the particles rather than the particles behaving as waves. But it also has some unreconcilable aspects to it. And it’s longer formula make it more annoying to calculate with.
Basically? Scientists salivate at the thought of proving other scientists wrong 😀 It’s one of the things that’s helped get science to where it is today. Nothing is sacred, no laws or rules or theories are off-limits to explore and attempt to disprove.
Force = mass x acceleration.
Gravity has no mass (as far as we know) but it provides the acceleration (9.81 m/s^2 on earth). We call gravity “acceleration” because we don’t know what else it is. Frankly, it’s a rather embarrassing fact that science cannot say what gravity IS, even though we can describe, with ridiculous precision, what it DOES. Who knows, one day it might be considered a force. We won’t know for sure until we figure out what it is and why it exists.
General relativity did not “disprove” Newtonian mechanics. It extended the range of scenarios where you can apply it and get valid answers. In certain specific scenarios, (e.g. throwing a ball into the air) Newtonian mechanics works really well. Relativity “simplifies” to Newtonian mechanics in those scenarios.
Similarly, a theory of quantum gravity wouldn’t “disprove” relativity, but it would allow us to compute accurate predictions in situations where we know classical relativity doesn’t apply, (e.g. in very hot or very dense scenarios like the fraction of a second just after the big bang). Such a theory would “simplify” to general relativity in situations where we currently know that relativity works well (e.g. for computing the orbits of planets). Part of the challenge of coming up with a good quantum gravity theory is getting it to “match” relativity in those mundane scenarios.
There are lots of reasons we expect a quantum theory of gravity. Here are a few I can immediately think of:
1) Singularity theorems. There are mathematical proofs that classical relativity breaks in certain scenarios. We need a way to avoid these.
3) Every other field is quantized. General relativity is something called a “classical field theory”. Every other time physicists have had a field like this which describes another type of interaction (i.e. electromagnetism, strong interaction, and weak interaction) we have been able to take the theory and “quantise it”. This quantized theory has worked really well. Why not do this for gravity?
4) There are [mathematical theorems](https://en.m.wikipedia.org/wiki/Weinberg%E2%80%93Witten_theorem) that show that you cannot make any quantum field theory where the graviton can be broken down into multiple “component particles” reduce to classical general relativity in those mundane situations I spoke about above. The graviton must be a fundamental particle, and no quantum theory could simplify to classical relativity without them.
5) Black hole thermodynamics. We can already “do quantum gravity” pretty well in under certain conditions (words to search here are things like “semiclassical gravity” and “effective field theory”). Using this, we can show that black holes have thermodynamic properties like temperature. Unfortunately, if you follow these ideas, you end up with certain difficulties relating to mathematical theories of information. One way to resolve these is with a full quantum theory of gravitons.
6) Holography and the AdS/CFT correspondence. It is pretty well understood that (at least under certain conditions) theories of gravitons can be rewritten as theories without gravitons. We understand quantum field theory very well when there are no gravitons. We can use this “correspondence” to understand things about quantized gravitons.
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