Just a random, baseless question I'm throwing out there; but how do we know that we haven't discovered the graviton? How do we know we haven't just labeled it as something else? i.e. how do we know for instance the Higgs boson isn't a graviton? If we found it, and it wasn't like what was predicted, would we know to label it as a graviton?
$\begingroup$
$\endgroup$
2
-
2$\begingroup$ Saying that we haven't discovered the graviton is like saying we haven't discovered the photon in 1850. This sentence means that "we have not yet detected quantum aspects of the gravitational wave". $\endgroup$– pathintegralAug 20, 2018 at 0:55
-
8$\begingroup$ It has not been proven that gravity is quantum. There may be no gravitons at all. $\endgroup$– safesphereAug 20, 2018 at 5:03
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
4
The properties of the graviton include:
- it has spin 2
- it is massless (so the force it carries is long range)
- it couples to the stress-energy tensor, which basically means everything should be able to emit and absorb gravitons
- it has zero electric charge and zero color charge
These are extremely distinctive properties, so it's really unlikely that we've already seen the graviton and not noticed. For example, the Higgs has spin 0 and it is massive.
In fact, since the graviton is massless and can be produced by anything, we hypothetically produce tons of them all the time; you produce them whenever you move. The issue is not that we've seen it and not noticed, but that a graviton is too feeble to be seen at all.
-
1$\begingroup$ It also has zero isospin charge (unlike the Higgs). More generally, it has no non-trivial internal charges, because the metric has no internal indices. $\endgroup$ Aug 20, 2018 at 1:12
-
$\begingroup$ Neutrino almost fits the bill, but it has spin 1/2 instead of 2. Would a composite of four neutrinos work? $\endgroup$ Aug 20, 2018 at 10:53
-
1$\begingroup$ @JohnDvorak the Weinberg Witten Theorem rules out composite gravitons in a local QFT $\endgroup$ Aug 20, 2018 at 11:28
-
1
$\begingroup$
$\endgroup$
1
I have checked this thread and e8 also says there must be a gravaton. How in linear thought can we phathom what doesn't fit our interpretation of existence. We can visualize life in 1d, 2d and we see and even understand how odd a ball might act or look like in these situations.
-
2$\begingroup$ This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review $\endgroup$ Mar 10, 2023 at 21:15