| MadSci Network: Physics |
Hello, Kirk.
Gravitons supposedly carry gravitational attraction. They do not cause it.
I say "supposedly" because gravitons might not exist.
In the universe we know of four fundamental forces; electro-magnetism
(electricity and magnetism), the strong nuclear force (which holds atoms
together), the weak nuclear force (which causes radioactive decay), and
gravity (which keeps me from slam dunking a basketball, no matter how hard
I try). Each of these forces is carried accross distances by sub-atomic
particles called bosons. It's a little misleading to call bosons
"particles" because they have no mass and behave somewhat like waves. The
electro-magnetic force is carried by photons. The strong nuclear force is
carried by gluons. The weak force is carried by weak bosons, and gravity
is carried by gravitons.
Or so we thought. Earlier in this decade, it was shown in a brilliant
piece of detective work by Sheldon Glashow, Abdus Salam, and Steven
Weinberg that the electro-magnetic force and the weak nuclear force are
actually one and the same. Radio-active decay is carried by photons after
all, and weak bosons don't exist.
It's very possible that the graviton doesn't exist, either. It's predicted
mathematically, but so were weak bosons. Once it was found that the weak
nuclear force was just a manifestation of electro-magnetism, it was
realized that the basis for predicting weak bosons was faulty.
If gravity is ever unified with the other forces, then gravitons won't be
needed anymore, and the theory will be discarded.
It's interesting to note that of the sub-atomic particles we've observed so
far (over 400!), we've yet to see the graviton.
But let's assume that gravitons do exist, and are just what the standard
model predicts they are - massless bosons with two units of spin
charge.
Gravitons carry gravitational attraction between two massive bodies, in the
same way that photons carry magnetism, or gluons hold electrons in orbit
around nuclei. How exactly that's done hasn't been explained. But I'll
give you my opinion about it.
Everywhere, even in a complete vacuum, there exists a sub-atomic network of
lines. They connect everything to everything else. Every particle is
linked to every other particle in the universe by these lines. They can't
be seen or detected, because they're not comprised of matter. But to help
us visualize this, we will imagine that these lines are actually ropes,
tying everything together. The difference between our imaginary ropes and
real ropes cowboys use is that our ropes can pass through other ropes, and
no damage is done.
The gravitational attraction between two bodies can be explained by waves
in the rope. Remember, the graviton exhibits wave-like behavior as well as
particle-like behavior. Since our rope can't stretch or break, waves
shrink the distance between the two bodies, like this -
0------------------------0
_ _ _
0\_/ \_/ \_/ \0
If this is the behavior of gravitons, we never can find them in particle
accelerators. They're not particles being emmitted from massive bodies,
they're waves traveling along the network of lines that connects massive
bodies. Their ability to carry the force of gravity is due to their
wave-like behavior, not their particle-like behavior.
It makes more sense that way.
Unfortunately, quantum happenings don't have to make sense. I may have it
all wrong. I'll leave you with two quotes from two of the fathers of
quantum physics.
"I think I can safely say that nobody understands quantum mechanics" -
Richard Feynman
"If you're not confused by quantum mechanics, you really don't understand
it" - Niels Bohr
I hope I was of some help,
Layne Johnson
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