Have scientists worked out the speed of the fundamental forces?
eg. Does changes in mass or movement of mass cause instant changes of gravity fields or does gravity propagate in waves at the speed of light (I’m pretty sure they haven’t figured out this one)
And the same goes for all the other fundamental forces, has the effective speed been test before? Are there any attempts to obtain their speed or is it too hard to measure or is it safely assumed it’s the speed of light?
Illuvitar: Good question. I think the working hypothesis is that all forces can be seen as waves in a field, like the electromagnetic field with radio waves, and that all waves propagate at Einstein’s Constant (speed of light in a vacuum). We are currently trying to measure gravity waves, or fluctuations in the gravity field, to test that hypothesis.
Of course, the particles that carry the fundamental forces are wavicles, like the good old photon. (I don’t know if we’ve ever been able to observe the graviton, but it’s hypothesized to exist. Gravity is a tough thing to rectify with the current model.)
Gravity waves haven’t been observed yet, though not for lack of trying. A number of ground based experiments have so far failed to detect them. IIRC a space based experiment is due to be launched fairly soon to answer this very question.
With any luck, definitive observations should arrive sometime in the next five years.
Oops… I didn’t read previous post correctly… It says pretty much the same as what I just posted (about gravity waves, that is).
-Oli
I believe that gravity and electromagnetism are carried by massless particles and thus transmit at the speed of light.
Weak and Strong Nuclear Forces have force carrier particles which have mass, therefore propagate at velocities slower than light.
Gravitational waves may actually have already been detected by the LIGO facility (ground-based), but the data analysis at LIGO is difficult enough that nobody’s really sure yet. This is not expected to be a problem for LISA (largely because LISA operates in a different frequency range), which should be launched sometime this decade. Even once the various gravitational-wave observatories are up and running, though, the detection of individual gravitons won’t occur any time in the forseeable future: Gravity is very weakly interacting, so it’s only when you have an insane number of gravitons all propagating together in a wave that you have a chance of detecting a very weak signal.
Gravity and electromagnetism, as Enola said, propagate at the speed of light. The weak force propagates at slower speeds, but given enough energy, the speeds can be as close to c as you’d like. The strong force is an odd case: It can be considered as being carried by mesons, which are massive. However, the meson interactions which are responsible for the strong force are themselves caused by a more fundamental force, sometimes called the color force. Since the color force is mediated by gluons, which are massless, it propagates at the speed of light, as well.
Except for electromagnetism (i.e., light), I don’t think that these speeds have ever been directly measured. However, the most successful theories we have for these forces seem to be pretty unambiguous in their prediction of the speed of the other forces, and any attempt to modify those speeds will cause some serious repercussions. Essentially, what it comes down to is that there can only be one fundamental speed in nature, which happens to be the speed of light. Try to incorporate another one, and Special Relativity falls apart completely. Since Special Relativity is at the core of all modern physics, and has been verified in every test, this would be a pretty serious issue.
Which is another reason it should be called “Einstein’s constant” instead of the “speed of light (in a vacuum)”.
Chronos: Has gravity been observed to propagate at the speed of light, or is that still a hypothesis?
I Am Not A Physicist, but I understood that gravity a fundamental feature of Einstein space-time-whatever that just is. Is it subject to time-distance considerations?
Ok. So electromagnetism has been measured, gravity’s speed is currently being investigated, but the other forces speeds haven’t been measured, why not? Are there/has there been any attempts to measure them? You’d think this would be a pretty important thing to check, what if the theories got the speeds wrong?
because the strong and weak forces act on particles within the nucleus or at very short ranges. Thus the effects are inferred by nucleus stability or particle collisions but cannot be measured over a decent distance (say atomic length), and so the time of action (and thus the speed) cannot be measured
The speeds for the two other fundamental forces, the weak and strong nuclear forces, would be quite difficult to measure, i would think
whoops sorry i didn’t see the (better) reply above my post
Good replies so far, except that the weak and strong forces should propagate at the speed of light, just as electromagnetic and gravitational. Yes, the weak force is carried by massive particles (the W+, W-, and Z0), and these particles must move slower than light speed, but the force field is mediated by virtual particles, whose effect moves at the speed of light. As mentioned already, the distances involved are too small for us to measure the actual speed, but the theory says c.
Also, predictions of gravity waves are due to General Relativity, which says that they should move at the speed of light, too.