# You CAN travel at up to nearly 3x the speed of light!!

:rolleyes: You’re in the sea and waves pass you by. Neither you nor the water moves forward - you both just bob up and down - but waves move on.
:dubious: You are now an electron. This time you do move to the next atoms shell, and another electron buggers off - and so on. You only move a little bit but the effect flows on.
Now you are a photon. This time you do move, and boy do you move, at a phenomenal rate. No bobbing up and down in the same place, or just moving into your neighbours house. BUT - you don’t in fact go in a straight line, you go up and down like a wave. So maybe the effect (i.e. light) moves at the speed of light, but you - the poor little photon has to do nearly triple the distance, following the path of the wave (like a sine wave).
Therefor the photon goes faster than the speed of light because it covers nearly 3x the distance in that same time. Therefor you can go faster than the speed of light. Is this TOTAL bollocks or is it QED (and am I famous)?

Yes. Your mistake is in assuming that the photon is following a sinusoidal path as it moves. It is not. Although a photon can act like either a wave or a pointlike particle, it is in reality neither. The more we learn about photons, the stranger they seem, but they’re still limited to i]c.

The photon doesn’t travel sinusoidally. The sine wave you’re thinking of is a graph of electrostatic field intensity versus distance. It isn’t a trajectory.

Actually, there is another sine wave which is a graph of magnetic field intensity versus distance. The two are 90 degrees out of phase and the field intensities are at 90 degree angles rotated about the direction of the distance.

It’s like a graph of how warm it is as you walk straight across Texas. The days are warmer than the nights, so you could graph that versus your distance, but it doesn’t mean you’re walking up and down ramps.

Oddly enough, I have to say “not quite”. The essential bit is here:

As covered, you’re misinterpreting the up-down of the amplitude graph as a distance. Still, there’s a subtler point in play here: the important thing is the effect, not the particle. The prohibition is on sending information faster than light. People have come up with dozens of ways for various things to travel faster than light, but none of them allow a signal to be sent along for the ride. Now, here’s the bit of trivia that will even wow the physics undergrads at yopur next party: tachyons cannot send signals faster than light.

“What?” I hear you cry. “Tachyons travel faster than light!” Yes, tachyonic particles do travel faster than light, but signals are made out of packets of field excitations which are localized in space at any given time. They have to be. The start of the message can only have travelled a finite distance by the time the end of the message leaves the sender, so the message must at that time be contained in a certain area of space (specifically, a “compact subset”, as us mathematicians call it).

Now, there are two kinds of solutions to tachyon propagation equations, depending on whether the “packet velocity” is faster or slower than light. A good way to think of the distance between particle and packet velocity is to think of a water wave. The water molecules move in roughly elliptical paths, but the wave moves ever forward. The wave is an emergent property of all the water molecules together. Similarly, signals in a tachyonic field don’t all move the same way the individual tachyons do. The amazing thing is that if the packet velocity of the solution is faster than the speed of light, the solution cannot be spatially localized.

To make a long story short, even if you do have a species of quantum particle that travels faster than light, the only way you can use it to send a signal is by waving it starting from where you are, and the only kinds of waves you can use propagate slower than light.

Mathocist would it be possible to send information as the tachyon itself, not as a wave in a tachyon field.
Envisioning two tachon generators and two tachyon detectors one light minute appart. Could information be sent by encoding which tachyon emmiter fires first, and be received at the tachyon detector. Say if I want tea or coffee, I could chose which emmitter to use, with a predefined rule that emmitter 1 = tea, whilst emmitter 2 = coffee. Then Mrs. Doubtfire at the detector end of the experiment will receive my signal in less than 1 minute (because the’re tachyons I’m sending) and know what drink to bring me in the lab within less than 1 minute.
I’d be intersted to know how my above scenario would be resolved without breaking information travels at <c rule.

Remember: there’s not really such a thing as a “single” quantum particle in the classical sense. A “single” tachyon is a single minimal excitation of the tachyon field. The minimal excitations that are analogous to plane waves of the electromagnetic (photon) field propagate faster than light, but as plane waves they’re highly nonlocalized, meaning you can’t really send one. The only combinations of them that you can send are localized, and the packet velocity for those solutions is subluminal.

Thanks mathochist and sorry for getting your name wrong earlier. I was sure there was an answer, but needed your help for the explanation. Well, and succinctly put answer, thanks.