# Quantum Ripples?

Would someone please explain what quantum ripples are? I've heard of gravitational waves, are they the same thing?

I overheard someone saying that it could allow for possible faster than light speed travel? Is this true or complete nonsense.

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"Quantum ripples" isn't a real term in physics. Sounds like pop-level science writing, or casual talk. What is the context of where you saw this? –  DarenW Feb 9 '13 at 8:00

I have never encountered the term "quantum ripple" as a technical term in physics. As s result, I'm not equipped to assert whether they are the same as gravitational waves, but I suspect that whoever you've been talking to about this is not using the term "quantum ripple" synonymously with "gravitational wave." Nonetheless, here are some quantum things that one might call a "ripple" in some sense:

1. In the context of quantum mechanics, the state of a particle is described by function, called its wavefunction, and this wavefunction essentially encodes the probability that you would obtain certain values for certain observable quantities if you were to make a measurement of these quantities on the particle. Often wave functions look like ripply, periodic functions, so one might be inclined to use the term "quantum ripple" to describe these functions.

2. In the context of quantum field theory, particles, like photons for example, can be thought of as excitations of certain quantum fields. The intuition that some physicists have, including myself, is to picture such excitations as sort of "ripples," in the fields, so you might also be inclined to think of these as "quantum ripples."

Faster than light travel is almost surely nonsense (I don't say complete nonsense only because I feel uncomfortable making such definitive statements, but complete nonsense might be a better description)

Hope that helps!

Cheers!

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Sometimes the phase velocity of a ripple can exceed the speed of light, as long as the group velocity, which sends information does not. en.wikipedia.org/wiki/… –  Mew Feb 9 '13 at 10:49
This link says ripples could allow faster than light travel of space-crafts: en.wikipedia.org/wiki/Alcubierre_drive. –  Mew Feb 9 '13 at 13:13
@Chris The Alcubierre drive wouldn't really allow for faster than light travel in the standard sense of an object moving through a spacetime background in such a way that it's 3-velocity at some point along its worldline is great than $c$. Instead, if allows for effective speeds greater than $c$ via warping spacetime in a partiucular way. Also, I don't see anywhere in the article where the word "ripple" is used. Also, the first link you posted points out that non of the superluminal speed examples can actually be used to send signals (information), which is the main issue. –  joshphysics Feb 9 '13 at 17:14
In my first link I quote: "One such distortion is the Alcubierre drive, which can be thought of as producing a RIPPLE in spacetime that carries an object along with it. Another possible system is the wormhole, which connects two distant locations as though by a shortcut." –  Mew Feb 10 '13 at 0:24
Thank you guys for the explanation! –  МикроПингвин Feb 10 '13 at 5:39