3 ms·
If you have a nonlinear interaction of a wave with a media, you might have a quadratic term A^2 cos^2(wt). If you remember your trig identities, you'll remember
by mjfl 8y ago
If you have a nonlinear interaction of a wave with a media, you might have a quadratic term A^2 cos^2(wt). If you remember your trig identities, you'll remember that two sinusoidal functions multiplied together decomposes into the sum of signals at the sum and difference frequencies: cos(w_1 t)cos(w_2 t) = 1/2*(cos((w_1 + w_2)t) + cos((w_1 - w_2)t)).
In this case the sum wave is at twice the frequency of the original wave, and the difference wave has 0 frequency - it is just mass transport. I have a feeling that is what is going on here.
- Tomminn 8y agoAgree. It's standard quadratic medium rectification, and they've dressed it up so much they can't see it. The rectification will be associated with a uniform translation of the sample the sound wave travels through.
- whatshisface 8y agoThe article said that it involved interaction with gravity and wasn't from GR, so that doesn't sound like a complete explanation. Nonlinear phonon interaction has already been demonstrated experimentally, but that doesn't seem to include the additional complexity of the interaction with gravity.
- whatshisface 8y ago>you might have a quadratic term A^2 cos^2(wt). If you remember your trig identities, you'll remember that two sinusoidal functions multiplied together decomposes into the sum of signals at the sum and difference frequencies: cos(w_1 t)cos(w_2 t) = 1/2(cos((w_1 + w_2)t) + cos((w_1 - w_2)t)).* The DC component isn't the same as mass transport, because the system still returns to its original state every period of cos(wt). The amplitude of the DC (A^2/2) is also much higher than the one part in a thousand the article was describing.