The dark side of light: negative frequency photons
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The dark side of light: negative frequency photons
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Re: The dark side of light: negative frequency photons
#2Here's the paper (PDF):
http://physics.aps.org/featured-article-pdf/10.1103/PhysRevL...
It's about observations & theory where you can get waves in Cherenkov radiation which propagate against the dominant direction.
Re: The dark side of light: negative frequency photons
#3The interesting bit is that solving the equations gives you a solution with a negative frequency. Generally those negative frequencies are ignored because for most people a negative light frequency doesn't make sense. But if you extend the analysis further you get a positive frequency light out of interactions with that negative frequency light. And the paper talks a bit about observing those second order effects:
"Here, we have shown how the same process generates a second, so-far-unnoticed peak that corresponds to resonant transfer of energy to the negative-frequency branch of the dispersion relation. "
which means the negative frequency light was something but what it means isn't clear. It could be the tip of a new way at looking at light, or it could be nothing. Some of the experiments it suggests with respect to gravity waves are interesting.
Re: The dark side of light: negative frequency photons
#4I still don't get what a negative frequency is. The frequency is the number of times something happens in a given amount of time. Would a negative frequency be the number of events that were expected to happen but didn't? If so, how could this be differentiated from an error in our expectations.
Re: The dark side of light: negative frequency photons
#5I love the way that math reveals ultimate truths. We consider math to be some abstract thing that we're applying to help explain reality. Instead, it often appears that the abstraction is somehow the True Reality(tm), and our reality is really just an imperfect view of Math(tm).
We view math about like we view electromagnetic waves with our eyes. We see effects of it and reflections and complex interactions of only small parts of the em spectrum.
It's interesting to wonder if we could develop a way to "see math" in its pure form.
(Sorry, Friday afternoon speculation... not currently taking any drugs.)
Re: The dark side of light: negative frequency photons
#6I still don't get what a negative frequency is. The frequency is the number of times something happens in a given amount of time. Would a negative frequency be the number of events that were expected to happen but didn't? If so, how could this be differentiated from an error in our expectations.
Physics often uses the sign of a frequency to indicate the direction of travel with regard to a reference frame.
E.g. 2 Hz is a wave oscillating two times per second and travelling to the right, -2 Hz is the same travelling to the left.
In some cases direction isn't really meaningful (standing waves, or the height or pressure of a medium as seen by a stationary observer). In others, the direction of propagation can be quite significant.
Re: The dark side of light: negative frequency photons
#7I love the way that math reveals ultimate truths. We consider math to be some abstract thing that we're applying to help explain reality. Instead, it often appears that the abstraction is somehow the True Reality(tm), and our reality is really just an imperfect view of Math(tm). We view math about like we view electromagnetic waves with our eyes. We see effects of it and reflections and complex interactions of only s…
Re: The dark side of light: negative frequency photons
#8I still don't get what a negative frequency is. The frequency is the number of times something happens in a given amount of time. Would a negative frequency be the number of events that were expected to happen but didn't? If so, how could this be differentiated from an error in our expectations.
Don't push the idea of a wave in space too much, that's not how stuff works in quantum mechanics. See Feynman Lectures of Physics, Vol 3, Section 3-3 for a text at the introductory level.
Re: The dark side of light: negative frequency photons
#9I still don't get what a negative frequency is. The frequency is the number of times something happens in a given amount of time. Would a negative frequency be the number of events that were expected to happen but didn't? If so, how could this be differentiated from an error in our expectations.
Physics often uses the sign of a frequency to indicate the direction of travel with regard to a reference frame. E.g. 2 Hz is a wave oscillating two times per second and travelling to the right, -2 Hz is the same travelling to the left. In some cases direction isn't really meaningful (standing waves, or the height or pressure of a medium as seen by a stationary observer). In others, the direction of propagation can b…
This is not true. A wave propagates both in time and space. You're mixing these two. A negative frequency is like a wave travelling backwards in time, not left/right spatial direction.
Re: The dark side of light: negative frequency photons
#10I still don't get what a negative frequency is. The frequency is the number of times something happens in a given amount of time. Would a negative frequency be the number of events that were expected to happen but didn't? If so, how could this be differentiated from an error in our expectations.
Physics often uses the sign of a frequency to indicate the direction of travel with regard to a reference frame. E.g. 2 Hz is a wave oscillating two times per second and travelling to the right, -2 Hz is the same travelling to the left. In some cases direction isn't really meaningful (standing waves, or the height or pressure of a medium as seen by a stationary observer). In others, the direction of propagation can b…
Is a -2 Hz wave travelling to the right the same as a 2 Hz save travelling to the right, but going backwards in time?
Could there be something to John G. Cramer's transactional interpretation of Quantum Mechanics? Instead of probability waves collapsing instantaneously, could everything be mediated by photons going backwards in time?