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The dark side of light: negative frequency photons

arstechnica.com

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Re: The dark side of light: negative frequency photons

#11

Post by beagle3 »

ChuckMcM wrote: post #3

The 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: "H…

At the turn of the 19th century, physicists were quite sure that they had a complete model of the universe, with just two minor unsolved problems: The aberration of light / michelson-morley experiment (which required the theory of relativity to explain), black body radiation (which was eventually explained by quantum mechanics). Actually solving these unsolved problems turned physics on its head.

Negative frequency light might be just a weird artifact. Or it might turn physics on its head. I'd put money on the former, though I hope for the latter.

edit: fix typo "native frequency" -> "negative frequency"

Re: The dark side of light: negative frequency photons

#12

Post by scoith »

stcredzero wrote: post #10
grueful wrote: post #6

Earlier quoted context omitted.

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?

The problem with such interpretations is that they violate causality. Check out Wheeler-Feynman absorber theory for history. Concepts such as collapse of a wave function aren't necessary when you stop treating the observer in a special way and start considering observer-particle as a big quantum system.

Re: The dark side of light: negative frequency photons

#13

Post by grueful »

stcredzero wrote: post #10
grueful wrote: post #6

Earlier quoted context omitted.

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?

"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?"

Yes, all other things being equal. It's a bit less confusing if you leave the signs off and just say that "a wave travelling to the right at f in t is the same as a wave travelling to the left at f in -t.

This is also very much in the "spherical cow" sense of physics - it's true of many ideal cases on chalkboards, but it gets fuzzy in practice due to thermodynamics and other nonidealities. Plus, you can only observe things from the perspective of time moving forwards.

"Could there be something to John G. Cramer's transactional interpretation of Quantum Mechanics?"

There's nothing I'm aware of which is implicitly wrong with a transactional interpretation - you just have no way to empirically prove that it's a valid "why." In physics, we are very often limited to "how" and "what."

It looks to have some ideas in common with Feynman's reaction diagrams and path integrals, so it may be an interesting approach if you're partial to those. The catch is that wavefunction collapse is equally true: it's a model which makes accurate predictions about observable experimental outcomes.

Re: The dark side of light: negative frequency photons

#14

Post by davorak »

scoith wrote: post #9
grueful wrote: post #6

Earlier quoted context omitted.

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.

I have seen a negative sign grouped with frequency. Which was used to distinguish directionality. Most of the time it is understood from context what is meant, if not the speakers fall back on to more something more formal to ensure understanding.

Re: The dark side of light: negative frequency photons

#15

Post by TheAmazingIdiot »

scoith wrote: post #12
stcredzero wrote: post #10

Earlier quoted context omitted.

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?

The problem with such interpretations is that they violate causality. Check out Wheeler-Feynman absorber theory for history. Concepts such as collapse of a wave function aren't necessary when you stop treating the observer in a special way and start considering observer-particle as a big quantum system.

Causality would not seem to be broken if the effects were shunted to an adjacent universe. This would directly assume that MWT is indeed true.

Re: The dark side of light: negative frequency photons

#17

Post by 46Bit »

scoith wrote: post #9
grueful wrote: post #6

Earlier quoted context omitted.

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.

Not quite. A wave going left forward in time is equivalent to a wave 'going right' but backwards in time. Since it is further right in the past than now, it is actually going left.

There's a lot of similar effects in Physics, especially with time and/or antimatter.

Re: The dark side of light: negative frequency photons

#20

Post by scoith »

46Bit wrote: post #17
scoith wrote: post #9

Earlier quoted context omitted.

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.

Not quite. A wave going left forward in time is equivalent to a wave 'going right' but backwards in time. Since it is further right in the past than now, it is actually going left. There's a lot of similar effects in Physics, especially with time and/or antimatter.

Save me the trouble an learn some basic physics. Read Jackson's Classical Electrodynamics, Chapter 7. If it's too complicated for you, read about waves. See how they propagate in time and space, and pay special attention to what happens to the equation when you change the sign of t. If it's too difficult to imagine, try plotting using a program. And anti-matter is not matter travelling backwards in time. See my post below.
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