# The Naked Scientists Forum

### Author Topic: Light Wave - Particle duality  (Read 3279 times)

#### Fluid_thinker

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##### Light Wave - Particle duality
« on: 10/10/2012 10:30:13 »
Is it that a light wave is not made of photons, but a form of energy in a wave (therefore it appears that the photon exists in a superstate position). So that when we choose to look at the properties of light or interact with it that it collapses the wave function into photon(s) with the properties of the wave (spin etc). Thus, the photons can be recombined to produce the energy wave.

This way can a wave  produce 1, 2 or 3 photons or more with them sharing entangled properties of the wave.

#### lightarrow

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##### Re: Light Wave - Particle duality
« Reply #1 on: 10/10/2012 12:26:41 »
Is it that a light wave is not made of photons,
This, for sure.
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but a form of energy in a wave
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(therefore it appears that the photon exists in a superstate position).
It's the em wavefunction which can exist as superposition of others wavefunctions. Photons are the energy of the states defined by the wavefunction
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So that when we choose to look at the properties of light or interact with it that it collapses the wave function into photon(s) with the properties of the wave (spin etc).
What does it mean "photon(s) with the properties of the wave"?
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Thus, the photons can be recombined to produce the energy wave. This way can a wave  produce 1, 2 or 3 photons or more with them sharing entangled properties of the wave.
This is possible as long as the energy is conserved.
« Last Edit: 10/10/2012 12:28:23 by lightarrow »

#### Fluid_thinker

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##### Re: Light Wave - Particle duality
« Reply #2 on: 12/10/2012 11:39:53 »
Thanks for this.

With reference to the photon.

As i understand high energy photons behave more like particles and have very discreet quanta. Where as low energy photons appear to have less discreet quanta to the point they blur into the background. Therefore not behaving like a particle.

How do both exist as a wave?

#### JP

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##### Re: Light Wave - Particle duality
« Reply #3 on: 12/10/2012 17:49:08 »
First, radio waves are made of photons, since all EM waves are.  But there are two issues with measuring or describing them as photons.

First, when we measure photons we detect them as they deposit their energy into a detector.  The less energy they deposit, the harder they are to detect and discriminate from background noise in our measurements.  For photons, energy is proportional to frequency, and radio waves have very low frequency (compared to other forms of EM waves such as light, X-rays or gamma rays).  It would be very hard to detect a photon of radio waves against background noise.

The other issue is that while all EM fields (and all particles/fields in general) are made of quantum objects, such as photons, that have both wave and particle aspects, the wave aspects dominate their behavior when the wavelength is large, while the particle aspects dominate their behavior when the wavelength is small.  Radio waves have relatively large wavelengths, on the order of meters, and so they tend to behave very much like waves.  The photon wave/particle model therefore isn't often needed to describe them.

#### sciconoclast

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##### Re: Light Wave - Particle duality
« Reply #4 on: 04/11/2012 01:04:50 »
In the prevailing interpretation of quantum theory, the Neils Bohr interpretation, light does not propogate at all.  There is no traveling photon or wave. Bohr was of the school in which the ultimate nature of reality is purely mathematical. Instead of a moving wave or photon there is an expanding quantum field which is only a mathematical abstraction defining the probability for a photon occurring at any position and time. If a photon is tested for and occurs the quantum probabilities are said to actualize, or collapse. In some versions the photon itself is considered as a mathematical abstraction but with deterministic properties rather than probable ones. If it is re-emitted or reflected it disappears into a new probability field.  The  time distance intervals of the linear algebraic vectors in an abstract Hibert space are referred to as wave functions and the possible positions for photon occurrence are referred to as an interference pattern only out of deference to the previous historic terminology. There is no wave and there is no interference. Classical wave formulas are usually used by those working with optics because the formulas are simpler and the results are the same. According to the Bohr principle of complimentarity the quantum field that solves much like a wave and the photon that solves much like a particle cannot both be exhibited at the same time. It must be one or the other. If you want further information on this I suggest:  http://plato.standford.edu/entries/qm-copenhagen       .

#### Bill S

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##### Re: Light Wave - Particle duality
« Reply #5 on: 04/11/2012 01:39:00 »
What is light made of: waves or particles? This basic question has fascinated physicists since the early days of science. Quantum mechanics predicts that photons, particles of light, are both particles and waves simultaneously. Reporting in Science, physicists from the University of Bristol give a new demonstration of this wave-particle duality of photons, dubbed the 'one real mystery of quantum mechanics' by Nobel Prize laureate Richard Feynman.

#### sciconoclast

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##### Re: Light Wave - Particle duality
« Reply #6 on: 04/11/2012 16:03:33 »
Thanks for the interesting reference.
There is more than one interpretation to quantum theory.  The one I gave is what I believe to the most currently adhered to. However, I do not personally adhere to it myself.

I would agree to the response to that article by EyeNStein: "With lose use of terminology like this article confusion remains ".  I personally think that the statement in the article that "the photon can be at different places at the same time" should be reworded to state that the quantum field allows for multiple possible positions for photon occurrence; but that only one can be actualized. Exaggeration by science writers for effect is very common.

The article statement that "when a photon is observed it behaves as either a particle or as as a wave. But both aspects are never observed simultaneously" is in agreement with Bohr's principle of complimentarity.

I would welcome any experiment that proves simultaneous occurrence of wave and particle aspects as it would correlate some of my own work. However, the sited experiment, which at present is only a thought experiment, relies on an interpretation of a variation of the delayed choice quantum eraser experiment and an interpretation of the Bell Theorem. Both interpretations are subject to criticism but that is another subject.

As I mentioned there is more than one interpretation to quantum theory. If you subscribe to the Dirac interpretation then there is a superposition of the wave and particle states. In response to the article both grondilu and Electronhelix referred to this interpretation. The statement by Electronhelix that "since a simple wave may be considered to be two in-phase contra-rotating, circular polarized waves, it should not be supprizing that particle like properties are observed" sounds a lot like something from one of my papers.

A main stream interpretation of quantum theory that is most like my own is the David Bohm interpretation in which two bound Dirac neutrinos form the photon core and generate a pilot wave.  This is a good statring point but I think the photon core and surrounding field is much more complicated than this. The Bohm interpretation does not rule out the Bohr insights on the ultimate nature of reality but it does restrict the photon to a complex system that remains actualized, or in other words meets the definition of what we would percieve as real rather than abstract.

Some time ago I posted some original experiments on this site which seemed to favor the Bohm interpretation over the Bohr interpretation; most of which were sent to the new theories dungeon.  There seemed to be a lack of understanding of the concepts involved in some of the responses.  I demonstrated one of the experiments by invitation at an international conference on new theories and I am currently trying to publish.

There is a famous quote, "the answers we get from nature depend on the questions we ask".

#### yor_on

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##### Re: Light Wave - Particle duality
« Reply #7 on: 04/11/2012 20:58:25 »
Heh:)

sweet quote Scico, and quite true.

#### yor_on

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##### Re: Light Wave - Particle duality
« Reply #8 on: 04/11/2012 21:07:50 »
As for if we have a 'simultaneous possibility/probability' of, for example, a electron to be in two places simultaneously I'm not sure. As you point out the probability of measuring should invalidate one of them, as I see it. You can see this occurrence several ways if so. Myself I take it as a statement of the arrow allowing only realized outcomes, to become the 'history' on which we build the probabilities of further outcomes. If we assume a reality in where a electron do occupy two different locations simultaneously we also must assume the the Pauli exclusion principle allowing for this. But it is also a question of how the arrow 'operates', and what it is.
« Last Edit: 04/11/2012 21:09:27 by yor_on »

#### evan_au

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##### Re: Light Wave - Particle duality
« Reply #9 on: 05/11/2012 02:23:43 »
The wave nature of light (and other electromagnetic radiation like radio waves & gamma waves) is more readily seen if the light is coherent (like a laser): A single frequency with constant amplitude, with all of the waves in-phase.

• Black-body radiation from hot objects like the sun contains a mixture of all frequencies, phases and amplitudes, so it is hard to single out the wave nature (which is why Newton, Huygens & others debated it for centuries).
• By heating pure vapours, it is possible to single-out specific sets of wavelengths where the gas emits strongly, but the amplitude and phase is still random.
• Radio waves from a radio transmitter tend to be very coherent, and the wave nature is very visible (especially if it is transmitting morse code, in which the transmitted signal is much like a sine wave).
• Unfortunately, it becomes harder to produce laser-like behaviour at higher frequencies - radioactive materials emit gamma rays randomly, and a Gamma-ray laser (GRASER?) is well beyond our current technical capabilities. However, with such a device, some wave-like properties of gamma rays may become visible.
• An X-ray laser may be more feasible in the short term: http://en.wikipedia.org/wiki/X-ray_laser
• Even with non-coherent X-ray sources, X-Ray Crystallography is a known science which utilises the wave nature of X-Rays: http://en.wikipedia.org/wiki/X-ray_crystallography#X-ray_analysis_of_crystals
« Last Edit: 05/11/2012 02:38:18 by evan_au »

#### waytogo

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##### Re: Light Wave - Particle duality
« Reply #10 on: 21/11/2012 11:30:44 »

Don't worry, you are not the only one. I'm still searching for an satisfactory answer to that, anyway, good luck.

#### Phractality

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##### Re: Light Wave - Particle duality
« Reply #11 on: 21/11/2012 20:38:38 »
I detest models that reduce all of reality to math, with no underlying substance. I believe particles have wave properties because every fundamental particle consists of an orbiting pair of waves. Since this is the mainstream forum, that's about all I can say without having my account suspended.

#### The Naked Scientists Forum

##### Re: Light Wave - Particle duality
« Reply #11 on: 21/11/2012 20:38:38 »