
First photograph of light as both a particle and wave (2015) - ThomPete
http://m.phys.org/news/2015-03-particle.html
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msimpson
This article is much more clear on what the image actually represents:
[http://www.livescience.com/50019-image-light-wave-
particle.h...](http://www.livescience.com/50019-image-light-wave-
particle.html)

"A clever technique and an ultrafast electron microscope have caught an image
of light behaving as both particle and wave at the same time. Here, the wave
nature is demonstrated in the wavy upper portion, while the particle behavior
is revealed below, in the outlines showing energy quantization."

Credit: Fabrizio Carbone/EPFL

Also, this was all published on March 2, 2015.

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deckar01
It took me a few reads for this to sink in.

Quantum interference causes standing waves. Electron-photon particle
collisions cause detectable energy release. The particle collisions occur in
an interference pattern.

~~~
EarthIsHome
Yes, and the colors describe the speeds of the particles as a result of tbe
electron-photon collisions.

It's not necessarily the particles we're seeing, just the particle behaviors
from their collisions.

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_nalply
Swiss here. The École Polytechnique Fédérale de Lausanne (EPFL), where this
experiment has been carried out, is one of the two federal institutes of
technology, the other one is the Eidgenössische Technische Hochschule Zürich
(ETHZ).

[https://en.wikipedia.org/wiki/%C3%89cole_Polytechnique_F%C3%...](https://en.wikipedia.org/wiki/%C3%89cole_Polytechnique_F%C3%A9d%C3%A9rale_de_Lausanne)
[https://en.wikipedia.org/wiki/ETH_Zurich](https://en.wikipedia.org/wiki/ETH_Zurich)

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nsxwolf
It didn't explain the picture.

~~~
leksak
Yeah, I don't know how to interpret it. It's not immediately obvious to me
that I'm looking at a wave and particles at the same time.

~~~
URSpider94
What the image represents is the energy loss/gain of a whole bunch of
electrons that interact one at a time with a light wave traveling along a tiny
metal wire (we call this kind of captive light wave a "phonon").

For each electron fired at the wire, it can either pass through unscathed, or
it can interact with an electron and scatter off with a different energy, like
two billiard balls hitting each other. The collision is fundamentally a
collision between two particles. However, the fact that the properties of the
collisions vary sinusoidally along the length of the wire imply that the
photon is also acting like a wave oscillating up and down the wire.

I disagree that this is the "first time" that we've observed simultaneous
wave-particle behavior, you can see the same thing by firing photons at two
narrowly-placed slits. This results in a diffraction pattern as if the photons
were interfering like waves, but we can confirm that we're detecting single
photons at the detector, and you can even confirm that each photon travels
through one slit or the other ... See [https://en.wikipedia.org/wiki/Double-
slit_experiment](https://en.wikipedia.org/wiki/Double-slit_experiment)

~~~
AnimalMuppet
One nit: A phonon is a vibration of a lattice, not light.

~~~
URSpider94
Yep, that should have said "plasmon". I messed up all of my comments on this
thread. A plasmon isn't technically light either, it's an oscillation of the
electric field in a conductor -- but it has wave/particle duality like a
photon.

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emerongi
It's hard to grasp what was really captured on that image, but this still
doesn't rule out the pilot wave theory. I think it's misleading to call it a
photograph of light "as both a particle and wave".

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amelius
I have a question about QM, which perhaps somebody here can answer: Is
quantization an inherent property of the photon, or is it a property of the
material (or of the interaction with it)?

~~~
URSpider94
The other answers posted here are not quite right. Light energy is indeed
inherently quantized, and a photon is one quantum of light. In other words,
you can't have a half-photon of light, only even multiples.

Einstein wrote the equation "E = h*(nu)", where h is the so-called "Planck's
constant", and nu is the frequency of light. Translated, this means that each
photon carries an amount of energy proportional to its frequency, higher-
frequency photons (IR -> red -> blue -> UV -> X-ray) carry more energy.

tl;dr: Quantization is an inherent property of light.

~~~
amelius
> E = h*(nu)

Yes, but the question is whether that is due to the material not being able to
produce non-quantized photons. Stated differently, suppose we had a different
way of generating photons, then could we theoretically create them in a non-
quantized way?

~~~
lisivka
Yep. They called "radiowaves".

~~~
amelius
Sounds logical, but then again, how fundamental is the "Q" in "QM"?

~~~
lisivka
Extremely. Broken quanta will release its energy. Check solitons (example:
[https://www.youtube.com/watch?v=JD32kkoFU3Y](https://www.youtube.com/watch?v=JD32kkoFU3Y)
). Soliton wave can cross ocean, but if you broke it pattern, you will have
regular waves, not a half of solition.

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shshhdhs
This is really cool! What's the reason for the blue & violet colors to be
raised more than others in the wave?

Is it just the timing of the snapshot? As in, another picture might show
another color at the top of the wave? Or is the standing wave "stuck" in that
position?

~~~
mdturnerphys
That's just the color scale they've used for the z axis.

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mzs
[https://www.eurekalert.org/pub_releases/2015-03/epfd-
tfe0301...](https://www.eurekalert.org/pub_releases/2015-03/epfd-
tfe030115.php)

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Koshkin
> _an exchange of energy "packets" (quanta) between electrons and photons_

I thought that photons _are_ the energy quanta (that electrons can _absorb_ or
lose).

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posterboy
Darn the ambiguous english language, do they mean the photograph is a
particle-wave? because that wouldn't be a first. /s

