Physicists create light out of nothing

http://www.abc.net.au/science/articles/2011/11/17/3368920.htm#

by ColinWright • 15 years ago

95 46 15 years ago

abc.net.au

fragsworth• 15 years ago

I have a great disdain for these kinds of BS titles, they cloud what really happened and make me feel like I'll just get dumber than I already am if I try to read the article.

That said, they didn't create light out of nothing, they created light out of the vacuum. The vacuum is something - at least its fluctuations are, so they didn't create light out of nothing.

dmbaggett3• 15 years ago

I agree with your sentiment, but this is actually a matter of philosophical debate. Nothing: A Very Short Introduction by Frank Close is an enjoyable treatment.

nsxwolf2• 15 years ago

But creating light out of quantum vacuum fluctuations and creating it ex nihilo in the theological sense are very different things. The title indicates the latter occurred.

nsxwolf2• 15 years ago

I suppose it is hard to write a pithy title that does a good job of summarizing what happened, but these titles definitely contribute to scientific confusion and ignorance.

Confusion• 15 years ago

Since I could sensibly say to my advisor "well, there's nothing in the environment, so it must be something in the device", I think 'nothing' is a perfectly valid word for describing a sufficiently low pressure vacuum. Especially if you are addressing a lay audience.

jxcole• 15 years ago

"Faster than the speed of light"

Though the underlying science is very interesting, I wish we could have less sensationalized coverage. Nothing under this section title involves going faster than light.

stcredzero2• 15 years ago

From the article:

While the static Casimir effect does this in the three dimensions of space, the dynamical Casimir effect does it in the dimension of time.

WTF!? This is the last line of the article. That's the most interesting line in the whole thing, and it's totally unexplained and left hanging. What's with the authors/editors? Science journalism is such fluff, that it's no longer about interesting ideas, but contentless amazing sounding word salad.

noduerme• 15 years ago

Yeah; that line struck me as well. Does this mean we're borrowing these particles from the future? Hopefully not from the past...? Also, wouldn't this qualify as a machine that outputs more energy than it uses?

pudquick• 15 years ago

The reason one is called static and involves 3d space and the other is called dynamic and involves time has nothing to do with stealing particles from the future or creating a perpetual motion/energy machine.

What differs in these effects (in space and in time) is the electromagnetic modes of the vacuum near the mirror(s).

http://en.wikipedia.org/wiki/Normal_mode#Quantum_mechanics

It's all about creating a differential - and the effect this has for static vs. dynamic is different for each.

In the static effect, a differential is created in 3d space: two mirrors are perfectly placed in parallel to each other with a gap less than that of a photon's wavelength. In the vacuum fluctuation of space, virtual photons and anti-photon pairs are created and annihilate each other all the time - but this tiny gap keeps them from appearing between the mirrors. The end result is a difference in the modes between the mirrors (total lack of any activity) and outside them (normal vacuum fluctuations) which results in a pressure differential (in 3d space) pushing the plates together (the static effect).

In the dynamic effect, a differential is created due to a change over time: a mirror is moved at a velocity significantly close to the speed of light (in this case, around 5%). Around the mirror, as always, the vacuum contains photon and anti-photon pairs coming into existence and annihilating each other. With a fast enough moving mirror, the mirror can change the ability of the particles to annihilate each other. This represents a change in time over the nature of the vacuum / space where the particles appear.

Thought example: Prior to pair formation, there is no mirror at coordinate XYZ. Proton and anti-proton pair appears - and mirror is moving so fast, it is now present at point XYZ, between the proton and anti-proton, faster than the two could reach and annihilate each other. Now, instead of annihilation, the proton is reflected by the mirror.

This is the dynamical Casimir effect. It is a change, over time, in the nature of vacuum.

Yes, photons are being reflected ("created from nothing") in this effect - but so are anti-photons, which quickly find some other photon to interact with and annihilates the pair of them. There is no net gain of energy here - in fact quite a bit is spent keeping the mirror moving at high speeds.

tokenadult• 15 years ago

Colin, was this submitted for disagreement? The comments here suggest that this popular press account is missing some of the nuance that I usually expect in articles you submit. Please help us out: what do you think about the underlying physics being reported on here?

ColinWright2• 15 years ago

The reporting is poor, and people are right to diss it. But having written extensively for semi-technical audiences, the kinds of criticisms being levelled here are out of place. In this kind of article or publication there's no point in splitting hairs in the title over the difference between vacuum and "nothing". People who won't appreciate the difference will get turned off by what they see as excessive nit-picking.

You need to get people to read. There's no point in having a fantastic finish if no one gets there.

About the article, I think the phenomenon itself is amazing. The Casimir effect is remarkable enough - completely at odds with classical physics and yet trivally predicted by quantum physics, it's a great piece of evidence for how weird the world is. To see it demonstrated using time as one of the dimensions is brilliant.

OTOH, sp332 seems to have found the same story from another source, and in the discussion there people are suggesting that the quantum explanation is out of place and/or unnecessary, because it's more-or-less just like an antenna. http://news.ycombinator.com/item?id=3511341

Then people just pick holes in the writing. I find that sad.

scott_s• 15 years ago

I think you make an excellent point, which I take to be: let's all just apply our popular-science-filter to the article and talk about the content, not the words. I still think there's value in someone providing an explicit translation. It may help to set the tone of the discussion by just stating up front "Yes, the writing is poor. Here's what they should have said. Now that we've established that, let's talk about the content." When I've submitted stories and I wanted the discussion to go in a certain direction, I've tried similar framing. (Although the stories didn't go anywhere. Ah well.)

With that said, can you provide more of an intuition for the Casimir effect? Specifically, a better intuition for why is there are less fluctuations between two plates than outside of them? Is it simply because there's so little space between the plates, and hence less space for fluctuations? The wikipedia article doesn't really provide this level of intuition.

sp3322• 15 years ago

Previous discussion, about 2 months ago: https://news.ycombinator.com/item?id=3252591

bdg• 15 years ago

This is where I quit reading:

> the spooky properties of quantum physics

Can we link to the actual research papers from now on? Pretty please? With sprinkles on top?

guelo• 15 years ago

I believe "spooky action at a distance" is a term used by actual physicists to describe some quantum phenomena. Though I don't know if the reporter used it in the same sense.

lnguyen• 15 years ago

Usually in reference to quantum entanglement. The quote is from Einstein (see http://en.wikipedia.org/wiki/Quantum_entanglement)

The reporter is probably referencing that to some extent but mainly in the sense that it goes against classical intuition.

ck2• 14 years ago

In practical terms that's impossible because it would take the output of a nuclear power plant to accelerate a mirror to such high velocities [speed of light]

No, in practical terms that's impossible because the mass of the mirror would become unfathomable when it got within 10% of the upper speed of light.

abecedarius• 14 years ago

Background: http://en.wikipedia.org/wiki/Casimir_effect#Analogies_and_th...

WhatsHisName• 14 years ago

Just a couple of points to consider. In the static Casimir effect the mirrors cancel out virtual 1/2 wavelength standing waves so there is pressure outside of the gap forcing the plates together. In the dynamic Casimir effect the mirrors move fast enough to cancel out only half of the pair of virtual waves. The other half whose energy is provided from the movement of the mirrors remains.

Physicists create light out of nothing

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