# The Naked Scientists Forum

### Author Topic: How Moving mirrors make light from nothing?  (Read 6296 times)

#### Spacetectonics

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##### How Moving mirrors make light from nothing?
« on: 06/01/2013 08:36:35 »
According to theory, a mirror can absorb energy from virtual photons onto its surface and then re-emit that energy as real photons. The effect only works when the mirror is moving through a vacuum at nearly the speed of light — which is almost impossible for everyday mechanical devices.

http://www.nature.com/news/2011/110603/full/news.2011.346.html

My question is ,If mirrors could do so then what is the deal with length contraction ;if this happen in real world running a mirror close to speed of light? Could someone explains please ?

Cheers

#### imatfaal

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##### Re: How Moving mirrors make light from nothing?
« Reply #1 on: 07/01/2013 17:14:39 »
spacetectonics - you are gonna have to be clearer in your question.

QM is completely consistent with SR so the theory will include contraction - but not sure what you are asking.

The "mirror" is just a wire that has its electrical length manipulated at extreme high frequency - this changes the boundary condition (the boundary condition at a perfect mirror is the electric field is zero) and its position. Thus in a vrey convoluted manner this acts in many ways as a reflective surface moving at about 1/20 of the speed of light

#### Spacetectonics

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##### Re: How Moving mirrors make light from nothing?
« Reply #2 on: 07/01/2013 17:29:21 »
spacetectonics - you are gonna have to be clearer in your question.

QM is completely consistent with SR so the theory will include contraction - but not sure what you are asking.

The "mirror" is just a wire that has its electrical length manipulated at extreme high frequency - this changes the boundary condition (the boundary condition at a perfect mirror is the electric field is zero) and its position. Thus in a vrey convoluted manner this acts in many ways as a reflective surface moving at about 1/20 of the speed of light

Thanks Imatfaal,

As you have mentioned they have used a SQUID for this test but what I am interested to know is what will happen (theoretically) if this test could have been done with a real mirror ;close to speed of the light?theory says "that a similar effect can be produced in a single mirror that is moving very quickly"

If I am not wrong(sorry I am Geologist! ) contraction should do some thing to the mirror before "emitting of light starts" but I don't see this mentioned either in this research or the theory .

"QM is completely consistent with SR so the theory will include contraction - but not sure what you are asking. "

Cheers

#### evan_au

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##### Re: How Moving mirrors make light from nothing?
« Reply #3 on: 07/01/2013 21:42:55 »
A conventional mirror is a flat surface. If positioned at right-angles to the direction of travel, Lorentz contraction will still leave it as a flat surface, emitting most photons in the direction of travel.

If the mirror were positioned at (say) 45° to the direction of travel, Lorentz contraction will make it appear to be at different angles, as seen by observers traveling at different relative velocities. This mirror will seem to emit most photons at various angles, as seen by observers traveling at different relative velocities.

#### Phractality

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##### Re: How Moving mirrors make light from nothing?
« Reply #4 on: 07/01/2013 22:52:07 »
The "mirror" is just a wire that has its electrical length manipulated at extreme high frequency....
Doesn't it take some energy to manipulate the electrical length? Doesn't that make the wire an ordinary radio transmitter? Isn't everything moving at .05% c relative to something?

I don't see how they've discovered anything new.

#### JP

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##### Re: How Moving mirrors make light from nothing?
« Reply #5 on: 08/01/2013 15:23:50 »
The "mirror" is just a wire that has its electrical length manipulated at extreme high frequency....
Doesn't it take some energy to manipulate the electrical length? Doesn't that make the wire an ordinary radio transmitter? Isn't everything moving at .05% c relative to something?

I don't see how they've discovered anything new.

There's no new theory here.  It's just a neat way of verifying what was already predicted.  We know a mirror moving in an electromagnetic field produces radiation.  We also know that quantum theory predicts that even in a pure vacuum, there is a purely quantum field associated with the zero-point energy of the vacuum (often describes as virtual particles flitting into and out of existence).  What this experiment does is to attempt to verify that a moving mirror can emit radiation due to this quantum field, which was already predicted by theory but not yet experimentally checked.

#### imatfaal

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##### Re: How Moving mirrors make light from nothing?
« Reply #6 on: 08/01/2013 15:39:28 »
as the static casimir force shows that a couple of mirror plates with an exceedingly small gap limits the denisty of modes the field can take up - and will produce a net force as there is a lower radiation pressure inside than outside; so the high speed moving mirror ie the dynamic casimir effect produces changes (in time rather than space according to article) to these vacuum modes available to the em field

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #7 on: 08/01/2013 21:35:46 »
It is not a proof of vacuum energy because the energy is still conserved. It is rather a proof of a special relation between photons and relative motions of particles. Inertia and motion are mediated by photons...

#### JP

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##### Re: How Moving mirrors make light from nothing?
« Reply #8 on: 08/01/2013 23:01:22 »
Yes, but if the vacuum energy were zero the mirror has no way of generating photons.  If the mirror generates photons, the argument goes, it must be interacting with an electromagnetic field, and since there is no classical field present, it must be a quantum zero point field.  Energy should of course be conserved in both cases.

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #9 on: 09/01/2013 00:07:57 »
The motion comes from energy from the magnetic field...

The measured photons are real and they are still Hawking-Unruh radiation.

The question is, is energy extended in space or is it confined to elementary particles?

Is space an emerging element?

I don't see how QM can really explained entanglement. Space seems to react instantly to changes in energy but all our tools are made of energy...

What buzz me is how interpretations of experiments have lead to acceptance of specific concepts in QM that are, in my opinion, conflicting with other parts of the theory. What is left is a probabilistic mixture of theories.

Are we in a simulation? We are in a computer age so it is normal to bridge the gap this way but it does not make it more true...
« Last Edit: 09/01/2013 00:12:29 by CPT ArkAngel »

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #10 on: 09/01/2013 00:43:44 »
In a computer simulation, time is relative and space is emergent...

Entanglement makes our universe look like a simulation...
« Last Edit: 09/01/2013 02:30:03 by CPT ArkAngel »

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #11 on: 09/01/2013 02:42:07 »
And by extension, space is simply the memory where information is stored...

Holographic principle!
:o)

#### JP

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##### Re: How Moving mirrors make light from nothing?
« Reply #12 on: 09/01/2013 14:55:14 »
I don't see how QM can really explained entanglement. Space seems to react instantly to changes in energy but all our tools are made of energy...
That's the point of using QM as a model, though--to calculate what happens to your measurement apparatus when it interacts with some experiment.

Quote
What buzz me is how interpretations of experiments have lead to acceptance of specific concepts in QM that are, in my opinion, conflicting with other parts of the theory. What is left is a probabilistic mixture of theories.
I'm not sure which parts you're referring to that are in conflict with other parts.  QM doesn't explain everything in the universe, but it is a very self-consistent theory and the most accurate model we have.

At any rate, I haven't run through the math, but I trust the authors when they say that QM does in fact predict that a mirror moving in a vacuum generates photons due to the quantum zero-point field, just as a mirror moving in a classical, non-zero field would.

#### Pmb

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##### Re: How Moving mirrors make light from nothing?
« Reply #13 on: 09/01/2013 18:18:39 »
According to theory, a mirror can absorb energy from virtual photons onto its surface and then re-emit that energy as real photons. The effect only works when the mirror is moving through a vacuum at nearly the speed of light — which is almost impossible for everyday mechanical devices. My question is - Moving close to c with respect to what frame?

http://www.nature.com/news/2011/110603/full/news.2011.346.html

My question is ,If mirrors could do so then what is the deal with length contraction ;if this happen in real world running a mirror close to speed of light? Could someone explains please ?

Cheers
Frankly I find this hard to believe. Just because someone claims that something is in accordance with QM and/or SR it doesn't mean it is. They could have made a mistake in theory. Please remember that all mirrors are moving close to c in some frame of reference.
« Last Edit: 09/01/2013 18:32:33 by Pmb »

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #14 on: 10/01/2013 01:22:15 »
The magnetic field moving the mirrors is the photon's source. From a QM point of view, these photons have to appear from the vacuum field. It is a circular argument by using a theory to prove itself. It is one solution among thousands...

What about dark energy vs vacuum energy?

There is the early theory that end somehow with the Schrodinger's equation, then you have QFT, QCD, QED and a few others.

These theories have mainly been built upon experimental observations. By having a probabilistic point of view, conceptual mechanics has been thrown out and left the physicists lost in theoretical equations. They added parameters to fit experiments then extended them and proposed many theories and kept the ones fitting the new experiments, and so on. Now, it is so stretched that it has lost all its predictive power.

Entanglement is mainly extended by experiments without any physical mechanism (opened parameters).

Quantum mechanics is a valid theory at microscale only and it can't explain many observations in nano materials experiments and many high energy astrophysical phenomena.  There is no description of elementary constituents, no gravity.

But there is almost no concepts so it is difficult to argue against it.

"But the maths are fitting with experiments"
"Certainly it does they have been modified to fit the experiments."

Why no one understand QM? Because it makes no sense... Dirac, Einstein, De Broglie and Schrodinger knew it.

Just bring back conceptual physics and it wil be alright... almost... :o)

#### Pmb

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##### Re: How Moving mirrors make light from nothing?
« Reply #15 on: 10/01/2013 01:50:01 »
The magnetic field moving the mirrors is the photon's source.
What magnetic field? Is there something describing all this in more detail somewhere?

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #16 on: 10/01/2013 02:06:35 »

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #17 on: 10/01/2013 02:27:41 »
My two cents about Dirac's point of view:

Mathematical beauty can only be expressed in beautiful physical concepts!

My theory:
http://www.thenakedscientists.com/forum/index.php?topic=34413.0

#### Pmb

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##### Re: How Moving mirrors make light from nothing?
« Reply #18 on: 10/01/2013 02:48:20 »

#### Pmb

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##### Re: How Moving mirrors make light from nothing?
« Reply #19 on: 10/01/2013 02:54:12 »
The magnetic field moving the mirrors is the photon's source. From a QM point of view, these photons have to appear from the vacuum field. It is a circular argument by using a theory to prove itself. It is one solution among thousands...

What about dark energy vs vacuum energy?
Nothing alike. The former is classical while the other isn't. Dark energy is merely a name we give for what is driving the accelerated expansion of the universe. For all we know it could be something as simply as particles which have negative active gravitational mass. Frankly, that's my guess, if not merely a name.

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #20 on: 10/01/2013 02:58:25 »
In fact, you don't need a mirror at all, anything goes, but a good emitter is more suitable...

There is no Dark Energy, no acceleration has really been measured yet.

« Last Edit: 10/01/2013 03:00:11 by CPT ArkAngel »

#### Pmb

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##### Re: How Moving mirrors make light from nothing?
« Reply #21 on: 10/01/2013 03:08:52 »
Quote from: CPT ArkAngel
There is no Dark Energy, no acceleration has really been measured yet.
Since when? Unless you're saying that we don't know the magnitude? We do know that it's accelerating though.

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #22 on: 10/01/2013 03:31:38 »
Only recessive velocities have been measured. The acceleration is infered by the model of the universe used.

If the bigbang is in fact the expansion of a black ring (black holes are particles) in a larger universe, you should be expecting these observations. Still, it is a mostly homogeneous expansion...

#### CPT ArkAngel

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##### Re: How Moving mirrors make light from nothing?
« Reply #23 on: 10/01/2013 03:37:35 »
And all observations about Dark Energy are compatible with my theory. For example, the larger scattering distances between galaxies in far clusters. But if we are not at the center, as we should expect, these effects will not be observed at the same distances in all directions.

#### JP

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##### Re: How Moving mirrors make light from nothing?
« Reply #24 on: 10/01/2013 16:54:46 »
And all observations about Dark Energy are compatible with my theory.

Let's keep promotion of new theories to the New Theory section of the forum, please.

There seems to be some confusion over what the theory claims.  From what I gathered by reading the article, this is a similar effect to Unruh radiation or Hawking radiation and it's the acceleration of the mirror with respect to the observer that's transferring energy to the virtual vacuum photons and making them real.  Of course, energy has to be conserved, so what I'm assuming happens is that the mirror decelerates a bit when it produces a photon, much as a black hole loses a tiny bit of energy when emits Hawking radiation.  Classical EM theory predicts that nothing will happen when you wave a mirror about in a vacuum, since there are no photons (virtual or otherwise) to transfer energy to.  That's why the claim is that it's a quantum effect.

And it's not as if we don't know the vacuum energy exists, since it's required to explain the Lamb shift, which we have measured and vacuum energy also comes in to play in high energy particle physics calculations, which have also been tested in particle accelerators.

#### The Naked Scientists Forum

##### Re: How Moving mirrors make light from nothing?
« Reply #24 on: 10/01/2013 16:54:46 »