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#3020 by TheTraveller on 21 Feb, 2016 17:14
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For electromagnetic radiation, where T is the Maxwell stress tensor, is the force density, S is the Poynting vector, c is the speed of light, and is the momentum density.
*Attached image
CoM is one of the most researched, powerful and fundamental laws about nature we have. I'm having a hard time wrapping my mind around it being violated, even with asymmetrical differential stresses the mass and energy will in total time be conserved. Maybe some are seeing something that I can't.
Even in the Alcubierre Warp Drive it stretches spacetime in a compression type wavefront and it still doesn't violate CoM.
Shell,
The EmDrive is a differential radiation pressure momentum transfer engine. Same as the constant radiation pressure, constant Force photonic thruster is a momentum transfer engine.
As spacecraft Velocity increases due constant Force & Energy from A = F / M, so too does spacecraft Momentum increase as M * V.
You ever wonder why someone couldn't punch their way out of a closed paper bag? If I'm not making the bag react to outside forces, floor, walls, ceilings, air, no mater how you impact you create on the sides of the bag, no matter the time it takes for the energy you impact the side of the bag in any form of mass or energy or even virtual particles it HAS TO get out to react to the outside world. IF I suck up and make Virtual Particles from the Quantum Vacuum and if they don't get out they will just increase the local energy inside of the bag.
You must take the force or energy you create in the bag to the outside world to get it to move. I've stated almost since day one give me a hole and I'll give you thrust from the drive. Our universe's first laws were entropy and the conservation of mass and energy even when it was just a mix of Quarks and Gluons and the fundamental forces hadn't even expressed themselves. The only thing that seemed to find a backdoor to violating that basic fundamental of CoM or CoE was spacetime which to me acts like a huge entangled Zero Point Energy force that can work with spooky actions outside the laws of causality.
On another note:
I am feeling much better and feel I've got my MoJo back.
Yesterday I tore apart a spare Panasonic magnetron and removed the heat fins to replace them with a water cooling jacket of copper wound tubing. Still need a little more work on it but here are the first results.
Shell
Shell,
The unbalanced momentum transfer between the small and big ends creates an internal to the EmDrive momentum gradient Force toward the big end. As nature does not allow an unbalanced Force to exist, it creates an reaction Force that opposes the momentum gradient being F = A * M.
Please note in this graphic that the big end thrust force is generated by a different set of conditions (big end minus small end radiation pressure) than the small end reaction force that only exists of the EmDrive is free to accelerate and create an accelerative force via F = A * M.
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#3021 by Rodal on 21 Feb, 2016 17:17
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Imagine then the analogy of a ball created out of one wall, inside the ship, since photon propulsion is propellant-less. Now imagine this ball is perfectly elastic and has an initial velocity. We are going to do a trick we modify the mass of the ball when it strikes one of the walls such that the energy exchange to the walls is more efficient. When the ball strikes the other wall it is back to its previous mass where the energy exchange is less efficient. Eventually the ball will slow down because its energy is being given to the composite walls.
The ball is in analogy to a photon so instead of slowing down it is red-shifted till either it disappears or exits the ship because the ship can't reflect that wavelength?
I attached a gif of the math I did below. It shows the % of energy exchanged between a wall and the ball depends on the mass of the ball. You then have to consider independently the exchange between two different walls where the mass of the ball is modified with each bounce. This is the reason I suggested the super-conductor because I think it suggested it could modify the mass of the photon. (One wall being a superconductor.) The idea is supposed to conserve momentum.
<<photon propulsion is propellant-less>>
in what sense is photon propulsion propellant-less? Photon rockets are not propellant-less. Actually the conceptions of interstellar photon rockets is of several kilometers long spaceships, due to the huge amount of mass that would be necessary to convert into photons for an interstellar photon rocket.
__________
<<a ball created out of one wall>> is mass-energy being created in this idea ? (in which conservation of mass-energy is not obeyed) ? -
#3022 by TheTraveller on 21 Feb, 2016 17:18
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There appears to be some confusion in these pages with people not familiar with Rocket Propulsion 1.00 and conservation of momentum.
See:
http://www.ux1.eiu.edu/~cfadd/1350/09Mom/Rock.html
http://www.braeunig.us/space/propuls.htm
Dr. Rodal,
Will you please answer my question?:
http://forum.nasaspaceflight.com/index.php?topic=39004.msg1494061#msg1494061
And the above post is relevant to a propellantless EmDrive that throws nothing out the tail pipe to accelerate how?
The only way that I am aware of that a closed system could self-accelerate its center of mass and respect conservation of momentum-energy is if its initial total mass-energy was zero (for example as a result of containing equal amounts of negative mass-energy as positive mass-energy).
Otherwise the rest mass of the system must be variable with time and there has to be creation of negative mass-energy.
See
http://forum.nasaspaceflight.com/index.php?topic=39214.msg1487251#msg1487251 and the following posts.
A much simpler solution is to consider the EM Drive as an open system, for which there are many coherent proposals.
Thanks for your reply.
You still have not answered my question, as I read your answers, about if you believe there are differential radiation pressures at the small and big ends of an EmDrive or not. -
#3023 by meberbs on 21 Feb, 2016 17:29
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Inside an EmDrive, the ball, being the resonant EM wave, delivers less momentum transfer at the small diameter end than at the large diameter end due to the guide wavelength being longer at the small end than the big end.
...
This variation in radiation pressure / momentum transfer between the small and big end plates, driven by guide wavelength variation, driven by diamater change, is purely speculative as I have no direct proof, other than Cullens 1951 experimental data and my measured ~8mN of reaction force generation at ~90W of forward Rf power into my badly constructed, hand made, low Q frustum.
...
The vector sum of the electromagnetic forces on the walls of the frustum is zero according to classical EM theory. We have covered this thoroughly in these threads already. Dr. Rodal has agreed with this statement before, and his posts clearly indicate that he does not agree that the EM forces alone would be unbalanced. I am not sure how much clearer you could want him to be.
Cullen's equations and experiments are irrelevant to this situation, because they are for a cylindrical waveguide, not a frustum resonator.
When you claim that the energy and momentum in the wave changes from one end of the frustum to the other without interacting with the side walls, you need to explain where that momentum and energy goes, or your hypothesis violates conservation of momentum and conservation of energy.And the above post is relevant to a propellantless EmDrive that throws nothing out the tail pipe to accelerate how?
A device that accelerates linearly without propellant violates the definition of conservation of momentum. Since this would invalidate everything we know about physics, it is difficult to even speculate what it would mean. The only tenable theories I have seen involve either general relativity or accelerating some type of (new) particle out the back. Dr. Rodal's post is relevant, because it helps people who are proposing thought experiments that don't violate momentum conservation. -
#3024 by dustinthewind on 21 Feb, 2016 17:30
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Imagine then the analogy of a ball created out of one wall, inside the ship, since photon propulsion is propellant-less. Now imagine this ball is perfectly elastic and has an initial velocity. We are going to do a trick we modify the mass of the ball when it strikes one of the walls such that the energy exchange to the walls is more efficient. When the ball strikes the other wall it is back to its previous mass where the energy exchange is less efficient. Eventually the ball will slow down because its energy is being given to the composite walls.
The ball is in analogy to a photon so instead of slowing down it is red-shifted till either it disappears or exits the ship because the ship can't reflect that wavelength?
I attached a gif of the math I did below. It shows the % of energy exchanged between a wall and the ball depends on the mass of the ball. You then have to consider independently the exchange between two different walls where the mass of the ball is modified with each bounce. This is the reason I suggested the super-conductor because I think it suggested it could modify the mass of the photon. (One wall being a superconductor.) The idea is supposed to conserve momentum.
<<photon propulsion is propellant-less>>
in what sense is photon propulsion propellant-less? Photon rockets are not propellant-less. Actually the conceptions of interstellar photon rockets is of several kilometers long spaceships, due to the huge amount of mass that would be necessary to convert into photons for an interstellar photon rocket.
__________
<<a ball created out of one wall>> is mass-energy being created in this idea ? (in which conservation of mass-energy is not obeyed) ?
Well, consider a ship with solar panels on the sides which then provide the power to run a laser. Even that small laser provides some propulsion. Maybe its a mistake to say it is propellant-less though but that's not the point that I wanted to make. The idea is to red-shift the trapped photon. -
#3025 by SteveD on 21 Feb, 2016 17:49
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I have to run in a bit. Just thought I would point this out:
A photon rocket with energy output of 299792458 watts.
Accelerates a 1 kg spacecraft from 100,000 km/s to 100,001 km/s
Under KE=1/2m*v^2 the kinetic energy of the craft increases by 100,001 joules.
Given the equation N=W/c one of those joules of energy can be accounted for the redshift of light due to imparting momentum on the craft. No matter how fast the craft is going, an observer directly behind it moving in the same direction at the same speed will always see the light being emitted at a redshifted by a frequency sufficient to remove the energy being turned into motive force.
A hypothetical, completely stationary observer will see the light redshifted as Initial Energy - 1 Watt - Dopplar Shift. The hypothetical moving observer will see redshift of Initial Energy -1 Watt - Spacecrafts Doppler Shift + Observers Dopplar Shift. In other words, the craft due to its velocity, causes light be emitted with a lower frequency (less energy). A moving observer loses some of his energy to blueshift the light back to the baseline. This is an example of conservation of energy.
We can now use the doppler shift formula of
(B is velocity/speed of light. Velocity should be negative for an object moving away from the observer and positive for an object moving towards the observer).
To get a ratio of new frequency / initial frequency. This ratio equals the ratio of Red/Blueshifted energy / initial energy.
The formula gives us a ratio of 0.999666488
When applied to c-1 joules of energy this means that redshift accounts for the loss of 99984.32669 joules of energy for the initial release of photons to power the photon rocket.
This results in an over unity of 15.6733098 joules.
A number that small suggest strongly that some term is missing from the equation. Given the current context, I would be very interested in seeing what that missing term is.
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#3026 by meberbs on 21 Feb, 2016 17:54
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Well, consider a ship with solar panels on the sides which then provide the power to run a laser. Even that small laser provides some propulsion. Maybe its a mistake to say it is propellant-less though but that's not the point that I wanted to make. The idea is to red-shift the trapped photon.
For the solar panel example, you are adding mass-energy to the spacecraft which you then expel in a different direction.
Any red-shifting of a photon means that whatever is doing the red shifting gains the momentum the photon loses. The total momentum of the system remains balanced and the center of energy does not move. (I use center of energy since we have to account for the mass-energy of the photons as well as the spacecraft, it is just the special relativity term for center of mass) -
#3027 by SeeShells on 21 Feb, 2016 18:10
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For electromagnetic radiation, where T is the Maxwell stress tensor, is the force density, S is the Poynting vector, c is the speed of light, and is the momentum density.
*Attached image
CoM is one of the most researched, powerful and fundamental laws about nature we have. I'm having a hard time wrapping my mind around it being violated, even with asymmetrical differential stresses the mass and energy will in total time be conserved. Maybe some are seeing something that I can't.
Even in the Alcubierre Warp Drive it stretches spacetime in a compression type wavefront and it still doesn't violate CoM.
Shell,
The EmDrive is a differential radiation pressure momentum transfer engine. Same as the constant radiation pressure, constant Force photonic thruster is a momentum transfer engine.
As spacecraft Velocity increases due constant Force & Energy from A = F / M, so too does spacecraft Momentum increase as M * V.
You ever wonder why someone couldn't punch their way out of a closed paper bag? If I'm not making the bag react to outside forces, floor, walls, ceilings, air, no mater how you impact you create on the sides of the bag, no matter the time it takes for the energy you impact the side of the bag in any form of mass or energy or even virtual particles it HAS TO get out to react to the outside world. IF I suck up and make Virtual Particles from the Quantum Vacuum and if they don't get out they will just increase the local energy inside of the bag.
You must take the force or energy you create in the bag to the outside world to get it to move. I've stated almost since day one give me a hole and I'll give you thrust from the drive. Our universe's first laws were entropy and the conservation of mass and energy even when it was just a mix of Quarks and Gluons and the fundamental forces hadn't even expressed themselves. The only thing that seemed to find a backdoor to violating that basic fundamental of CoM or CoE was spacetime which to me acts like a huge entangled Zero Point Energy force that can work with spooky actions outside the laws of causality.
On another note:
I am feeling much better and feel I've got my MoJo back. Yesterday I tore apart a spare Panasonic magnetron and removed the heat fins to replace them with a water cooling jacket of copper wound tubing. Still need a little more work on it but here are the first results.
Shell
Shell,
The unbalanced momentum transfer between the small and big ends creates an internal to the EmDrive momentum gradient Force toward the big end. As nature does not allow an unbalanced Force to exist, it creates an reaction Force that opposes the momentum gradient being F = A * M.
Please note in this graphic that the big end thrust force is generated by a different set of conditions (big end minus small end radiation pressure) than the small end reaction force that only exists of the EmDrive is free to accelerate and create an accelerative force via F = A * M.
Your drawing is close but this is the way I see it with your arrows.
Shell
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#3028 by Vultur on 21 Feb, 2016 18:25
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Actually the conceptions of interstellar photon rockets is of several kilometers long spaceships, due to the huge amount of mass that would be necessary to convert into photons for an interstellar photon rocket.
Does that assume speeds very near lightspeed? I think you could get to more reasonable interstellar speeds*, maybe 15-25% of lightspeed or so, with a much more reasonable mass ratio.
*I think near-lightspeed ships would be destroyed anyway by colliding with interstellar medium matter/interstellar dust. -
#3029 by CW on 21 Feb, 2016 18:34
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(...)
Shell,
The unbalanced momentum transfer between the small and big ends creates an internal to the EmDrive momentum gradient Force toward the big end. As nature does not allow an unbalanced Force to exist, it creates an reaction Force that opposes the momentum gradient being F = A * M.
Please note in this graphic that the big end thrust force is generated by a different set of conditions (big end minus small end radiation pressure) than the small end reaction force that only exists of the EmDrive is free to accelerate and create an accelerative force via F = A * M.
I see a problem with that logic. If, as you say, nature does not allow an unbalanced force to exist - how does the EM-drive overcome this, as a physical object of 'nature', in the first place, to cause nature then to counteract a force, that couldn't exist, by definition? Sounds like circular reasoning, IMHO. Because you'd have to 'break' nature first, just to get the basis for the argument made. At least it seems to me like so.
When can we expect to see a public demonstration of the advanced EM-drive, e.g. from Mr.Shawyer? Do you have an estimate?
Best regards -
#3030 by Monomorphic on 21 Feb, 2016 22:14
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This question is for Dave. I remember you mentioning something about solid state microwaves a while back, but do you know if these microwave RF transistors are available and if they would be good for emdrive experiments?
http://www.nxp.com/products/rf/rf-power-transistors/rf-cooking/2450-mhz-250-w-cw-32-v-rf-ldmos-transistor-for-consumer-and-commercial-cooking:MHT1003N
Seems to me this would eliminate the magnetron, transformer and capacitor - we could easily run the RF transistor directly from a battery.
EDIT: This is a better video of the upcoming microwave ovens that use these transistors:
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#3031 by rfmwguy on 21 Feb, 2016 22:38
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This question is for Dave. I remember you mentioning something about solid state microwaves a while back, but do you know if these microwave RF transistors are available and if they would be good for emdrive experiments?
Freescale and nxp merged recently and at last check has not made these available yet but they are ideal for what we are doing.
http://www.nxp.com/products/rf/rf-power-transistors/rf-cooking/2450-mhz-250-w-cw-32-v-rf-ldmos-transistor-for-consumer-and-commercial-cooking:MHT1003N
Seems to me this would eliminate the magnetron, transformer and capacitor - we could easily run the RF transistor directly from a battery.
This is an example of the upcoming appliances that use these transistors:
Mht-1003n specifically
http://tinyurl.com/hzbats4 -
#3032 by Notsosureofit on 21 Feb, 2016 23:23
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Interesting... [via Jack Sarfatti]
http://www.nature.com/ncomms/2015/150324/ncomms7665/full/ncomms7665.html
I'm interested in a decomposition of the Hamiltonian into a time-independent component and a sum of attenuating waves. (that looks to me like a homodyne situation) The demonstration of non-locality would seem to be a bonus for an open system....but open to what ? -
#3033 by Monomorphic on 21 Feb, 2016 23:34
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Quote
Mht-1003n specifically
I found a supplier that claims to have 148 Mht-1003n transistors. I have requested a quote for 4 units. Hopefully they aren't that expensive! -
#3034 by rfmwguy on 21 Feb, 2016 23:48
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Wow, looks like they may have just been released! If you choose to go this way, it will take experiments to another level. Specifically, the ability to analyze whether pulsing is required. These chips are 250W CW rated, so there's a lot that can be learned here! Also check to see if the ctr freq is adjustable +/- a few mhz.QuoteMht-1003n specifically
I found a supplier that claims to have 148 Mht-1003n transistors. I have requested a quote for 4 units. Hopefully they aren't that expensive! -
#3035 by rq3 on 22 Feb, 2016 00:14
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This question is for Dave. I remember you mentioning something about solid state microwaves a while back, but do you know if these microwave RF transistors are available and if they would be good for emdrive experiments?
Freescale and nxp merged recently and at last check has not made these available yet but they are ideal for what we are doing.
http://www.nxp.com/products/rf/rf-power-transistors/rf-cooking/2450-mhz-250-w-cw-32-v-rf-ldmos-transistor-for-consumer-and-commercial-cooking:MHT1003N
Seems to me this would eliminate the magnetron, transformer and capacitor - we could easily run the RF transistor directly from a battery.
This is an example of the upcoming appliances that use these transistors:
Mht-1003n specifically
http://tinyurl.com/hzbats4
Cool device, well...not actually cool.
It's a 250 watt (54 dBm) CW output transistor, with a gain of 15.9 dB. Each device will require about 6.5 watts of drive. If you want to get to microwave oven output levels (1 kW), you will need to combine the output of (at least) 4 of these devices, with the requisite 26 watts of RF drive, appropriately split and applied.
With a typical efficiency of 59% (per the specs), you will also have to dump 410 watts of heat, just for the power stage.
It's all completely do-able, and with the data sheets being so old (2014), I'd be willing to bet that NXP has these things kicking around for evaluation. They won't be cheap, but a phone call to the right person might get you some samples for free.
Pro:
1) It's solid state, and runs at 32 VDC, rather than kilovolts
2) It appears to have a high tolerance for severe mismatch (10:1 VSWR)
3) It's narrow band and CW, so probably has a reasonably clean output spectrum, unlike a magnetron.
4) Due to 3 above, it could probably be easily modulated to ACT like a magnetron with the appropriately synthesized drive signal.
5) Could be driven from batteries (BIG batteries). Very clean and reliable DC source.
6) Doesn't require dual supplies (low voltage/high current filament, high voltage anode).
Cons:
1) It's solid state, and a bear to heatsink (think water cooled beryllium oxide or copper core printed circuit boards). May even need vapor/liquid phase heat pipe mounting, especially if done in multiples.
2) It's very narrow band. Gain drops off rapidly when not at the design frequency. This makes the frustum design more critical. If the two don't match, you won't get the frustum injection level you expect, so you're back to tuning the frustum, not the source (not good for automatic S11 detection and tuning, but do-able).
3) The board layout and material will be critical. Tuning 4 individual 250 watt devices so that they phase combine properly is not trivial.
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#3036 by ramachandra on 22 Feb, 2016 01:02
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Is there a possibility that a powerful magnetic field can force the virtual particles to real particles? Suppose the frustum is surrounded by a powerful magnetic field which can force the virtual particles in one direction, would that affect the thrust?
https://www.technologyreview.com/s/425029/magnetic-fields-turn-the-vacuum-into-a-superconducting-superlens-says-physicist/
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#3037 by masterharper1082 on 22 Feb, 2016 01:16
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For electromagnetic radiation, where T is the Maxwell stress tensor, is the force density, S is the Poynting vector, c is the speed of light, and is the momentum density.
*Attached image
CoM is one of the most researched, powerful and fundamental laws about nature we have. I'm having a hard time wrapping my mind around it being violated, even with asymmetrical differential stresses the mass and energy will in total time be conserved. Maybe some are seeing something that I can't.
Even in the Alcubierre Warp Drive it stretches spacetime in a compression type wavefront and it still doesn't violate CoM.
Shell,
The EmDrive is a differential radiation pressure momentum transfer engine. Same as the constant radiation pressure, constant Force photonic thruster is a momentum transfer engine.
As spacecraft Velocity increases due constant Force & Energy from A = F / M, so too does spacecraft Momentum increase as M * V.
You ever wonder why someone couldn't punch their way out of a closed paper bag? If I'm not making the bag react to outside forces, floor, walls, ceilings, air, no mater how you impact you create on the sides of the bag, no matter the time it takes for the energy you impact the side of the bag in any form of mass or energy or even virtual particles it HAS TO get out to react to the outside world. IF I suck up and make Virtual Particles from the Quantum Vacuum and if they don't get out they will just increase the local energy inside of the bag.
You must take the force or energy you create in the bag to the outside world to get it to move. I've stated almost since day one give me a hole and I'll give you thrust from the drive. Our universe's first laws were entropy and the conservation of mass and energy even when it was just a mix of Quarks and Gluons and the fundamental forces hadn't even expressed themselves. The only thing that seemed to find a backdoor to violating that basic fundamental of CoM or CoE was spacetime which to me acts like a huge entangled Zero Point Energy force that can work with spooky actions outside the laws of causality.
On another note:
I am feeling much better and feel I've got my MoJo back. Yesterday I tore apart a spare Panasonic magnetron and removed the heat fins to replace them with a water cooling jacket of copper wound tubing. Still need a little more work on it but here are the first results.
Shell
Shell,
The unbalanced momentum transfer between the small and big ends creates an internal to the EmDrive momentum gradient Force toward the big end. As nature does not allow an unbalanced Force to exist, it creates an reaction Force that opposes the momentum gradient being F = A * M.
Please note in this graphic that the big end thrust force is generated by a different set of conditions (big end minus small end radiation pressure) than the small end reaction force that only exists of the EmDrive is free to accelerate and create an accelerative force via F = A * M.
Your drawing is close but this is the way I see it with your arrows.
Shell
I know it's easier to think about the forces on the end plates due to the (area-averaged) group velocity on the ends, but isn't there also a radiation pressure on the tapered side walls that could have a net component acting vertically as well? Why don't I see this in anyone's diagrams? Just a simplification, or are we missing things?
masterharper1082 -
#3038 by glennfish on 22 Feb, 2016 01:23
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No, you don't achieve any self-acceleration of the center of mass of the closed system that contains both mirrors. The center of mass of the closed system that envelopes both mirrors does not self accelerate. The center of mass of the system that envelopes both mirrors does not experience any force. All you are doing is to re-distribute the location of the center of mass-energy of the system with respect to the mirrors, the center of mass-energy will not self-accelerate or experience a force.
Ah heck, given what I wrote, you're right.
My failure was to assume if reflection didn't occur it would be transmission out of the system. BUT, since I didn't state that, it could either be absorbed (your assumption), or transmitted (my assumption). I've worked with mirrors for too many years and I have many bad memories of painting the back surface black to ensure that reflection failures wouldn't go anywhere. My bad.
Net net, your assumption is more justified than mine.
Given my well required mea culpa, if a reflection failure resulted in the photon PASSING through the mirror to infinity, would I be right or have I made another error.
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#3039 by dustinthewind on 22 Feb, 2016 01:26
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It is obvious that it was dustinthewind the one that raised this example:As an analogy, think of an astronaut inside a spacecraft, throwing a ball towards an inner wall of the spacecraft.
And this example is related to EM waves propagating from small end plate to big end plate and back to small end inside a resonant EmDrive with a tapered waveguide how?
......I wonder if it is possible to have a single device (closed system) that has two mirrors but one mirror is more effective at harnessing energy from the photon than the other mirror. Maybe by giving the photon some added mass when striking one mirror? (one mirror being a super-conductor possibly?). ...
My understanding is that dustinthewind raised this example as an independent thought experiment. You can address your question of any possible analogy to the EM Drive to dustinthewind, as to whether he intended any such analogy. I certainly did not interpret dustinthewind as claiming that there was any such analogy, as you appear to infer.
Sorry, just noticed this. I brought up an idea that may allow red-shifting of trapped light inside if some how the mass of the photon is being changed before reflection. This changes the efficiency of energy exchanged between each bounce. If the photon hitting one wall delivers a larger ratio of energy to the cavity than the photon hitting the other wall then it may be possible for the photon to be red-shifted when the cavity starts to accelerate. The idea uses the conservation of energy and momentum. The analogy used a ball inside the a ship that was perfectly elastic and starts inside with velocity. The ratio of energy exchanged between the ball and the wall has to do with the mass of the ball. If the mass of the ball changes when hitting one wall as opposed to the other wall but momentum is conserved then the ratio of energy delivered to one of the walls is greater than the energy delivered to the other wall. The result of this is the ball loses energy after many bounces till it comes to a rest.
The parallel to this is that the ball is a photon in a cavity. If the photon is changing in mass (but conserving momentum) with respect to one of the walls then the ratio of energy delivered to one wall (energy conserved) will be greater than the other wall. As a result the photon will lose energy as the cavity accelerates. This losing energy would not be the slowing down of the photon but rather the red-shifting of light inside the cavity. The signature to look for would be allowing the cavity to freely accelerate and looking for the red shifting of light inside the cavity.
As a method of changing the mass of the photon before reflection I suggested the use of a superconductor as one of the walls/mirror which supposedly makes a photon massive, or more efficient at exchanging its energy.
The link to the math worked out to show the ratio of energy exchanged upon the bounce which depends on the photon or balls mass. http://forum.nasaspaceflight.com/index.php?topic=39004.msg1494106#msg1494106
Yesterday I tore apart a spare Panasonic magnetron and removed the heat fins to replace them with a water cooling jacket of copper wound tubing. Still need a little more work on it but here are the first results.