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Quantum vacuum plasma thruster

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Re: Quantum vacuum plasma thruster

#11

Post by DennisP »

moocowduckquack wrote: post #5

This reference looks interesting: "A net unidirectional and reversible force on the order of ± 3.14 milli‐Newton or 0.069% of the suspended test article mass was recorded by us in our first high frequency 2.2 MHz test article. The authors also developed a W‐E model that integrates the various engineering parameters affecting the design, construction, and performance of W‐E based MLTs for the next generation of system…

Woodward's idea is something different though. It's based on general relativity. https://en.wikipedia.org/wiki/Woodward_effect

Re: Quantum vacuum plasma thruster

#12

Post by gus_massa »

All the information about this is very confusing, and in some press report it looks like a perpetual motion machine. I’ll try to explain what I had understood trying to find an explanations that don’t break the physics laws.

You must use some particles to carry the momentum. It’s not clear, but the main candidates are photons (aka light). The quantization of the electromagnetic field is the cause of the Casimir effect, and the name of the particles that arrays due to the quantization of the electromagnetic is photons. Some other explanations talk about a moving mirror, and an oscillating mirror produces photons.

The number of photons is not conserved, so they can be created or destroyed “out of thin air”. (Really you need another particle like and electron to carry the difference of energy and momentum. The electron then bounce against the ship to accelerate it forwards, and picks a little of energy to compensate the energy that used to create the photon. It’s plenty of electrons, and you can reuse them.)

So this is equivalent to pointing a laser backwards, so the spaceships accelerate forwards. The discussion should be about efficiency. Is this more efficient than a laser?

(Well, it’s not necessary to use a laser, a simple light bulb with a mirror that reflect the light that tries to go forward will work. If it’s not directional you will lost a lot of energy because the light that goes to the sides doesn’t accelerate the ship (I don’t want to do the integrals now, but I guest 1/3 of efficiency.) With a more directional setting, like the mirrors in a flashlight the efficiency will improve.)

Re: Quantum vacuum plasma thruster

#13

Post by moocowduckquack »

DennisP wrote: post #11
moocowduckquack wrote: post #5

This reference looks interesting: "A net unidirectional and reversible force on the order of ± 3.14 milli‐Newton or 0.069% of the suspended test article mass was recorded by us in our first high frequency 2.2 MHz test article. The authors also developed a W‐E model that integrates the various engineering parameters affecting the design, construction, and performance of W‐E based MLTs for the next generation of system…

Woodward's idea is something different though. It's based on general relativity. https://en.wikipedia.org/wiki/Woodward_effect

Sorry, I sort of ignored the article and just had a look at the references instead.

Re: Quantum vacuum plasma thruster

#14

Post by throwaway_yy2Di »

gus_massa wrote: post #12

All the information about this is very confusing, and in some press report it looks like a perpetual motion machine. I’ll try to explain what I had understood trying to find an explanations that don’t break the physics laws. You must use some particles to carry the momentum. It’s not clear, but the main candidates are photons (aka light). The quantization of the electromagnetic field is the cause of the Casimir effec…

This is inconsistent with the claimed "specific force performance of 0.1N/kW". The ratio a photon's momentum to energy is fixed at 1/c, which is 3.3E-6 N/kW.

Re: Quantum vacuum plasma thruster

#15

Post by claudius »

throwaway_yy2Di wrote: post #14
gus_massa wrote: post #12

All the information about this is very confusing, and in some press report it looks like a perpetual motion machine. I’ll try to explain what I had understood trying to find an explanations that don’t break the physics laws. You must use some particles to carry the momentum. It’s not clear, but the main candidates are photons (aka light). The quantization of the electromagnetic field is the cause of the Casimir effec…

This is inconsistent with the claimed "specific force performance of 0.1N/kW". The ratio a photon's momentum to energy is fixed at 1/c , which is 3.3E-6 N/kW.

Which is why using the vacuum fluctuations makes sense – these are particle/antiparticle pairs created randomly in the vacuum. Since these do have finite masses, you can accelerate them to larger momenta than would be possible with photons (which can also carry arbitrarily large momenta ℏω, but creating these high-frequency photons is difficult).

Re: Quantum vacuum plasma thruster

#16

Post by throwaway_yy2Di »

claudius wrote: post #15
throwaway_yy2Di wrote: post #14

Earlier quoted context omitted.

This is inconsistent with the claimed "specific force performance of 0.1N/kW". The ratio a photon's momentum to energy is fixed at 1/c , which is 3.3E-6 N/kW.

Which is why using the vacuum fluctuations makes sense – these are particle/antiparticle pairs created randomly in the vacuum. Since these do have finite masses, you can accelerate them to larger momenta than would be possible with photons (which can also carry arbitrarily large momenta ℏω, but creating these high-frequency photons is difficult).

That doesn't solve anything, it only shifts the violation somewhere else? Of course you can't keep the virtual particles, that's a net creation of mass-energy.

"which can also carry arbitrarily large momenta ℏω,"

With proportionally large energy. That's the concern here, not photon count.

(For anyone confused, it's ℏω/c in conventional units. Some unit systems define c=1 for convenience)

Re: Quantum vacuum plasma thruster

#17

Post by [deleted] »

slacka wrote: post #9
victorquinn wrote: post #6

This sounds a lot like a perpetual motion machine...

Did you even read the article or just feel like spamming HN with some uninformed snarky comment? I also am skeptical about this and don't fully understand the physics behind it. But I did RTFA and all of the references checked out.

[deleted]

Re: Quantum vacuum plasma thruster

#18

Post by throwaway_yy2Di »

moocowduckquack wrote: post #5

This reference looks interesting: "A net unidirectional and reversible force on the order of ± 3.14 milli‐Newton or 0.069% of the suspended test article mass was recorded by us in our first high frequency 2.2 MHz test article. The authors also developed a W‐E model that integrates the various engineering parameters affecting the design, construction, and performance of W‐E based MLTs for the next generation of system…

That reference could hardly be sketchier. It's a non-peer-reviewed conference proceeding (basically, open forum free for anyone), by people with no academic affiliation, and no apparent publications on any topic besides this one:

http://scitation.aip.org/content/contributor/AU0239062

http://scitation.aip.org/content/contributor/AU0214881

Re: Quantum vacuum plasma thruster

#19

Post by gus_massa »

claudius wrote: post #15
throwaway_yy2Di wrote: post #14

Earlier quoted context omitted.

This is inconsistent with the claimed "specific force performance of 0.1N/kW". The ratio a photon's momentum to energy is fixed at 1/c , which is 3.3E-6 N/kW.

Which is why using the vacuum fluctuations makes sense – these are particle/antiparticle pairs created randomly in the vacuum. Since these do have finite masses, you can accelerate them to larger momenta than would be possible with photons (which can also carry arbitrarily large momenta ℏω, but creating these high-frequency photons is difficult).

The generalization of the well known E=mc^2 equation is E^2 = p^2 c^2 + m^2 c^4 (where p is the momentum and m is the “rest mass”).

So: p = Sqrt( (E/c)^2 - (mc)^2 )

Therefore, for massive particles, you get less moment for the same energy. (An easy way to get a general idea this without calculation is that part of the energy goes to create the mass, and the other part goes to create the moment. But I prefer calculations.)

So the best Moment/Energy ratio is for massless particles, like the photon. And the photon is the easiest particle to create and direct.

But as throwaway_yy2Di said, the ratio with photons is 30000 smaller than the ratio they claim.

So the only consistent explanation is that they are measuring something in a wrong way.

Re: Quantum vacuum plasma thruster

#20

Post by scythe »

throwaway_yy2Di wrote: post #16
claudius wrote: post #15

Earlier quoted context omitted.

Which is why using the vacuum fluctuations makes sense – these are particle/antiparticle pairs created randomly in the vacuum. Since these do have finite masses, you can accelerate them to larger momenta than would be possible with photons (which can also carry arbitrarily large momenta ℏω, but creating these high-frequency photons is difficult).

That doesn't solve anything, it only shifts the violation somewhere else? Of course you can't keep the virtual particles, that's a net creation of mass-energy. " which can also carry arbitrarily large momenta ℏω, " With proportionally large energy. That's the concern here, not photon count. (For anyone confused, it's ℏω/c in conventional units. Some unit systems define c=1 for convenience)

See: https://en.wikipedia.org/wiki/Woodward_effect#Propellantless...

The claim appears to be that the momentum is transferred first to the local stress-energy tensor, and then to celestial bodies. It almost sounds feasible at a glance, but, well, it's quantum gravity.

I would say it certainly seems like there's something to be learnt by this, though. A quantum effect with measurable gravitational consequences is... almost unheard of.

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