IBTimes UK ; EmDrive Exclusive: Roger Shawyer confirms MoD interested in space propulsion tech (Full Version)

Quote from michaelharney1

This is correct - when a resonance condition exists between photons inside the walls of a metal cavity, the vacuum pressure from the outside of the cavity increases one the longer side as opposed to the shorter one. This is evidence of a underlying wave structure that is enforced with electron wave centers both inside and outside of the cavity. It's the confinement of an internal standing wave in the cavity that requires a balance of pressure from the incoming waves on the outside of the cavity.

In your telling as I understand it, in the case of the EM Drive we have (microwave) photons being generated and reflecting in the cavity. You have suggested that this sets up a kind of vacuum pressure differential on two sides of one wall of the cavity as a result of a difference in group velocities of the microwave photons at one end of the cavity and the other. The resulting vacuum pressure is presumed to be related to the Casimir effect. Conservation of momentum is explained by an opposite momentum that is imparted to the vacuum as the Shawyer device experiences thrust.

Here our description has been purely in terms of photons and the vacuum. Can you elaborate on how electrons as "wave centers" enter into this explanation?

/* Can you elaborate on how electrons as "wave centers" enter into this explanation? */

This is just an OT marketing of Millo Wolf theory.

How is Milo Wolff's WSM theory off-topic if Michael claims that it explains the EM Drive, which is the topic of this thread?

Quote from michaelharney1

The pressure differential is real and very similar to what happens in the Casmir Effect (math.ucr.edu/home/baez/physics/Quantum/casimir.html )

In the Casimir effect, there are two metal plates of (relatively) infinite extent that attract one another. The Wikipedia article states that "The Casimir force is fundamentally a property of the coupled system of matter and fields, in which the interaction between the plates is mediated by the zero-point fields. In more traditional interpretations, however, the emphasis has fallen either on the electromagnetic field or the fluctuating material in the plates." It further says that at the microscopic level the Casimir effect requires a description in terms of van der Waals forces (residual attraction of atomic groups or molecules that does not arise from ionic or covalent bonds). So here we have (1) two plates that are attracted to one another, with (2) the zero-point fields simply mediating van der Waals forces.

In contrast to the picture seen in (1) and (2), in your description of the EM Drive the thrust arises from interaction with the vacuum itself, to which momentum is imparted. Instead of pushing off of something with mass, the EM Drive pushes off of the vacuum. Above you suggest that the pressure differential is similar to what happens in the Casimir affect. Can you elaborate on this suggestion in light of the key differences that have been raised?

Quote from AlainCo

I'm more optimistic about MiHsC interpretation.

I have read the book (Physics from the Edge) and concluded that what was proposed by Michael McCulloch in his MiHsC theory violated causality. I emailed him about this and he responded that MiHsC did seem to violate causality. He was working on a mathematical way around that. Until he can solve that problem, I think the theory is at least partly wrong. Michael's equations seem to fit, like Shawyer's equations seem to fit, natural behavior. However, they may fit for a different underlying reason. Many fundamental equations, like Newton's laws of motion, were derived ad hoc on the basis that they seemed to fit natural behavior. In most (if not all) cases, we still don't have an explanation of WHY nature behaves that way (an epistemological issue).

Quote from BobHiggins

Michael's equations seem to fit, like Shawyer's equations seem to fit, natural behavior. However, they may fit for a different underlying reason. Many fundamental equations, like Newton's laws of motion, were derived ad hoc on the basis that they seemed to fit natural behavior. In most (if not all) cases, we still don't have an explanation of WHY nature behaves that way (an epistemological issue).

Let's assume for the moment that the EM Drive is producing genuine thrust. Note that two of the variables Michael is looking at, power and taper angle, a likely proxy for anisotropy, are probably going to be found in any interesting theory.

IMO the microwaves could get polarized in EMDrive with reflection - and the polarized photons are moving more slowly. This effect could explain the momentum and thrust of EMDrive in rather classical way without resorting to any exotic phenomena and undiscovered effects yet: the photons spread along its walls like the plasmons and they get polarized by reflection, thus being slowed down and behaving like the massive particles.

Quote from Zephir_AWT

IMO the microwaves could get polarized in EMDrive with reflection - and the polarized photons are moving more slowly. This effect could explain the momentum and thrust of EMDrive in rather classical way without resorting to any exotic phenomena and undiscovered effects yet: the photons spread along its walls like the plasmons and they get polarized by reflection, thus being slowed down and behaving like the massive particles.

For the thrust of the EMDrive to be explained by the photons becoming massive and carrying away momentum, the photons would need to exit the cavity in an anisotropic way. And once they are outside of the cavity, there will no longer be the conditions to produce the effect you propose. They'll be in free space, and no longer slowed down. But I think the cavity acts like a Faraday cage, so to my knowledge only blackbody radiation is escaping.

(And there's something about the group versus phase velocity of light which is likely to add more subtleties to the description.)

@Eric Walker /* the photons would need to exit the cavity in an anisotropic way */

Here are two basic ways how to create a thrust: 1) by acceleration and ejecting the particles in anisotropic way or 2) by their anisotropic braking and absorption. IMO other reaction-less drives can still work in other way but given the fact that EMDrive cavity behaves like the Faraday cage and it cannot radiate the photons into outside, the second option seems to be more relevant.

Quote from Zephir_AWT

Here are two basic ways how to create a thrust: 1) by acceleration and ejecting the particles in anisotropic way or 2) by their anisotropic braking and absorption. IMO other reaction-less drives can still work in other way but given the fact that EMDrive cavity behaves like the Faraday cage and it cannot radiate the photons into outside, the second option seems to be more relevant.

Can you elaborate on your option (2)?

Think of people sitting in a rowboat. If all they're doing is pushing back and forth on the hull of boat itself, the boat will just slide back and forth beneath them, without any net movement forward. (This is how I understand your second option.) In order for the boat to move forward, they must either row (imparting momentum to the water outside of the boat, in the opposite direction) or jettison something with mass.

Quote

It seems consensual among theorist that to merge GR and QM you need to abandon one of the 3 laws :

causality.
locality.
speed of light limit for information exchange.

Another good reason is to remember that early version of relativity, gravity waves, big bang theory, and of many theories, have great flaws.

QM require that you lose locality, or else get overly complex. This does not as far as we know break causality or allow FTL signalling. The claims that this can happen are not strong.

Anyone who has noticed macroscopic quantum coherent phenomena (e.g. BECs) would not want to insist on any narrow notion of locality!

@Eric Walker: The photons spreading at free vacuum are indeed massless. But the photons inside the EMDrive aren't spreading at free vacuum but along conductive walls of resonator like so-called plasmons. Their speed is already way lower and as such they thus behave like the massive pseudoparticles there. These photons gain their mass from massive environment, along which they're spreading.

In addition, even the photons can gain some minute mass during their polarization. The polarized light is spreading more slowly and thus like massive wave with respect to normal light - and this is all still quite classical effect. But at the surface of metals this effect gets way more pronounced. Their speed can be lowered not be just few promiles, but by multiple orders there. IMO the microwaves could get polarized in EMDrive with reflection - and the polarized photons are propagating more slowly. Because the level of this process (i.e. the loss of momentum by polarization) has its gradient along EMDrive resonator length, it also remains the source of drag at the inner surface of resonator.

Quote from Zephir_AWT

Because the level of this process (i.e. the loss of momentum by polarization) has its gradient along EMDrive resonator length, it also remains the source of drag at the inner surface of resonator.

Can you formulate your idea in terms of the people in the rowboat? They're either jettisoning something (photons, neutrinos, etc.), or they're imparting momentum to something (the vacuum, the aether, etc.), making it travel in the opposite direction?

The interference pattern that the microwaves produce generate lines of positive vacuum energy. On those lines of enhanced positive energy, virtual particle productions goes way up. These virtual particles last longer before they decay. The production of momentum creates an oposit reaction that produces trust.

/* Can you formulate your idea in terms of the people in the rowboat? */

I'd say, these people collect the rain (of photons) and they're redistributing its (mass) water along the board, thus creating the trust. Excessive water evaporates from boat (in form of merely omnidirectional thermal radiation), thus enabling this process to run continuously.

/* Its positive and negative vacuum energy that does it. */

This hypothesis should be proved by detection of different levels of vacuum energy at both ends of EMDrive. But IMO the EMDrive could be explained even without resorting to hypothetical-yet concepts.

Quote from Zephir_AWT

I'd say, these people collect the rain (of photons) and they're redistributing its (mass) water along the board, thus creating the trust. Excessive water evaporates from boat (in form of merely omnidirectional thermal radiation), thus enabling this process to run continuously.

It sounds like you are saying that your idea involves the generation of thrust through the emission of photons preferentially in one direction outside of the EM Drive. Is this correct?

Quote from Eric Walker

It sounds like you are saying that your idea involves the generation of thrust through the emission of photons preferentially in one direction outside of the EM Drive. Is this correct?

I thought that particle generation conserves momentum? For that purpose the vacuum needs to be polarized and the particle must in average be expelled/ produced to fly opposite the thrust (in line with movement) direction...

Wasn't the theory originally about massless propulsion?