I'm always saying to my students that "The best way to learn is to do", and I always enjoy scribbling back-of-the-envelope calculations (in the manner of Hans Bethe and Enrico Fermi) so here's a quick MiHsC-emdrive calculation I did recently. Note that it is not as rigorous as my paper, it is a heuristic simplification.

It is important to have a real experiment as a basis, so I've used Shawyer's first experimental setup, with a cavity Q = 5900, power input P = 850W, cavity length L = 0.156m, wide end width = 0.16m, narrow end = 0.1275m, and I've assumed a mass of 10 kg (as you'll see this last is unimportant as it cancels out).

The time for a photon to dissipate, given Q is

T = distance/c = QxCavityLength/c

T = 5900x0.156/3x10^8 s

T = 3.1x10^-6 s

Energy input into the cavity in this time is

E = PowerxT = 850x3.1x10^-6 = 0.0026 J

The mass (m) of the microwave energy is

m = E/c^2 = 0.0026/(3x10^8)^2 = 2.9x10^-20 kg.

The new effect predicted by MiHsC is that photons' centre of mass is continually shifted towards the wide end. Normally, as in my paper, I would calculate the photon mass change implied by MiHsC as more Unruh waves are allowed at the wide end, increasing photon mass there in a new way. Here, in order to point out the wider connection with MiHsC-cosmology, I'm going to take a short cut and calculate photon behaviour by noting that in MiHsC, a volume (sphere) bounded by a horizon must have a minimum acceleration of

a = 2c^2/L

where L is the diameter of the sphere. If you put in the Hubble volume L = 2.6x10^26 metres, then MiHsC predicts the recently-observed cosmic acceleration (usually attributed arbitrarily to dark energy) and it also predicts the acceleration below which galaxies misbehave and their rotation (usually attributed to arbitrary dark matter). We can regard each end of the cavity as being a little Hubble sphere (introducing an error of probably a factor of two) but the acceleration of the photons along the length of the emdrive cavity is then the difference between the accelerations at the wide end (the big cosmos) and narrow end (small cosmos), which is:

a = 2c^2/Lwide - 2c^2/Lnarrow = 2x(3x10^8)^2 x (1/0.16 - 1/0.1275)

a = 2.87x10^17 m/s^2

As the microwave photons are shifted rightwards by MiHsC (see the red arrows in the Figure) the cavity must shift left to conserve momentum (see the black arrow).

We can calculate the acceleration of the cavity, much smaller due to its greater mass, by differentiating the conservation of momentum:

Acceleratn of cavity x CavityMass = Light Acc x MicrowaveMass

Ac x Mc = Al x Mm

Ac = Al x Mm / Mc = 2.87x10^17 x 2.9x10^-20 / 10

Ac = 0.00083 m/s^2

So F = ma = 10x0.00083 = 8.4 mN (The observed force was 16 mN for this case).

I always enjoy the closure and elegance of this sort of calculation and I believe that the ability of a theory to predict something openly on a single sheet of paper speaks well for it, in contrast to theories that require adjustable parameters hidden in labyrinthine computer programs or in the small print of complex derivations. There are no such parameters here.

It is important to have a real experiment as a basis, so I've used Shawyer's first experimental setup, with a cavity Q = 5900, power input P = 850W, cavity length L = 0.156m, wide end width = 0.16m, narrow end = 0.1275m, and I've assumed a mass of 10 kg (as you'll see this last is unimportant as it cancels out).

__Step 1. Calculate the mass of light in the cavity__The time for a photon to dissipate, given Q is

T = distance/c = QxCavityLength/c

T = 5900x0.156/3x10^8 s

T = 3.1x10^-6 s

Energy input into the cavity in this time is

E = PowerxT = 850x3.1x10^-6 = 0.0026 J

The mass (m) of the microwave energy is

m = E/c^2 = 0.0026/(3x10^8)^2 = 2.9x10^-20 kg.

__Step 2. The MiHsC-acceleration of photons in the cavity__The new effect predicted by MiHsC is that photons' centre of mass is continually shifted towards the wide end. Normally, as in my paper, I would calculate the photon mass change implied by MiHsC as more Unruh waves are allowed at the wide end, increasing photon mass there in a new way. Here, in order to point out the wider connection with MiHsC-cosmology, I'm going to take a short cut and calculate photon behaviour by noting that in MiHsC, a volume (sphere) bounded by a horizon must have a minimum acceleration of

a = 2c^2/L

where L is the diameter of the sphere. If you put in the Hubble volume L = 2.6x10^26 metres, then MiHsC predicts the recently-observed cosmic acceleration (usually attributed arbitrarily to dark energy) and it also predicts the acceleration below which galaxies misbehave and their rotation (usually attributed to arbitrary dark matter). We can regard each end of the cavity as being a little Hubble sphere (introducing an error of probably a factor of two) but the acceleration of the photons along the length of the emdrive cavity is then the difference between the accelerations at the wide end (the big cosmos) and narrow end (small cosmos), which is:

a = 2c^2/Lwide - 2c^2/Lnarrow = 2x(3x10^8)^2 x (1/0.16 - 1/0.1275)

a = 2.87x10^17 m/s^2

__Step 3 - By conservation of momentum__As the microwave photons are shifted rightwards by MiHsC (see the red arrows in the Figure) the cavity must shift left to conserve momentum (see the black arrow).

We can calculate the acceleration of the cavity, much smaller due to its greater mass, by differentiating the conservation of momentum:

Acceleratn of cavity x CavityMass = Light Acc x MicrowaveMass

Ac x Mc = Al x Mm

Ac = Al x Mm / Mc = 2.87x10^17 x 2.9x10^-20 / 10

Ac = 0.00083 m/s^2

__Step 4 - The Predicted Force__So F = ma = 10x0.00083 = 8.4 mN (The observed force was 16 mN for this case).

I always enjoy the closure and elegance of this sort of calculation and I believe that the ability of a theory to predict something openly on a single sheet of paper speaks well for it, in contrast to theories that require adjustable parameters hidden in labyrinthine computer programs or in the small print of complex derivations. There are no such parameters here.