I've suggested (& published in 21 journal papers) a new theory called quantised inertia (or MiHsC) that assumes that inertia is caused by horizons damping quantum fields. It predicts galaxy rotation & lab thrusts without any dark stuff or adjustment. My University webpage is here, I've written a book called Physics from the Edge and I'm on twitter as @memcculloch. Most of my content is at patreon now: here

Friday 22 May 2015

Emdrive: whence motion?

Imagine an object in empty space accelerating rightwards. Now information from beyond a certain distance to its left, limited to light speed, can't catch up so there is an  information horizon, and the volume to the left of that horizon can never be seen by the object. A radiation like Hawking radiation comes off this horizon (Unruh radiation).

The first new contribution of MiHsC is that it says Unruh radiation is damped between the object and the horizon. Ernst Mach said, 'what can't be seen, can't exist', so from the point of view of the object all fields beyond the horizon must be zero, so they must be zero on the horizon too. Therefore, only waves with nodes at the horizon can be allowed. This cuts out many Unruh waves on the left side but not on the right, so more Unruh radiation hits the object from the right, slowing its acceleration. This correctly models what we call inertia, which has never before been explained. In general the horizon makes the zero point field, hitherto hidden, suddenly vary in space and able to push on real objects (see reference McCulloch, 2013, below).

The second part of MiHsC is that the Unruh radiation is also damped slightly by the far off Hubble horizon which cuts out some long wavelength Unruh radiation. This weakens the part of MiHsC described above, and so weakens inertia slightly in a new way. This makes more difference for low acceleration objects (which see long Unruh waves) and in this way MiHsC correctly models galaxy rotation without dark matter, and cosmic acceleration without dark energy (McCulloch, 2012).

Now to the emdrive: the photons in the cavity have inertial mass (photons in a mirrored box do) so MiHsC should apply. If we assume that the cavity walls are like the cosmic horizon in MiHsC then they will damp some Unruh radiation and make inertia weaker, but less so at the wider end. So the photons at the wide end have more inertia, and photons gain mass going from the narrow to the wide end. You'll note that mass-energy is not conserved in the usual way here because the horizon causes the zero point field to become real: just as black hole horizons cause virtual particles to become real (Hawking radiation). To conserve momentum the cavity has to move towards the narrow end. This predicts the emdrive results quite well, see here.

The application of MiHsC to the emdrive is summarised and derived properly (mathematically) in the paper below (McCulloch, 2015) and I'm mentioning it here in the hope of stimulating much needed debate.


McCulloch, M.E., 2013. Inertia from an asymmetric Casimir effect, EPL, 101, 59001. Link

McCulloch, M.E., 2012. Testing quantised inertia on galactic scales. Astrophys. and Space Sci., 342, 2, 575- Link

McCulloch, M.E., 2015. Can the emdrive be explained by quantised inertia. Progress in Physics, 11, 1, 78-80. Link


Alain_Co said...

since photons bounce in both directions, why is it not symmetric, thus globally null?

what accelerate the emdrive is just the difference in mass in both sides, not caring of the direction?

another question arisen, is that if momentum is conserved, given it is speed multiplied by inertial mass as MiHsC define it, is there a logical reason of tha conservation ?

all conservation laws are associated with symmetries of physics equations (over time translation, over space translations, over CPT parity)... what is CoM meaning in MiHsC?

Mike McCulloch said...

An analogy to the MiHsC explanation of emdrive would be a crazy person (photon) on a ship (cavity) who walks continually between the front & back. Every time they go back they pick up a weight from the deck, when they go forward they pick up nothing (or antimass if you like). The mass on the ship is now slightly moving backwards so the ship moves slightly forwards. The 'weights' are provided by MiHsC.

Alain_Co said...

ah, it is cleared

unruh wave depend on on the position but on the directions too

I now need to analyse the papers.
what is complex is that we have to think in term of acceleration, which is not easy for "finger intuition"...

Unknown said...

Hi Mike, I really like the MiHsC solution to the emdrive conundrum. In your paper you suggest that thrust will be improved by using a longer pointy cone filled with water. Can you give a ballpark figure for how much more efficient such a drive would be compared to (say) NASA's prototype?

Shawyer claims that using a superconductor with Q=1e9 would result in a thrust of 30kN/kW (flying car territory). Does that match with your model?

Mike McCulloch said...

Taking Shawyer's 2nd cavity geometry, where P=1kW, Q=1e9, length=0.345m, w_big=0.28m, w_small=0.1289m, then by MiHsC, F=(PQl/c)*(1/w_big-1/w_small)=4.8kN/kW.

Unknown said...

>You'll note that mass-energy is not conserved in the usual way here because the horizon causes the zero point field to become real: just as black hole horizons cause virtual particles to become real (Hawking radiation)

Can you expand on this a bit more? Does the EMdrive's kinetic energy (which will eventually exceed that of the input) derive from the zero point field?

Mike McCulloch said...

In MiHsC, inertia itself is due to a gradient in the zpf caused by the formation of a Rindler horizon when objects accelerate (see http://arxiv.org/abs/1302.2775). For the emdrive, MiHsC says that the new kinetic energy comes from the gradient in the zpf caused by the cavity which forms an asymmetric horizon: the zpf is less effective at the narrow end, so inertia is lower in that direction so the emdrive moves preferentially in that direction.

Unknown said...

Hi Mike,

I'm having a hard time understanding how the zpf can provide the missing energy. Does the emdrive leave behind a "wake" of high inertia?

Mike McCulloch said...

Hi Eirinn. Here's an analogy to explain where the energy in MiHsC comes from. A boat is on a sea with waves equal in all directions (the zpf). Suddenly a wall is put into the midst of that sea and damps waves near to it. Now the boat sees fewer waves hitting it from the direction of the wall than from the other direction so it moves towards the wall. If you were working with a physical model that usually ignores the sea and the wall (as standard dynamics does) then you'd think the energy was coming from nowhere. Hope this helps..

Unknown said...

Hi Mike,
That's a very nice analogy! I see that the placement of the wall could consume energy, but it's entirely unrelated to the energy that propels the ship towards the wall. That energy comes from the waves themselves.

Anonymous said...

Hi. Just a fan here. I'm sure you know about the subreddit regarding the emdrive. You're kind of a big deal there, and your work has inspired a lot of conversation and interest. If you're ever so inclined, people would love hearing directly from you - instead of relayed by others doing their best to understand or shrewdly passed on under the guise of someone else's own thoughts. (link to a post hijacking your boat analogy here):


Disclaimer: I haven't yet purchased your book, but am looking forward to it as a birthday present :)

Mike McCulloch said...

Hi John. I do read the subreddit threads. They are useful to me for many reasons, including finding out what I need to explain better. If I see a specific need I will jump in with a comment. Do let me know what you think of my book.