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

Monday 28 November 2016

Emdrives & dielectrics: the NASA shift

The NASA paper further supporting the previous emdrive experiments (in which a microwave-filled conical cavity moves towards its narrow end without expelling anything, as standard physics says it just shouldn't do) has finally been published. Apparently Eagleworks had a terrible time publishing it, so well done to them.

It is interesting that all the NASA results are anomalous in comparison with results from the other teams: Shawyer's, the Cannae group and Tajmar's. The plot below shows the thrust predicted by quantised inertia (MiHsC) on the x axis, and the y axis shows the thrusts observed in the lab. It would be great if all the diamonds representing the different emdrive experiments were along the diagonal line (a perfect agreement). The Shawyer, Cannae and Tajmar experiments are, but the NASA experiments are all shifted rightwards. This shows that MiHsC over-predicts the thrust for NASA's tests by a factor that can be as much as ten.
I may have an explanation for this. MiHsC predicts the emdrive's thrust by saying that the inertia of the microwave photons is caused by Unruh radiation (a radiation you only see if you accelerate). At the wide end of the cavity more Unruh wavelengths fit within, and are 'allowed', due to the bigger space available, but at the narrow confined end fewer are allowed (as for the Casimir effect). Thus, MiHsC is continually shifting the photons' collective centre of mass towards the wide end so that to conserve momentum the cavity has to shift the other way, as indeed it does, but more slowly as it is far more massive than the microwaves (more detail).

A new possibility to explain NASA's anomaly within an anomaly (the NASA shift) is as follows. Most of the NASA experiments, including the latest one, put a dielectric at the narrow end of the cavity. A dielectric means that Unruh waves will be slower and have shorter wavelengths, and so more of them will fit at the narrow end. MiHsC therefore predicts that having a dielectric at one end is rather like widening that end, and if you put it at the narrow end, then you reduce the taper and reduce the thrust.

I've already worked out some of the maths for dielectrics, after I read an interesting, but inconclusive, 2016 report by a group at CalPoly (Kraft and Zeller, 2016) who tested a cylindrical emdrive with a dielectric at one end. I just need to account now for both a dielectric and taper and see if the numbers fit the NASA shift.


McCulloch, M.E., 2015. Testing quantised inertia on the emdrive. EPL, 111, 60005. Preprint

K. Zeller and B. Kraft, 2016. Investigation of a partially-loaded resonant cavity. CalPoly research report.

White, H., P. March, J. Lawrence, J. Vera, A. Sylvester, D. Brady, P. Bailey, 2016. Measurement of impulsive thrust from a closed rf cavity in vacuum. AIAA J. of Propulsion and Power. Online


Alain_Co said...

ah, interesting...
I remind me Jed Rothwell explaining that it is very difficult to make scientists replicate the same experiments, they always improve and adapt according to their own pet theory.

by the way, off-topic, Ethan Seagle make is regular LENr Emdrive experiment bashing session...
Some interesting theory that Emdrive may just trigger darkmatter disintegration...


as you say, darkmatter can explain all!

Zephir said...

/* MiHsC therefore predicts that having a dielectric at one end is rather like widening that end, and if you put it at the narrow end, then you reduce the taper and reduce the thrust */

This is very interesting and undoubtedly testable easily - but why NASA should willingly eliminate the effects sought by placing dielectric insert at the wrong end of EMDrive?

TheTraveller said...
This comment has been removed by the author.
TheTraveller said...


Can you explain why when NASA removed the dielectric, the measured force had a direction small to big, vs the big to small force direction measured with the dielectric?

Dielectric force direction:

Non dielectric:

Mike McCulloch said...

Alain: In my opinion there's more scientific spirit in one LENR or emdrive researcher than in the 1000s of dark matter-ists, bcos the former are risking their career to curiously investigate a new observation (whatever it is), while the latter are inventing invisible and unfalsifiable entities to follow the crowd (the safe career route) & defend an old theory (which is the opposite of the scientific method).

Mike McCulloch said...

Zephir: NASA put the dielectric there for their own reasons and because they were unaware of this possibility, which is a prediction of MiHsC. As far as I know, the Eagleworkers do not accept MiHsC. I intend to write a paper about this aspect of it..

Zephir said...

Hello, Mike: The inserting of insert into EMDrive will not only change the level of thrust, but it may reverse its sign https://www.reddit.com/r/EmDrive/comments/5fhg46/force_direction_reverses_with_and_without Personally such a result doesn't suprises me, as it confirms for me, that the thrust is the function of standing EM wave geometry, not the EMDrive geometry.

TheTraveller said...

That is correct.

Have done a new graphic to tie it all together:


According to radiation pressure theory, then end plate with the shortest 1/2 wave will have the highest radiation pressure and thus the force will be directed to that end late as shown.

Zephir said...

To be honest, I don't believe, that the very local quantity i.e. the inertia has its origin at the very distant particle horizons. Note that radiation pressure of Unruh radiation also relies on sorta circular reasoning, because such a pressure must be introduced with inertia of that radiation after then - and it just transfers the problem to another subject.Such a mechanism would introduce a delay into inertia during material particles formation from bosons and/or oscillations (neutrino) not to say, when Unruh radiation is propagating with speed of light? IMO the inertia is closely connected with relativistic mass defined with speed of objects toward ZPE fluctuations of vacuum and its reference frame. I.e. it's connected with local Cassimir effect rather than to hypothetical Hubble scale Cassimir effect, considering that the Cassimir effect is composite manifestation of ZPE fluctuation.

IMO the actual contribution in MiHSC theory is 1st order approximation into quantifying of quantum effects, which modulate relativity at low energy density scales due to ZPE fluctuations. The energy density of these fluctuations can be estimated from cosmological observations, as they also result into red shift and scattering of light. MOND theory therefore considers its acceleration to product of Hubble constant and speed of light, whereas MiHSC utilizes diameter of observable Universe, which is also determined with this scattering.

But the correlation doesn't imply causation: the fact, that the period of solar eclipses can be calculated from epicycle model and the results even fit the reality well still doesn't imply, that the Sun is revolving the Earth in epicycles. No matter how well the formal model works in some circumstances - Galielo could talk about it.

DataPacRat said...


Is there a standard method for calculating the Q of a resonant cavity, which can be paired with formula 14 of https://arxiv.org/pdf/1604.03449v1.pdf and run through some software to figure out what shape would provide maximum thrust for a given input power? Rephrasing myself, is it possible to take your work and apply it to try to build a better EmDrive, and if so, what's the resulting design?

Thank you for your time.

TheTraveller said...

Cavity Q calc is not difficult and is driven by Rs.

Cavity Qu scales the Rs.

Typical room temp Cu Rs is 15,000 uOhm.

Good 2016 77K YBCO at 3.85GHz Rs is 3uOhm.

SPR measured 326mN/kW at 60,000 Qu with Cu at room temp.

Rs difference is 5,000x so Qu increases for a YBCO coated cavity at 77K at 3.8GHz to 30,000,000 or 5,000x.

Thus specific force increases 5,000x from 0.326N/kW to 1,630N/kW.

DataPacRat said...


If that's accurate, that's certainly a good start; but what I'm wondering is if changing a cavity's shape significantly affects its Q. If it doesn't, then as best as I can figure from formula 14, the maximum thrust you can achieve by varying Length, Width (small end) and Width (large end) comes if you maximize the Width (large end), shrink Width (small end) down to 0 (thus turning the truncated cone into an actual cone), and shrinking Length to as close to 0 as possible without actually reaching 0. In other words, something that looks a lot more like a hollow flat plate than the typical blocky microwave cavities that are currently being tested.

However, if Q does change based on the cavity's shape, then that would probably have a much more significant effect than the gains from the shape I just described. And, as you described, any other factors that can change Q, such as lining the cavity with a superconductor instead of copper, would also be more worth pursuing.

By the way, how much does "good 2016 YBCO" cost these days?

Fervent Dissent said...

This tells you how to calculate Q losses of a cavity, sort version is use a superconductor and have no holes.