This is a summary of the visit I have just made to Prof Martin Tajmar's esteemed Institute fuer Raumfahrttechnik at the Technische-Universitat-Dresden (TU-Dresden). I arrived on time at 10am. One of his students met me and took me to his office and then after a short chat, I gave a one-hour talk on quantised inertia (QI) to him & his research group of 30 or so. Martin Tajmar asked a few questions, eg:
- How does the cosmic horizon interact with local dynamics in QI given the speed of light limit? (Answer: there is no relativistic speed limit for monochromatic waves).
- Your assumption of an average acceleration of photons in the emdrive is wrong, they accelerate only when they rebound (Answer: true, but my assumption now has more backing, see below).
- What is the degree of shielding of Unruh radiation by matter? Won't that introduce an adjustable parameter to QI? (Answer: Maybe).
After the talk we all went for a meal at the nearby canteen, and I made it clear, as I tried to do in my talk, that I am very confident about quantised inertia on a galactic scale, but I need Tajmar and his team's world-class experimental expertise to bring it down to the lab scale.
Then he gave me a tour of his labs, in which he seems to be testing most of the anomalies I have heard of. I saw the equipment he used for the 'Tajmar effect' that I tried to explain in a paper in 2011 (see refs). It is still embedded in its concrete well. I held his small emdrive. He also has a massive wind tunnel for more mundane aeronautical experiments. At one point he said "And here is my Stargate..". I looked through a window and saw a huge room in which he is building something that looks like the fictional stargate (it's not).
Back in his office, a student who has just started a PhD devoted to the emdrive gave a talk on recent progress. They have applied 3-10 Watts to an emdrive and measured a thrust of two microN, but it disappears when they subtract thermal changes due to an asymmetrical expansion of the cavity and the resulting changes in the centre of mass. Note that this is a thrust ten times smaller than the thrust NASA JPL was getting for a similar power and this work is still in progress.
We talked about Travis Taylor's mirror proposal. It may not be possible to build as originally proposed, due to the dielectric and mirrors not being able to fit together - manufacturing limitations. So they suggested a simpler arrangement where the dielectric and mirrors do not touch.
Martin then said "We are physicists, let's play" and started writing on a white board, asking me for the relevant QI formulas to put in, and this way, we derived the maximum acceleration of a photon of given frequency. The result was interesting because it means that for visible light bouncing off a mirror the Rindler horizon will be so close that a shield will not effect it, but it also shows that for microwaves the horizon is cavity-sized, so they can see the emdrive shape, or a shield.
The most unexpected thing that Martin said to me was in the evening while socialising (I had some delicious Saxische Sauerbraten and dumplings, and rather more than my usual amount of beer). He criticised most of the well-known lab anomalies as being debatable due to often sloppy technique, and yet showed some interest in an anomaly I thought had been wildly discredited: Hutchison's. I thought I'd had too much beer.. Good physics is of course predictive, but the profession itself is not!
McCulloch, M.E., 2011. The Tajmar effect from quantised inertia. EPL, 95, 3. http://iopscience.iop.org/article/10.1209/0295-5075/95/39002/pdf