In what spirit do we pursue experimentation, and with what criteria do we judge the results? Marc Millis has been thinking and writing about such questions in the context of new propulsion concepts for a long time. As head of NASA’s Breakthrough Propulsion Physics program, he looked for methodologies by which to push the propulsion envelope in productive ways. As founding architect of the Tau Zero Foundation, he continues the effort through books like Frontiers of Propulsion Science, travel and conferences, and new work for NASA through TZF. Today he reports on a recent event that gathered people who build equipment and test for exotic effects. A key issue: Ways forward that retain scientific rigor and a skeptical but open mind. A quote from Galileo seems appropriate: “I deem it of more value to find out a truth about however light a matter than to engage in long disputes about the greatest questions without achieving any truth.”
by Marc G Millis
A workshop on propellantless propulsion was held at a sprawling YMCA campus of classy rusticity, in Estes Park Colorado, from Sept 10 to 14. These are becoming annual events, with the prior ones being in LA in Nov 2017, and in Estes Park, Sep 2016. This is a fairly small event of only about 30 people.
It was at the 2016 event where three other labs reported the same thrust that Jim Woodward and his team had been reporting for some time – with the “Mach Effect Thruster” (which also goes by the name “Mach Effect Gravity Assist” device). Backed by those independent replications, NASA awarded Woodward’s team NIAC grants. Updates on this work and several other concepts were discussed at this workshop. There will be a proceedings published after all the individual reports are rounded up and edited.
Before I go on to describe these updates, I feel it would be helpful to share a technique that I regularly use to when trying to assess potential breakthrough concepts. I began using this technique when I ran NASA’s Breakthrough Propulsion Physics project to help decide which concepts to watch and which to skip.
When faced with research that delves into potential breakthroughs, one faces the challenge of distinguishing which of those crazy ideas might be the seeds of breakthroughs and which are the more generally crazy ideas. In retrospect, it is easy to tell the difference. After years of continued work, the genuine breakthroughs survive, along with infamous quotes from their naysayers. Meanwhile the more numerous crazy ideas are largely forgotten. Making that distinction before the fact, however, is difficult.
So how do I tell that difference? Frankly, I can’t. I’m not clairvoyant nor brilliant enough to tell which idea is right (though it is easy to spot flagrantly wrong ideas). What I can judge and what needs to be judged is the reliability of the research. Regardless if the research is reporting supportive or dismissive evidence of a new concept, those findings mean nothing unless they are trustworthy. The most trustworthy results come from competent, rigorous researchers who are impartial – meaning they are equally open to positive or negative findings. Therefore, I first look for the impartiality of the source – where I will ignore “believers” or pedantic pundits. Next, I look to see if their efforts are focused on the integrity of the findings. If experimenters are systematically checking for false positives, then I have more trust in their findings. If theoreticians go beyond just their theory to consider conflicting viewpoints, then I pay more attention. And lastly, I look to see if they are testing a critical make-break issue or just some less revealing detail. If they won’t focus on a critical issue, then the work is less relevant.
Consider the consequences of that tactic: If a reliable researcher is testing a bad idea, you will end up with a trustworthy refutation of that idea. Null results are progress – knowing which ideas to set aside. Reciprocally, if a sloppy or biased researcher is testing a genuine breakthrough, then you won’t get the information you need to take that idea forward. Sloppy or biased work is useless (even if from otherwise reputable organizations). The ideal situation is to have impartial and reliable researchers studying a span of possibilities, where any latent breakthrough in that suite will eventually reveal itself (the “pony in the pile”).
Now, back to the workshop. I’ll start with the easiest topic, the infamous EmDrive. I use the term “infamous” to remind you that (1) I have a negative bias that can skew my impartiality, and (2) there are a large number of “believers” whose experiments never passed muster (which lead to my negative bias and overt frustration).
Three different tests of the EmDrive were reported of varying degrees of rigor. All of the tests indicated that the claimed thrust is probably attributable to false positives. The most thorough tests were from the Technical University of Dresden, Germany, led by Martin Tajmar, and where his student, Marcel Weikert presented the EmDrive tests, and Matthias Kößling on the details of their thrust stand. They are testing more than one version of the EmDrive, under multiple conditions, and all with alertness for false positives. Their interim results show that thrusts are measured when the device is not in a thrusting mode – meaning that something else is creating the appearance of a thrust. They are not yet fully satisfied with the reliability of their findings and tests continue. They want to trace the apparent thrust its specific cause.
The next big topic was Woodward’s Mach Effect Thruster – determining if the previous positive results are indeed genuine, and then determining if they are scalable to practical levels. In short – it is still not certain if the Mach Effect Thruster is demonstrating a genuine new phenomenon or if it is a case of a common experimental false positive. In addition to work of Woodward’s team, led by Heidi Fearn, the Dresden team also had substantial progress to report, specifically where Maxime Monette covered the Mach Effect thruster details in addition to the thrust stand details from Matthias Kößling. There was also an analytical assessment by based on conventional harmonic oscillators, plus more than one presentation related to the underlying theory.
One of the complications that developed over the years is that the original traceability between Woodward’s theory and the current thruster hardware has thinned. The thruster has become a “back box” where the emphasis is now on the empirical evidence and less on the theory.
Originally, the thruster hardware closely followed the 1994 patent which itself was a direct application of Woodward’s 1990 hypothesized fluctuating inertia. It involved two capacitors at opposite ends of a piezoelectric separator, where the capacitors experience the inertial fluctuations (during charging and discharging cycles) and where the piezoelectric separator cyclically changes length between these capacitors.
Its basic operation is as follows: While the rear capacitor’s inertia is higher and the forward capacitor lower, the piezoelectric separator is extended. The front capacitor moves forward more than the rear one moves rearward. Then, while the rear capacitor’s inertia is lower and the forward capacitor higher, the piezoelectric separator is contracted. The front capacitor moves backward less than the rear one moves forward. Repeating this cycle shifts the center of mass of the system forward – apparently violating conservation of momentum.
The actual conservation of momentum is more difficult to assess. The original conservation laws are anchored to the idea of an immutable connection between inertia and an inertial frame. The theory behind this device deals with open questions in physics about the origins and properties of inertial frames, specifically evoking “Mach’s Principle.” In short, that principle is ‘inertia here because of all the matter out there.’ Another related physics term is “Inertial Induction.” Skipping through all the open issues, the upshot is that variations in inertia would require revisions to the conservation laws. It’s an open question.
Back to the tale of the evolved hardware. Eventually over the years, the hardware configuration changed. While Woodward and his team tried different ways to increase the observed thrust, the ‘fluctuating inertia’ components and the ‘motion’ components were merged. Both the motions and mass fluctuations are now occurring in a stack of piezoelectric disks. Thereafter, the emphasis shifted to the empirical observations. There were no analyses to show how to connect the original theory to this new device. The Dresden team did develop a model to link the theory to the current hardware, but determining its viability is part of the tests that are still unfinished [Tajmar, M. (2017). Mach-Effect thruster model. Acta Astronautica, 141, 8-16.].
Even with the disconnect between the original theory and hardware now under test, there were a couple of presentations about the theory, one by Lance Williams and the other by Jose’ Rodal. Lance, reporting on discussions he had when attending the April 2018 meeting of American Physical Society, Division of Gravitational Physics, suggested how to engage the broader physics community about this theory, such as using the more common term of “Inertial Induction” instead of “Mach’s Principle.” Lance elaborated on the prevailing views (such as the absence of Maxwellian gravitation) that would need to be brought into the discussion – facing the constructive skepticism to make further advances. Jose’ Rodal elaborated on the possible applicability of “dilatons” from the Kaluza–Klein theory of compactified dimensions. Amid these and other presentations, there was lively discussion involving multiple interpretations of well established physics.
An additional provocative model for the Mach Effect Thruster came from an interested software engineer, Jamie Ciomperlik, who dabbles in these topics for recreation. In addition to his null tests of the EmDrive, he created a numerical simulation for the Mach Effect using conventional harmonic oscillators. The resulting complex simulations showed that, with the right parameters, a false positive thrust could result from vibrational effects. After lengthy discussions, it was agreed to examine this more closely, both experimentally and analytically. Though the experimentalists already knew of possible false positives from vibration, they did not previously have an analytical model to help hunt for these effects. One of the next steps is to check how closely the analysis parameters match the actual hardware.
Quantum approaches were also briefly covered, where Raymond Chiao discussed the negative energy densities of Casimir cavities and Jonathan Thompson (a prior student of Chiao’s) gave an update on experiments to demonstrate the “Dynamical Casimir effect” – a method to create a photon rocket using photons extracted from the quantum vacuum.
There were several other presentations too, spanning topics of varying relevance and fidelity. Some of these were very speculative works, whose usefulness can be compared to the thought-provoking effect of good science fiction. They don’t have to be right to be enlightening. One was from retired physicist and science fiction writer, John Cramer, who described the assumptions needed to induce a wormhole using the Large Hadron Collider (LHC) that could cover 1200 light-years in 59 days.
Representing NASA’s Innovative Advanced Concepts (NIAC), Ron Turner gave an overview of the scope and how to propose for NIAC awards.
A closing thought about consequences. By this time next year, we will have definitive results on the Mach Effect Thruster, and the findings of the EmDrive will likely arrive sooner. Depending on if the results are positive or negative, here are my recommendations on how to proceed in a sane and productive manner. These recommendations are based on history repeating itself, using both the good and bad lessons:
If It Does Work:
- Let the critical reviews and deeper scrutiny run their course. If this is real, a lot of people will need to repeat it for themselves to discover what it’s about. This takes time, and not all of it will be useful or pleasant. Pay more attention to those who are attempting to be impartial, rather than those trying to “prove” or “disprove.” Because divisiveness sells stories, expect press stories focusing on the controversy or hype, rather than reporting the blander facts.
- Don’t fall for the hype of exaggerated expectations that are sure to follow. If you’ve never heard of the “Gartner Hype Cycle,” then now’s the time to look it up. Be patient, and track the real test results more than the news stories. The next progress will still be slow. It will take a while and a few more iterations before the effects start to get unambiguously interesting.
- Conversely, don’t fall for the pedantic disdain (typically from those whose ideas are more conventional and less exciting). You’ll likely hear dismissals like, “Ok, so it works, but it’s not useful. ” or “We don’t need it to do the mission.” Those dismissals only have a kernel of truth in a very narrow, near-sighted manner.
- Look out for the sharks and those riding the coattails of the bandwagon. Sorry to mix metaphors, but it seemed expedient. There will be a lot of people coming out of the woodwork in search of their own piece of the action. Some will be making outrageous claims (hype) and selling how their version is better than the original. Again, let the test results, not the sales pitches, help you decide.
If It Does Not Work:
- Expect some to dismiss the entire goal of “spacedrives” based on the failure of one or two approaches. This is a “generalization error” which might make some feel better, but serves no useful purpose.
- Expect others to chime in with their alternative new ideas to fill the void, the weakest of which will be evident by their hyped sales pitches.
- Follow the advice given earlier: When trying to figure out which idea to listen too, check their impartiality and rigor. Listen to those that are not trying to sell nor dismiss, but rather to honestly investigate and report. When you find those service providers, keep tuned in to them.
- To seek new approaches toward the breakthrough goals, look for the intersection of open questions in physics to the critical make-break issues of those desired breakthroughs. Those intersections are listed in our book Frontiers of Propulsion Science.