Tuesday, December 23, 2014

The Breakthrough Propulsion Concept Sanity Checker

Propulsion is, on the surface, a very simple science: I make a machine which uses stored propellants or some medium my vehicle is interacting with to generate a momentum exchange with my surroundings, thus making my vehicle move in the opposite direction. But once you dive into the details of any propulsion system you will quickly find that mastering this 'simple' science requires a lot of detailed knowledge: thermodynamics, fluid dynamics, chemistry, heat transfer physics, statistical mechanics, material science, electronics and of course rigid body mechanics and dynamics are essential. If you work with space propulsion odds are you will also need to know quite a bit about quantum mechanics, electrodynamics, and plasma physics as well. Put synoptically, it's really hard to make a completely new propulsion system which will be a fundamental 'breakthrough' in the field. Many have tried; most have failed. But that of course doesn't stop a wide variety of scam artists as well as honest-to-goodness crackpots from standing up and claiming they have a viable 'breakthrough' propulsion concept. Sadly these people can often find support both among laymen (who have little resources to distinguish viable new concepts from obviously spurious claims) and even propulsion engineers who may be specialized in a different area.

I've been getting tired of these claims being reported in the media and discussed as if they had any merit. Not only does this spread false information among non-experts, but it also takes time and reporting space away from true progress in propulsion. Imagine for instance if the coverage of the garbage NASA reactionless drive coverage I posted about in August had instead been dedicated to the co-development of a full-flow staged combustion rocket engine by NASA and SpaceX. Not only is this more interesting than a reactionless drive because it actually exists, but it's also more useful as a technology and the story gives a better picture of how the aerospace industry actually works. Thus in the hopes of assisting not only prospective inventors of 'breakthrough' propulsion concepts but also laymen and elsewhere specialized engineers, I've compiled a list of guidelines for any would-be propulsion innovator. If there's something that's not on here which should be please let me know in the comments!

The List:

1. If your breakthrough propulsion concept relies on unobserved or falsified physics, it is exceedingly likely to be spurious. 

2. if your breakthrough propulsion concept achieves delta-V without expending reaction mass, it is exceedingly like to be spurious. 

3. Indeed, if your breakthrough propulsion concept violates the conservation of momentum or angular momentum in a closed system in any way, it is exceedingly likely to be spurious.

4. No propulsion system can ever, ever, EVER lead to a macroscopic violation of energy conservation. EVER.

5. building on that last point, if your breakthrough propulsion concept violates ANY of the laws of thermodynamics, it is purely fictitious.

6. No Unobtanium Principle: If your breakthrough propulsion concept requires propellants, power sources, or materials which either do not currently exist or have been shown to not be able to exist, it is fiction until those materials become available.

7. Math is your friend. If you cannot present and justify simple, first-order performance calculations for your breakthrough propulsion concept, the odds are it is flawed or impossible. 

8. Fallacious and unjustified reasoning is not an "approximation", it's just wrong.  

9. Almost any concept relying on the "quantum vacuum" is exceedingly likely to be spurious, most likely due to the proposer not understanding the physics of the QFT vacuum. 

10. Conference papers which have not been peer-reviewed are not evidence of concept validity. Neither are websites, blog posts, articles in low-impact/poor quality/obscure/for-profit journals, non peer-reviewed articles on online repositories or publications, self-published books, angry letters or emails to legitimate propulsion researchers, snarky comments on websites/blogs/online publications, or abstract macaroni portraits of your idea. 

11. Your tests of your prototype of your breakthrough propulsion concept are not evidence of validity until (1) they are written up, peer-reviewed, and accepted for publication in a well-known, mainstream aerospace or propulsion journal, (2) they are successfully duplicated by other mainstream propulsion researchers, and (3) these successful duplications are themselves written up, peer-reviewed, and published in a well-known, mainstream aerospace or propulsion journal.

12. Test results reported without a rigorous propagation of uncertainty, comprehensive analysis of systematics, and a significant number of data points, are meaningless and can (and should) be dismissed without review.

13. Similarly, test results obtained at a low level of statistical significance do not validate nor falsify a concept.

14. Preparing a press release or giving a talk on your idea before submitting it for peer-review is tantamount to being so arrogant you think you don't need any feedback from your colleagues. Since the most arrogant people in any subject are usually the least capable (see the Dunning-Kruger effect) this is a valid cause for skepticism in and of itself.

15. Patents are not the same as peer-review, nor are they evidence of validity. Just because you have the legal right to patent your idea doesn't mean anyone else has to take it seriously. In truth any idea which is patented before it is constructed, tested, and peer-reviewed is likely to be spurious. 

Sunday, December 21, 2014

Walter Lewin Barred From MIT After Serious Allegations of Harassment

For those who don't know already, MIT professor emeritus Walter Lewin has been barred from MIT and his ties with the University cut after a secretive investigation of Lewin claimed he had violated MIT's sexual harassment guidelines during an online course. In the wake of the decision, all of Lewin's video lectures on physics have also been pulled from MIT's open courseware site and several press statements released. There is more detail here and another blog about it here.

If these allegations are true it is truly a shame. I remember watching Lewin's now famous basic physics lectures while I learned the same stuff from my much loved but sometimes overworked physics professor, Erik Kramer of the College of the Redwoods (known simply as "CR" to any Humboldt county native). Prof. Kramer's class, unlike so many physics courses, was something students looked forward to and he put a lot of his soul into making it as good as possible. This was sometimes hard to do at a small community college where he was the only physics professor and which had no money for any new lab equipment, often making lab sessions and demonstrations minimal. Those of us who were interested in physics, including myself and my friend Noah Flemens (now a grad student in applied physics at Cornell), would supplement Kramer's lectures with Lewin's from MIT and pretty soon the small group of 'physics kids' at CR were comparing and contrasting their "two favorite Dutchmen", though of course only Kramer could truly be thanked (or blamed) for how any of us turned out.

To hear the decision on Lewin is heartbreaking and I don't think it's right that MIT is being so secretive regarding the evidence which pushed them to dismiss a legend in physics education. Sources I found say it was clear the incidents were real and serious and this may be true, but it is no more than hearsay until we are given something--anything--to back it up beyond MIT's word.

Another bizarre decision is MIT's removal of Lewin's physics lectures from their Open Courseware website. In my opinion this is one of the best ideas MIT has had in a long time and one of the only things keeping them relevant in a world where their prestige is based more and more on their brand rather than their research quality (aside: I could write multiple posts about my view on 'big' school brands but now's not the time). Lewin's lectures were undoubtably some of the best on Open Courseware and recent events don't change that. Instead it robs the world at large from hearing good, well put together lectures on basic physics, and is MIT breaking a promise they (very publicly) made to the world at Open Courseware's inception.

Thus it seems as if MIT has two responsibilities in dealing with this incident: (1) make public the evidence of Lewin's harassment; for those of us who once idolized him as a teacher, it's the least they could do. (2) restore Lewin's lectures to Open Courseware. These lectures in and of themselves have nothing to do with this incident and it is pointless to punish those who would like to learn more about basic physics for inappropriate things the presenter may or may not have subsequently done.