Thursday, April 13, 2017

A star drive which might work (Mach Effect)

NASA has just announced this: "Mach Effects for In Space Propulsion: Interstellar Mission".

From Centauri Dreams:
" In this case, the work goes toward a so-called Mach Effect Thruster (MET). Mach effects are transient variations in the rest masses of objects as predicted by standard physics where Mach’s principle applies. Proponents believe they offer the possibility of producing thrust without the ejection of propellant, as discussed in James Woodward’s Making Starships and Stargates: The Science of Interstellar Transport and Absurdly Benign Wormholes (Springer-Verlag, 2012).

What Fearn proposes is to investigate such thrusters by continuing the development of laboratory-scale devices while designing and developing power supply and electrical systems that will determine the efficiency of the Mach Effect Thruster. The analytical task is to improve theoretical thrust predictions and build a reliable model of the device. At the theoretical level, this team is definitely talking deep space, with part of the proposal being to:

'Predict maximum thrust achievable by one device and how large an array of thrusters would be required to send a probe, of size 1.5m diameter by 3m, of total mass 1,245 Kg including a modest 400kg of payload, a distance of 8 light years (ly) away.'"
Here's the book mentioned.

Amazon link

I downloaded the book-sample to my Kindle app and so far it's both well-written and interesting. Unlike the 'EM Drive', which was widely criticised and seems to violate conservation of momentum, the Mach Effect appears to be a valid consequence of General Relativity when combined with Mach's principle - at least, no-one so far has come forward with a convincing theoretical refutation.

Experimental effects so far appear to be small (if they exist at all) and unproven, but NASA evidently considers there could be something to it.

I'll probably read the book a little later. At least Jerry Pournelle will be pleased.


  1. From what I have read so far, this looks like another technique involving negative mass matter = negative energy matter = exotic matter. Yes this will have an interesting effect on GR if it exists...

    1. That would be the stargate; the star *drive* as proposed for propulsion uses high-frequency capacitor charging AFAIK ...

    2. The Wikipedia article has more:

    3. Informative WP article, but:

      1. A "theoretical refutation" is proposed that the relativistic form of F=ma has a dm/dt term which cancels this sort of effect (disputed by Woodward - details maybe in the book?).

      2. Woodward has an equation whose second term generates negative mass/exotic matter. So the Woodward effect does seem to rely on this. This "Woodward equation" does seem to have a long pedigree dating back to Sciama, so it would require further work to evaluate it.

      3. I like (sound of) the reformulation as a "gravinertial transistor". So the theory might still be worth studying.

      4. No-one may have noticed yet, but the Penrose approach to Quantum Gravity involves mass movements too. Were this to generate an effect when things became high frequency then this effect might either confirm or cancel the above theory.

      Engineering Students at the forthcoming Space Academies will need to be familiar with whatever the outcome of all this is, since it promises e.g. Mars in 2-5 days.


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