[ExI] EmDrive again

Anders Sandberg anders at aleph.se
Sat Apr 23 17:17:34 UTC 2016


I like the concept of a Hubble-scale Casimir effect. I am not convinced 
people are getting real data from the drive (still seems to be awfully 
close to noise levels), but this is at least a theory suggesting a 
nontrivial testable consequence (reversed thrust for a particular 
geometry).

Quantized inertia is not that weird. But if the drive can only work in 
increments of the inertia quantum it will be pretty wussy. McCulloch 
formula however seems to imply potentially bigger forces for very sharp 
cavities; presumably there is a softening below the microwave wavelength.


On 2016-04-22 16:17, Giulio Prisco wrote:
> MIT Technology Review reports that a recent article by Plymouth
> University physicist Mike McCulloch proposes an explanation for the
> anomalous EmDrive experimental results. According to the physicist,
> inertia is the pressure the Unruh radiation predicted by general
> relativity exerts on an accelerating body, and must be quantized at
> small accelerations. McCulloch claims that the EmDrive effect can be
> predicted by assuming that the photons in the EmDrive cavity have
> inertial mass caused by Unruh radiation, whose wavelengths must fit
> exactly within the cavity.
>
> McCulloch derives the order of magnitude of current experimental
> results and proposes new tests to validate or invalidate his theory.
> As it always happens when the EmDrive is mentioned, the MIT Technology
> Review article is already triggering strong emotional reactions and
> mass hysteria from both enthusiasts and skeptics. McCulloch's
> theoretical framework is explained in the book "Physics from the Edge
> - A New Cosmological Model for Inertia."
>
> "It is a prediction that was first made in the early 1970s by a
> brilliant young Canadian physicist, Bill Unruh, who was then barely
> out of graduate school. What he found was that, as a result of quantum
> theory and relativity, there must be a new effect, never observed but
> still universal, whereby anything which is accelerated must experience
> itself to be embedded in a hot gas of photons, the temperature of
> which is proportional to the acceleration." - Lee Smolin, "Three Roads
> to Quantum Gravity."
>
> https://www.technologyreview.com/s/601299/the-curious-link-between-the-fly-by-anomaly-and-the-impossible-emdrive-thruster/
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-- 
Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University




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