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Questions about Nasa's space drive answered

wired.co.uk

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Re: Questions about Nasa's space drive answered

#51

Post by readerrrr »

tobinfricke wrote: post #41

Here are two nice posts by physicist John Baez with some reasons to be skeptical about the "reactionless drive": https://plus.google.com/117663015413546257905/posts/WfFtJ8bY... https://plus.google.com/117663015413546257905/posts/C7vx2G85...

He seems to be makings some mistakes as well. He says: This is baloney too - but now it's graduate-level baloney. "Quantum vacuum virtual plasma" is something you'd say if you failed a course in quantum field theory and then smoked too much weed. There's no such thing as "virtual plasma". If you want to report experimental results that seem to violate the known laws of physics, fine. But it doesn't help your credibility to make up goofy pseudo-explanations.

The original description might be clumsy, but the idea of empty space being full of virtual particles is not wrong.

Here is Dr. Laurence Krauss's description of empty space:

especially the idea that what we think of empty space is really not empty, correct?

KRAUSS: That's exactly right. Empty space is a boiling, bubbling brew of virtual particles that pop in and out of existence in a time scale so short that you can't even measure them. Now, that sounds of course like counting angels on the head of a pin; if you can't measure them, then it doesn't sound like it's science, but in fact you can't measure them directly.

But we can measure their effects indirectly. These particles that are popping in and out of existence actually affect the properties of atoms and nuclei and actually are responsible for most of the mass inside your body. And in fact, really one of the things that motivated this book was the most profound discovery in recent times, and you even alluded to it in the last segment, the discovery that most of the energy of the universe actually resides in empty space.

Re: Questions about Nasa's space drive answered

#53

Post by [deleted] »

spingsprong wrote: post #48
tobinfricke wrote: post #41

Here are two nice posts by physicist John Baez with some reasons to be skeptical about the "reactionless drive": https://plus.google.com/117663015413546257905/posts/WfFtJ8bY... https://plus.google.com/117663015413546257905/posts/C7vx2G85...

"They're claiming to see a force one thousandth as big as the Chinese - probably because they are doing the experiment one thousand times more accurately. And still, some people are excited about this. " I think he's slipping from skepticism to cynicism here.

[deleted]

Re: Questions about Nasa's space drive answered

#54

Post by mnw21cam »

mrfusion wrote: post #30

Would this be how impulse drives are supposed to work in Star Trek work? Just curious.

No, the impulse drives (according to the Haynes manual for the Enterprise) are standard reaction drives, with weak warp fields around them, so they can eject propellant faster than the speed of light.

Re: Questions about Nasa's space drive answered

#55

Post by cousin_it »

readerrrr wrote: post #51
tobinfricke wrote: post #41

Here are two nice posts by physicist John Baez with some reasons to be skeptical about the "reactionless drive": https://plus.google.com/117663015413546257905/posts/WfFtJ8bY... https://plus.google.com/117663015413546257905/posts/C7vx2G85...

He seems to be makings some mistakes as well. He says: This is baloney too - but now it's graduate-level baloney. "Quantum vacuum virtual plasma" is something you'd say if you failed a course in quantum field theory and then smoked too much weed. There's no such thing as "virtual plasma". If you want to report experimental results that seem to violate the known laws of physics, fine. But it doesn't help your credibil…

Baez is right, there's no such thing as "virtual plasma". Just Google the phrase.

Re: Questions about Nasa's space drive answered

#56

Post by madaxe_again »

tfgg wrote: post #39
madaxe_again wrote: post #16

Earlier quoted context omitted.

Indeed. As to the whole "we don't actually understand how it works" - we still can't make up our minds as to how wings work, so this isn't overly novel. Sure, we can explain the outcome, but whether it's Navier-Stokes or Bernoulli or something else, we can't make up our minds. I suspect this will be similar for a long while - although puts physics hat on I think this is likely a relativistic temporal quantisation eff…

None of the things mentioned so far that we "don't know how they work" are on a par with this. Flying with wings doesn't violate fundamental, and experimentally very well supported, symmetries like conservation of momentum, nor do high temperature superconductors. Your final sentence is actually nonsense.

My final sentence was getting at a mechanism by which momentum is conserved in this system.

If you assume that time is quantisable (big assumption, I know), and that the planck time is lorenz invariant (not as much of an assumption), then an EM wave at a fixed frequency moving from one reference frame to another could experience quantisation due to the shifting time-base, resulting in an apparent net deceleration - resulting in a measurable acceleration of the system as a whole.

And now I'll take off my fringe hat and get back to the day job.

Re: Questions about Nasa's space drive answered

#57

Post by tobinfricke »

pantalaimon wrote: post #3
didgeoridoo wrote: post #2

Deep breaths. Probably experimental error. Extraordinary claims require extraordinary proof... God DAMN this is exciting.

As the article points out in 8., there have been previous, independent experiences that support the results.

These were other, earlier experiments, which the current experiment is attempting to duplicate. Importantly, while the new experiment has superficially "confirmed" the previous ones, it shows a much smaller effect.

When the magnitude of the observed effect scales roughly with the margin of error of the experiment, one has very good reason to be skeptical ...

Re: Questions about Nasa's space drive answered

#59

Post by nanofortnight »

mrfusion wrote: post #52

Why does number 7 say a superconducting version of this drive does not require energy to hold things up? Are they just referring to how superconductors can float in an external magnetic field? That doesn't seem to give general purpose hover boards.

Not requiring energy is a mistake from Wired.

A superconducting version of the drive would be able to provide much higher Q, and thus much higher static thrust to power ratio.

It would also have much better performance at higher waveguide velocities.

http://www.emdrive.com/theorypaper9-4.pdf#page=9

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