Does "EmDrive" quantum effect produce thrust, in violation of Newton's Third Law?

[tuxgeo]

An article on dailyreckoning says the following:

by Stephen Petranek.

Posted Sep 11, 2014

. . .

7. As Einstein Said, This Stuff Is Really Spooky

As any physics student knows, “Every action produces an equal and opposite
reaction,” and in the vacuum of space, that means you need a propellant to
push you along. You need something that you can eject from your spaceship to
move you in the opposite direction.

. . .

British aerospace engineer Roger Shawyer of Satellite Propulsion Research
Ltd. has said that when a beam of microwaves is directed inside a specially
shaped, enclosed container, it appears to produce measurable thrust without
a propellant.

He called it the EmDrive. Shawyer proposed a relativity-based theory for why
it works, but there is a lot of disagreement.

Recently, when Chinese researchers built their own version of the EmDrive,
they too confirmed that it produced thrust.

Now NASA has stepped in and added additional confirmation that such a device
can actually produce thrust. They were very careful to try to rule out other
causes during a recent eight-day test.

NASA says: “Test results indicate that the RF resonant cavity thruster
design, which is unique as an electric propulsion device, is producing a
force that is not attributable to any classical electromagnetic phenomenon
and therefore is potentially demonstrating an interaction with the quantum
vacuum virtual plasma.”

So, does it do that? Does it violate Newton's Third Law? Any comments or elaboration welcome. (Just don't say "Impulse Drive," because that's part of the proprietary trade dress of a famous TV and movie franchise. A person might get sued.)

 

[Morrus]

I don't understand it myself, but when this happened a few months back I seem to recall it got fairly widely debunked in various places. And the reports on NASA involvement were in some way misleading, though I don't recall the details.

 

[Dannyalcatraz]

http://blogs.discovermagazine.com/o...date-imposible-space-drive-word/#.VBSG-WK9KSM

http://www.armaghplanet.com/blog/no-nasa-has-not-verified-an-impossible-space-drive.html

So, not looking the real thing.

 

[freyar]

Well, this is the first I heard of it (though I did go on the radio this week to talk about Hawking's latest doomsday predictions). But I read through the links here and some of the links in them. My physicist's opinion is that this is just silly. The Discover Magazine blog linked has quotes from a couple of well-known and very good physicists about why this doesn't look like well-performed or thought-out physics. Just now, I looked at one of the EmDrive Inventor's papers, which looked pretty shoddy math-wise and certainly didn't have the appropriate math to talk about quantum mechanics (unless my eyes had glazed over by that point). Of course, it's worth noting that the EmDrive inventor doesn't think quantum mechanics is responsible for the effect --- that's an explanation from other scientists who know there's not a loophole to conservation of momentum in classical mechanics.

Then there's NASA's involvement. That was through the Eagleworks lab, which came up in this forum a few months ago regarding Alcubierre-like warp drive. As others in the links Dannyalcatraz posted note, Eagleworks' tests had some fatal flaws, including not running their tests in vacuum, which is absolutely critical if you're going to try to measure such a tiny effect. It's ridiculous they even announced the results.

And it's sad this is in the media when there's so much other cool science to talk about.

 

[Mustrum_Ridcully]

Hmm. Is Eagleworks job perhaps a kind of propaganda/media machine of science to convince people that something really cool is out there and we just need to give NASA some more money?

I don't really disagree with the goal, but the method seems questionable. (And could in the end stand int he way of the goal, if the money comes attached to :" Pursue this highly questionable line of experiments and hypothesis, rather than the one with reasonable expetations of working out", no one wins. Except perhaps the guys keeping their jobs thanks to the funds?)

 

[Morrus]

Hmm. Is Eagleworks job perhaps a kind of propaganda/media machine of science to convince people that something really cool is out there and we just need to give NASA some more money?

Nope. Interesting theory though!

 

[Umbran]

Hmm. Is Eagleworks job perhaps a kind of propaganda/media machine of science to convince people that something really cool is out there and we just need to give NASA some more money?

Not as I understand it. Eagleworks is more, "Here is some small money (on NASA's standards). Go look into some of the weirder stuff, just in case."

They haven't generally followed what we'd call the strictest of scientific procedure. I would guess (and it is only my guess) that is because they aren't a strict theoretical research group, or a practical development department. They are just turning over rocks to see if there's anything under them. They tend to operate on academic research budgets (equivalent to a couple of profs and grad students, working on borrowed or otherwise underutilized hardware) to build test devices for some of the edge concepts out there.

 

[freyar]

Not as I understand it. Eagleworks is more, "Here is some small money (on NASA's standards). Go look into some of the weirder stuff, just in case."

They haven't generally followed what we'd call the strictest of scientific procedure. I would guess (and it is only my guess) that is because they aren't a strict theoretical research group, or a practical development department. They are just turning over rocks to see if there's anything under them. They tend to operate on academic research budgets (equivalent to a couple of profs and grad students, working on borrowed or otherwise underutilized hardware) to build test devices for some of the edge concepts out there.

The problem is that, because they're not following a strict scientific procedure, what work they are doing is not helpful, except to generate excitement in a media that doesn't really know what it's talking about.

 

[Umbran]

The problem is that, because they're not following a strict scientific procedure, what work they are doing is not helpful, except to generate excitement in a media that doesn't really know what it's talking about.

I think of Eagleworks as the physical equivalent of Fermi estimation. It is by no means a full calculation with four part harmony and feeling, but you can still use it as a guideline.

Let us note that Eagleworks is by no means the only people who claim to have gotten results from the setup. A group in China, if I recall correctly, claimed to get a result orders of magnitude larger than Eagleworks did, if I recall correctly. But, that result (r at least the reporting of it to the science community in the rest of the world) also lacked rigor.

So, say you are NASA. You hear the Chinese claim a result. They don't turn over data. You have three choices:

1) Ignore the Chinese entirely.
2) Put theoreticians and thorough and expensive experimentalists on a deep analysis for years - and remember that Clarke's First Law applies*
3) Hand some chump change to someone to see if they can replicate the result, quick and dirty.

In terms of risk analysis, tossing chump change at fast and dirty projects may make sense, as a cost-effective vetting process. You don't actually expect any of these to turn out results, but if one does... the return on that investment will be *huge*. Take it sort of as... NASA playing the lottery with pocket change.

It does tend to churn up media attention. I don't see that as a bad thing, really. NASA has a problem that Congress won't back a solid mission plan. But vision and inspiration for new STEM students is a major payoff of NASA - normally, this is accomplished with the big missions that they now don't have. If they can't do it with the big money, they can try with the tiny money. I'm okay with that. Kids today won't care in five years if that result turned out to be nothing. Their imaginations and passions will be stirred into study anyway!




* "When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong." - Arthur C. Clarke

 

[Janx]

The problem is that, because they're not following a strict scientific procedure, what work they are doing is not helpful, except to generate excitement in a media that doesn't really know what it's talking about.

Is anything the MythBusters doing helpful or useful?

The MB guys ain't doing real science either, but they do run tests that reveal interesting things.

In some ways, I don't get the feeling Tesla had scientific method-ful practices going on when he invented most of his stuff either. He had some ideas, jiggered around with them, and got some amazing results.


So the real questions for this EmDrive are:
does it actually work (provide thrust)
is it efficient (or are we paying $100 for $1 worth of thrust)
how does it work?

If the answers to the first 2 questions are Yes! then the answer to the third is truly academic.