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

[Jhaelen]

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.

I'm not sure about that. Having read a biography about him, I think the problem with his scientific approach was his photographic memory: He didn't bother to document much because he could keep everything in his head. He was also rather sceptical about any new theories that someone other than himself had come up with. Like most inventors his main interest was in finding practical applications for physical phenomena, make them work and optimize them and not in doing research just for the sake of it.

 

[Umbran]

I'm not sure about that.

I am.

Having read a biography about him, I think the problem with his scientific approach was his photographic memory: He didn't bother to document much because he could keep everything in his head. He was also rather sceptical about any new theories that someone other than himself had come up with.

Exactly. As Janx said, not really in line with good scientific methodology. Good documentation *outside* your own head is crucial to good science. If you keep it in your head, you are dreadfully susceptible to personal biases, and nobody can check your work, or add to it. Now, admittedly, he worked in an age that was more interested in patents than in the body of science knowledge, so he perhaps can't be blamed for it. But this does not leave him a paragon of science as some folks might like.

Tesla was a brilliant man, and a testament to what you can do when you don't actually understand what you're dealing with - Tesla was a forerunner in electrical development, but didn't believe in the existence of electrons!

 

[Scott DeWar]

. . . . . - Tesla was a forerunner in electrical development, . . . . . .

and as an electrician, I greatly appreciate his work ! !

 

[Janx]

I am.



Exactly. As Janx said, not really in line with good scientific methodology. Good documentation *outside* your own head is crucial to good science. If you keep it in your head, you are dreadfully susceptible to personal biases, and nobody can check your work, or add to it. Now, admittedly, he worked in an age that was more interested in patents than in the body of science knowledge, so he perhaps can't be blamed for it. But this does not leave him a paragon of science as some folks might like.

Tesla was a brilliant man, and a testament to what you can do when you don't actually understand what you're dealing with - Tesla was a forerunner in electrical development, but didn't believe in the existence of electrons!

and that more precisely puts a finger on it.

It felt like to me from watching some "about tesla" shows, that the guy just had visions of doo-hickeys. I suspect he put more thought into how/why the AC motor worked than the Tesla Coil.

 

[Umbran]

I notice that this has gotten rather far afield from the original question....

So, does it do that? Does it violate Newton's Third Law?

As others have noted - probably not. The supposedly observed effect was extremely small, making it very possible that the result is within experimental error for the setup.

The only vaguely appropriate description I've see for how the thing supposedly works requires a "virtual plasma" for the electromagnetic waves to interact with. The problem with that is that our basic understanding of the virtual particles that pop into and out of existence for short periods (a real thing in quantum mechanics) *don't* work like a plasma.

So, lacking a reason for them to work at all, I am skeptical.

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.)

What they have here is in no way like a Star Trek impulse drive. Those use a reaction mass, and are described basically as a form of ion drive in the Trek literature.

 

[freyar]

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.

There is a massive difference between a rough back-of-the-envelope calculation and reporting a "non-null" result to an experiment when, in reality, you haven't set up the experiment in such a way that you have any idea of the systematic uncertainties, which are by reasonable estimates much larger than your result. The first is a useful estimate, and the second is not. In other words, from the reviews I've read of the Eagleworks experiment (which Dannyalcatraz posted), it's completely unreliable. And these are reviews from sympathetic people (in their own words).

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.

As I've noted before, I don't have a problem with NASA's expenditures of tiny amounts of money on these ideas. (Although it should be noted that playing the lottery has quite a negative expectation value.) What I have a problem with is the sloppiness of the research that comes out of Eagleworks.

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!

There's no such thing as bad publicity... I just think there are lots of cool things in science that actually _are_ happening right now that could be inspirational.

 

[Umbran]

There is a massive difference between a rough back-of-the-envelope calculation and reporting a "non-null" result to an experiment when, in reality, you haven't set up the experiment in such a way that you have any idea of the systematic uncertainties, which are by reasonable estimates much larger than your result. The first is a useful estimate, and the second is not. In other words, from the reviews I've read of the Eagleworks experiment (which Dannyalcatraz posted), it's completely unreliable. And these are reviews from sympathetic people (in their own words).

Yes, but they do demonstrate something - if Eagleworks are, in fact, reproducing the Chinese results... they're pretty much showing that those results were likely bogus. Do they show the effect exists or not? No. Do they show the Chinese didn't see something reliable? Probably.

As I've noted before, I don't have a problem with NASA's expenditures of tiny amounts of money on these ideas. (Although it should be noted that playing the lottery has quite a negative expectation value.) What I have a problem with is the sloppiness of the research that comes out of Eagleworks.

As my first professor of thermodynamics said - there's no such a thing as a free lunch. Good, Quick, Cheap: pick two.

There's no such thing as bad publicity... I just think there are lots of cool things in science that actually _are_ happening right now that could be inspirational.

Well, *right now*, (literally, as I type, I have NASA TV on in another tab) NASA's making an announcement about the commercial crew transport program...

Which amounts to:
1) Boeing and SpaceX have contracts to move on to the next stage of certification: manned test flights of their vehicles.
2) In December, NASA's own Orion craft (designed for beyond Low Earth Orbit) will have it's own first flight.

 

[tomBitonti]

I think it's ... curious ... that we end up discussing the "EmDrive" and not any of these:

http://en.wikipedia.org/wiki/2014_in_science

Also, having just listened to information about the discovery of the DNA structure, I am wondering: What recent discovery has the same level of importance? Reading through the "2014 in science" review, I don't find anything that stands out anywhere close.

What's happening in science now-a-days?

Thx!

TomB

 

[freyar]

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.

I haven't watched MythBusters, so I can't really answer that with personal experience. My admittedly second- or third-hand understanding is that MythBusters is showing people that they can think about and test claims critically, even if in a non-rigorous way. That's great! It's an introduction to the scientific mindset. That's vastly different than claiming to produce quantitative scientific research.

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.

That's fine, but we'd be in bad shape if someone didn't come along behind him and do the work in a scientific way --- we'd end up like pakleds from TNG.

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.

The answers to your questions are
a) We have no data from experiments that can be expected to provide results sensitive enough to tell. If EmDrive worked, it would violate not just an empirical law of physics but a mathematical theorem, so it would be indeed amazing.
b) With extreme certainty, I would say we are paying $100 for 0 thrust. This kind of machine comes up now and again --- it seems like you could make a perpetual motion machine out of one of these, and perpetual motion machines are a dime a dozen. But none of them work (and the US Patent Office has a policy against granting patents to them, when it remembers to follow it).
c) Unless you want to be a pakled, this is not just an academic question....

 

[Mishihari Lord]

I was kind of excited to read the story in CNN. With a master's in electrical engineering I could see immediately that the initial premise about how the drive worked was nonsense, but measurable results are measurable results. I'm still hopeful of seeing a cool, working discovery along these lines sometime in the future. Yes it would contravene current scientific, but knowing something of the history of science, most major discoveries do. Contradicting math is a bit harder, but math is only as good as the assumptions behind it.

If there's anyone to blame for the unjustified hubbub, it's the press. NASA taking at least a brief look at out there ideas seems like a really good idea, and with the Freedom of Information Act, it's not like they could keep it a secret,