Scientists pinpoint source of “impossible” EmDrive's thrust | Hacker News Reader

Scientists pinpoint source of “impossible” EmDrive's thrust

newatlas.com

38 pointsdgudkov12 comments

I assume they always "knew" the drive was not working and the real exercise was to find why the measurements failed? Which makes this finding interesting because they can design for better experiment next time?

What makes the finding interesting is that a lot of people really, really, really, really wanted it to work. They wanted big wins for free. They wanted fundamental science laws to fall. They wanted a revolution. They wanted it to come from somebody just playing around, rather than more boring incremental results by somebody who dragged their ass through a PhD and postdoc.

And several agencies, including NASA, threw money at it. Why? Honestly, I'm not sure. A combination of really, really wishing it was right, and wanting to be able to say they looked.

So to scientists this isn't really interesting at all. Just like with the faster-than-light neutrinos, they knew all along that it was a measurement error. The specific source of the measurement error is mildly interesting, but not a billionth as interesting as New Physics would have been.

Everybody wants New Physics, including scientists. The scientists are just extremely doubtful that we're going to just stumble on it, because all that stuff is well-worn territory, and it's unlikely that there's something really obvious that they've missed. But it's not impossible, which means that this isn't the first story we've gotten like this, and it won't be the last.

(It's probably not even the end of this one, to be honest. I'm sure people will keep working on this. But the scientists can legitimately stop.)

Couldn't it just be that some scientists saw a problem with an experiment and used the hype to gather money to get that problem fixed?

Not much money either.

It didn't start with scientists. It started with tinkerers (who prefer to be called "inventors", though I'm unable to find anything else that they've invented). It wasn't really an "experiment" in that it wasn't testing a well-defined hypothesis. It really was just a guess.

For some reason it attracted the attention of Harold White, a genuine scientist who NASA employs to do nutjob work. It never produces anything. It looks for all the world as if NASA likes having a pet mad scientist they can trot out to say, "Look, we're taking your stupid ideas seriously, now leave us alone." He couldn't figure out why pumping vast amounts of energy into a thing produced a tiny effect he couldn't otherwise account for, though "it made something hot that you didn't measure" seems a pretty obvious answer. Entropy is squirrely, and we all knew that.

It did attract White more hype, so I guess you're right on that score. And as the sibling post notes, it's not all that money, and it comes out of NASA's PR budget. It then attracted more money and that's the money (and time) that really feels wasted. No problem got fixed. It was just an expensive version of the "Is it possible that dark matter is made of the socks that disappear from my washing machine?" type questions that plague scientific Q&As.

Well, one way or another, once you get reproducible experimental results that conflict with known physics, someone has to do the due diligence in finding the flaw, it would be irresponsible to shrug and say "ah, must be a fluke, who cares why".

Perhaps if we had a whole range of other promising avenues to explore for new phsyics (like natural scientists a century or two ago), then it would be different, but as of now it seems there's not much competition that's more promising than the EmDrive was.

That's the ideal, but we actually do it all the time. No real experiment actually corresponds precisely to the model. Experiments go Just Plain Wrong all the time, and we don't look at them; we just assume we made a mistake in the setup and repeat it. If we engaged in due diligence for every single thing we noticed, we'd do nothing else.

Science is much messier than the neat models we set ourselves. There's a whole subdomain of studying the Demarcation Problem, which is trying to figure out the difference between "hypothesis revision" (science) and "goalpost moving" (pseudoscience). Turns out it's harder to define rigorously than you'd expect it to be.

A huge number of scientific decisions end up being made on a combination of "who has money to spend", "who has time", and "who is interested". That's utterly non-rigorous, but it's actually pretty fundamental to how real science gets done.

I'd say there's a lot of stuff more promising than EmDrive. We all knew it was a mistake, and if it hadn't somehow attracted some prominent backers and a ton of people hoping that this time we were gonna get green Orion slave girls in metal bikinis, it would have been ignored years ago. We could have spent that money and time on other things, but they would have been boring even if they'd worked out.

"I'd say there's a lot of stuff more promising [...] but they would have been boring even if they'd worked out." - so which is it?

That's kind of my point, we have a bunch of ideas that are more likely to succeed, but anything that would be boring even if they'd worked out aren't really promising in the "can it result in a meaningful impact" sense; and there seems to be a lack of experimental ideas that are within our grasp and could potentially reveal something interesting instead of just re-confirming thins that we're almost certain about.

I remember seeing a device that used flywheels to “generate lift” and I couldn’t help but noticing it involved counterrotating units, meaning that where they approached each other they were both spinning the same direction (up or down, I don’t recall which). I thought, “I bet this doesn’t work in a vacuum chamber”.

Later I remembered rotor ships. He essentially stood a complex one on its ear, and made some math errors that backed up his discovery.

At least the Mach Effect thruster had a half-plausible mass/energy sort of hand-wavy theory behind it. Alas it too has slipped fully into the realm of wishful thinking... in this universe anyway.

> The ability to generate thrust without having to carry the parasitic mass of fuel would be a game-changer in space

This is poor phrasing. You can already do this with lasers. You just cannot do it sustainably.

Would have been more fun if they had proven it works hehe.

> “When power flows into the EmDrive," he continued, "the engine warms up. This also causes the fastening elements on the scale to warp, causing the scale to move to a new zero point. We were able to prevent that in an improved structure.

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