Uncertain Propulsion Breakthroughs? • Hacker News Board

Re: Uncertain Propulsion Breakthroughs?

#51

Post by gus_massa » Sat, Dec 31, 2016, 3:21 AM UTC

freehunter wrote: post #36

cjensen wrote: post #35

Earlier quoted context omitted.

The "premise" for the em-drive has been determined to be a thorough misunderstanding of the physics involved, so you cannot rule out any potentially contributing force in the experiment. Yes you heard that right: guys who misunderstand physics go and design a reactionless thruster which, when measured in their shoddy experimental setup, produces a measurable thrust. If there really is a measurable thrust, then the La…

You sound very negative towards conducting more experiments on this, when the results have been unexpected every time it's been tested. You're displaying the kind of dogma that science has been fighting against since the dawn of time. Either it's true or it's not, but we can't tell until we test it. And so far, it's only been disproven in theory, not in practice. That's worth more experiments.

> You sound very negative towards conducting more experiments on this, when the results have been unexpected every time it's been tested.

This is wrong. There is a strong selection bias, where a many team tried this and only those that got a "successful" measurement get press.

It's very difficult to get the list of all the unsuccessful (unpublished) experiments, but someone recollected a list em-drive test http://emdrive.wiki/Experimental_Results The important column is the last one. More than 1 means that if it's correct the device is breaking the current laws of physics. Anyway, I count 5 zeros in that list. [And I think that the other are experimental errors.]

Re: Uncertain Propulsion Breakthroughs?

#52

Post by gus_massa » Sat, Dec 31, 2016, 3:29 AM UTC

alasdair_ wrote: post #18

xupybd wrote: post #14

Wow, I've not read something like that in a long time. More news needs to be like this. Examining what we know presenting where we are. Not taking sides and polarizing the discussion. I do think people miss one small aspect of this story. How long has it been since we've had a device built that we've no understanding of the principles of it's operation? I think that's an amazing fluke and (if the effect is genuine) s…

Quite a few medicines (especially antidepressants) state something like "we don't really know why this stuff works, only that it does."

But they (hopefully) tested the drugs in a double blind experiment. So they may not understand the exact mechanism, but they have a strong proof that taking the drug is useful.

In this case, all the em-drive test only give a very weak force that is very difficult to measure and may be caused by other causes (probably thermal because the device gets hot or something equivalent to an electromagnet because it use a current).

Re: Uncertain Propulsion Breakthroughs?

#53

Post by disposablezero » Sat, Dec 31, 2016, 3:40 AM UTC

Busted by Thunderf00t

https://youtu.be/jCAqDA8IfR4

It's amazing people are still giving this bollocks the time of day.

Re: Uncertain Propulsion Breakthroughs?

#54

Post by gus_massa » Sat, Dec 31, 2016, 3:42 AM UTC

evo_9 wrote: post #38

cperciva wrote: post #8

Earlier quoted context omitted.

Being in space doesn't solve the problem of errant forces completely. You can push against the earth's magnetic field, for example.

So no proof will ever be enough for some? Are EM-Deniers going to be a 'thing' now?

I'm also a yeti-denier!

With enough proof you can convince the physics community, even if the result is initially weird. My favorite examples are https://en.wikipedia.org/wiki/Wu_experiment and https://en.wikipedia.org/wiki/High-temperature_superconducti... .

I think you can push a little against the magnetic field to rotate and change your orientation, but to gain height the magnetic field is not useful.

[Edit: Mmmm I'd change "but to gain height the magnetic field is not useful." to "but to gain height pushing against the magnetic field is not efficient."]

Re: Uncertain Propulsion Breakthroughs?

#55

Post by davros » Sat, Dec 31, 2016, 3:48 AM UTC

xupybd wrote: post #25

greglindahl wrote: post #23

Earlier quoted context omitted.

It is not unusual for a physics experiment to produce a weird result, and it turns out to be experimental error.

Yeah there is a very good chance that's still the case here. But would be cool if it's not experimental error.

It would be cool. But I've done similar measurements and this bears all the hallmarks of bad experiments. There are plenty of other ways the experiment might have gone wrong than those mentioned in the article - one that leaps to mind is RF interference (if that doesn't sound plausible to you you've never worked with lab RF).

Re: Uncertain Propulsion Breakthroughs?

#56

Post by davros » Sat, Dec 31, 2016, 3:52 AM UTC

Others wrote: post #5

empath75 wrote: post #3

tl;dr; > First, I cannot stress enough that there is no new EmDrive “effect” yet about which to theorize. The physical evidence on the EmDrive is neither defensible nor does it include enough operating parameters to characterize a new effect. The data is not even reliable enough to deduce the force-per-power relationship, let alone any other important correlations.

I don't think that's a fair summary... The author provides a more nuanced view than just "there is no effect." You're nitpicking from one section about theory, without considering the article as a whole. This is especially egregious considering that the article spends so much time talking about confirmation bias.

Actually, reading the article as a whole, I would say an even stronger conclusion is warranted - almost certainly bad science but we should keep investigating just in case.

Re: Uncertain Propulsion Breakthroughs?

#57

Post by intrasight » Sat, Dec 31, 2016, 4:13 AM UTC

xupybd wrote: post #25

greglindahl wrote: post #23

Earlier quoted context omitted.

It is not unusual for a physics experiment to produce a weird result, and it turns out to be experimental error.

Yeah there is a very good chance that's still the case here. But would be cool if it's not experimental error.

That's my sentiments here also - weird outcome would be cool, but I expect that we'll find experimental error. However, there is also the possibility of something in the middle - meaning no laws of physics are broken but the experimental error is itself an interesting engineering discovery.

Re: Uncertain Propulsion Breakthroughs?

#58

Post by misnome » Sat, Dec 31, 2016, 4:14 AM UTC

techdragon wrote: post #46

powera wrote: post #19

IMO the "rational" approach is to treat the claims as a bunch of pointless lies until there's a repeatable demonstration. Remarkable claims demand at least some evidence before wild speculation commences. As it is, Harry Potter is just as credible a theory of reality. After all, they've made the same claim repeatedly for 15 years after their first experiments were demonstrably not what they claimed.

If it's rational to ignore everything unproven then science is irrational. Science is about proving things. Proving how they work, why they work, etc. We have a thing, it's owner claims it works by either Method_A or Method_B, science is about taking the thing, testing the crap out of it, and being able to say at the end of all if it, "actually it turns out it works by Method_C" It seems you have some wires crossed s…

No, science is about disproving things. You come up with experiments to test if method a or b are wrong. The more experiments that fail to disprove a theory, the stronger the evidence for that theory is - and any new theory has to Either match the old results under the same tests, or give a good reason why it doesnt match.

Extraordinary claims require extraordinary evidence, which is why every good scientist expects this effect to go away (regardless of hope as to whether it is a real effect or not).

Re: Uncertain Propulsion Breakthroughs?

#59

Post by greglindahl » Sat, Dec 31, 2016, 4:17 AM UTC

stale2002 wrote: post #34

powera wrote: post #19

IMO the "rational" approach is to treat the claims as a bunch of pointless lies until there's a repeatable demonstration. Remarkable claims demand at least some evidence before wild speculation commences. As it is, Harry Potter is just as credible a theory of reality. After all, they've made the same claim repeatedly for 15 years after their first experiments were demonstrably not what they claimed.

This is what they are doing. They are sending something into space to demonstrate the effect. Let the experiments decide what is right or wrong.

There are a ton of simple experiments that can be done in the lab that aren't being done by the people claiming that this thing works. The article mentions a few. The people launching something are going to get another inconclusive result with a high price. At least it isn't tax dollars.

Re: Uncertain Propulsion Breakthroughs?

#60

Post by ufmace » Sat, Dec 31, 2016, 5:47 AM UTC

thearn4 wrote: post #4

I know Marc Millis, let me know if anyone has any questions and I can try to get his feedback here.

Cool, I read all of the BPP pages a while back. I wonder what happened to them, they seem to have been down for a while.

I had always wondered about something there, though it isn't related to the EM Drive. The original pages posted a few numbers claiming that even with a Fusion rocket-based propulsion system, interstellar travel was still wildly impractical, like thousands of supertankers of propellant to send a Space Shuttle-sized capsule past the nearest star system in 900 years without stopping. Yet many Sci-Fi and semi-scientific sources make it seem as if nuclear rockets are a viable interstellar propulsion. I always wonder who's right, and if I can find some more detailed numbers to back it up either way. Thought about it enough that I might actually try and calculate it myself one of these days.