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The 'impossible' EmDrive could reach Pluto in 18 months?

wired.co.uk

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Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#51

Post by nickff »

evincarofautumn wrote: post #49
eevilspock wrote: post #40

Earlier quoted context omitted.

> I think the last thing anyone wants to see here is "new physics". The article's responds with the nonsensical "Some damage to our theories of physics is an acceptable payoff if we get a working space drive." EDIT: Let me clarify why it's a nonsensical statement: First, I think it meant to say "cost", not "payoff". Second, there would be no cost. None of the things we were able to do with our existing theories would…

Well, it’s improbable, not nonsensical. If someone goes and implements a technology that trounces our working theories, we certainly need to update those theories. It’s just that that’s exceedingly unlikely to happen.

Photoelectric cells were invented before we understood the photoelectric effect, alcohol and preserves were used to store drinks and foodstuffs before we understood microbes, forging and annealing used before anyone had a theory on metallic crystal formation, and incandescence was used before anyone understood electromagnetic radiation; to name but a few examples. Why would it be surprising that someone invented a device which functions in a manner which is not understood?

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#52

Post by hekoshi »

evincarofautumn wrote: post #49
eevilspock wrote: post #40

Earlier quoted context omitted.

> I think the last thing anyone wants to see here is "new physics". The article's responds with the nonsensical "Some damage to our theories of physics is an acceptable payoff if we get a working space drive." EDIT: Let me clarify why it's a nonsensical statement: First, I think it meant to say "cost", not "payoff". Second, there would be no cost. None of the things we were able to do with our existing theories would…

Well, it’s improbable, not nonsensical. If someone goes and implements a technology that trounces our working theories, we certainly need to update those theories. It’s just that that’s exceedingly unlikely to happen.

I think it would be really exciting if we found a flaw in our model of physics.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#53

Post by thaumaturgy »

javert wrote: post #39
searine wrote: post #35

I've been following this story pretty closing for several months now. So here's the opinion of an actual research scientist. Q. Does the Em drive produce thrust? A. Undetermined. Several tests from multiple independent labs have reported thrust, including in a vacuum. However several of the labs that reported positive thrust come from a sketchy background. Q. Does it violate conservation of momentum? A. Undetermined.…

Thanks, nice summary. > I think the last thing anyone wants to see here is "new physics". I really want to see new physics, because I want to see us get off this rock and far away. I think most people want to see new physics. I think that's why this topic is so popular. That said, I can understand physicists not wanting to see new physics. Wait. In a way, that sentence is crazy . In a way, physicists should want to s…

Laymen tend to underestimate the very vast body of research which supports current physical models. "New physics" would imply that something has been fundamentally wrong with physics for a long time, and that is unlikely.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#54

Post by Anjin »

Niten wrote: post #7

It's good to see that someone finally got around to testing this in a vacuum. Here's the paper mentioned in this story: http://arc.aiaa.org/doi/abs/10.2514/6.2015-4083 High levels of skepticism are still warranted, as much as I would love for this to pan out. Every time this gets tested—presumably more and more carefully—the measured force gets smaller. The original test at Chinese Northwestern Polytechnical Universi…

The difference in measure thrust is due to different test articles and testing done in different labs. The 720 mN result was from China and they dumped a ton of energy into it. The smaller 20 μN result was from NASA's testing which used far less power, so the resulting thrust measure was also smaller.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#55

Post by Anjin »

Animats wrote: post #44
Niten wrote: post #7

It's good to see that someone finally got around to testing this in a vacuum. Here's the paper mentioned in this story: http://arc.aiaa.org/doi/abs/10.2514/6.2015-4083 High levels of skepticism are still warranted, as much as I would love for this to pan out. Every time this gets tested—presumably more and more carefully—the measured force gets smaller. The original test at Chinese Northwestern Polytechnical Universi…

"Every time this gets tested—presumably more and more carefully—the measured force gets smaller." Uh oh. That's a classic sign of a bogus effect. It's like physicists at Stanford trying to replicate the Pons-Fleischmann cold fusion experiment. At first, they were enthusiastic, and expected big results. They started out with the apparatus surrounded with radiation alarms in case it generated dangerous amounts of neutr…

No it is because the Chinese test dumped kilowatts of energy into the test item but the NASA test used only miniscule power. The guy you replied to presented the facts in a misleading way.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#56

Post by thaumaturgy »

nickff wrote: post #51
evincarofautumn wrote: post #49

Earlier quoted context omitted.

Well, it’s improbable, not nonsensical. If someone goes and implements a technology that trounces our working theories, we certainly need to update those theories. It’s just that that’s exceedingly unlikely to happen.

Photoelectric cells were invented before we understood the photoelectric effect, alcohol and preserves were used to store drinks and foodstuffs before we understood microbes, forging and annealing used before anyone had a theory on metallic crystal formation, and incandescence was used before anyone understood electromagnetic radiation; to name but a few examples. Why would it be surprising that someone invented a de…

Oh! This is one of my favorite questions about scientific progress.

People seem to regard scientific progress as this kind of wave function, where some theory comes along and then some other theory or discovery disproves the previous one and so on and so forth.

But if you want to think of scientific progress that way, then you have to think of it as a dampened sine wave (https://en.wikipedia.org/wiki/Damped_sine_wave) -- that is, discoveries and theories tend to refine previous discoveries and theories, and scientific progress over the millenia has been rapidly zeroing in on the truths of our reality.

What is left at this point is mostly things at very large scales -- cosmological stuff like dark matter, dark energy -- and very small scales -- stuff like sub-subatomic particles and the Higgs boson and the nature of mass and so on -- and very complex things like biology and climate science.

What isn't left at this point is a revision of the laws of conservation. It is exceedingly unlikely that anything will be discovered at any point in the future which will do anything other than add perhaps the very smallest of exceptions to those laws, and even then, I doubt very much that will happen.

So, essentially, the age of physics discoveries in garages is mostly over. There will be many more discoveries in physics, but they now require the collective efforts of entire nations.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#58

Post by cabinpark »

javert wrote: post #39
searine wrote: post #35

I've been following this story pretty closing for several months now. So here's the opinion of an actual research scientist. Q. Does the Em drive produce thrust? A. Undetermined. Several tests from multiple independent labs have reported thrust, including in a vacuum. However several of the labs that reported positive thrust come from a sketchy background. Q. Does it violate conservation of momentum? A. Undetermined.…

Thanks, nice summary. > I think the last thing anyone wants to see here is "new physics". I really want to see new physics, because I want to see us get off this rock and far away. I think most people want to see new physics. I think that's why this topic is so popular. That said, I can understand physicists not wanting to see new physics. Wait. In a way, that sentence is crazy . In a way, physicists should want to s…

I'd love to see new physics! Every physicist I know loves new physics.

But if you claim to violate the conversation of momentum, everyone is going to be skeptical and not believe it. We have hundreds of years of experiments and observations that support the law and have looked in many places from small to large and not seen violations. This is what makes people not believe it and thus physicists are going to assume you are wrong and not physics. It's not so much a negative concern, but more of a practical one. But should it be tested in a rigorous manner and reproduced, then physicists will believe it. It's just it hasn't and thus we are going to stick with the established very well understood and tested theory. Like are you sure you have properly counted all the initial momentum? Are you 100% you are not introducing energy to the system? The possible explanations is long and a good experiment will eliminate as many of these as possible.

As an example, look at the OPERA experiment which found to have superluminal signals. New physics? Nope, just a faulty piece of equipment. BICEP showing gravitational waves? Nope, just poor data interpretation and neglecting interstellar dust. So if you want to claim new physics, be damned sure you have ironclad proof.

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#59

Post by nickff »

thaumaturgy wrote: post #56
nickff wrote: post #51

Earlier quoted context omitted.

Photoelectric cells were invented before we understood the photoelectric effect, alcohol and preserves were used to store drinks and foodstuffs before we understood microbes, forging and annealing used before anyone had a theory on metallic crystal formation, and incandescence was used before anyone understood electromagnetic radiation; to name but a few examples. Why would it be surprising that someone invented a de…

Oh! This is one of my favorite questions about scientific progress. People seem to regard scientific progress as this kind of wave function, where some theory comes along and then some other theory or discovery disproves the previous one and so on and so forth. But if you want to think of scientific progress that way, then you have to think of it as a dampened sine wave ( https://en.wikipedia.org/wiki/Damped_sine_wav…

I'm sorry, but your reasoning completely escapes me. The only things that are left are very big, and very small? In addition to this being an incredibly vague catchall (which misses all the possible discoveries of 'black swans', that is phenomena and occurrences we have never seen), your statement more importantly misses the fact that humans don't even understand what something as common and important as light (or electromagnetic radiation in general) is. Is light really big or really small? We've certainly characterized light's behavior (to some degree), though we still have basically no understanding of what it actually is (though I may be the only one who finds the circular definitions of electromagnetic fields unsatisfying). The same is true of things like matter and gravity. Once we have better understandings of what these are, I may grant that further fundamental insights will be difficult to come by; but we're not there yet.

You might be correct in saying that humans have characterized particles, objects, and phenomena that are closest to their scale and location, but we have done a poor job of understanding their fundamental nature. We also don't understand and have not even characterized things we've never observed (the 'black swan' problem).

Re: The 'impossible' EmDrive could reach Pluto in 18 months?

#60

Post by repsilat »

leni536 wrote: post #57

Conversation of momentum is strongly tied to the conservation of energy through relativity theory. If it actually works (I doubt it) it has really strong implications.

Conservation of momentum is a much bigger deal than conservation of energy. We already know of situations in which energy isn't conserved (like the energy of a photon decreasing when there is metric expansion where it is.)

Conservation of momentum is a consequence of the translational symmetry of physics via Noether's theorem, so that's what we'd need to give up to hope to see it broken.

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