Live data from Hacker News

What we know about the EmDrive and Cannae Drive

reddit.com

31–40 of 180 posts

Re: What we know about the EmDrive and Cannae Drive

#32
post #6

Earlier quoted context omitted.

> And don't send these folks money that could do real good elsewhere until they give at least some small reason to expect that it's not a wild goose chase. Is it even possible to give them money? I wasn't aware that NASA accepts earmarked donations, or contributions from private individuals in general.

They don't accept earmarked donations, but they do accept unsolicited and unconditional private contributions. http://nodis3.gsfc.nasa.gov/displayDir.cfm?Internal_ID=N_PD_...

I suppose "unsolicited" is why I've never heard of this. Thanks, learned something new today.

Re: What we know about the EmDrive and Cannae Drive

#33

I think this technology, if real, should be shut down and controlled by the government. Officially, it should be denied and declared to be quackery. It would likely cause grave security problems. Just think of the capabilities this would give the bad guys. We already went too far with technology with the discovery of nuclear weapons and enormous effort has been invested in controlling that technology for decades. The…

> to prevent them from getting technology (WMDs)

WMDs = pretext, real reason: Oil and GeoPolitical

Re: What we know about the EmDrive and Cannae Drive

#34
post #24

Comparing the Chinese results with the American results, it seems that raising the wattage by a factor of 50 raises the thrust by a factor of 15000. That's somewhat hard to believe. On the other hand, the linked pdf from the Chinese team suggests that at just 3 times the wattage of the American group, they got 1500 times the thrust. I think there is some confusion somewhere.

Well, the natural world is full of non-linear and/or discontinuous responses, so it's not crazy if there's some sort of threshold at work.

But yeah, it's more likely there's some confusion in there.

Re: What we know about the EmDrive and Cannae Drive

#35
post #17

Earlier quoted context omitted.

According to physicist Harold White, leader of the NASA Eagleworks team, it can't simply be a "photon rocket": The NASASpaceflight.com group has given consideration to whether the experimental measurements of thrust force were the result of an artifact. Despite considerable effort within the NASASpaceflight.com forum to dismiss the reported thrust as an artifact, the EM Drive results have yet to be falsified. After c…

Yes, sure, they've measured something surprising. I have no reason to doubt that. A few years ago, the enormously more respected folks at the OPERA experiment were willing to announce that they had seemingly detected neutrinos moving faster than light. Despite this coming from a large group of scientists with top-notch credentials, that was immediately doubted by almost the entire physics community, and sure enough,…

That was one experimental setup, that was not replicated by other experiments though. It is a bit different when you get multiple experiments by lots of different teams.

Re: What we know about the EmDrive and Cannae Drive

#36

Earlier quoted context omitted.

"But I also wish that I could cure cancer with a single magical kiss, and that I had my very own pet dragon" This kind of condescending response doesn't do science or scientists any good. It's actually actively harmful. Don't do it.

Nonsense. These devices are on the far extreme end of the "requires extraordinary evidence" spectrum. Until this extraordinary evidence is provided, they are well within the prior probability category of providing pet dragons.

If the evidence is out of the ordinary, no one will believe it anyway. /s

Re: What we know about the EmDrive and Cannae Drive

#38
post #16
post #10

Earlier quoted context omitted.

In the back of my mind, I suppose I'm hoping that some administrator involved with the NASA budget is reading my comment. (Just for instance, I would say that the possibility that we could find life on Europa or the other outer moons is many, many orders of magnitude higher than the possibility that these drives turn out to be even a little bit worthwhile.)

Are you serious? If you had the power, you would actively prevent NASA from doing these experiments and trying to falsify the claims? I could somehow understand that if the experiments cost a billion dollars. But they don't. Any Europa mission is in no way related to nor threatened by these drive tests.

Yes, actually. Every dollar that NASA spends has the potential to accomplish something for humanity. To my eye, even the vast potential benefits of this technology are more than washed out by the tremendously low probability that it will turn out to be real.

I absolutely do not want NASA to give money to every person who comes to their door claiming to have a recipe for a warp drive. There has to be some threshold of viability, or else all of the folks with home-brewed theories of everything who spam my inbox (I'm a theoretical physicist) could secure their own grants. I honestly have no idea what about this project put it over that threshold, but it seems to imply that the threshold is too low. I want NASA to spend some money on speculative ideas! But surely there are speculative ideas out there that don't require us to rewrite all the laws of physics. Let's fund those.

Re: What we know about the EmDrive and Cannae Drive

#39
post #7

1 micronewton / watt is a surprising amount of thrust. The implied velocity of whatever it's pushing against is 1e6 m/s, which is 1/300 the speed of light.

isn't that super low? if 1 micronewton = 1 newton * 10^-6 then to push against 1kg it would require 1.000 MWatts?

Super-low compared to pushing against matter. But 300x higher than pushing against photons.
Post reply on HN