What we know about the EmDrive and Cannae Drive
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Re: What we know about the EmDrive and Cannae Drive
#2I'm not a physicist but as someone that's always looked at over-the-top headlines and groaned while internally wishing they were true, I just want to say: this is all so very cool and I'm so excited to see where this takes us.
Even if it's not the start of a Star Trek-eseque future, this is some pretty neat stuff and I'm really anxious to hear more about what new gates of knowledge this unlocks. The plot line is right out of sci-fi and it's what makes me love technology so much: we truly never know what we will find.
Re: What we know about the EmDrive and Cannae Drive
#3I know it's unlikely that the EmDrive is real, and even more unlikely that the "warp drive" effects that some have been talking about are real. But...I really hope they are. What a world it'd be if these things prove out to be real.
Re: What we know about the EmDrive and Cannae Drive
#4This is not worth getting excited about. Really.
Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordinarily deep level. It is obviously not impossible that our known laws are wrong, but the alternative would be to somehow produce a radically different set of physical laws that nevertheless reproduce every test of existing theory to high precision (as much as 14 digits of accuracy in some cases). And you probably also need to explain why the existing theory worked so very well if its bedrock foundation doesn't describe our universe.
So really, don't get excited. 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.
(Edit to add: I wish this were real, too. With all my heart. But it's not a realistic wish.) [Re-edited to cut some less-appropriate phrasing.]
[0] Yes, I know the EmDrive site FAQ (http://emdrive.com/faq.html) claims that it doesn't violate conservation of momentum. The explanation of why it doesn't actually indicates that it does: "The electromagnetic wave momentum is built up in the resonating cavity, and is transferred to the end walls upon reflection." But the wave's momentum has to come from somewhere, too. So either this is just equivalent to a photon drive (propelled by shooting light out the back), or their device is pulling momentum out of nowhere.
Re: What we know about the EmDrive and Cannae Drive
#5I'm not a physicist but as someone that's always looked at over-the-top headlines and groaned while internally wishing they were true, I just want to say: this is all so very cool and I'm so excited to see where this takes us. Even if it's not the start of a Star Trek-eseque future, this is some pretty neat stuff and I'm really anxious to hear more about what new gates of knowledge this unlocks. The plot line is righ…
Understand that the most likely gate of knowledge that this unlocks is, "oh, there was some kind of magnetic interaction between the test drive and the harness," or something to that effect.
The proper Bayesian approach to these tests is to downgrade your prior of "drives require reaction mass" from 99.99999999% to 99.999999%
Re: What we know about the EmDrive and Cannae Drive
#6This is not worth getting excited about. Really. Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordinarily deep level. It is obviously not impossible that our known laws are wrong, but the alternative would be to somehow produce a radically different set of physical laws that neve…
> 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.
Re: What we know about the EmDrive and Cannae Drive
#71 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.
Re: What we know about the EmDrive and Cannae Drive
#8This is not worth getting excited about. Really. Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordinarily deep level. It is obviously not impossible that our known laws are wrong, but the alternative would be to somehow produce a radically different set of physical laws that neve…
Even if something disproves the functionality of these things it's still likely to be quite interesting. I think there's room to be excited either way.
Re: What we know about the EmDrive and Cannae Drive
#9This is not worth getting excited about. Really. Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordinarily deep level. It is obviously not impossible that our known laws are wrong, but the alternative would be to somehow produce a radically different set of physical laws that neve…
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 consistent reports of thrust measurements from EM Drive experiments in the US, UK, and China – at thrust levels several thousand times in excess of a photon rocket, and now under hard vacuum conditions – the question of where the thrust is coming from deserves serious inquiry.
And also, a quote from the paper he co-authored in mid-2014 (http://ntrs.nasa.gov/search.jsp?R=20140006052):
Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma. Future test plans include independent verification and validation at other test facilities.
i.e. "Something weird and exciting may be going on and let's all verify it and figure it out"
edit 2: io9 has a handy pop-sci summary of the EmDrive: http://io9.com/new-test-suggests-nasas-impossible-em-drive-w...
vvvv edit: Yes, it's very probably a minor phenomenon that's occurring (barring an outright error), and not new physics. But it's a somewhat consistent phenomenon (in separate China & US experiments) associated with this particular test setup, so hopefully we'll learn something of decent interest in the coming years. The skeptical crowd should do its important job and scrutinise the research, and in the meantime, we (and the admittedly enthusiastic Dr White) can hope :)
Re: What we know about the EmDrive and Cannae Drive
#10This is not worth getting excited about. Really. Extraordinary claims require extraordinary evidence. These drives would violate conservation of momentum.[0] Conservation of momentum is built in to the known laws of physics at an extraordinarily deep level. It is obviously not impossible that our known laws are wrong, but the alternative would be to somehow produce a radically different set of physical laws that neve…
> 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.
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.)