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What we know about the EmDrive and Cannae Drive

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Re: What we know about the EmDrive and Cannae Drive

#41
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.

NASA did acknowledge that at the power level the American team tested, thrust is generated in a more omnidirectional manner, which is focused into a directional jet as power levels are increased, so that might account for some of it.

Re: What we know about the EmDrive and Cannae Drive

#42

I 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.

I think even if it proves real, it would still take around 50 years to put in flying cars and such. But perhaps a bit less for using it in satellites. Still it's not too long on the humanity scale of time.

Why would it take fifty years? This isn' the 1800s where it takes a half century for flush toilets to catch on. We're in an era where things go from laboratory to ubiquitous inside of a decade.

Re: What we know about the EmDrive and Cannae Drive

#43

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…

The irony of your misinformed statement is that the alleged WMDs were American made and sold to Iraq.

The classic quote from the time "We know they have WMDs because we have the receipts!"

Re: What we know about the EmDrive and Cannae Drive

#44
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.

It could be you aren't getting the full effect at the lower wattage?

What is the ratio of wattage to thrust, that's what I'd be curious about? And how efficient is it?

I guess change in kinetic energy can never be greater than energy inputted to the device, correct?

Re: What we know about the EmDrive and Cannae Drive

#45
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,…

So, it is worth bringing up: GR doesn't require global conservation of momentum or energy.[0,1]

I'm not saying anything about the experiment, but I think your statement that "conservation of momentum is more deeply embedded..." isn't quite so accurate.

[0] http://www.preposterousuniverse.com/blog/2010/02/22/energy-i... [1] http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_g...

Re: What we know about the EmDrive and Cannae Drive

#46

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…

Realize that this is the exact same level of verification as superliminal neutrinos, except at a vastly decreased level of rigor. At this point the overwhelmingly likely explanation is that there is some phenomenon at work which we don't understand or haven't properly accounted for, not that there is new physics afoot.

Really what's the difference. Either we can fit it in to our models or we have to change the models. It always bothers me that so many people in the scientific community speak of our scientific models of the physical world as if they were truth itself.

All models are flawed and only imitate reality by definition. We must accept that our models are only a glimpse of the real thing. We barely manage to grok our own planet let alone galaxies unfathomably beyond our reach yet we are consistently surprised when our models turn out to yet again be wrong. We know for a fact that our currently accepted physical models are flawed. To start with, we cannot fully reconcile gravity or "spooky action at a distance." The only reason our current models are useful, like any useful model, is that they are somewhat good at predicting a very limited set of future outcomes given measurable parameters.

Why can't we admit that what we currently know only seems impressive to a few moderately advanced apes but in reality it is likely only tiny drop in the bucket compared to the knowledge our universe holds.

All that said I'm very pro skepticism. Just because science is dumb does not mean every other random idea is valid. It's the common arogance of the scientific community that grates on my nerves.

End rant.

Re: What we know about the EmDrive and Cannae Drive

#47
post #4

This 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…

Also conservation of energy. Thrust can't vary by velocity because there's no such thing as absolute velocity. So your velocity (relative to whatever) keeps increasing linearly, while kinetic energy increases quadratically. At some point you start getting more energy out than you put in.

For some reason, this disturbs a lot of people more than violating conservation of momentum.

The alternative is that there really is absolute velocity, so the basic assumption of relativity is false. But that makes it a pretty big coincidence that atomic bombs work.

Still can't say I mind them checking just to be sure.

Re: What we know about the EmDrive and Cannae Drive

#48
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,…

Happens the other way too. In the 80s high-temperature superconductors were discovered, which were 'impossible' by previous understanding. The theory is still catching up to that.

Re: What we know about the EmDrive and Cannae Drive

#49

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…

The irony of your misinformed statement is that the alleged WMDs were American made and sold to Iraq. The classic quote from the time "We know they have WMDs because we have the receipts!"

Hey, don't forget the British. We tried to build them that super-gun thingy.

Re: What we know about the EmDrive and Cannae Drive

#50
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.

It's an important question because the article claims "The applications for a device that functions as these appear to would basically replace every form of transportation and thrust invented by humans to date. Such a device would easily be used to make cars, planes, bikes, boats, etc., all more efficient, clean, and cheap." Given that the thrust required for a car would be something like 40,000N, unless the device scales far better than linearly, you'll need a 25GW power station in your car to even make it go.
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