
What we know about the EmDrive and Cannae Drive - curtis
https://www.reddit.com/r/Futurology/comments/34cq1b/the_facts_as_we_currently_know_them_about_the/
======
MCRed
I've some direct experience with a similar situation. I can speak to the issue
of "why hasn't spaceX or other major company experimented with this".

During the "Cold Fusion" era, when Pons & Fleishman had claimed to develop
room temperature fusion, I worked for a major US lab doing superconductor
research. (We invented the first superconductors that operated at liquid
nitrogen temperatures-- Y1B2C3O)

While fusion isn't our area of investigation we, being physicists, were
curious. We managed to get our hands on a pre-print of the Pons & Fleishman
study and did our own experiments.

We kept this very hush hush. We didn't want it getting out that we were doing
the experiments or people would claim that we replicated them.

So, I believe that SpaceX and other companies are experimenting with this, and
if they found good results (as the eagle works tests imply they would) they
would continue to do so, but in secret.)

We eventually published our paper because we constructed a novel experiment
that disproved the P&F observation, from our perspective.

None-the-less, true to our fears, this was later reported by "Mondo 2000" (The
"arse technica" crossed with WIRED of the day) that we had "confirmed cold
fusion is real!!1!1". The letter to the editor I wrote and got our most
eminent physicist to sign was never printed by the magazine (IIRC).

When you get to the fringes-- that's where the action is-- but it's also where
you can have confusing or odd results.

And even 30 years ago the media was not trustworthy enough to reveal these
results to. Our paper was published in a journal, and yet the media still mis
represented the results.

~~~
drzaiusapelord
This is one of the many reasons why I consider all "fururist" media as just
sci-fi wish fulfillment for kiddies. Its just incredible how unreadable
/r/futurology is, for example. Its just a lot of pats on the back about some
amazing life-changing technology, that is eternally 10 years away.

I don't have access to the Mondo 2000 stuff today, but if any of that was to
believed we'd have AI masterminded rockets to moon condos and eternal life by
now. The big advances were actually missed as things like interchangable and
standardized protocols, power saving SoCs, incremental battery improvements,
touchscreens, and fast networks are "boring" compared to spacetravel and
robots and such.

I feel I'm also seeing the same hype train today with VR, which has unsolved
major issues like motion sickness and questionable applications in gaming, let
alone anywhere else. To a lesser extent I see the same thing with electric
cars that are always somehow 2-3 years from affordability and economic and
range parity with ICE cars. These 2-3 years keep blowing past us, but there's
no 200 mile range $20,000 car yet, if there will ever be.

Its a shame that practical and real advances are often "boring" to the typical
sci-fi obsessed INTJ males who dominate science on the internet. I see so much
spilled ink about SpaceX and very little about the upcoming SLS and its
planned pioneering manned missions or NASA's robotic and science missions,
which are all mindblowingly amazing to me. Sadly, this has all become
politicized in the most asinine way possible with a dedicated libertarian
group on the web voicing this private vs public rivalry to attack NASA, which
is ironic as SpaceX is more or less a welfare program of NASA and the US
taxpayers.

I hope this fad doesn't last long and good science, real breakthroughs, and
the largely unpredictable and usually unsexy, in terms of whiz bang space
operas, future continues to unfold before us in a wonderful way. The SLS will
have us on an asteroid with just boring old chemical rockets, while the
futurists continue to sell snake oil to the low information true believers and
diminish the amazing and real accomplishments of the day.

"Everything's amazing and nobody's happy." \- Louis CK.

~~~
pauloday
I love reading /r/futurology comments for comedy purposes, but I have a weird
sense of humor

~~~
kbenson
I just skip straight to /r/HFY. Might as well go to the source.

------
Steuard
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 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](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.

~~~
jdjdps
I get really tired of these ignorant psuedo sceptic responses. It's so
obviously a straw man attack it makes me cringe. Why are you so set on
assuming that it is violating conservation of momentum? No one of import is
claiming this. My god, authority must always be right! All who move beyond
appeals to authority when constructing arguments must be decried as beyond the
fringe! Heathens! Infidels! Traitors! Expell them from within the walls of
science, from the walls of Freedom. Yeah muh
Science/freedom/nationalism/whatever makes me feel safe by allowing me to feel
like I belong and satisfies a psychological need to construct a them and us
world. Ffs. Grow up. Seriously hacker news. Grow up. Please, please humanity,
grow up. Arrrrgggghhhh. I cant even. - Edited to remove swear words

~~~
Steuard
I honestly don't even know where to begin in responding to this. You've called
me (or my words) "ignorant" and "pseudo-skeptic", you've suggested that I have
relied on appeal to authority in making my arguments, and you've implied that
I'm motivated by an ignorant "us vs. them" mentality. You've told me to "grow
up". All of that seems like pure personal attack, rather than any sort of
robust engagement with ideas.

The only actual point of science that I can find here is your claim that "No
one of import is claiming" that these drives violate conservation of momentum.
In my original comment, I explicitly addressed this: the EmDrive FAQ's own
attempt to explain how their drive doesn't violate momentum conservation seems
to imply a violation of momentum conservation. Maybe I'm mistaken about that
somehow: if so, I'd very much appreciate knowing how! (At the very least, I
find it perhaps telling that the site's authors don't understand that their
attempted answer is no answer at all.)

As for the personal attacks, I'll just give one piece of context for the
"ignorant" bit. I'm a tenured professor with a Ph.D. in theoretical high
energy physics from the University of Chicago. That doesn't give me any
special magical authority to declare truth about the universe, but it does
mean that I've got a pretty solid base of knowledge for my statements and (I
hope) decent judgement about how confident to be in my beliefs about questions
in my area of expertise. I work on crazy theories that might or might not wind
up describing our world at all, so I'm very aware of both the vastness of our
ignorance and the importance of pushing at its boundaries in bold and
unconventional ways. And with all that background, I think these drive ideas
sound entirely unreasonable. If you've got equally solid reasons to believe
otherwise, more power to you, and I'd love to hear them.

~~~
jdjdps
I was angry at a great deal of posts like yours over a range of topics.
Perhaps in this instance the anger was missplaced. In a previous post I have
worked out how to articulate my concerns: A lot of the time posts with an
overtly negative tone that claim to come from a place of rationality, are in
fact reactionary. They claim to be defending a core of rationality from
encroaching confusion, when in fact they are a symptom of irrationality, a
result of the innapropriate application of emotional reasoning to areas of
life where it has no explicative power. I believe that the rigidity of the
models to be found within the minds of certain kinds of folks has less to do
with the defense of rationality and more to do with the defense of identity. I
find it extremely irritating to deal with people who are irrationally certain
in an uncertain world - especially when they justify themselves by claiming
they are just being more reasoned than the next man. Having said that I can
hardly claim my post was anything but an emotional outburst.

------
digitalzombie
Sweet.

Best case, we get a new awesome thrusters.

Worst case, we get the learn new things. So far these drives have pass tests
and stumped experts and researchers. So even if it doesn't violate the current
laws of physic, it'll paint a better picture of the current laws of physic and
better testing method in the future.

~~~
issa
This is exactly my attitude. I'm shocked that people don't think twice about
spending money on frivolous or even harmful things, but balk at the idea of
paying for pure research.

~~~
Retra
You don't want to shovel fuel into a crackpot industry. That actually prevents
real science from being done.

~~~
Intermernet
Being snarky, but a lot of the world's consumer economy can be seen as
shoveling fuel at crackpot industries.

You're correct, but I'd rather a few million dollars going to this research
than a few million dollars going to some magnetic-healing-band toting pseudo-
guru.

The "first world" wastes ridiculous amounts of money every second. Can we
divert at least some of it to disproving crack-pot scientific ideas? It'd at
least be entertaining (like Mythbusters on steroids!).

------
binalpatel
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.

~~~
higherpurpose
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.

~~~
astrodust
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.

~~~
mahranch
This is less like flush toilets and more like computers. It took nearly 50
years for the first computers to sit in consumer's home offices. It took time
for the technology to be miniaturized and cheap enough to make its way to
consumer electronics.

Or even cell phones. We were using radio signals in hand held devices for
nearly 50 years before a vast majority of consumers were walking around with
phones in their pockets in the mid to late 90s. Sure, there were early
adopters in the late 80s and early 90s, but the technology was still
expensive. And the technology (like walkie talkies) had existed for decades
before...

~~~
danielweber
If this were proven true, there would be a completely manic gold-rush of
capital into the area. Flying cars that operate at less than 1/10th the energy
of cars on the road now?

This would very quickly move from "let's wait for NASA to do more tests" to
"let's beat NASA to the test."

That's all assuming it's real, of course. I'd bet against it.

~~~
TheLoneWolfling
Where are you getting that 1/10th number from?

The most thrust anyone was getting was 750mN at 2.5KW. At that efficiency you
need to have something that produces >32.7W/g _just to hold itself up_. That's
rocket engine territory: [http://en.wikipedia.org/wiki/Power-to-
weight_ratio](http://en.wikipedia.org/wiki/Power-to-weight_ratio)

We _barely_ have supercapacitors that'll deliver that sort of power output.
For a few seconds, maybe. Not accounting for the mass of the device itself.

Hopefully if this ever turns out to be something the efficiency will improve.
But I'm not holding my breath.

(Number taken from here:
[https://news.ycombinator.com/item?id=9474610](https://news.ycombinator.com/item?id=9474610)
)

------
wbhart
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.

~~~
waterlesscloud
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.

~~~
wbhart
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.

------
ComputerGuru
I'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.

~~~
aetherson
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%

~~~
kristjankalm
exactly -- I'd guess not too many non-physicits realise what's a prior for
'conservation of momentum violated'

------
hooo
I'd really like this to be real.

I think they need to precisely measure the mass of the whole device before and
after the experiment, to make sure the thrust isn't coming from ionization or
some decay.

~~~
TheLoneWolfling
They also need to check their vacuum.

There's a whole lot of power being thrown around inside those boxes.

------
tlb
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.

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

~~~
tlb
Super-low compared to pushing against matter. But 300x higher than pushing
against photons.

~~~
TheLoneWolfling
Not to mention you don't have a high-powered beam of photons cooking
everything behind you.

------
techdragon
I would like to suggest to anyone really interested in understanding this
topic better, read about the Casmir effect
[http://en.m.wikipedia.org/wiki/Casimir_effect](http://en.m.wikipedia.org/wiki/Casimir_effect)

The Casmir effect and the Casmir-Polder Force is considered by many scientists
to be a result of asymmetrical forces being generated by and or from the
quantum vacuum based on the materials and geometries being used.

It did take decades to verify to the level people don't consider it experiment
error, and we're sill arguing over if it's really a quantum mechanical effect.
Some people do not like the whole quantum field theory thing and their efforts
to disprove things related to it is important for science.

Personally QFT makes a lot of sense to me so I look at the work being done at
Eagleworks and wish there was a way to help accelerate the pace of research
because this thing isn't the LHC its not trillion dollar stuff, a few million
is probably the total bill to do all the work and the subsequent re
verification by JPL, NASA and Johns Hopkins that they want to do. This could
be "done" in a year if we stop going slowly. It's 2015 and I would like my
hover car next year thanks.

------
FrankenPC
What's the deal with power scaling? The OP says: 50W of power = 50uN. That's
0.05mN. 2500W of power = 750mN

2500W is 50x 50W of power. 0.05mN x 50 = 2.5mN, not 750mN.

That's a hell of a ramp up in thrust. Does it keep ramping the more power you
put into the cavity? If so, how much power is required to say get a fighter
jet to fly which is around 100,000N of thrust?

Or is my math WAYYY off?

------
nsxwolf
As far as I have seen, NASA hasn't actually said anything about this. Is the
story even real?

------
mrfusion
If (big IF) this turned out to be real, could we use these on helicopters
instead of blades? Or are blades more efficient?

Also would it make the hoverboard feasible, or does it require way too much
energy?

~~~
indrax
Blades are much more efficient. I've done some back of the napkin estimates
that this would levitate if paired with lockheed's supposed small fusion
reactor. (and works at all, and if the drive reaches improvements that one
paper thought possible, and if it scales with power input, and ....)

This inefficiency would still be great in space because you don't have to
carry reaction mass with you. (and hovering on earth would mean sustained 1g
acceleration in space, which is fantastic.) But if you're swimming through
reaction mass anyway, then just push it as efficiently as possible.

------
tmp-20150107
The Cannae Drive was obviously not invented by a Scotsman... ;)

------
railgun2space
Can such a drive be built at home? Would be a wonderful maker pet project.

~~~
ivanb
Easily. Here is one created by a Russian guy
[https://youtu.be/vcaOKX7Ko7w](https://youtu.be/vcaOKX7Ko7w)

------
narrator
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 whole reason we went into Iraq
was to prevent them from getting technology (WMDs) that we think they
shouldn't have access to. I don't think humanity will be ready for this kind
of technology until we have elevated our civilization to a "higher level".

~~~
astrodust
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!"

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

