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Leaked NASA Paper Suggests The 'Impossible' EM Drive Really Does Work (sciencealert.com)
A source close to NASA Eagleworks has leaked the test results of the 'impossible' EM Drive. While it's important to note that the results that have been leaked haven't been published in an academic journal, they do suggest that the system works and is capable of generating force of 1.2 millinewtons per kilowatt in a vacuum. ScienceAlert reports: The paper concludes that, after error measurements have been accounted for, the EM Drive generates force of 1.2 millinewtons per kilowatt in a vacuum. That's not an insignificant amount -- to put it into perspective, the super-powerful Hall thruster generates force of 60 millinewtons per kilowatt, an order of magnitude more than the EM Drive. But the Hall thruster uses fuel and requires a spacecraft to carry heavy propellants, and that extra weight could offset the higher thrust, the NASA Eagleworks team conclude in the paper. Light sails on the other hand, which are currently the most popular form of zero-propellant propulsion, use beams of sunlight to propel them forward rather than fuel. And they only generate force up to 6.67 micronewtons per kilowatt - two orders of magnitude less than NASA's EM Drive, says the paper. The NASA Eagleworks team measured the EM Drive's force using a low thrust pendulum at the Johnson Space Centre, and the tests were performed at 40, 60, and 80 watts. They were looking for any sign that the thrust could be a result of another anomaly in the system, but for now, that doesn't appear to be the case. "The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust, however none were identified," the team, led by Harold White, concluded in the paper. "Thrust data from forward, reverse, and null suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 millinewtons per kilowatt." But the team does acknowledge that more research is needed to eliminate the possibility that thermal expansion could be somehow skewing the results. They also make it clear that this testing wasn't designed to optimize the thrust of the EM Drive, but simply to test whether it worked, so further tweaking could make the propulsion system more efficient and powerful.
Because if Trump wins, we need a way to leave this planet...
Mostly random stuff.
The physical laws went out the door months ago.
How can I believe you when you tell me what I don't want to hear?
They are directly related. https://ntrs.nasa.gov/search.jsp?R=20110023492
Ran some numbers. Assuming the power generator and thruster itself has zero mass (obviously not, but it lets us set an upper limit), the energy available in 1kg of U235, at 1.2 millinewtons/kw, would accelerate that 1 kg mass to about 0.35 C, over the course of about 1000 days.
Add in mass of ship, generators and thrusters and you're looking at considerably less acceleration and top speed, but if this thing works at all (a big IF, granted), manned starships are just within the range of possibility. It'd still be a multi-year (probably multi-decade) trip, but hey.
I thought the science was settled on Newton's laws...
First rule of science: Science doesn't settle
Hanlon's Razor -- Never attribute to malice that which is adequately explained by stupidity.
And if they pump in 1.21 Gigawatts, they're going to see some serious shit!
I thought the science was settled on Newton's laws...
Firstly, Newton's laws are based on observation and assumptions.
The observations gives us formulas that seem to fit, but there's no guarantee that those formulas describe all situations in the universe.
The assumptions, from Noether's theorem stating that symmetries imply conservation laws, are that the universe is smooth, in the mathematical sense of smooth being that space is infinitely divisible. We know that last part isn't true: you cannot measure position to an arbitrary precision in the universe.
It is therefore seen that Newton's laws become increasingly inaccurate when the scale is very large (relativity), or very small (quantum mechanics).
You might check out the Casimir effect some time.
It's not predicted by Newton's laws, but measurable and predictable using QM.
Anyone who says "EM drive cannot work because it violates my understanding of physics" should really check out the Casimir effect.
If your understanding of physics does not predict the Casimir effect, you probably shouldn't be commenting on the EM drive, or results from NASA rocket scientists.
That's not why the EM drive is neat. The force provided by emitted radiation is a fairly well understood and predictable phenomenon. The EM drive has a sealed microwave cavity, so it doesn't emit many photons, and those that it does through thermal radiation are measured and accounted for. Despite that, the EM drive appears to produce an additional force, that is what makes it neat.
Yes photons have momentum and a photon drive would be 1kW / 0.00334 millinewtons.
I'm no physicist myself, and physicists don't understand this thing anyway, but here's my understanding:
Yes, appears that the only input is electricity, and it seems to produce thrust. So if electricity is free, a tiny amount of thrust is free. I say it APPEARS that the only input is electricity- many reactions which we now understand include oxygen from ambient air as an input, and that might have easily go unnoticed in an experiment before the reaction was understood. Similarly, it's possible that this thruster is using some non-obvious input, such as ambient radiation.
We don't know if one could be built much larger, or what the current capacity is for a given size. Maybe a 100,000 watt one could be small, maybe it would need to be very large. Maybe it would be far more efficient, maybe far less. We're still trying to confirm that the thing works at all.
> would I be right in thinking this thing would incredibly slowly start moving the ship and over a ridiculous amount of time, eventually be moving very rapidly and in theory (?) just keep on accelerating?
Yes, in theory, up to near the speed of light. Or maybe not. 1500 years ago someone discovered that if you burned charcoal mixed with livestock poop in a bamboo shoot, you got a similarly weak thrust. Later we figured out it was the dried pee, not the poop, that mattered and adding sulfur helped. So a thousand years ago they had black powder rockets, which kept accelerating through the air as long as the engine kept burning. Now we know that a rocket won't keep accelerating forever in air, but it took a thousand years to figure that out. We're still in the "poop in a tube" stage of EM drives, so we really don't know what the potential is.
Here's a link to the NASA paper on the apparently successful test: https://drive.google.com/file/...
And here is a presentation by the technology's inventor, Roger Shawyer https://vimeo.com/channels/Emd...
Warning: Shawyer may well be brilliant, but he is the Anti-Musk in terms of his presenting and motivational skills. This guy could seriously announce a working warp drive in a way that would make people walk out of the presentation half way through. If he has funding problems, he needs to get someone else to present his technology and business case for him.
Where are we going and why are we in a handbasket?
The Eagleworks paper has already been accepted by the AIAA, which could fairly be described as "reputable". It will appear in the December 2016 issue.
Why would anyone engrave "Elbereth"?
I believe your math is wrong. U235 releases 202.5 MeV per atom undergoing fission, so that means 1 kg can generate 83.14 TJ from fission. Assuming 100% efficiency, a massless drive, and no mass loss from propellants, that means there is enough energy from fission to reach a velocity of 0.043 c relative to the rest frame.
dE = (m - m') c^2 = m' c^2 (gamma - 1) => m' c^2 = m c^2 (1 - dE/(m c^2)) = m c^2 (1 - rho)
rho = dE/(m c^2) = 83.14 TJ / 89.88 PJ = 9.25e-4
rho = (1 - rho) (gamma - 1) => gamma = 1/(1 - rho) = 1/sqrt(1 - beta^2)
(1 - rho)^2 = 1 - beta^2 => beta^2 = rho (2 - rho) = 1.85e-3
beta = sqrt(rho (2 - rho)) = 0.0430
http://www.americanthinker.com...
http://www.killclimatedeniers....
http://www.climatedepot.com/20...
Calling upon the government to execute those with a different point of view is something I'd consider a death threat.
Well, if the drive works, then either the symmetry underlying conservation of momentum isn't entriely true (it wouldn't be the first time we discovered a surprising lack of symmetry, you know), or the drive isn't entirely reactionless. I think it is important to always be willing to keep an open mind, when we don't know for certain; what you are saying is "No, impossible, so I am not even going to look". Personally, I think preservation of momentum is true; so in my view there must be an escape of momentum that we haven't figured - if this works. This doesn't strike me as unthinkable - after all, energy is put in, so it must go somewhere. We just need to find an explanation.
The problem with the paper is twofold:
1) After one year, it is still not published in a peer reviewed journal. This happens on occasion. However:
2) The data is about as flakey as it gets. Eg. the forces measured for the 60W power level range from 40 micronewton to 120 micronewton. This goes completely unexplained and all they do in the paper is some statistics voodoo to get some nice looking numbers out of this mess.
Separating graphite layers does not contradict our basic understanding of physics. I don't have any problem with doing it with scotch tape. Ditto for hunting axions: it is an extension of known theories, not a breakdown of our fundamental theories (that is speculated to happen at high energies). But even hunting axions is already much harder than building this stupid EM drive: they had to make a very specialized very sensitive apparatus, for the simple reason that if axions were easy to detect they would have already been detected.
Large Extra Dimensions, on the other hand, is another story: there is no half-way decent theoretical model that predicts them, they are just pure speculation. And they were predict to show up at the LHC scale, with the prediction now changed to just above LHC scale, since they did not show up. And doing that is free, since there is no model to build, you just need to throw some numbers in the air.
Contrast this with fundamental discretization, which is expected to happen for good theoretical reasons, and there are actually some speculative theories (string theory and loop quantum gravity) that implement it.
entropy happens
If it has mass, how can it travel at c?
It doesn't, but not for that reason.
A simplified answer is that because it travels at c, spacetime doesn't apply to it, only to what it passes through. c is an asymptote, which other particles can only approach. Photons live inside the asymptote, and are not subject to the standard rules for what occurs.
In E=mc^2 (or the general expanded version), "c" is a constant for distance divided by time. As Einstein discovered, time itself is suspect - it varies. Which is fine as long as you only approach c, because distance compensates exactly. But when time no longer approaches zero but is zero, "c" becomes infinity divided by zero, which is meaningless. A single photon is then everywhere, anywhen, which doesn't match our observations.
We can only assign a photon "mass" through equivalence - what mass changes occur when a photon is created or destroyed. While[*] it exists, it's meaningless to assign it mass, but it's meaningful to assign it a mass change potential, or momentum.
[*]: Also a meaningless term for a photon, as a photon's life span is instantaneous or infinite, never anything in-between. Any "while" only affects the surroundings, not the photon itself. It laughs at clocks.
I would think a space drive powered by experimental error would be quite useful, considering what a unlimited resource it could tap.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff