Cannae/EmDrive

[Iskierka]

The problem with considering it as like a fluid medium is that it's a fluid medium that doesn't exist - it's almost literally the same as spinning a special propeller in space and having water appear to push against with it.

I admittedly don't have the education to fully understand what's going on - my particle physics education has just been general absorption from discussions since 18 - but from what I see, for this to be pushing against virtual particles, it could not be realising those particles truly. The particles would have to remain virtual, and be destroyed once again - then imparting their momentum onto space-time. Given space-time can stretch and be distorted, and move, this doesn't sound like a total impossibility, it simply raises the question then of what happens to space-time with momentum, and where does that momentum go? Is it absorbed by the nearest large space-time distortion, such as the earth, and if that's the case, how does motion and distance affect the power, and thus feasibility, of the drive?

K^2 clearly does have the right that it cannot be creating matter for free energy, and thus far, no matter of negative energy has been observed, even in the largest particle colliders, so it's not maintaining zero mass-energy exchange that way, which means it's not creating matter. Thus, it must push off matter that already exists (surface ablation or test chamber interaction), or push off something else entirely. It'll certainly be interesting to see what it's creating a reaction force from, but only certain answers might be even slightly useful.

[rtxoff]

It'll certainly be interesting to see what it's creating a reaction force from, but only certain answers might be even slightly useful.

most probably from the material the experimental drive itself is built from

[magnemoe]

Argue over theory only after MORE EVIDENCE, 3RD PARTY VERIFICATION, REPEATED MULTIPARTY VALIDATION, until then you might as well be arguing over how many angels fit on the head of a pin. If and when it is absolute verified to produce thrust, then there is no arguing that it can't work, only arguing over how the heck it does work.

Just want to say though if this works, and that a very doubtful if: Die Hoffman transfer, die! Oh unholy space cthulhu would this be awesome!

http://4.bp.blogspot.com/-i8ERUjGAbzw/U-F3jAwLrRI/AAAAAAAAxLo/4savWVpmFIM/s1600/nasatestemdrive7.png

Yup, and the images show why NASA is interested even if it probably don't work, it pretty much define high risk / high payoff

[K^2]

Given space-time can stretch and be distorted, and move, this doesn't sound like a total impossibility

That's called gravitational waves. They require 300MW per 1N of thrust. Same as photon drive.

[Northstar1989]

No, there is no one here like that. If there is independent verification by an outside reputable source, and we start seeing some peer-reviewed journal papers, minds will change. The skeptics are skeptics because they simply don't see enough evidence. A small NASA lab who hasn't published any peer-reviewed papers on this, and some small Chinese lab are NOT reputable sources.

Also, the skeptics are skeptics because they are NOT the kind of people who let their hopes and desires interfere with what they believe. A proper scientific mindset removes your desire from the results, because the greatest desire should always be the TRUTH. And the truth is, as awesome as a reactionless drive would be, it conflicts with centuries of science. I may not be an expert in the field, but when confronted with the "explanation" on how these EM drives work, my understanding is that the real experts in quantum mechanics scoffed at the idea. I can't be an expert in every field, and so I have to trust in their judgement. I'm not one of those people who, even though I have very little (or no) education in a field of study, is dumb enough to question the judgement of the actual experts in that field, and think I could possibly come up with something that they hadn't already thought of yet. The people (not talking about any of the people in this thread) who think they can second-guess what scientists and experts have to say on a subject really irritate me. /rant off

But I think that's why we're skeptics. Until strong enough evidence is presented and/or the experts start changing their minds, the most logical conclusion is that this EM drive does not in fact work, and that this small NASA lab is not taking some factor into account or has some kind of other experimental error. To get all excited over these results is only setting yourself up for what is almost certainly going to be a big let-down.

Velocity, experts DON'T always change their mind, even when confronted with mountains of evidence.

In real life, I trained as a Stem Cell Biologist. And you'd be amazed how long it took to even convince people of the existence of Stem Cells (or now, to convince people they're not the magical cure-all for everything). The senior scientists, in particular, were hard-headed and ignored mountains of evidence for the new concept...

Now, we're seeing something similar with the Cancer Stem Cell theory- which is far less developed than Stem Cell Theory, but still has LARGE amounts of evidence to support it...

The fact is, skeptics are skeptics because of precisely what you warned against- they let their emotions get in the way of logical reasoning. Their egos, their pessimism, or their desire not to get hurt again after being disappointed by a potentially-exciting discovery in the past are usually what lead senior scientists and many such skeptics to refuse to acknowledge new discoveries...

People, as a rule, are remarkably illogical. I'm currently residing in Illinois, and you would not *BELIEVE* how many people out here are evolution-deniers, or think that the Moon Landings were a hoax...

Why do I mention all this? Because the comment you were responding to was right- there are some "skeptics" who will continue to call this a hoax even if it works out to the point we're sending interplanetary probes with this...

Centuries of modern science have taught us one thing above all else: we know *NOTHING* compared to what there is to know...

Regards,

Northstar

Edited February 11, 2015 by Northstar1989

[CptRichardson]

Really the observation is the key. Just as with the "superliminal neutrinos". It was a measurement/apparatus/calculation error with those, and the solution was going back over new observations (again and again until found). The same here. No amount of head crunching will give a solution. Even Einstein needed his observations during a solar eclipse to prove his theory... it was not his theory that proves light is bent by gravity...

So everyone here trying to use theory to prove the drive works.... um...

Well, we're trying to craft theories as to why it works, with... uh, middling success. But the thing is, they've been eliminating all the potential causes of error, and it just keeps on thrusting. They've eliminated instrument error, almost every single known electromagnetic interaction, atmosphere, the copper ablation theory everyone keeps spouting is right out given that it doesn't even get as hot as a particularly sunny day, so on and so forth.

And we still have the clearly defined and measurable thrust. More thrust than we should be getting from a photon drive, and the projected scale puts it at .1 newton per kilowatt. We've got a model that predicts, but it might be complete and total crap like early theories on the atom. Heck, we're almost certainly getting the 'why' wrong. But, it IS doing stuff. Stuff that... doesn't make sense according to our knowledge. It's not reason to go screaming 'bah, ABSOLUTELY BADWRONG, STOP TRYING' like a lot of skeptics keep screaming. It's reason to go 'huh, WHY?' and keep testing until we figure out what we're missing.

The NASA guys have a whole bunch of PhD's going through their results, and they're not outright dismissing the results, they're just going back and forth on the theories and wanting a better vacuum test rig so they can test at other labs, with the two big labs wanting to get a 100 watt model that should produce enough thrust to be measurable on the less sensitive equipment.

All the same, I'm waiting for Sawyer to get arrested for accidentally blowing a hole in the side of his house if his theory works out and his updated model produces increased thrust like he thinks. Hard to top vindication by 'holy crap, what have I done!?'

Edited February 11, 2015 by CptRichardson

[Duxwing]

Hear, hear, Northstar. Whoever forgets his heart is of not stone but "wishes" and "affections" pathologically believes and defends appealing ideas; whoever breaks this defense therefore breaks him, too.

And I further argue that hating such people as him for their bitter words and unreasonable skepticism, like I see many do, is callous. The scientists and engineers among them are comrades owed at least pity and the sobering thought of joining them. The rest are ordinary folk--civilians in our battles of ideas--whose harm should unsettle us all.

-Duxwing

[Leszek]

Well, we're trying to craft theories as to why it works, with... uh, middling success. But the thing is, they've been eliminating all the potential causes of error, and it just keeps on thrusting. They've eliminated instrument error, almost every single known electromagnetic interaction, atmosphere, the copper ablation theory everyone keeps spouting is right out given that it doesn't even get as hot as a particularly sunny day, so on and so forth.

And we still have the clearly defined and measurable thrust. More thrust than we should be getting from a photon drive, and the projected scale puts it at .1 newton per kilowatt. We've got a model that predicts, but it might be complete and total crap like early theories on the atom. Heck, we're almost certainly getting the 'why' wrong. But, it IS doing stuff. Stuff that... doesn't make sense according to our knowledge. It's not reason to go screaming 'bah, ABSOLUTELY BADWRONG, STOP TRYING' like a lot of skeptics keep screaming. It's reason to go 'huh, WHY?' and keep testing until we figure out what we're missing.

The NASA guys have a whole bunch of PhD's going through their results, and they're not outright dismissing the results, they're just going back and forth on the theories and wanting a better vacuum test rig so they can test at other labs, with the two big labs wanting to get a 100 watt model that should produce enough thrust to be measurable on the less sensitive equipment.

All the same, I'm waiting for Sawyer to get arrested for accidentally blowing a hole in the side of his house if his theory works out and his updated model produces increased thrust like he thinks. Hard to top vindication by 'holy crap, what have I done!?'

No one is saying "stop trying". The thing is that there are very GOOD reasons to still be sceptical. Granted it might work, but there are lots of people counting chickens before they have hatched, heck before the eggs have been laid. This device was thought up by some mathematical voodoo that didn't work. (That is why no one can say how the engine works now.) This means that parts were thrown together and a working device was made completely by accident! Think about that. You go into your garage and throw some parts together and try to accidentally come up with an internal combustion engine, or a jet engine.

Not impossible, but completely fictional effects have been discovered and confirmed in multiple labs before. I present to you N-Rays http://en.wikipedia.org/wiki/N_ray

So while the device might end up working, don't hold your breath and don't be so quick to defend it. When the device has undergone some more testing it might be vindicated, but probably not. There is no unreasonable scepticism here, only healthy scpeticism.

Edited February 11, 2015 by Leszek
Fixed unfortunate accidental inuendo.

[peadar1987]

But continued testing is absolutely a good thing, even if the most likely outcome is that we discover some previously unknown or unthought-of effect that was causing an error in measurement, as it will make all future tests of low-thrust engines that bit more accurate.

[Frozen_Heart]

I think at this point we can rule out calibration errors on the equipment. Considering several different teams have all had similar results.

My bet is copper ablation or something. Testing to see if any particles are coming out the back would be interesting.

[Stargate525]

My bet is copper ablation or something. Testing to see if any particles are coming out the back would be interesting.

And if it's that, we've found a way to ablate metals without heating it up past a hundred degrees!

[Mazon Del]

In a video I watched a while back where Harold White was giving a partial update on information about the test (I think this was back in Dec?), he stated that the working theory (as we know) is the virtual particle one. One method he proposed to try and test this was to set up two of the drives in various configurations (back to back, follow the leader, etc). If the theory is true, he believes the drives should be creating 'wakes' in the virtual particles that will interfere with each other.

Just tossing that out there.

[SuperFastJellyfish]

And if it's that, we've found a way to ablate metals without heating it up past a hundred degrees!

Paul March of Eagleworks Labs said, 'Please note that what was used for the both the large and small endplates in the Eagleworks copper frustum was 0.063 inch thick FR4 printed circuit board with 1.0 oz copper, (~35 microns thick of Cu epoxied to the FR4 fiberglass), facing the interior of the cavity.'

The IR camera was viewing the outside of the large endplate. Obviously, the thermal conductivity for FR4 fiberglass is much lower than copper so it doesn't tell us how hot the copper itself is inside the device.

Edited February 11, 2015 by SuperFastJellyfish
typo

[Technical Ben]

They can. The excitations in these fields are called particles. For example, if you try to push off electromagnetic field, as you would from water, you produce photons which take the recoil. You just built a photon drive. You can do the same with gravitational waves. Which sounds all sorts of awesome, but gives you the same 1N / 300MW of power input. You can even push from fermion fields, producing particle-antiparticle pairs in your wake. That requires even more energy.

The reason things are so easy with water is because water already has mass. Vacuum is at zero point, and there is no way to bring it bellow zero point, so anything you do to push from it requires extra mass. And that is tons and tons of wasted energy. Efficiency that EMDrive demonstrates absolutely proves that what it pushes off from is a bunch of real, massive particles. Whether it's something from the environment, say, ionized upper atmosphere, or if it's something ejected from the craft, say a leak, there is a reaction mass. Which means that all they've really built is an ion drive. It might end up the most efficient ion drive we know with some work. So it's worth looking into. But it's going to have all the limitations of a conventional ion drive. If the thrust is due to environment, it will be fundamentally limited to tiny fractions of N, because atmo is so rare so high up. If it's due to a leak, it will be limited to stored propellant. Either way, this keeps us within current limitations of ion drives.

Thanks. That is what I was assuming, but it was doing so without all the math, so had no idea if I was correct.

Though I'm all for the flying car in 15 years time...

[Rakaydos]

They can. The excitations in these fields are called particles. For example, if you try to push off electromagnetic field, as you would from water, you produce photons which take the recoil. You just built a photon drive. You can do the same with gravitational waves. Which sounds all sorts of awesome, but gives you the same 1N / 300MW of power input. You can even push from fermion fields, producing particle-antiparticle pairs in your wake. That requires even more energy.

So you're saying that an Electrodynamic tether has the efficency of a photon drive? I was under the impression it was more powerful than that.

[78stonewobble]

They can. The excitations in these fields are called particles. For example, if you try to push off electromagnetic field, as you would from water, you produce photons which take the recoil. You just built a photon drive. You can do the same with gravitational waves. Which sounds all sorts of awesome, but gives you the same 1N / 300MW of power input. You can even push from fermion fields, producing particle-antiparticle pairs in your wake. That requires even more energy.

The reason things are so easy with water is because water already has mass. Vacuum is at zero point, and there is no way to bring it bellow zero point, so anything you do to push from it requires extra mass. And that is tons and tons of wasted energy. Efficiency that EMDrive demonstrates absolutely proves that what it pushes off from is a bunch of real, massive particles. Whether it's something from the environment, say, ionized upper atmosphere, or if it's something ejected from the craft, say a leak, there is a reaction mass. Which means that all they've really built is an ion drive. It might end up the most efficient ion drive we know with some work. So it's worth looking into. But it's going to have all the limitations of a conventional ion drive. If the thrust is due to environment, it will be fundamentally limited to tiny fractions of N, because atmo is so rare so high up. If it's due to a leak, it will be limited to stored propellant. Either way, this keeps us within current limitations of ion drives.

The experiment was performed at a vacuum "5.0x10^-6 Torr". If it is pushing off real massive particles (as would be my utterly unscientific guess), how much thrust would it loose when going into interplanetary space, where the vacuum is afaik. quite a bit lower?

Couldn't there still be a niche for a photon drive, that you can "boost" or "dope", with whatever particles you do come by, in the vacuum of space, possibly combined with an exceedingly lean form of a buzzard ramjet?

[N_las]

So you're saying that an Electrodynamic tether has the efficency of a photon drive? I was under the impression it was more powerful than that.

K^2 meant something different with "pushing off electromagnetic field". The electrodynamic thether just pushes off the earth, using its magnetic field. He was talking about pushing off the actual electromagnetic field itself (kinda) by expelling photons.

[NFUN]

K^2 meant something different with "pushing off electromagnetic field". The electrodynamic thether just pushes off the earth, using its magnetic field. He was talking about pushing off the actual electromagnetic field itself (kinda) by expelling photons.

Particles can be thought of as excitations in their respective fields, so pushing off of the electromagnetic field and expelling photons are synonymous.

//I think

[PB666]

For deflecting asteroids from Earth collision, *if detected early enough* - The Planetary Society proposes laser satellites. Vaporization at target points would cause outgassing, microscopically nudging the asteroid over time.

MOre likely you would compount the problem by rapid outgassing of the objects core causing an explosion, many threats were there was once one.

- - - Updated - - -

As I've pointed out I'm sceptical this is real...

But there is some people here that still won't believe it works even if we have satellites being propelled by them.

Just wait for further test results. Don't denounce it out of hand.

There are people who deny we are in space, or went to the moon. So......not much of a claim there..

If a beam of EM is produced in a sealed vacuum does it not have to eventually hit a wall, thus converting the field into a photo. Cannot that be the source of the thrust.

IIRC a massless photon does not feel the distance it travels, it simply transfers momentum from its source to its destination.

[-Velocity-]

MOre likely you would compount the problem by rapid outgassing of the objects core causing an explosion, many threats were there was once one.

That's correct because real-life lazors work exactly like they do in Star Wars.

Actually, using lasers to slowly ablate the surface of an asteroid can in fact work... but like most deflection schemes, it just takes a long time.

[Rakaydos]

MOre likely you would compount the problem by rapid outgassing of the objects core causing an explosion, many threats were there was once one.

Given the difference in surface area/mass ratio between one big rock and a bunch of smaller rocks, that would actually be a good thing if you did it early enough.

[PB666]

Well if these can't be scaled up, just use more of them.

Thousands upon thousands of mass produced cheap EM drives....

Drives have mass and thus need themselves to be accelerated, in addition are you going to lift 100 Tonnes of drive/power supply into space to get 100 dV.

[PB666]

You are aware of the fact that I've done graduate work in particle theory, right? As in, this is my actual field of study?

This simply isn't how virtual particles work. Particle-antiparticle ocean is a very bad analogy for vacuum. While certain parallels between quasi particle-antiparticle systems in solid states do exist, the particles, virtual or otherwise, that we are talking about here are not quasi particles. There is no lattice to absrob the momentum. These particles are excitations in fields, and carrying momentum means having an excitation in the field.

But more importantly, if vacuum simply picks up that amount of momentum, it must gain mass. Whatever else happens, anything that carries away the momentum must be on the shell. So it either has mass, and we have regular reaction drive, or it is a null current, and what you have is a photon drive, which drains ridiculous amounts of energy. Anything else violates conservation laws in very fundamental ways.

What if the field propagates in all directions and goes unseen as it spreads from the experiment. Particle physicist you may be, but there are thing about the new boson (e.g. how many flavors of Higgs are there?) in the standard model that go unexplained. Could the momentum be carried to the closest masses in the vicinity because of quantum effects.

[magnemoe]

Drives have mass and thus need themselves to be accelerated, in addition are you going to lift 100 Tonnes of drive/power supply into space to get 100 dV.

Well the emdrive itself is very lightweight, the power source is the heavy part.

[Technical Ben]

Again. That's just theorising. Theorising helps no one. Observations do.

We observe a force, currently unexplained. If it's "magnetically pushing off the large metal chair the scientist is sitting on" then we don't get much of a "space engine". But if it's "pushing out fuel/pushing off something else" we will soon know from more observations.

As said. No amount of "what ifs" or "but it could be" will tell us anything. We need more observations. Guessing what it could be, is like saying "my dice is likely to roll a 3, because it does contain a 3". We know the possibilities, we are yet to observe what it will "roll".