Slashdot Mirror
Thrust from Microwaves - The Relativity Drive
dfenstrate writes "The latest New Scientist has an article about an engine that exploits relativity and microwaves to generate thrust. There is a working prototype." From the article: "Roger Shawyer has developed an engine with no moving parts that he believes can replace rockets and make trains, planes and automobiles obsolete ... The device that has sparked their interest is an engine that generates thrust purely from electromagnetic radiation — microwaves to be precise — by exploiting the strange properties of relativity. It has no moving parts, and releases no exhaust or noxious emissions. Potentially, it could pack the punch of a rocket in a box the size of a suitcase. It could one day replace the engines on almost any spacecraft. More advanced versions might allow cars to lift from the ground and hover."
"The latest New Scientist has an article about an engine that exploits relativity and microwaves to generate thrust.
That sounds a bit more advanced than these two guys, who exploit explosives and a microwave to generate thrust.
The theory of relativity doesn't work right in Arkansas.
A) Any pressure from the microwaves on the walls.
and
B) Conservation of Momentum
Ewige Blumenkraft.
It also warms soup, and is great for reheating food.
Roger Shawyer has developed an engine with no moving parts that he believes can replace rockets and make trains, planes and automobiles obsolete ... The device that has sparked their interest is an engine that generates thrust purely from electromagnetic radiation
Of course, his first effort was to create a drive that ran purely on improbability, but you could never be sure where you'd end up or even what species you'd be when you get there.
The theory of relativity doesn't work right in Arkansas.
Seriously, we were supposed to have these things *years* ago. The scientific community should be ashamed of themselves.
( yes, this is a joke )
Mod me down with all of your hatred and your journey towards the dark side will be complete!
The complete and utter bogosity of this story has prompted Greg Egan to try to start a movement to save New Scientist. Anyway, check out this story.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
"In this house we obey the Laws of Conservation of Momentum!"
What's the difference between letting the microwaves bounce around in a cavity and just shooting them out the back? Or if you must bounce them, just bounce them off a 45 degree reflector. What's the benefit of the multiple bounces?
I wouldn't tell anyone. I'd maybe show a few keen investors what my prototype could do, but that's it. Then I'd develop a flying car, a launch vehicle, whatever, and insidiously take over existing markets. "So, SpaceX has made you the best offer for launch services eh? I'll beat it." "What kind of safety guarentees can you give us?" "Err, umm, what kind of safety guarentee is SpaceX giving you, I'll beat it!" "Right.. hmm, ok. You don't even have a rocket do you?" "Look, do you want your satelite in orbit or what?" and so on. That's me though, could be this guy just doesn't have balls that big.
How we know is more important than what we know.
However, it talks about hovering. There's nothing intrinsically unscientifically sound about two black boxes that exert a force on each other despite being physically disconnected (think maglev), effectively hovering one on the other - the transmission of force just doesn't happen via a physical carrier. I, for one, look forward to my hoverboard.
I am one of many. My idea is not unique, nor do I expect my voice alone to sway you. I speak in a chorus of opinion.
Would somebody please just go right ahead and post a scanned copy of Roger Shawyer's maths paper online after tracking him down and ordering the paper version from him? He says he has a maths paper, so let's cut out these waffling, nonsensically hand-waving explanations much loved by New Scientist that "relativity somehow causes microwaves to create thrust but we don't really know how it works but it does because I say so" and see the maths paper. Show us the maths and it will quickly become apparent whether he is a quack or a clever guy deliberately being a honeypot taggant for Chinese military procurement folks.
you can have it for free:
</i>
If you don't know what AltaVista is (was), get off my lawn.
Because that would be a photon drive. And we already know how well those work - the amount of energy you need to input to get even a tiny amount of thrust out of them is astronomical (pun not intended). We've had the basic idea of light propulsion for at least fifty years, and it's been a major cornerstone of hard science fiction. But it just isn't workable with modern power generation.
You could describe either a photon drive, or it's passive counterpart, the light sail, as a "relativity drive", since they too operate on the oddities of conservation of momentum as it applies to light. Doesn't mean we're going to be using them in lieu of rockets anytime in the next few centuries.
Either this guy has found a revolutionary new way to build a photon drive (and I'm more than a little skeptical), or else the device doesn't actually work. I'm more optimistic about this than I am about the usual lot of crackpot science, since from TFA it sounds like this guy is applying good scientific procedures to his work (documenting, trying to get outside review), but I'm not exactly holding my breath.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
Um, I didn't read TFA, but wouldln't this require a power source? Specifically, eletricity? How does one generate that much wattage? Flux capacitor?
-matthew
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
...of those cartoons where Bugs Bunny or someone is sitting in a sailboat, pulls out a fan, aims it at the sail... ...and the boat moves?
Comment removed based on user account deletion
The benefit of the multiple bounces is that they never leave the chamber. The chamber is shaped like a horn, and he's claiming that the force on the big part of the horn is greater than the forces towards the little side of the horn. An imbalanced force inside the chamber result in a net force from a closed system. Plus side, no moving parts and sealed. Minus side, current physics indicate this to be impossible. I know of no theory, even including the magical "relativistic" physics that allow for or predict unbalanced forces in a closed system. I'll believe it when I see it demonstrated to move a satellite in space. If he can do that, I'll drink the cool-aid.
Learn to love Alaska
I hope his invention is better than his explanations for why he has no investors (I know, I know, it's not).
"'Yrch!' said Legolas, falling into his own tongue."
Now I can have what I've always dreamed of, a flying car with a Phantom game console running Duke Nuke'em Forever on HURD with Copland running in virtualization on a BitBoys Oy Glaze3D graphics system whose driver was programmed in Perl 6 running on top of Parrot!
I love it when dreams come true.
I'm rolling on the floor laughing at that article, but have to remind myself that it's probably an ignorant reporter and (not necessarily) Shawyer.
"Since the microwave photons in the waveguide are travelling close to the speed of light"... no, the microwave photons ARE light and are, by definition, moving at the speed of light at that point. I'm not really weaseling -- 'c' is the speed of light in open vacuum and is the same thing for all photons, but a waveguide is only a few multiples of the photon's wavelength and various weird things (to us) happen. See also the (Shamir?) pressure you can get when you hold two conductive plates close together. Longer wavelengths can't exist between the plates but can exist outside of them so you get a very slight net force pushing the plates together.
"any attempt to resolve the forces they generate must take account of Einstein's special theory of relativity."... no, standard EM theory will suffice. (Well, you might need some QM in there, but definitely not special relativity.)
and my favorite
"by mounting it on a sensitive balance, he has shown that it generates about 16 millinewtons of thrust, using 1 kilowatt of electrical power."
Let that sink in. This is as much power as a hair dryer or stove element, and it generates 16 mN of thrust. Could it be, oh, Satan?! I mean, thermal?!
This is particularly ironic since the article referred to the discovery of light pressure earlier. Everyone knows those little bulbs with white and black fans that "demonstrate" this effect. What most people don't know is that it isn't a perfect vacuum in there and, gosh, the dark side gets slightly hotter than the white side. That means the gas heats up on one side, expanding, you know the rest. IIRC they spin leading with the white side. It should be the other way since you have twice as much momentum transfer to reflect light (white) than to simply absorb it (black).
(BTW, I agree 100% with everyone who's pointing out that the walls of the cavity account for the rest of 'thrust' and that the device will just sit there driving up your power bill.)
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
Tue Sep 19 17:56:42 PDT 2006
Russell McMahon wrote:
I don't know that a reactionless drive can't work - although I don't know how to build one
Without having gone into it in detail, his math seems okay up to eq 6 (when he is quoting well-known math), but thereafter he veers into the realms of error and fantasy.
Eqation 7 is incorrect in so far as it purports to describe the total forces on the waveguide - while it does correctly describe the sum of the forces on the ends of the waveguide, it does not take into account the forces produced on the sides of the tapered waveguide.*
All by itself that is enough to blow the conclusions of the paper completely out of the water. It is simply wrong. It doesn't work. You can stop reading here.
Now we get into the rather more dubious portion of the paper.
Eq. 8 is also in error - it is based on the incorrect statement "...as the two forces Fg1 and Fg2 are dependent upon the velocities vg1 and vg2, the thrust T should be calculated according to Einsteins law of addition of velocities." - but the conclusion does not follow, and use of Einstein's equation is inappropriate. There is no real-world summing of velocities, it is a mathematical trick (and there is an error int the math too). The ends of the waveguide are stationary relative to each other.
That is an elementary schoolboy (or snake-oil salesman's) mistake.
There are several other obvious mistakes in the paper, and he frequently states as fact things that are unjustified and on occasion untrue. There are also parts of it which seem to be meaningless.
For example, this is also incorrect: "The second effect is that as the beam velocities are not directly dependent on any velocity of the waveguide, the beam and waveguide form an open system."
The conclusion does not follow.
This is actually very confused - I don't think he even knows what he is saying. Relativity theory does not (directly) come into it at all.
I stopped looking for more errors about here.
Snake oil or error?
There was some mention of licencing the technology, but as it is in the UK patenting it here would be impossible - it is, after all, a perpetual motion machine (or it would be if Q approached infinity, which there seems no theoretical reason to suppose impossible), and you cannot patent a perpetual motion machine in the UK.
Even if it worked.
The question of how he got a grant is still
To the DTI, NASA etc: Please can I have half his grant for pointing out his mistakes? I promise I will use it do space r+d.
*Of course if you want to consider the waveguide as two pieces, forces on the tapered walls do not affect the result - but the math in eq7 would be wrong if you are looking at it that way, eg the lambda-g1 and lambda_g2 figures are for the ends of the waveguide, not the middle.
I think he first went wrong in his mind here - in fig 2.4 there is a vertical line in the middle of the diagram, implying that he was looking at the waveguide as two pieces, rather than as two ends and a tapered middle. You can of course look at it in either way, but in his analysis (even before we get into the error-full "relativity" stuff) he is trying to do both at once, and that will and has lead to error.
--
Peter Fairbrother
--a different AC
Potentially, it could pack the punch of a rocket in a box the size of a suitcase.
That seals it. The terrerists could use this, so we must ban all further research!
By the way, this engine would violate conservation of momentum, and is thus incredibly dubious. On top of that, the "working" prototype was measured to generate an incredibly tiny force, a measurement which was given without error bars in the only numbers I've seen, so he's probably just measured his noise floor. It has never been published in a peer reviewed journal. Because of this article, John Baez has posted an open letter from Greg Egan to the editors of New Scientist, which includes gems like "I really was gobsmacked by the level of scientific illiteracy in the article".
In other words, reader beware. Crackpots abound.
I'm pretty sure that the Phantom gaming console has that business model patented...
Nephilium
It's not enough to be able to pick up a sword. You have to know which end to poke into the enemy. -- (Terry Pratchett, Lords and Ladies)
I'm very surprised that this is being reported on. There's nothing to this.
What's probably happening is that the microwaves are leaking out heating up one side of the thruster more than the other causing the air on that side to warm up and become bouyant which is whats creating the apparent thrust. I could make a lot more thrust with a 700 Watt fan than 88 millinewtons.
I'm starting to dispair over the state of science in this so called modern world when I see articles like this. Maybe next we could have an argument over whether sidereal or tropical based astrology is more accurate at predicting the future.
"..much of it bemoaning the abysmal standards to which New Scientist has slipped. "
well.ets be honest here, scientist always have a habit of doing that when something they don't agree with is published.
". Not only does the article suggest that this "drive" violates conservation of momentum,"
There is nothing in Relativity that says this someone can't exploit the difference in frames.
Do I have my doubts? certianly, and strong ones at that. strangly, the article doesn't ring the BS meter.
Having a working prototype(alledgedly) is a good start. His credtionals seem good.
Agreeing to independent review is also good. Most people BSing about this stuff say things like 'the scientific community is keeping me down.' and won't allow third parties to review the work unless they are paid money in advance.
The Kruger Dunning explains most post on
It was a really bad article. It was clearly a dodgy claim and you would think they would have an expert in the area totally vet the article, but alas no.
/ YaBB.pl?num=1157719780/0)
There are some other worrying things in the article. For example, the author says...
What of the impact of such a device? On my journey home I have plenty of time to speculate. No need for wheels, no friction.
Yet it is precisely the friction between the wheels and road which make a car go forward. Friction with the car wheels is not bad, you need it. Friction with the air is bad, but not the wheels.
If I had do the EM Drive story, a story which sounds highly suspect, I would have looked at some critiques of similar schemes. Within a few minutes of searching I found similar "Reaction-less Drive" schemes which all turned out to be Oscillation drives. It's the same phenomena as when you move across the room in a swivel chair (without touching the floor) by shifting your body-weight around. When you do that you are exploiting the non-linear nature of friction between surfaces. A similar thing can happen with these reaction-less drives interacting with air, water or other surfaces. So it's quite possible that a prototype drive would appear to work. So I would have asked for some kind of proof that this was not an oscillation drive.
Another issue is that it's not clear that this Em Drive prototype has been tested in a vacuum. In one of the other articles on it, it says that the thrust only reaches the maximum after a few seconds. Now that sounds much more like a mechanical oscillation effect (building up to maximum amplitude) than a photon/microwave effect.
Some of what I have said here is re-posted from a discussion I had on the Elmurst Solutions Science forums. (http://www.elmhurstsolutions.co.uk/cgi-bin/yabb2
You are confusing nonlinearity of acceleration at a given thrust with nonlinearity of the thrust itself.
As a visceral example go ride a bicycle through air. Doubling your thrust will not double your speed, but you will experience directly that you have, indeed, doubled your thrust.
In the best case scenario, i.e. if this guy can solve the little problems such as pressure on the chamber walls, his engine, by his own calculations, does not simply run with nonlinear acceleration with a given thrust, but actually "runs out of juice."
In the colloquial, it stops working.
KFG
Assuming that part of TFA is true, then he's already way ahead of the usual "free energy" crowds.
Typically when somebody's claims violate the laws of physics, the usual challenge is for them to provide a repeatable experiment for others to test the theory in question with. This challenge is most often met with weaseling or silence. When such theories are tested from outside, they most often do not pan out (see the cold fusion experiments as an example).
If he's willing to get outside review already, then I at least will acknowledge that he is an honest crackpot rather than a snake oil salesmen. And it's always better to actually test the blue sky ideas than it is to dismiss them out of hand.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
Yeah. Get the prototype tested. Evidence beats theory any day, well almost.
Bitter and proud of it.
Yet it is precisely the friction between the wheels and road which make a car go forward. Friction with the car wheels is not bad, you need it. Friction with the air is bad, but not the wheels.
I thought it was the exhaust coming out of the back that propelled the car forward.. I mean, if electromagnetic radiation can propel something forward surely gaseos exhaust can?
// MD_Update(&m,buf,j);
If he's willing to get outside review already, then I at least will acknowledge that he is an honest crackpot rather than a snake oil salesmen. And it's always better to actually test the blue sky ideas than it is to dismiss them out of hand.
Oh, there have been any number of people who have put forward various intertialess drives for independant review. You are right, there is a difference between the honest crackpot and the snake oil salesman (thank god, or I might be in real trouble myself), but sometimes tests actually just waste time and resources when the theoretical failures can be defined without actual test.
And my point was that he hasn't actually built anything legitimately testable in a lab yet. The forces are so small that we'll need to fly the puppy to judge it at all. This is different from the solar sail which already know could work by theory and ground based test.
I can build you three or four mechanical variations on the theme that will even stand up to review in the sense that they seem to work perfectly well in the lab, much better than this one does because they'll actually scoot across the airtable, but the reason why they won't work in space are well enough understood that no one is going to waste a bird to send one up.
It's perfectly possible to become an honest crackpot by simply getting a bit of the equations wrong and have that failure perfectly obvious to other people.
KFG
Comment removed based on user account deletion
Maybe they are just borrowing the momentum from a future frame of reference.
Any old timers here remember the 'Dean Drive'? Probably from the late 50's or so, but there was quite a bit of interest in it back then. Supposedly, it obtained a thrusting force from mechanical means. Tests at the time showed potential but no theory could explain how it might work. It came from someone tinkering outside of the conventional envelope thinking and hoping that they had discovered something. The least it did was give the tinkerer's some fun. Though it didn't work as hoped, probably as this microwave device doesn't work as hoped, the experimenters shouldn't be discouraged. As long as they're not taking funding away from mainline research, I encourage the experiments into oddball ways of obtaining thrust. It's fun to think that someday, sometime, someone will find an exploitable hole in the laws of physics we know today.
Hm.. it looks like there isn't a Wikipedia article on Roger Shawyer, but there is an article on his "EmDrive":
http://en.wikipedia.org/wiki/EmDrive
It's a fairly interesting read, and even though it's still rough in spots it's certainly better-informed than the scientifically-confused New Scientist piece linked in the submission. I particularly suggest reading through the analysis of Shawyer's claims.
I won't contradict you on Faraday, but as of Marconi, it's very very different in nature ; scientists believed transatlantic radio to be impossible because of the straight travel of electromagnetic waves ; therefore, as earth is round, they thought falsely that radio waves would go out in space following a straight path, and would never reach the other side. That was an established *law*. What they didn't knew, and learnt on that occasion, is that earth's atmosphere is not uniform and some of its layers bounce electromagnetic waves down. It doesn't change physics but it adds to the knowledge of another field of science. And the device (if it works) may uncover some "structures" we don't know about - yet. That doesn't mean it would prove current theories to be false, but it may change our views on something remote.
Is anyone else reminded...of those cartoons where Bugs Bunny or someone is sitting in a sailboat, pulls out a fan, aims it at the sail... ...and the boat moves?
That actually works. A little bit.
But it works MUCH BETTER if you just point the fan to the rear.
The fan sucks air from a lot of directions and ejects it in one direction, creating a net thrust (and reaction - backward - on the boat via the person holding the fan) and a net wind.
Diverting that wind to the rear via the sail produces somewhat more reaction forward on the boat via the sail and the mast than the reaction backward from the fan - IF the trim is good enough that the diverted wind ends up going backward rather than just off to the sides. Result: Slight net forward thrust on the boat.
But pointing the fan to the rear - using it as a jet - eliminates the inefficiencies of using the sail in this way, putting the fan's whole reaction into moving the boat forward.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
This isn't a closed system. TFA mentions that microwaves are transferred into the chamber. Sounds like energy transfer to me.
note: i'm known as plugwash most places but i screwd up registering that here somehow in the past and now can't regist
But even if this is the reporter's goof, confusing acceleration and velocity, the inventor claims that the device would work better for hovering (presumably in Earth's gravity) instead of accelerating. This shows that the inventor does not understand relativity or basic physics. If his device could make a car hover then it could also accelerate the car at 1 G.
According to the physics fact book, a 2001 Jaguar KX8 and a 2000 Mitsubishi Eclipse can each accelerate at 3.8 m/s^2 which is less than 1/2 G.
Since the inventor does not understand one of the simplest applications of relativity (gravity is the same as acceleration) I do not trust his calculations that claim some relativistic effect is giving him a force that will violate the conservation of momentum and energy.
We don't see the world as it is, we see it as we are.
-- Anais Nin
Plausible? Yes. But as the critique said, only to the extent that sending a particle beam in a specific direction will give you thrust. Which is both weak, quite well-known, and anything but what the inventor is claiming.
Now, just what the heck are you talking about with "weak thruster = strong levitator"? Thrust (force) is thrust, no matter if it's pointed down for levitation or not.
Okay, in my opinion, this statement is a big warning sign you should be more careful commenting about what obeys the laws of physics and what doesn't.
Magnets do exchange particles when repelling eachother. They're called "exchange particles" (shock!), and to be specific, the exchange particle for the electromagnetic force is the photon. Even more specifically, virtual photons. They transfer momentum between magnets, both when repelling and attracting. (The latter case is of course harder to visualise, since there's no classical analogy. Nevertheless it's true.)
You also made another pointless distinction: Matter versus particles?
An analogy never ever proves anything in physics. At most you can use it to explain something. Your analogy doesn't do that, though. Nevertheless, conservation of momentum always holds. Or if you like, Newton's third law: For every action there's an equal and opposite reaction. You need two magnets to push against eachother, or they won't move.
And that's the gist of it: What does this thruster push against? The only thing it could ever "push against" are the created particles, and then only if they exit. Any momentum it gains is exactly equal (and opposite) to the momentum of the photons. No bouncing-around, cavity-wall pressure, relativity or other physical concepts can change that. Again, all the forces are equal and opposite: Every force in the engine must be balanced by another force in the engine.
The net effect can't be other than zero unless something else is moving. The only moving things here are the microwave photons, and unless they leave, their net force on the non-moving parts must be zero.
The inventor claims they are not leaving. He also claims that they exert unequal force within the cavity. This is just as wrong as claiming a gas could exert higher pressure on one end of a box (however shaped). In fact, a gas of photons act more like an ideal gas than a real gas does. The concept of photon gases is well studied and understood. (google for it, and while you're at it, you can read up on electron gases, neutron gases, neutrino gases, boson gases, and even entirely fictional substances like jellium.)
Any half-decent physicist, should immediately recognize that you can ignore whatever the purported internal working of the machine is. The thrust will always equal the momentum carried away by the particles leaving the engine, be they rocket exhaust, jet exhaust or a particle beam.
In this case it's entirely trivial. First, nothing is leaving, hence it's bullshit. And if the photons were to leave, the exact momentum is given by P/c (a formula stated in the critique), and the thrust can never be higher than that. (since that would represent creating photons with 100% efficiency, and assume none are absorbed on the way. Which is actually highly unlikely with microwaves, since they're a form of heat radiation, which most materials have quite
If there is a sustained, measurable deviation not explained by known physics, the guy will get a Nobel. That's 1.1 million dollars. If I was sure I had a winner for getting a million, I'd certainly be ready to invest into a vaccum chamber and build a prototype.
If we don't see this happen, then the drive doesn't work. End of story.
--
Mad science! Robots! Underwear! Cute girls! Full comic online! http://www.girlgeniusonline.com/
(If that sounds dubious, you can see why I'm skeptical of the premise.)
This apparatus is a Radiometer. And it's not really working by the expansion of gas on 'hotter black side' -- the pressure throughout is essentially constant. The effect is caused by the movement of the rareified gas at the edges of the vein due to the temperature gradient.
Better explanation (and historical context): http://math.ucr.edu/home/baez/physics/General/Lig
When the apparatus is refined, by using a much better vacuum, suspending the 'blades' in a way with less resistance, and coating them in inert material the light pressure can be observed directly -- it will spin with the dark side leading. The link above says this was first achieved in 1901.
Read Heinlein's 1953 Revolt in 2100, now more than ever.
It's only a closed system if you think in terms of eletro-magnetics. Assuming the prototype works to any degree, what if he's found an electro-gravitational effect? Yes, I'm reaching a bit here, but gravitational effects aren't limited to an enclosure... or maybe even our dimensions... so it wouldn't be a closed system.
Forget thrust, drag, lift and weight. Airplanes fly because of money.
A PhD in physics.
I have a swimming pool with a tapered bottom. The force on the wall at the deep end is much greater than the force at the shallow end. I drive it around the city all the time. As soon as I can figure out how to turn it upright, I'll be giving free flights to slashdotters and Jerry's Kids.
Where can I locate the anonymous "Air Force visitor" who always gets trotted out as "proof" the inventor isn't a crackpot?
Here is an old article from 2002 with pictures. You would think in 4 years he would have already proven this... http://www.shelleys.demon.co.uk/fdec02em.htm
Weight : 9 kilograms Thrust : 88 milinewtons Quite better than the european ion engine but still awfully far away from being able to lift its own weight (in earth gravity field). And I don't even speak about the weight of a car or a plane. Still an interesting effect though, but the reporter obviously overhyped it. I'll reconsider when it can thrust its own weight, that would only be a x1000 factor...
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
I think the key part of your debate falls down with discounting things by predicting theoretical failures before a test is made.
Theory always alters to fit the observed facts. And every now and then, something pops out of the hat that changes everything.
It may be possible to be an honest crackpot by getting the equations wrong, and have that failure obvious to everyone else.. It's also possible to find something that works despite what the equations say..
That's called advancing science..
Wrong or right though, it'll be interesting to see how it pans out..
But what really got me fuming wasn't the author's total failure to notice that any of these were an issue - which I'll grant got me quite livid, being as bad as a football report from someone who doesn't know the offside rule. That it violates basic physics is bad, and should certainly have been seriously raised as an issue in the article, but if it works then that's just too bad for basic physics.
What upset me most of all was the lack of imagination. What if this thing works as advertised? Oh, then we can have planes that work a bit differently. Hovercars, perhaps. For the love of God, man, it's a reactionless drive! Strap a few to a nuclear reactor and go to Saturn and back in a week! A rocket that doesn't have to carry vast tanks of reaction mass around with it? The whole galaxy would open up!
I'll buy this week's New Scientist in the hope of some sort of grovelling apology for this appalling mess of an article. Or at least of a proper flaming of the editors in the letters pages. And then I think I'll see if I can't get a reliable supply of Scientific American - it's quite scarce in UK newsagents but always has some really solid science in it.
Real Daleks don't climb stairs - they level the building.
(A big IF no less) Under the premise that this thing works, he's found a replacement (almost) for the ion drive/thruster. One thing that the article ignores until its reaching a bit past the claimed results is the cooling of the "thruster". That will add weight & require some engery too. Adding 1kw+ heaters to any spacecraft should be done carefully. I doubt this thing can radiate heat faster than it will generate it. (add a coiled cooling tube, have the microwaves heat the working fluid and use that thrust?)
Excuse me, for I am not educated a physicist, but I have some small questions on how this works.
Judging by the drawing, it seems that a lot of microwaves are released into a chamber which they bounce around in, only that one wall is less bouncy than the other walls (i.e. flat and nonreflective) so more of them hit this wall.
My questions are:
- Why can't this be replicated organically, by putting a herd of mice into a room with one hard broad end and the rest padded material, so that most of the mice will exert most force on the broad end?
- Why can't it be replicated with sound waves?
- Why can't it be replicated with photons?
- Why can't it be replicated with a tank of water? (hard jagged wall on one end, rounded on all others, create motion in the water)
- Is the thought behind it that microwaves DO exert force when they hit something, but DO NOT exert backwards force on their point of release? In that case fair enough - sound waves would probably be out - but what about thermal energy? Couldn't you put a match in a room where every wall but one is mirrored and achieve the same effect?
- If the concept is so simple, surely it should have been discussed even in fairly simple textbooks? Basically, if you have a system with a source that generates waves with momentum without itself being subject to the momentum, what happens if you place it inside a box on a trolley and most of the waves are absorbed by one side?
This purported 'invention' will surely not work. Relativity or not, conversation of momentum still holds true. A closed system (which his cylinder appears to be, at least in terms of E/M radiation) will never generate any net thrust. Even when E/M radiation can escape, it will impart at most a momentum of E/c - a very tiny amount indeed.
Couldn't you just point the fan backward, you know, like this?
My amazing wife - Artist, Author, Philosopher - Laurie M