A force for space with no reaction (microwave spacedrive?)

EUREKA (Euro Tabloid?) ^ | 2002, 2004 update, 2005 note | Tom Shelley

[theFIRMbss]

A force for space with no reaction

Tom Shelley reports on an extraordinary concept, which if it turns out to be as good as it seems, could change a large part of engineering

A reactionless force motor, designed for space use, has the potential to drive objects on until they reach speeds close to that of light.

Looking at first sight as if it cannot possibly work, a prototype has been developed by one of our leading engineers, and is endorsed by academics and government.

Defying intuitive understanding, it is low cost to make, is said to obey the laws of physics as they are currently understood, and in the longer term, could revolutionise transport and actuation.

The Emdrive is the brainchild of Roger Shawyer, who, in the past, has had charge of some of Britains most advanced aerospace projects. He says the germ of the present idea started when he was at Sperry Gyroscope, and was asked to look for a reactionless system for missile guidance. Conventional engineers, may at this point, throw up their hands and say that a reactionless system is not possible, citing Newton's Third Law. However while light photons obey Newton's Laws in some respects, the idea of the solar sail being a typical example, in other respects, light and objects travelling at or near light speed do not obey them.

In essence, the Emdrive is a resonating bottle full of microwaves. Because microwaves are a low frequency form of light, their behaviour is governed by Einstein's Theory of Special Relativity. And while microwaves and other forms of electromagnetic radiation may be thought of as very fast moving particles, they also have to be thought of as waves. At the same time that the constituent particles are moving at light speed, or their phase velocity, energy is transferred by the wave aspect travelling at group velocity. Group velocity is the result of waves of different wavelengths interacting with each other. While, according to Einstein, the phase velocity of electromagnetic waves is the speed of light in the appropriate medium whatever happens, and in whatever moving frame of reference the observer happens to be, group velocity varies. Group velocity can be any speed from stationary to light speed (a few physicists suggest the additional possibility of faster than light), and this varies the amount of momentum striking an impenetrable barrier, and thus the force exerted on it. Hence, it is possible to have a bottle full of electromagnetic waves exerting more force on one end than the other, whereas this is not possible for anything else that an engineer would normally be expected to encounter.

In the case of the prototype Emdrive, the closed resonating cavity is wider at one end than the other. Mathematical analysis shows that group velocity is higher at the wide end than the narrow end and that consequently, there is a net force exerted on the wide end. Furthermore, the net force exerted is proportional to the Q, or the effectiveness that the cavity shows as a resonator.

Most academics have run away frightened at the very idea of getting involved in an idea which is so controversial. One, however, Dr Richard Paris, a reader in mathematics at the University of Abertay in Dundee has endorsed the calculations. While the theoretical analyses, may of course, still be wrong, there is no denying that the prototype device appears to behave as predicted.

A curiosity of the constructed prototype is that when switched on, it takes some seconds to apparently build up to full thrust. Shawyer at first suspected that the apparent thrust might be due to some buoyancy effect arising from heat generated within the EMC enclosure. Careful modelling and analysis, however, shows that the effect arises purely from the time constants of the pulsed output of the microwave source, and the way these interact with the time constant of the balance system used to measure the forces developed.

The device uses a resonator made of copper, filled with microwaves from a commercial magnetron running at 2.5GHz, delivering 850W at an efficiency of around 70%. Enclosed in an EMC enclosure for safety reasons, the total weight of the box of apparatus is 15kg. When the box is placed upon a balance one way up and is switched on, it exerts a downward force of 15kgf + 2gf, and when it is placed the other way up, it exerts a force of 15kgf - 2gf. (The force motor and microwave generator weigh only 9.4kg, the remaining weight is that of the EMC enclosure).

A force of 2gf, or about 0.02N, may not sound much, but on a spacecraft, it is dramatic, because it can be constantly applied for hours, days, weeks, months or years. A 3 tonne satellite typically carries 1.7 tonnes of propellant. If it did not need to do this, its weight would be halved, and so would the launching cost of each satellite, currently a minimum of £80 million (Russian launcher). It would also greatly increase the working life of satellites, since this is presently ended when they run short of propellant, and are no longer able to keep themselves in their correct orbit. The end result is the increased economic viability of satellite communication and navigation systems, especially those that presently have marginal economics, tipping the balance between fibre optic ground based and space based systems. Wrist mounted communication systems and PDAs which would never lose signal, unless underground, would be the most immediate result noted by the 'man in the street'. Even on the basis of present satellite launch programmes, projected cost savings of £15.5 billion over the next 10 years earned the idea a DTI SMART Award in August 2001, and are encouraging the raising of serious money for the next stage in development.

Assuming that the measured effects are as real as they appear to be, and that the theoretical analyses are correct, it is possible to speculate where the technology might go after this. In space, it would reduce the journey time to Mars from nine months to three, rendering feasible the proposed NASA/ESA manned mission to Mars program, presently a pipe dream because of cost.

On the ground, it may be possible to make the engine much more powerful, even powerful enough to lift a flying machine against the force of gravity. We have been asked not to say how this might be done, but we can reveal that it involves a drastic improvement in the 'Q' factor, possible by a means which is available using present day technology, but one which would require a fair amount of expenditure to develop. Shawyer insists that such an engine would not be an anti gravity machine, which it may or may not be possible to construct, but would certainly behave like one.

One of the curiosities of the idea is that as the size goes down, the working frequency goes up. Hence, it may one day be possible to make very small force motors working on the same principle, but powered by light. These would be more compatible with very small scale robotics than trying to build very small mechanical actuators.

A means seems to have been found to generate force and thrust without a reaction and without a propellant

The technology has been developed for use as a satellite thruster, potentially halving the launch weight of satellites, but could well have many other uses in the longer term

The idea exists as a demonstrable working prototype.

UPDATE: MAY 2004 (News item in Eureka

Emdrive powers towards space

The Emdrive, which can drive spacecraft without the need for rocket propellant, originally revealed in the December 2002 edition of Eureka, has received further support.

Roger Shawyer, the Emdrive's inventor has written to us to tell us that: "The study results were independently reviewed and further support was then given by the DTI in the form of a Research and Development grant. This has enabled work to be started on the design, manufacture and test of a complete Demonstration Engine. The £250,000 programme is presently on target to provide a convincing demonstration of the technology. A fully representative spacecraft engine is being built and will be 'flown' on an air bearing to demonstrate the performance. A paper giving the theory and a summary of the experimental work is available free by e mail application to TheEmdrive@aol.com , giving name and affiliation. More information may be found at www.emdrive.com . TS

[theFIRMbss]

Pournelle has a note
in his current view on this.
Anyone know more?

[theFIRMbss]

ping for real spaceships!
(Do you know who keeps ping lists
for such space tech threads?)

[dead]

Looking at first sight as if it cannot possibly work

Often a good indicator that it won’t.

[TommyDale]

What kind of brakes would the space ship need?

[Little Pig]

Seriously cool, if true.

I'm still waiting for spacecraft engines that allow non-Newtonian flight, as well as the fabled supra-light or "warp" engine (depending on which school of thought you prefer).

[RadioAstronomer]

btt for a later read.

[ABG(anybody but Gore)]

A means seems to have been found to generate force and thrust without a reaction and without a propellant

No fuel? Maybe they use some magic dust on Santa Claus, a little bit magic dust for his reindeer, a little bit more magic dust for Santa Claus...

[theFIRMbss]

>Looking at first sight as if it cannot possibly work
>>Often a good indicator that it won’t

A Jane's reporter
hinted in this book Britain
might be working on

a wild, blue sky thing
that could really work. And now
Pournelle's dropping hints

that he's "hearing" stuff . . .
If this is true, it's the BEST
news I've ever heard . . .

[Lekker 1]

Investors sought (desperately, no doubt).

[Las Vegas Dave]

Ping for real spaceships!

[dirtboy]

In essence, the Emdrive is a resonating bottle full of microwaves.

Hmmmm ... I've been wondering why my Microwave oven moves slightly over time.

[BroncosFan]

Okay, finally I've found someone who read that thing. All that kept me from dismissing it out of hand was the fact that the author was a Jane's guy, and they tend to have their stuff together. Is their any consensus on that book among people "in the know"? It all seemed plausible (to a history major with a law degree).

[theFIRMbss]

>No fuel?

"The device uses a resonator made of copper, filled with microwaves from a commercial magnetron running at 2.5GHz, delivering 850W"

They don't say "no fuel,"
they say "without propellant."
They still need power

for the magnetron
which generates force -- somehow --
then with microwaves.

[cripplecreek]

"On the ground, it may be possible to make the engine much more powerful, even powerful enough to lift a flying machine against the force of gravity"


Not to mention cook a whole heap of turkeys.

[Coyoteman]

What kind of brakes would the space ship need?

Disk brakes. Can't use drum brakes in space.

[theFIRMbss]

> Is their any consensus on that book among people "in the know"?

The book puzzles me.
It's very buttoned down, but
other than the stuff

about the Nazis,
it's "informed speculation."
Don't know what to think.

[duffthor]

By Space Ordinance: Engine Braking Prohibited

[datura]

Remove the door interlock and the door once. Then AIM the microwave oven at a glass of water a few feet away for a couple of minutes. It will be near boiling.

DO NOT STEP IN FRONT OF THE UNIT WHILE IT IS ON!!!!!

[theFIRMbss]

>Remove the door interlock and ...

(I've often wondered
why Mafia types don't use
something similar . . .)

[ABG(anybody but Gore)]

I'll take your word for it. The idea of having two headed kids doesn't really appeal to me. ;^)

[thoughtomator]

Spaceships brake by reversing the direction the ship is pointed and applying thrust... accelerating in the direction opposite that of their current vector.

[johnny7]

“ ...and in the longer term, could revolutionise transport and actuation.”

S • E • G • W • A • Y

[theFIRMbss]

>S • E • G • W • A • Y

[ModelBreaker]

What kind of brakes would the space ship need?

Well, just turn the Q chamber the other way and hold it there for a really long time.

[ModelBreaker]

No fuel? Maybe they use some magic dust on Santa Claus, a little bit magic dust for his reindeer, a little bit more magic dust for Santa Claus...

My first thought too. If it generates more power than it takes to run it, you have a perpetual motion machine.

[brooklin]

You won't need to worry about having any kids after the experiment.

[JoeFromSidney]

The headline is misleading. The thing IS NOT reactionless. On the contrary, the thrust they apparently generate is a REACTION to the emitted microwaves. It wouldn't matter whether they were emitting microwaves, light, UV, or even gamma rays. They would get a reaction. The point of using microwaves is that they are easy to generate and control. However, the thrust is going to be very low for any reasonable power level. I doubt they'll ever get enough thrust to lift off from Earth. Once in space, though, continuous thrust at even low levels can achieve high speeds.

[GarySpFc]

Ping

[mcshot]

Great thoughtomator!

mc:>))

[theFIRMbss]

>The point of using microwaves is that they are easy to generate and control. However, the thrust is going to be very low for any reasonable power level

"Group velocity can be any speed from stationary to light speed (a few physicists suggest the additional possibility of faster than light), and this varies the amount of momentum striking an impenetrable barrier, and thus the force exerted on it. Hence, it is possible to have a bottle full of electromagnetic waves exerting more force on one end than the other, whereas this is not possible for anything else that an engineer would normally be expected to encounter

Well, it's not simply
a "plain" ion drive, because
the speculation

is that resonance
creates "group velocity"
energies quite high.

And "reactionless"
is a general term that's
used for Dean Drive things.

[aught-6]

"Scotty, we'll need everything you've got." -- Kirk,
"Aye. Warp drive standing by." -- Scotty

[hiho hiho]

I've seen one of these before somewhere.

[billybudd]

is endorsed by academics and government.

Which academics and which agencies?

in the longer term, could revolutionise transport and actuation.

I've heard that before.

Mathematical analysis shows

Mathematical analysis shows a *lot* of things. How about experiments?

Dr Richard Paris, a reader in mathematics at the University of Abertay in Dundee has endorsed the calculations.

Is this the only guy? How about someone with a degree?

there is no denying that the prototype device appears to behave as predicted

Assuming that the measured effects are as real as they appear to be, and that the theoretical analyses are correct

That's an awful lot of assumptions.

We have been asked not to say how this might be done,

Hint: magic!

Conclusion: somebody is fishing for a government grant.

[Wiseghy]

The key seems to be HOW FAST can you eventually get going on an 850w motor. Even in space it would seem that physics (particle drag, etc?)would start to catch up with you as you approach light speed.

[GOPJ]

WOW! Thanks for the ping. Real spaceships. It's possible.

[GOPJ]

We have been asked not to say how this might be done, Hint: magic! Conclusion: somebody is fishing for a government grant.

No, please no. This would be so cool if it would work...

[NewMexLurker]

I once made instant coffee in my microwave oven, and went backward in time.

[Sentis]

It uses electricity just like your microwave oven at home. There is no fuel needed because it can use solar power.

[pillbox_girl]

Just because it's "reactionless" does not mean it's necessarily a good or useful thruster. This thing might generate a thrust without a propellant mass. However, it almost definitely needs a hell of a lot of power to generate even a tiny force. Any satellite equipped with one of these things would need some enormous solar panels, or nuclear battery, to drive the thing. The satellite would have a longer lifespan, but I doubt it would be any lighter or cheaper to launch.

[MRMEAN]

[Arkie2]

An idea for achieving faster-than-light travel suggested by the Mexican theoretical physicist Miguel Alcubierre in 1994.1 It starts from the notion, implicit in Einstein's general theory of relativity, that matter causes the surface of spacetime around it to curve. Alcubierre was interested in the possibility of whether Star Trek's fictional "warp drive" could ever be realized. This led him to search for a valid mathematical description of the gravitational field that would allow a kind of spacetime warp to serve as a means of superluminal propulsion. Alcubierre concluded that a warp drive would be feasible if matter could be arranged so as to expand the spacetime behind a starship (thus pushing the departure point many light-years back) and contract the spacetime in front (bringing the destination closer), while leaving the starship itself in a locally flat region of spacetime bounded by a "warp bubble" that lay between the two distortions. The ship would then surf along in its bubble at an arbitrarily high velocity, pushed forward by the expansion of space at its rear and the contraction of space in front. It could travel faster than light without breaking any physical law because, with respect to the spacetime in its warp bubble, it would be at rest. Also, being locally stationary, the starship and its crew would be immune from any devastatingly high accelerations and decelerations (obviating the need for "inertial dampers"), and from relativistic effects such as time dilation (since the passage of time inside the warp bubble would be the same as that outside).

Could such a warp drive be built? It would require, as Alcubierre pointed out, the manipulation of matter with a negative energy density. Such matter, known as exotic matter, is the same kind of peculiar stuff apparently needed to maintain stable wormholes—another proposed means of circumventing the light barrier. Quantum mechanics allows the existence of regions of negative energy density under special circumstances, such as in the Casimir effect.

Further analysis of Alubierre's warp drive concept by Chris Van Den Broeck of the Catholic University in Leuven, Belgium,2 has perhaps brought the construction of the starship Enterprise a little closer. Van Den Broeck's calculations put the amount of energy required much lower than that quoted in Alcubierre's paper. But this is not to say we are on the verge of warp capability. As Van Den Broeck concludes: "The first warp drive is still a long way off but maybe it has now become slightly less improbable." See also interstellar propulsion

[TommyDale]

"Spaceships brake by reversing the direction the ship is pointed and applying thrust... accelerating in the direction opposite that of their current vector."

Yeah, I know. But at near the speed of light -- 186,000 miles per hour, that must be one heck of a stop. Imagine hitting a small piece of space junk or a small meteor at that speed. Bye-bye! Ya' think rack and pinion steering would help?

[ModelBreaker]

There is no fuel needed because it can use solar power.

So it would have to have solar cells strong enough to power the craft at its furthest distance from the Sun, is that correct? That extra weight would limit the top speed before deceleration would have to start. So solar cell electricity generated per gram of solar cell mass would be a key limiting factor as well as the Q efficiency, right?

[TommyDale]

186,000 miles per SECOND -- not per hour!!
duh!

[thoughtomator]

Human beings won't be able to travel at the speed of light, or even near it, because at that speed every particle acquires the relative properties of cosmic rays - living flesh would get cooked, no matter how well you shielded it. As far as hitting a meteorite, the chances are amazingly small for such a thing to happen in interstellar space, there are so few objects in such a large space it's nearly impossible to end up in a collision.

The way long-distance space travel would work is that you'd accelerate for half the distance, reverse the direction of your ship, and accelerate in the other direction for the other half of the distance, resulting in a net speed of zero at the destination.

[Eepsy]

That's why it's relatively common in SF novels to find clairovoyants/telepaths as space pilots. They can see where the stuff is and avoid it. I don't know how they'd take care of the problem in real life ;)

[AFreeBird]

There is no fuel needed because it can use solar power.

If you want to go inter-stellar, then you'll need a nuclear power source. And inter-stellar is where you could get some real speed going.

This engine sounds really cool!

[cannonball]

Why is it that everyone seems to ignore viscous friction in space?

[Brett66]

The website:

The EmDrive

He really needs to add some content to the site.