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« "...on the Road to Mars?" Musk | Main

November 23, 2016

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Degringolade

I would offer the following for folks to read who are new to this discussion.

http://www.emdrive.com/theorypaper9-4.pdf

Pons and Fleischmann were my physical chemistry professors at the U of Utah......you have to wait until reproducibility occurs.

I have hopes...I really, truly hope that this data is supported by further experiments and there is something there. But the folks at NASA seem have made a pretty good effort at keeping their claims reasonable and have laid out the ground work for future work

http://arc.aiaa.org/doi/pdf/10.2514/1.B36120

Wouldn't it be great if these folks actually proved that there might in fact be a "Luminiferous Aether Wind" that could be manipulated.

Michelson and Morley might be just a touch miffed. Newton would just sit back contentedly.

mike

"...without burning any fuel."?

Perhaps no fuel in the main engine itself, but there must be some fuel involved to generate the microwaves. Electromagnetic radiation is not free and nowhere close to a perpetual motion unicorn. Even SWMBOs microwave oven consumes a kiloWatt plus. More about the energy source that drives propagates the microwaves should be made clear by the researchers before any judgement could be made IMHO.

mongo

Interesting...

Claims of "this may violate the laws of physics" seem a little premature at this point IMO. Not requiring any fuel means a non-chemical process -- it still requires an input of energy.

It's also very unclear to me if the observed effect can be produced at a scale that is meaningful for space travel (remember the "ion drive" excitement from the 1960s). For this to work in a practical sense I would think that whatever power plant provides the input energy would have to have a small enough in mass that the engine could move it along with any payload.

One also wonders about the potential terrestrial applications, like using it to replace jet engines for travel or transporting goods... fun stuff. Maybe flying cars will happen some day after all.

Regards,
mongo

TTG

Why not? I would not pretend to understand the intricacies of the theories behind this, but I do understand the intricacies of another impossible fuel-less engine - the canvas sail. Actually, the EM drive and the canvas sail do use fuel. While the wind, obviously, powers the sail, the EM drive is powered by solar energy gathered by solar cells and converted, some how, to microwaves to bounce around the copper cone. I don't understand the premise that this violates a fundamental law of physics.

I was always intrigued by the idea of solar sails appearing in space art of the 60s. Now instead of massive solar sails, we may see massive solar panel arrays. Cool.

bemildred

For what it is worth: violations of Newton's Laws have been around for some time: relativity, quantum mechanics.

And the actual physicists don't sound all that confident about it not working either.

And it's not free energy.

Degringolade

I have always found things that fly in the face of the "Scientific Consensus" to be particularly fascinating. Most folks don't pay enough attention to Carl Popper.

"In so far as a scientific statement speaks about reality, it must be falsifiable; and in so far as it is not falsifiable, it does not speak about reality."

Be hopeful my friends, trust, but verify.

Generalfeldmarschall von Hindenburg

Scientific consensus is usually built around political utility of existing elites. There's an entire ontological structure built around the idea of 'no free lunch (for you).' This engine reminds me of the aethyr. Which supposedly was debunked. By an experiment which was constructed to make sure a positive result was as unlikely as possible. Or how physics shows all these completely weird effects at the quantum level but somehow none of that is supposed to have any effect on us or the universe we inhabit. When it's clear that nature is self similar across scale. Funny how these dramatic announcements happen and are invariably followed by a 'nothing to see here, folks. It's all just drudgery and work for you. Go on back to your cube."

Allen Thomson


There's confusion in the reporting between fuel and propellant. Fuel in many rocket designs provides the energy, propellant is the reaction mass that makes rockets work while conserving overall momentum. In chemical rockets they're combined, but in other systems, like ion thrusters, the energy source is quite distinct from the propellant.

Also, there are several examples of systems that are fuel-less and propellant-less in various combinations, like solar sails, electrodynamic tethers and gravity-assist. All of these manage to operate while not offending conservation of mass or momentum.

Just what the EM drive is doing, if anything, is totally unclear. Unfortunately, it's being presented in a way that strongly resembles other "reactionless" drives that have come and gone.

I'd like to see it demonstrated on a free-flying satellite, which some people are apparently planning to do. Wait and see.

Babak Makkinejad

All:

I have read of actual systems for maintaining altitude on satellites which basically consist of something like an electric coil that radiate heat.

The heat - in the form of electromagnetic radiation (or photons) - is the ejected effluent in this case.

This seems to be built on similar physical principle; electromagnetic field (or photons) carry momentum and thus, per the Law of Conservation of Linear Momentum, will cause an opposite motion.

Since the electromagnetic field also carries angular momentum, there should be an equal and opposite amount of angular momentum to the source, causing it to turn. Potentially, if this could be scaled up and harnessed, one could have the ship turning and thus generating artificial gravity.

Sans racines

To cast doubt on the fundamental theories you have to understand on what evidence they are built, and compare them against observables via experimentation - you have to try to test the theory in different ways. That was Einstein's principle method, i.e. the scientific method, and rather than regarding his discoveries as violations of Newton's laws it has been recognised that physical theories have limits to their domain of applicability. Strongly suggest reading Feynman's Lectures (vol 1), also 'Surely you're joking, Mr. Feynman' and also his tale of developing Quantum Electrodynamics. (Feynman being a notable American genius who also worked on the Manhattan project. These theories can produce astoundingly accurate predictions when applied within their domain of applicability and the real work these days is in discovering these limits. Where the theory fails lies new science... Conservation of energy is still regarded as a fundamental principle and many would like to find provable exceptions as not only would it be really astounding but you'd have cemented your name in the history books. However, the book on cold fusion by Huizenga is a good overview of what happened there - my take on it at the time was that if it really worked they should develop a motor based on the principle, and heck, if there was political opposition just publish the plans on the Internet which was just taking off (a la Wiki-leaks). Never happened...

Terry

The paper is exciting. Roger Sawyer is claiming that his next generation design can produce a far more powerful thrust. An em drive tied to solar panels to generate electricity as fuel makes for a highly reusable spacecraft and would be great for keeping satellites in position.

What I find exciting is the use of pilot wave theory as a possible explanation describing the em drive as a working application of zero point energy. Pilot wave theory takes the mystery out of quantum mechanics and makes it understandable. As John Stewart Bell said: pilot-wave theory “seems to me so natural and simple, to resolve the wave-particle dilemma in such a clear and ordinary way, that it is a great mystery to me that it was so generally ignored.”

An interesting overview of pilot wave and the hydrodynamics research mentioned in the Nasa paper.

https://www.quantamagazine.org/20140624-fluid-tests-hint-at-concrete-quantum-reality/

TTG

Degringolade,

Do you understand all that calculus in the theory paper? I don't remember a lick of it. I do remember that I was certain it was a hoax, a cruel joke played on us non-engineering students by a great technological university.

TTG

Here's a Nat Geo article that explains things well without calculus.

http://news.nationalgeographic.com/2016/11/nasa-impossible-emdrive-physics-peer-review-space-science/

Ken Roberts

The article is open-access, via the link given above, and one can click on PDF, and read to heart's content. Most of the article is about the engineering aspects -- how the device was built, how the test frame was built, how tests were run, and results. Section 10 at end has the discussion of speculative theories of "why it may be working".

I think this is fascinating, wonderful news. Concerns about the energy cost per thrust obtained are beside the point. This may be a physics experiment demo only, but very profound even if so. Or it may indeed be that this effect is capable of being scaled up, used in outer space for propulsion.

I am not at all sure that the effect has been suitably tested. There are so many aspects to consider. Radiation of photons from the apparatus in a directional manner, though it seems on first quick read that the investigators have considered that. However, much more work needed. In fact, a sort of year-long Michelson-Morley investigation is in order. We (Terrans) appear to occupy an asymmetrical position in the universe, as I interpret a report of anisotropy of the cosmic microwave background radiation to suggest we have a velocity of about 600 km/sec (0.2 percent lightspeed) relative to the average. One would want to see whether there is a year-long cycle in the thrust, to test if there is a coupling to CMBR.

The de Broglie - D. Bohm "pilot wave" possibility, mentioned in section 10, is intriguing. The consensus view, I believe, is that pilot wave is considered to be a mathematical curiosity as there are no observable differences between PW and the Copenhagen model. However, I believe that David Bohm in some paper or book stated that there could be opportunities for observable differences. I would not wager against the instincts of the co-author of the Aharonov-Bohm effect!

Someone on other site mentioned Casimir effect. Yes, I think it suggestive. The ratio of energy input vs thrust obtained might well be due to the thrust arising from a coupling with or focus / directing / other anisotropy of fluctuations.

I an no expert on any of this, just someone who like the topic.

kr

Balint Somkuti, PhD

Sir,

first it reminded me of the Douglas Adams' improbability drive. As a side note I have my own version of it: the Somkuti-Bernek probability drive. which is fueled by another theoretical question about probability: Why are you here exactly? With the same force that keeps you exactly here, you could be anywhere else in the galaxy.

To be more serious the Age of Reason has provided a giant leap forward while at the same time a big step back. We have forgotten to be able to think out-of-the-box or to accept that phenomena exist even though we might not have a clue about its existence (black swan effect so nicely summed up by Nicholas Taleb). And we also gradually have lost our holistic and/or transcendental self.

Babak Makkinejad

I think it correct that the drive violates the Third Law of Newton. That is, however, correct - the electromagnetic phenomena do so.

Please see Oleg Jefimenko's discussion:

https://www.amazon.com/Causality-Electromagnetic-Induction-Gravitation-Gravitational/dp/0917406230/ref=sr_1_1?ie=UTF8&qid=1480011711&sr=8-1&keywords=jefimenko

walrus

Unless someone can explain why the equations have no term for radiation pressure on the conical sides of the microwave cavity, then. the drive is BS.

It is all very well to arrive at a net force by subtracting radiation pressure force at the smaller end of the cave from the larger, however there is the question of radiation pressure on the sides of the conical cavity walls that joins the ends. By definition, at least in classical mechanics, the force on the conical section, added to the force o the bottom section, exactly balances the force on the top of the cavity. What new effect am I missing here?

Degringolade

TTG:

My son just finished up his third quarter of Calc at PSU. I had him come over, fed him an ungodly amount of food (he is an offensive lineman), and had him work through it with me.

He did help me bring it all back, but my calculus was 40+ years ago, Unless something this interesting comes around again, I plan to let it return to the placed described by Galadriel in "The Lord of the Rings":

“And some things that should not have been forgotten were lost. History became legend. Legend became myth. And for two and a half thousand years, the ring passed out of all knowledge.”

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