Em Drive; Speed of light; and other science.

Monday, November 28, 2016

If Republicans want to force through massive tax cuts, we will fight them tooth and nail.

Senator Elizabeth Warren

Liberalism is a philosophy of consolation for the West as it commits suicide.

James Burnham

If a foreign government had imposed this system of education on the United States, we would rightfully consider it an act of war.

Glenn T. Seaborg, National Commission on Education, 1983

“Deriving their just powers from the consent of the governed.”

Immigration without assimilation is invasion.

if Romney had treated Obama half as roughly as he treated Gingrich in the primaries, he might have won in ’12 and saved us all a LOT of trouble.



Roberta comes home tomorrow, and we’re in the throes of repairs and alterations to make things ready for her. She’ll still be in a wheel chair, unable to get about very far with a walker. I’ve got more support for her, as she’ll need more than I did. It’s likely to be hectic, and I’ll have less time for work including this place, but I’ll manage somehow. There aren’t a lot of places for rational discussion despite what the web offers.


I spent part of the weekend at LOSCoN, the LASFS run Thanksgiving weekend local science fiction convention. The topic I was most interested in was the Em Drive, and it got brought up on every panel as well as in dinner discussion with Greg Benford, retired UC professor of physics. The problem is, there’s nothing to discuss: either it produces thrust, force, action, without losing mass, or it doesn’t. The evidence is that it does, but the run times have been short and the force is low.

We all pretty well agreed that if it works at all, we’re going to need some new physics, possibly a meld of Newtonian and Quantum physics, and we have given that a lot of thought but got nowhere in decades; but if this thing does work and produces a reactionless drive, it changes the nature of space exploration. The observations calculate about 1.02 (they give it to two decimal places) milliNewtons per kilowatt of electric power inputted.

http://www.digitaltrends.com/cool-tech/emdrive-news-rumors/ has a picture and a purported video of a “flight” (rotation, similar to what G. Harry Stine said he witnessed when Dean showed him the famed Dean Drive). In both these cases and in all other claims I know of, there is a hard connection to an immovable object. The digital trends report is of a purported leak of a NASA test; NASA has since released the report, and published it in a peer reviewed journal. The test reports force exerted against a torsion pendulum; that is it turns about a central hard and fast anchor, as do all the other tests I know of. That reports 1.02 millinewtons per kilowatt, but does not report the total thrust measured, and my reading did not detect any claim to long term operation.

There is a detailed and revealing analysis of possible errors of measurement, and the conclusion that none of them, or even all combined, could account for the observed forces.

That seems to be more than sufficient data to warrant an experimentum crucis to settle once and for all if this “works”. I propose that they hang it in a gravity swing; leave it unpowered long enough to determine the exact resting position; and turn it on. Presumably it will thrust forward to some angle off vertical, where the thrust will be more or less equal to the gravity forces dragging it back to the rest position. Now leave it on for a week, or weeks if possible. If at the end of the run it still hangs off vertical and has lost no mass, I would think that enough evidence to warrant spending the money for a test in orbit. If it can change orbits consuming power but expending no mass, I see no other explanation than reactionless drive. Thrust without mass loss, and the length of the experiment overcomes any possible error of measurement.

Depending on the ship size and how large the Em drive can be built, time to Mars is reduced by hundreds of days; forty days or so depending on when you depart. No fuel expended: the whole ship makes the trip, and doesn’t through 90% of it overboard for propulsion. I don’t know how to keep a crew alive in orbital travel to Mars for hundreds of days; I can imagine ways to do it for forty.

I am not saying we have a reactionless drive: I grew up with Newton’s Third Law and the physicists notion of conservation and I’m not ready to give them up easily. On the other had, I had old physics textbooks in science class that stated that matter could be neither created nor destroyed: Conservation of matter, and conservation of energy. Then, in 1945, just as I was leaving grade school, came Trinity… We got new textbooks.


I have been experimenting with Precious, the Surface Pro 3 tablet/laptop with a Surface Pro 4 keyboard. The 4 has a fingerprint reader, which the 3 did not have, but the software for the 3 runs the ID program. That has worked, but otherwise the software has been a nightmare. Now understand, my granddaughter is perfectly happy with her Surface, and I’ve got used to windows 10, sort of, and 10 is running on all my systems; and I suspect that if I hadn’t enlisted in the experimental “insiders” program which gets me early releases of Windows 10; I’d be happier. Microsoft seems to have too many updates even for my big machines, but I can live with that; but Windows 10 Insider has made a living Hell out of using the Surface Pro. When I first had the stroke, Eric was able to get the Surface Pro out to me in the hospital, and I could use it; I soon reverted to the ThinkPad because it was bigger and easier to read, but I used the Surface and liked it.

I was hoping to use the Surface Pro the way I used my old Compaq tablet long ago; that laptop/tablet combo was great. I took it to COMDFEX and other shows, and it was all I needed. The Tablet with keyboard and Microsoft OneNote were the best research tool I have ever had. It was too slow, of course, and both the system and disk memory were too small, but it was enough to get my BYTE columns done, take notes in presentations and lectures in both keyboard and handwriting, and do Internet searches either wireless or the Ethernet connections usually supplied in the Press Room,and even in motels that still made you use modems.

But every time I’d get used to the Surface they’d have an update, usually needless improvements, and more complications, and more, and crazier defaults, and no accommodation for those who had learned on DOS and earlier versions of Windows. At this point I’d only wish the Surface on enemies. It has now decided that it must access some pst files on OneDrive. I don’t recall ever telling it, or Microsoft, that I want any of my pst files on OneDrive. I don’t want any of my mail files on Microsoft servers or anyone else’s.

Meanwhile, Outlook won’t open without access to that OneDrive pst, and without Outlook the Surface isn’t much use for me.

I’m going to scrub the Surface and reinstall a release copy of Windows, as vanilla as I can get, and update only when forced to, and see if I can make the Surface work for me, stand by. But as of now, I sure think learning to live with the frequent updates makes the Surface Pro more trouble than it’s worth to a user.

While I am at it, I love the ASUS ZenBooks. I have the big ones, and they have the best keyboards I know of: that is, for a two-finger typist which I have been since the stroke. The keys are BIG, and well separated, and I do not often hit two keys at once. I can see the big screens pretty well. All told, excellent. Recommended if you need that much laptop, which I do.


I’ve just got a final notice from email updates to go get their malware or else. I sure wish I could believe it was their final notice…


EM Drive Potential


The recent peer-reviewed paper on EM-drive tests showed 1.2 milliNewtons of thrust per kilowatt input power. That’s not much, no. Not a practical space-drive due to ridiculously low thrust-to-weight for any realistic power source.

But (assuming the effect is real at all) nobody seems to think that 1.2 milliNewton per kilowatt is any sort of a theoretical limit.

The drive’s inventor, for what it’s worth, has been quoted in the press saying he thinks up to five orders of magnitude (100,000x) efficiency improvement are possible. I’ll take that with a LARGE grain of salt for now, as I’m still not entirely convinced the effect is real at all.

But just to see what the outer bounds are, that’d be 120 Newtons thrust for a kilowatt input (in english units, 27 pounds force.)

To illustrate the possibilities at those levels, an LM-2500 marine power gas turbine puts out about 25 Megawatts (MW) of torque and masses about five tons. A 787’s ~200 kilowatt engine-mounted generators mass 235 lbs each – I assume they’re near state-of-the-art. That works out to roughly another 15 tons for 25 MW of generators. Call it 20 tons total to generate 25 MW of mobile power (not counting fuel, structure, thrusters, etc.)

That 25 MW, at 27 lbs thrust per kilowatt, would produce almost 340 tons of thrust. Plenty to spare for fuel, structure, thrusters, and substantial payload. Aerial battleships, anyone? Or add oxidizer storage and have a space battleship… And that’s WITHOUT even looking at what you could build around a submarine reactor.

The stuff of a Doc Smith novel, yes.

But the EM-drive would be immensely useful at far short of those 100,000x efficiency levels. Figuring 10 kg of (space) ship per kilowatt of power available and a goal of 2 kilometers/second per day acceleration capability, we’d need 20,000 Newton-seconds per day for our kilowatt of power. At 86,400 seconds in a day, that’s 230 milliNewtons per kilowatt, or a mere 200 times more efficiency than the peer-reviewed test article.

Ships that can accelerate continuously at 2 km/sec per day give us the Solar System. The WHOLE Solar System. 10 weeks to Mars at average distance – and less than a year to Pluto. We’d still need old-fashioned rockets to get into space in the first place, but once there, if real, and if improvable a hundred-fold or more, this thing would change everything.

Improve it 100,000-fold, and we get flying cars – that can reach the Moon in three hours. I’m not greedy though, I’ll take 200-fold.

Here’s hoping. We’ll see.


Even if it’s limited to millinewtons / kw, it’s a key to the solar system. But as Carl Sagan (quoting Descartes) was fond of saying, extraordinary claims require extraordinary evidence, and these are certainly extraordinary claims…




From the outside, Trump may seem to be thrashing around. I think most observers don’t get that when you base your decisions on values, you make decisions this way. You try one thing on for size – it doesn’t fit, so you toss it away and try on something else, something different. Eventually you zero in on what you want. This is not ideology-based or strategy-based decision making. This is making decisions based on values.

This is also like markets. And, like markets, you see overshoots. You see people throwing things against a wall and seeing what sticks. You see what products sell, what services are profitable. Expect to see mistakes, and rapid corrections. The problem with ideology-base decision-making is that they make as many mistakes but they don’t correct them. We had many years of not correcting mistakes. I like Trump’s way.



Inside the project to rebuild the EDSAC, the world’s first general purpose computer


    As a Communications Technician in the Navy, I was trained on tubes (or valves as the Brits refer to them) as well as semiconductors.  I’m all in favor of this reconstruction and I’d love to see it when it’s finished.


New ultra-thin semiconductor could extend life of Moore’s Law



Old and new…


In addition to the reactionless drive, we have another potential physics revolution:

The speed of light is constant? Physicists plan to test a new theory that questions Einstein’s assumptions — Quartz

It will be interesting if they prove to be correct. If the speed of light varies (or varied over time) then a few assumptions have to change.

Magueijo proposed that to solve one of the biggest physics problems, called the “horizon problem,” we might have to challenge the idea that the speed of light is constant. The problem states that the universe reached a uniform temperature long before energy-carrying photons traveling at constant speed could have had the time to reach all corners of the expanding universe.

The most accepted explanation for the horizon problem is something called inflation. It suggests that, after the Big Bang, the temperature evened out before the universe went through a rapid phase of expansion. But the inflation theory doesn’t sit well with many physicists, mainly because nobody can explain why inflation started and why it stopped.


John Harlow

Special Relativity requires an absolute constant speed of light. Given that gravity propagates at the observed local speed of light, the advance in the perihelion of Mercury, the observation that drove Einstein to formulate the Special Theory, can be accounted for by Newton’s model; he assumed infinite propagation speed. Of course General Relativity assumes that what we think of as gravity is in fact a distortion in the fabric of space, and I’m not sure that propagates at all, but it’s not my subject; I don’t do math above vectors and matrices.


Freedom is not free. Free men are not equal. Equal men are not free.



Bookmark the permalink.

Comments are closed.