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Comment Re:so is there a good theory? (Score 2) 470

It doesn't, it just changes the numbers at which breakeven occurs to ones not easy to achieve on earth.

Unless you get to 1N/300000000W (in which case it is a well understood photon drive)

Yes, the claimed EM drive thrusts are much larger than a photon rocket would produce for the consumed power.

Comment Re:so is there a good theory? (Score 2) 470

It's a perpetual motion machine.
If you have an engine that produces one newton per 10W of input power, then move it 20 meters a second, you can extract 20W from this.
At 200m/s, 200W. Leaving 10 (or 190W) of free energy output after you subtract the first.

Agreed. Let's make this a little more rigorous.

Suppose that the device has a mass of X kg and produces A Newtons per Watt of power, with a power of 1 Watt. Turn it on. It is consuming 1 Joule / sec and producing A Newtons, so the device is (in free space) accelerated at A/X m/sec^2 and (after N seconds) is moving at NA/X m/sec, giving it a kinetic energy (1/2 mv^2) of (X/2) * (NA/X)**2 = N^2 A^2 / 2X Joules for an expenditure of N Joules.

When N^2 A^2 / 2X is >= N you break even (ignoring losses), i.e., when N >= 2 X / A^2. If X is 5 kg and A is ~ 5 x 10^-6 N/W (typical numbers claimed), then N needs to be ~ 4 x 10^11 seconds (12,675 years) and the device velocity will be 400 km/sec. Clearly, energy is being created and (at this relatively low velocity, 0.0013c) special relativity will not change this situation.

Whether this actually works and, if it did, whether it would be a practical means of creating energy are, of course, rather different questions.

Comment Re:so is there a good theory? (Score 2) 470

It seems that every test of EM drives by credible scientific organizations so far has been successful. Is there some theory now to explain how and why they work?

IMHO, no.

There are plenty of theories, but not one of them would stand up to five minutes of review by a proper theorist. When JASON reviewed Sonny White's work, they were (to be euphemistic) not kind about the theories presented.

Note, by the way, that testing in orbit is not the same as confirmation in orbit, which if you read carefully they are not claiming.

If you want to read about this closer to the source in Chinese, here you go.

Comment Re:I agree Apple is losing its' panache (Score 1) 230

The company that overtakes Mac as the main laptop of serious computer users ...

Actually, the market is NOT serious computer users.

Those stick with the PC models.

Mac users were/are mostly portable form factor.

I was in the IT business for 30 years and the only business I ever saw that had a Mac system, with desktops, servers and printers was the one I donated to Goodwill in favour of Windows shit.

The users at that firm were were appreciative.

Macs are for niche users -- mostly students and artists.

Sounds like a blast from 1990. Let's just say you obviously don't hang out at the same businesses that I do.

Comment Re:We don't need no stinking badges (Score 3, Informative) 357

But Uber is right in this case, so they're not breaking any laws.

The State of California disagrees. Note this little detail: over 20 companies have gotten permits from the State of California to test (drive) autonomous cars on public streets. That means that Uber is not acting in a regulative vacuum, it is just choosing to ignore the regulations that do exist.

Comment Re: Basic small-government argument. (Score 1) 357

So those road signs and the marks on the road and the traffic lights... those have no legal standing? They weren't put up by the government? They're just decorations? Driver's licenses are optional and there's no law against driving without one as long as you have insurance? You can drive drunk?

Apparently so, if you you have $ 8 billion or so in the bank.

Comment Re:Yet another attack on public education (Score 3, Insightful) 165

Unless you'd like to succeed in physics, chemistry, biology, mathematics, statistics, economics, computer science (not programming), electrical or chemical or mechanical or civil engineering, law, medicine, architecture, etc.

Gosh, I wonder how humanity ever survived learning and training these concepts for hundreds of years without spending $100,000+ on it.

For most of human history, becoming a scientist required that either you be wealthy, or that you find a wealthy patron. For most of human history, there were not very many scientists, and scientific progress was very slow. If we go back to the first condition, we can expect to obtain the second condition as well.

Comment Re:We knew this going in (Score 2) 588

We knew Trump had shortcomings, and still elected him - warts and all. We did it because he promised to fix certain issues that we felt were more important in the near term.

The perspective that I have is that anyone who believes anything Trump promises has totally lost touch with anything resembling reality. The man burns everyone who trusts him.

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