uvdiv

41 ms·

331.
by uvdiv 14y ago
Ion engines have been tested at effective exhaust velocities of 90 km/s [0], which allows delta-v's up to 500 km/s or so. [0] https://en.wikipedia.org/wiki/High_Power_Electric_Propulsion
332.
by uvdiv 14y ago
There's a perverse irony in staging hunger strikes to protest cheap food.
333.
by uvdiv 14y ago
Were they errors like these? http://book.realworldhaskell.org/read/using-typeclasses.html... http://www.haskell.org/haskellwiki/Monomorphism_restriction
334.
by uvdiv 14y ago
I didn't read this article as discussing satellite internet. They propose connecting cell phone towers with free-space microwave links: a microwave relay from one cell phone tower to another, direct, no satellites involved.
335.
by uvdiv 14y ago
That's a terrifying thought, that centrally-run social networks are actually in a position to perform this kind of conditioning. What could Facebook do, if it tried to socially engineer the entire world?
336.
by uvdiv 14y ago
Only the US bothers with lasers because everyone else understands that lasers don't work for fusion. https://en.wikipedia.org/wiki/Laser_Mégajoule I personally think lasers are much more promising, if only because of how much room there
337.
by uvdiv 14y ago
isn't it released in many ways that cannot really be harnessed directly eg: gamma radiation, x-rays, emf. Yes, just like nuclear fission! All this radiation gets absorbed by surrounding matter, and its energy becomes heat. Powers a steam
338.
by uvdiv 14y ago
But as I said, only a fringe minority care even slightly about the things Schneier wants regulated: e.g. data retention. To most people these are very low priorities. Should government actually being empowered here, it will push in the op
339.
by uvdiv 14y ago
...it's time we step in in our role as governments (both national and international) to create the regulatory environments that protect us... Or putting on other imaginary hats: ...it's time we step in in our role as technology corporati
340.
by uvdiv 14y ago
Judging by your essay, they prefer feeling cheated to having a shortage -- it's other people's shortage they don't care much about. They buy the price-"gouged" products, then they support arresting the guy who sold them. They are free to
341.
by uvdiv 14y ago
They could have dug into their own pockets and paid their drivers the 2x pricing, That would do nothing about demand (spiked because of mass transit closures). Discouraging consumption with price increases is to customers' benefit: it kee
342.
by uvdiv 14y ago
Wrong and wrong. AR1 predicted 5-14 cm over 20 years; the actual rise was 6 cm. The reality? 11 mm or less over the last 2 decades! The article claims 11 mm of water solely from melting ice sheets. It says the total increase was five time
343.
by uvdiv 14y ago
Until recently we didn't even think natural thorium isotopes were radioactive, since the half life is close to the age of the universe. Huh? Thorium was the 2nd element Marie Curie discovered to be radioactive, in 1898 according to wikipe
344.
by uvdiv 14y ago
More than one thread: * He says the energy input is very large. I say it's reasonable for it to be so, because it's converting a cheap form of energy into a valuable one * He says it is CO2-intensive because of the large energy inputs. I sa
345.
by uvdiv 14y ago
We destroy perhaps as many as 7 units of free energy in the environment and human economy to produce 1 unit of free energy as corn ethanol And yet they still make a profit, and it is still highly rational to do so. Because it turns ou
346.
by uvdiv 14y ago
Oh that's easy to solve: simply insert a gene that makes biofuel corn toxic to humans, rendering them non-edible and solving the fictitious moral dilemma.
347.
by uvdiv 14y ago
He really, really misses the point: what matters most is economics, not technical metrics in vacuo. “… these values even do not take into account that more than 50% of the energy stored in the biofuel had to be invested in order to obtain
348.
by uvdiv 14y ago
Could be a page/offset in a one-time pad.
349.
by uvdiv 14y ago
Some companies are still issuing those today: Rethinking the 'Long' Bond: Bankers Pitch 100-Year Debt, but Given the Risks, Would Investors Bite? http://online.wsj.com/article/SB2000142405274870448840457544...
350.
by uvdiv 14y ago
It's not a rectangle, it's clearly either an iPad or Galaxy Tab. It's a rectangular slab of particular dimensions/proportions, rounded corners of a particular curvature, and a 4-sided front bezel of a particular, uniform width. In combinati
351.
by uvdiv 14y ago
I'm not splitting hairs -- suing a company for cloning a CPU, versus spying on citizens to preemptively check that they're not pirating -- the difference isn't a hair, it's an enormous gulf. I'm not hostile to slippery-slope rhetoric, but y
352.
by uvdiv 14y ago
it's $9M used to pay the US Government as your startup requires all the infrastructure, legal framework and military protection provided to get where it is (feel free to move your startup to Somalia, where I hear the taxes are close to zer
353.
by uvdiv 14y ago
Just as an example, a really tight "intellectual property" regime would have to have... This is a logical fallacy: for an act to be illegal, it does not follow that the state is empowered to preempt it from ever occurring at all, especi
354.
by uvdiv 14y ago
Appreciate the effort, but there's some huge errors there. The reactor you mention will fission 1,500 kg of one isotope, U-235 -- out of some ~50,000 kg of nuclear fuel (3-5% U-235, rest being useless U-238), and 300,000 kg of mined urani
355.
by uvdiv 14y ago
Or to solve this at an earlier point, why not just turn off the windmills when the power's not needed. Because the subsidies in Germany are tied to the amount of electricity sold. That's why they're selling even at negative market price
356.
by uvdiv 14y ago
Of course, I don't know of a better system, just that the current system seems archaic. (You probably couldn't create a centralized "contract bureau" in the federal government, because many contracts are private, until someone sues.) Of c
357.
by uvdiv 14y ago
Somewhat importantly, no one else claims isolated protons (hydrogen nuclei, which are stable) undergo EC. It's an effect of unstable, radioactive nuclei with too many protons and excess energy. Not free protons. In fact, naively that violat
358.
by uvdiv 14y ago
There doesn't seem to any strong evidence yet that the process described in the article actually produces net energy output. Massive overstatement. They don't have evidence the process exists in any form.
359.
by uvdiv 14y ago
It's a stretch of terminology to call neutron capture "fusion". This would make all (non-spontaneous) fission "fusion" too. Neutron capture is trivial to accomplish; there's no Coulomb barrier, as neutrons are uncharged. What's nontrivial,
360.
by uvdiv 14y ago
It can be much better than that. The ion thrusters in Dawn have a specific impulse of 3,100 seconds (30 km/s exhaust velocity). Later thrusters designed for the Jupiter Icy Moons Orbiter achieved 9,600 seconds in a lab (94 km/s e.v.) JIMO i

More ›