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Comment: Re:Uber has demonstrated contempt for the law (Score 1) 38 38

by ErikTheRed (#50015641) Attached to: Uber France Leaders Arrested For Running Illegal Taxi Company

So what? Have you seen who writes laws? A bunch of vote-leeching sociopaths that span the moral spectrum between used car salespeople and outright pedophiles... Let's just support the whims of every elected bunch of assholes. War, slavery, genocide, hey, gotta do it! It's the law!

Seriously, this is one of the lamest reasons for anything, ever.

Comment: Flagrantly anti-consumer (Score 0) 38 38

by ErikTheRed (#50015443) Attached to: Uber France Leaders Arrested For Running Illegal Taxi Company

Let's be honest: in most countries, taxis suck and belong in a forgotten age. They're the epitome of tightly-government-regulated industry: slow, filthy, rude, overpriced - assuming you can get one to actually show up. Uber is fast, clean, polite, and - most importantly - reliable. The whole argument here is that some group of people paid the government a stupid amount of money for the special privilege of shitting all over a captive customer base, therefore throw the Uber guys in jail, take or smash the driver's cars, throw rocks at them, riot, jump up and down, scream and shout, and take Courtney Love hostage (OK, that last one I can get behind).

If some government is going to ban Uber, just go ahead and consider yourself a third-world country. If you're going to start piling stupid inconveniences onto my visit, you might as well go ahead and make me boil my drinking water as well.

Comment: Re:What plan? (Score 1) 83 83

How do you come to that assumption?

By linking to a peer-reviewed paper on the subject?

A nuclear warhead has lots of trouble to even "hit" an asteroid.

Essentially every space mission we have launched for the past several decades has had to navigate with a far more precision than that needed to get close to an asteroid and activate a single trigger event when close by.

Comment: Second law of thermodynamics. (Score 2) 186 186

by Ungrounded Lightning (#50012745) Attached to: Bill Gates Investing $2 Billion In Renewables

we have a way to turn electricity directly into heat. But there is no direct way to turn heat into electricity. It has to go thru a second step of mechanical energy to spin a magnet to create electricity.

You can go from electricity directly to heat because that increases entropy. You can't go from heat to anything useful because that decreases entropy, and entropy of a closed system only increases. The best you can do is a heat engine, working off a temperature DIFFERENCE. (Some of them also work backward as heat pumps, to go from electricity to heat more effectively, by also grabbing some heat from elsewhere to include in the hot end output.)

There ARE at least two major forms of electronic heat engines - direct from temperature differences to electricity, with only charge carriers as the moving parts: Thermoelectrics (thermocouples, peltier junctions, and thermopiles of them) and thermionics (both heat-driven vacuum diode generators and a FET-like semiconductor analog of them). Both are discussed in other responses to the parent post.

Comment: Thermionics (Score 3, Interesting) 186 186

by Ungrounded Lightning (#50012607) Attached to: Bill Gates Investing $2 Billion In Renewables

TEs are ridiculously inefficient and aren't looking to be much better anytime soon

Because thermoelectric effect devices leak heat big time.

However there's also thermionics. The vacuum-tube version is currently inefficient - about as inefficient as slightly behind-the-curve solar cells - due to space charge accumulation discouraging current, but I've seen reports of a semiconductor close analog of it (as an FET is a semiconductor close analog of a vacuum triode) that IS efficient, encouraging the space charge to propagate through the drift region by doping tricks (that I don't recall offhand). The semiconductor version beats the problems that plague thermoelectrics because the only charge carriers crossing the temperature gradient are the ones doing so in an efficient manner, so the bulk of the thermal leakage is mechanical rather than electrical, and the drift region can be long enough to keep that fraction down.

Comment: Re:What plan? (Score 3, Interesting) 83 83

We send spacecraft on comparable missions all the time. And it doesn't really take a spectacularly large payload to destroy (yes, destroy) an asteroid a few hundred meters in diameter. 1/2-kilometer-wide Itokawa could be blown into tiny bits which would not recoalesce, via a 0,5-1,0 megatonne nuclear warhead, a typical size in modern nuclear arsenals (in addition, the little pieces would be pushed out of their current orbit).

I know it's a common misconception that "nuking" an asteroid would simply create a few large fragments that would hit Earth with even more devastation, but that's not backed by simulation data. And anyway, even if it didn't blow the asteroid to tiny bits (which simulations say it would) and even if it didn't push the remaining pieces off trajectory (which they say it does), anything that spreads an Earth impact out over a larger period of time is a good thing - it means the higher percentage of the energy that's absorbed high in the atmosphere rather than reaching the surface (less ejecta, lower ocean waves, a broader (weaker) distribution of the heat pulse, etc), the weaker the shockwaves, the weaker the total heat at any given point in time, and the more time for Earth to radiate away any imparted energy or precipitate out any ejecta cloud. If the choice is between 15 Chelyabink-sized impactor (most of which will strike places where they won't even be witnessed) or one Meteor Crater-sized impactor (same total mass), pick the Chelyabinsk ones. 50 10-megatonne meteor crater impactors or one 500-megatonne Upheaval Dome impactor? Pick the former. The asteroid impacts calculator shows the former generating a negligible fireball and 270mph wind burst at 2km distance, while the latter creates the same winds 25km away (156 times the area) and a fireball that even 25km away is 50 times brighter than the sun, hot enough to instantly set most materials on fire.

But that's all irrelevant because, quite simply, simulations show that nuclear weapons do work against asteroids.

What we need is enough detection lead time to be able to launch a nuclear strike a few months before the impact date (to give time for the debris to disperse). There is no need to "land" or "drill" for the warhead. There is no pressure wave; instead, an immense burst of X-rays is absorbed through the outer skin of the asteroid on the side of the explosion, causing it to vaporize (unevenly) from within, especially near the ground zero point, and creating powerful shockwaves throughout its body. In addition to ripping it apart, the vaporized material and higher energy ejecta flies off, predominantly on the side where the explosion was detonated, acting a broad planar thruster.

Comment: Re:200 cycles? (Score 3, Insightful) 119 119

by Rei (#50008581) Attached to: Samsung Nanotech Breakthrough Nearly Doubles Li-Ion Battery Capacity

On the other hand, if they're doubling capacity, then you only need half the number of cycles (it actually even works *better* than that, as li-ion cells prefer shallow charges and discharges rather than deep ones - but yes, fractional charge cycles do add up as fractional charge cycles, not whole cycles). If you have a 200km-range EV and you drive 20 kilometers a day, you're using 10% of a cycle per day. If you have a 400km-range EV and you drive 20 kilometers a day, you're using 5% of a cycle per day.

Comment: Re:well then (Score 5, Insightful) 119 119

by Rei (#50008563) Attached to: Samsung Nanotech Breakthrough Nearly Doubles Li-Ion Battery Capacity

Top commercial li-ion capacities are about 30% more than they were 5 years ago. And today's batteries include some of the "advances" you were reading about 5 years ago.

I'm sorry if technology doesn't move forward at the pace you want. But it does move forward when you're not looking. Remember the size of cell phone batteries back in the day?

Comment: Then again. (Score 1) 61 61

I got the impression from the (sketchy) article that repeater AMPLIFIERS were still needed but repeater REGENERATORS were not.

Then again - another part of the article makes it look like an additional result was that they could boost this less-subject-to-degradation-by-nonlinear-distortions signal at the start until the fibre itself was acting non-linearly, in order to get a signal strong enough to survive a much longer hop.

So it's not clear to me whether the distance was achieved by:
  - long hops enabled by strong signals, and NO amplifiers
  - longer propagation without regenaration using JUST amplifers
  - a combination of the two: Both getting long total length without regeneration AND being able to use stronger signals and thus use larger space between the amplifier-type repeaters.

Comment: but not amplifiers (Score 1) 61 61

Since the diameter of the earth is 7 926.3352 miles, this could conceivably remove any need for repeaters.

I got the impression from the (sketchy) article that repeater AMPLIFIERS were still needed but repeater REGENERATORS were not.

I.e. you still needed to boost the strength of the signal to make up for the losses. But the progressive degradation of the quality of the signal - with data from different frequency bands bleeding into other bands (especially in the amplifiers themselves) due to nonlinear "mixing" processes - had been headed off, by synchronizing the frequencies of all the carriers to exact multiples of a common basic difference-between-the-carriers frequency.

This apparently sets up a situation where the distortion products of each carrier's interaction with nonlinear processes cancel out with respect to trying to recover the signals on another carrier - much the way the modulation products do in OFDM modulation schemes. In OFDM it allows you to make essentially total use of the bandwidth. In this system it lets you use simple, cheap, amplifiers to get your signal boost, rather than ending the fibre before things get too intertwingled, demodulating all the signals back to data streams and recovered clocking, then generating a fresh set of modulated light streams for the next hop - MUCH more expensive and power hungry.

Comment: Re:Randomness can't come from a computer program (Score 1) 64 64

by Bruce Perens (#50004185) Attached to: NIST Updates Random Number Generation Guidelines

Most of us do have a need to transmit messages privately. Do you not make any online purchases?

Yes, but those have to use public-key encryption. I am sure of my one-time-pad encryption because it's just exclusive-OR with the data, and I am sure that my diode noise is really random and there is no way for anyone else to predict or duplicate it. I can not extend the same degree of surety to public-key encryption. The software is complex, the math is hard to understand, and it all depends on the assumption that some algorithms are difficult to reverse - which might not be true.

Real Users know your home telephone number.

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