Follow Slashdot blog updates by subscribing to our blog RSS feed


Forgot your password?

Comment: Re:What are the practical results of this? (Score 1) 425

by DanielRavenNest (#48935709) Attached to: FCC Officially Approves Change In the Definition of Broadband

How about the same people who actually wired up rural areas, the Rural Electric Cooperatives? The TVA built dams and power plants, but the REC's did the local work. As cooperatives, they are customer-owned. The government helped them get started with loans, but those are long since paid off. The advantage of using the Electric Co-ops is they already have poles going everywhere necessary.

Comment: Re: Hey! I've been gypped! (Score 1) 145

by DanielRavenNest (#48900305) Attached to: NVIDIA Responds To GTX 970 Memory Bug

> Who knows about the bitcoin mining because that's all nonsense anyway.

Nobody in their right mind uses GPUs to mine bitcoin any more. They use custom mining chips (ASICs) which are about 100 times more efficient, because the calculations are done entirely in hardware, and being fairly simple, can be parallelized much more than graphics cores.

As far as bitcoin being nonsense, the New York Stock Exchange and a large bank just invested in a bitcoin company:, and Microsoft accepts bitcoins: . Evidently they don't think it is nonsense.

> But I'll bet their little programs that they run using $1 of electricity to get 50 cents in bitcoins

I did mine at a loss sometimes back in the day, but it was in the background, for a graphics card I was already using in this PC. So I only had to pay for the incremental electricity of the card running full bore instead lower levels. The $60 of extra electricity is worth $680 in bitcoins today. I stopped mining in mid-2013 when the custom chips started going into volume production. Not all of us are idiots.

Comment: Re:Business model? (Score 1) 105

Space solar arrays are also 2.5 times as efficient than in 1998. That's because they now use triple-layer cells, that convert more of the solar spectrum to electricity. The biggest shift will be if SpaceX can reuse their rocket stages. They are already the low-cost launch provider, and that would given them another factor of 3 or so in cost.

Reducing launch cost also will reduce satellite cost. The cost optimum is when the marginal cost of removing 1 kg from the satellite = the marginal cost of launching that kg. So cheaper launch means heavier but less expensive satellite parts.

Comment: Re:Business model? (Score 1) 105

> Private corporations may soon have more space technology than the US government.

That's already the case. NASA's share of total space industry is only 6% ($18 vs $300 billion/year). Commercial satellites have had ion thrusters for a number of years before the NASA Dawn spacecraft had them. For-profit corporations have more incentive to update their tech sooner, to get a competitive advantage.

Comment: Re: Unconstitutional too (Score 1) 382

The Fourth Amendment reads in part:

> "...and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized ."

This looks like an attempt to get around that provision. Sorry, FBI, you actually have to do police work.

Comment: Re:Time to abandon normal phones? (Score 1) 217

> It does limit the functionality though since you don't get emergency calls where someone you know had to borrow a phone and such.

Those people can leave a voicemail message. Most telemarketers and robocalls don't. When I get a mystery calling number, I let it go to voicemail. If it's important they can leave a message, and I can call them back.

Comment: Re:Fastest Probe? [Re:Exciting stuff] (Score 2) 170

> I wonder what the fastest possible chemically-propelled-rocket probe is?

Slower than a Nuclear-ion probe. Nuclear in this case means a small nuclear reactor, say in the 1 MW power range. Plasma thrusters have an exhaust velocity of ~ 50 km/s, and it is reasonable to reach 3x exhaust velocity, thus 150 km/s. The mass ratio (propellant to empty mass) would be 20:1 in that case. For any kind of chemical rocket to reach that velocity, it would need a mass ratio of 10 trillion, which is seriously impractical.

150 km/s = 31.6 AU/year, therefore missions to around 300 AU would be reasonable (10 year trip time). 1 MW reactor with radiators would mass ~ 20 tons. 300 AU probe would mass ~ 5 tons. Propellant load would be 25x20 = 500 tons. Propellant flow rate is .57 grams/sec or 49 kg/day. So thrust time is 28 years, which is a bit long. It would help if the reactor could be made lighter.

Comment: Re:Slow Interstellar (Score 1) 272

by DanielRavenNest (#48725405) Attached to: How Civilizations Can Spread Across a Galaxy

> The hard part is getting up to speed, and slowing down at the destination.

The diffusion method I call "slow interstellar" doesn't require that. If you already live in the Sun's Oort Cloud, and another star gets close enough that the Oort Clouds overlap, you only have to match velocity, which is on the order of 50 km/s. After that you drift along with the other star, spreading to fill their environment, until another close stellar encounter happens. This method requires more patience than humans possess, though.

Comment: Re:explain to me (Score 1) 108

by DanielRavenNest (#48720697) Attached to: Fraud, Not Hackers, Took Most of Mt. Gox's Missing Bitcoins

> We know (or can know) which bitcoins were "lost" in MtGox

No, we can't, because those were not block chain transactions. They were funds transactions internal to Mt. Gox's account books. Let's assume Mt. Gox had 500,000 bitcoins in "cold storage" (the private keys printed out and stored in a safety deposit box, where no hacker can get to them). Some of those 500,000 coins belong to Mt.Gox itself, from accumulated trading fees. The rest belong to customers. Who owns what is kept track on their internal database. By fiddling with the database, they can move ownership between accounts without ever touching the coins in cold storage. Being able to trace what shenanigans happened to the database depends entirely on available backups of the database *before* the shenanigans happened.

> So couldn't the top 5 or 10 players in the network, who collectively have something like 75% of the computing power, collude and simply invalidate the transactions out of MtGox?

If by that you mean transactions from a Mt.Gox owned address to one outside Mt. Gox, again no. Blocks from 9 months to 3 years ago (when Mt. Gox was presumably messing around are linked to every block afterwards (that's why it is called a "block chain"). The linkage is by including the hash value of one block as part of the data in the next block (along with new transactions). If you change an old transaction, the hash of that block will change, and no longer match the value stored in the next block. You would have to recalculate new hashes for every block after the one you want to change. This is basically impossible, as it took the whole network's combined power to generate the existing series of block hashes. If 75% of the network gave up working on new blocks, they would lose future income *and* past income, as a different set of people would get the coins generated in each recalculated block. In turn, all the people who spent all those block rewards, or parts thereof, downstream of the miners, would have their balances invalidated.

Comment: Re:Bitcoin != Coins (Score 1) 108

by DanielRavenNest (#48720461) Attached to: Fraud, Not Hackers, Took Most of Mt. Gox's Missing Bitcoins

> "Inherently worthless" is the salient feature of money. When you trade things of intrinsic value you are bartering.

They are not disjoint sets. Money was whatever commodity had the most acceptability and was easiest to trade. Normally that happened to a commodity with features like durability, scarcity, divisibility, etc. The US dollar is backed almost entirely by debt, so it is not true to say it is inherently worthless. Those debts (Treasury bonds, mortgage-backed securities, and bank loans) have value because they pay interest, and you can trade a pile of dollars for any of those debts if you want to hold them directly. Paper money and coin are just convenient size trading units. A home mortgage or Treasury bond are inconvenient for day-to-day purchases.

Comment: Re:Do I buy it? (Score 1) 235

by DanielRavenNest (#48712425) Attached to: The Billionaires' Space Club

> VG won't be doing anything special,

Actually "Son of SpaceShip Two", otherwise known as Stratolaunch ( , is the special thing. It's the same basic idea, carrier airplane and rocket stages, but much bigger and able to put significant payloads in orbit. Yet another billionaire, Microsoft co-founder Paul Allen, started this up. The same people (Scaled Composites) are building this as SpaceShip Two. But this time they are using parts from *two* 747's to build the world's largest airplane, to maximize launch capacity.

At first, the rocket stages are disposable, and only the airplane comes back, but in the long run I expect them to reuse the rocket stages too, it would save a lot per flight.

If a thing's worth doing, it is worth doing badly. -- G.K. Chesterton