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Comment Re:Why can't they roll it back? (Score 1) 73

> negative inflation (deflation) is really really bad, because in that situation, the economy grinds to a halt because nobody wants to spend money (because it'll be worth more tomorrow),

This is a fallacy, because most people need to spend most of their income on immediate needs (food, mortgage/rent, utilities, car payments, gasoline, etc.). Therefore the economy will still function. For the people who have surplus income to invest, they already calculate a "real rate of return" by subtracting inflation from the nominal rate of return (i.e. measured in inflating currency). Thus if your stocks went up 2%, but inflation was also 2%, your real return is zero, because you can only buy the same amount of goods and services as the original investment could. If inflation was -2% (deflation) instead of +2%, it doesn't affect the method to calculate of real return, only the value you subtract. The market values of various investments would adjust to yield the same real return they do now. This is no different than what happened in past times when the inflation rate changed from one value to another.

This discussion applies to *mild* deflation, on the order of a few percent per year. Rapid deflation and rapid inflation are both bad. We have an example of the first in India, where they are trying to suddenly withdraw large bills from circulation, disrupting the normal flow of funds. We have an example of the second in Venezuela, which is now probably classed as hyperinflation (>100%/year)

Comment Re:Long range space probes? (Score 2, Interesting) 154

> Putting something radioactive on the launch pad and having it detonate in the atmosphere would be terrible too (Which is why we don't send nuclear materials into the sun.)

That's not why we don't do it. I worked on a "Space Disposal of Nuclear Waste" study at Boeing, under contract to the DOE. The risk reduction (about two cancer deaths a year on a statistical basis) was simply not worth the extra cost (about double that of burying it underground). Also, the Sun is not the safest place to dispose of it. If your rocket fails and leaves it crossing the orbit of Venus or Mercury, they could send it back to Earth by accident. The lowest risk is to place it in an orbit halfway between Venus and Earth (0.85 AU), and that also takes much less delta-V than hitting the Sun.

The nuclear waste was assumed to be glassified into coke-can sized segments, then formed into 2-meter "waste balls" surrounded by 20 cm thick steel alloy, which in turn was surrounded by heat shield tiles. The worst case accident is no on the launch pad, which is merely a lot of fire. The worst case is the rocket failing just before reaching orbit, where the payload kinetic energy is twice that of the best rocket fuel. So the heat shield enabled surviving re-entry, and the thick steel shell enabled surviving a terminal-velocity ground impact. It was also a corrosion-resistant alloy, because most launch failures end up dropping the payload in the ocean. We assumed a 2% launch failure rate.

The waste balls were so damage-resistant, that the study manager would have been happy to take one home and put it in the basement to keep the house warm in the winter (they generate 2 kW from radioactive decay heat). House fires, natural gas explosions, earthquakes, none of those would do any damage to it.

Comment Re:"Likley grow" - Bullshit (Score 1) 275

> the basic food for plants without which plants would not grow and we would all starve to death is not a bad thing.

Too much food, or anything for that matter, is a bad thing. We humans need water, but too much of it is called drowning. In the case of Carbon Dioxide, too much is a poison for people. Occupational guidelines are not to exceed 0.5% for extended periods.

Comment Re:So scared (Score 1) 742

There is no competition. Cotton farming in Alabama, for example, where I used to live, is highly mechanized. They spray the fields by airplane with herbicides to kill the leaves. Then the harvesting machine chews up the remainder of the plants. Stems are denser than the light and fluffy cotton bolls, so they get separated by air, and the stems are discarded. When the harvester is full, it dumps the cotton into a baler, making bales larger than a tractor-trailer in size (cotton is light). The bales eventually go to the mill to be processed. Around three people can harvest hundreds of acres at at time.


Comment Re:Long time bitcoin user (Score 1) 45

I used it as a long-term investment. I accumulated them from 2011 to earlier this year at an average price of $76/btc. Now that it has gone over my price target of $600/btc I'm selling. Unless the current block size logjam is broken, I don't anticipate it will go up that much more in the near term, so I will keep selling until it's gone.

The block size is currently limited to 1 MB/10 minutes. Blocks are sets of transactions which are secured by a series of special hashes that are chained together (hence the name blockchain for the whole transaction record). 1 MB can fit a few thousand transactions, and ~250,000 transactions per day simply can't serve day-to-day uses like coffee at Starbucks. It's fine for my purpose, or things like international payments and remittances, where bitcoin is far cheaper than bank wires or services like Western Union. Unless the limit is changed, it will have to be "second layer" payment services to handle small daily transactions, and bitcoin itself used for settlement between such services. This is similar to how banks use clearing-houses to settle up payments between themselves, on behalf of their individual customers. In other words, your bank doesn't send money to Walmart each time an individual shops there. Instead, they batch together all the payments for the day from your bank to Walmart's bank, and in turn that bank forwards the right amount to Walmart's account. Since Walmart's bank is doing the same thing to pay employees and suppliers, the daily clearing is a single payment between the two banks for the net amount going in both directions.

Bitcoin only reached filling the 1 MB of transactions per block on a regular basis earlier this year. People are working on second layer solutions, but they are mostly not ready yet.

Comment Re:Am I reading this right? (Score 2) 79

No, the liquid Oxygen is delivered as liquid on trucks, and stored in large tanks at the pad as liquid. The Helium would be cooled to LOX temperature by virtue of being inside a tank full of the stuff. This would lower the pressure of the stored helium, allowing you to put more in the tank, but it's not cold enough to liquefy.

One possible failure mode is something preventing the Helium from cooling down, in which case it could overpressure the tank and it blows up. That could be a problem with getting the LOX into the tank, bubbles around the He tank, etc. Or it could be something simple like a flow valve fracturing. They have all the telemetry data, so I can only speculate.

Comment Re: Huh. (Score 2, Interesting) 79

Nah, that's too obvious. A sniper rifle fired by a CCAFS security person with money troubles is less conspicuous. Security staff have a reason to be on the base, even patrolling the launch pad area. On the other hand, there's a whole lot of nobody else around the launch pads, for safety reasons. So all he has to do is find a good spot, pop off a shot, then drive over to the launch pad like a concerned security guy would do when something goes boom.

Why money troubles? The people with a motive, like United Launch Alliance, could pay off someone for a whole lot less than what they stand to lose by SpaceX eating their business. Even a six month delay and a few customers moving payloads to "spread their risks" is worth a billion or so in revenue.

Comment Re:40 years in a box (Score 2) 289

Luxembourg is a forward-looking country. They invested in communications satellites in the 1980's, and now operate the largest commercial constellation of satellites. Recently, they started investing in asteroid mining, and they are also a SpaceX customer. I don't think Musk is so dumb he didn't know a big rocket could go other places than Mars. I think what's happened is he has a customer who is *interested* in going other places than Mars. And he needs lots of commercial customers to help pay for the big rocket he wants to build.

Comment Re:Wacky? Maybe, but at least he's got vision. (Score 1) 289

Look, he's developing the Raptor engine ( ) Assuming he uses 9 of them in the first stage, like the Falcon 9 has, that's 20.7 MN of liftoff thrust. Liquid rocket T/W on liftoff is typicall 1.3:1, which gives 2100 tons liftoff mass. A good chemical rocket typically has 4% payload mass, so 84 tons payload to LEO. All of that follows directly from the engine size and how many you use.

If you can put that much mass into Low Earth Orbit, you can get variable amounts of payload to different higher orbits. This is obvious to anyone who has much experience with rocketry. User handbooks for different launch vehicles have graphs showing the payload as a function of mission velocity, and that velocity is set by where you are going and the trajectory you follow. Perhaps Musk is slow to realize this, because of his focus on colonizing Mars, but it's no surprise to people in the industry like me, and probably to a lot of the people working at SpaceX either. I can imagine the staff meeting at SpaceX:

Musk: You mean this giant rocket we're building can go other places than Mars?
Staff in unison: No shit, Sherlock.

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APL is a write-only language. I can write programs in APL, but I can't read any of them. -- Roy Keir