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Comment Re: Don't confuse SpaceX and Blue Origin. (Score 1) 163

The energy required to lift a spacecraft to 100 km altitude is about hg=100 km*10 m/ s^2=10^6 J/kg. for orbital velocity you need an additional 1/2 (7 km/s)^2 = 26*10^6 J/kg. So maybe the SpaceX problem was 27 times harder. Except we should be multiplying by the mass of the payload. What was the payload for the Blue Origin demo flight?

Comment Re:Lunatic Unicorn Farts (Score 1) 267

I agree 97%. Nuclear fission is the right solution for grid electricity at least for the next 50 years. But there is more to the energy story than grid electricity. Molten salt reactors can also provide a lot of the necessary process heat (unlike the water cooled reactors which are restricted to lower temperatures). (It might be easier to fund development of those reactors if it isn't necessary to also buy the turbines and generators for producing electricity. At least that's how Terrestrial Energy proposes to attack the problem.) I believe synfuels can be produced more efficiently using process heat rather than electricity. Once that infrastructure is in place, it might be better to produce more synfuels instead of replacing our inventory of cars and trucks with electric vehicles and adding enough grid capacity to keep them charged.

Small Modular Reactors have advantages even if they don't get sold to every village. If they're small enough to build on an assembly line and ship where needed, you can get big improvements in cost and reliability. A utility doesn't have to pay for a 6GW power plant all at once, but can instead install a smaller unit, and let it generate revenue while further units are under construction. It can also adjust the construction rate if the demand growth doesn't match predictions. (That said, I would still like to see most military bases powered and heated by their own nuclear reactors.)

Comment Re:Off-Earth habitation (Score 1) 684

No, the rotating space station should be much cheaper. Note that it does not have to be a big doughnut as in "2001" - we could just separate the nuclear reactor from the manned part, connect them with a cable, and set them to rotating. Any deep space transit craft should be set up the same way (except there you'll have nice heavy fuel tanks for the counterweight), so the astronauts arrive healthy.

Comment Re:Worse than the space station? No. (Score 1) 684

You may find it convenient to get part of your power from solar panels, but it does entail a big capital investment. The batteries or grid-connected power for night time power would be another big capital investment. Currently many of the power companies are using gas-fired generators to minimize that investment (and to enable them to ramp up quickly when solar or wind power suddenly drops). You suggest backing up the solar with nuclear, and that can work. However, the current generation of nuclear power requires an even bigger investment in capital. Few owners want to let any significant amount of its capacity go unused. I think the ideal approach is to (1) invest today in enough research that the next generation of nuclear power (e.g., LFTR) will be much less expensive, (2) also invest in battery technology for grid-connected storage, (3) put a price on carbon dioxide emissions, (4) let the price of electricity float during the day, and (5) let the market decide what combination of solar panels, extra nuclear capacity, and grid-connected storage makes the most sense.

The real fantasy is that the 600M people in India without electricity could rely on solar power. They do not have the land or the money to invest that way.

Comment Re:Not so much outdoors (Score 1) 60

"Time spent with eyes focused on close objects (such as reading or computering) = myopia." RIGHT.

How it's supposed to work: Child is born farsighted -> much time spent outside looking at distant objects, but focusing muscles in the eye can still bring those objects into focus -> muscles get tired -> brain concludes "I'm still farsighted" -> eyes grow -> eyes can relax most of the time - i.e. while looking at distant objects = perfect vision.

How it's working in industrialized countries: Much time spent with eyes focused on close objects -> focusing muscles in the eyes get tired -> brain concludes "I'm still farsighted" -> eyes grow -> eyes can relax most of the time - i.e. while looking at CLOSE objects = myopia. If you get glasses that "correct" for myopia, and wear them while reading, then you go around the loop again and the myopia gets worse. That's what happened to me - I need a correction of -4 diopters or so.

Lesson #1: if you have myopia, so you need glasses for distant work, then take those glasses off if you're doing a lot of close work. Or else get bifocals.

Lesson #2: To prevent myopia in the first place, get kids to wear READING GLASSES (+1.5 or +2 diopters) while doing a lot of close work. That way their eyes are focused at infinity (therefore relaxed) even though they're doing close work. My daughter was willing to do this, because it was only while she was at home working on the computer or reading, and not when she was out with other kids. She graduated as an engineer, and still doesn't need glasses.

Comment prevention...cure...treatment...diagnosis (Score 2) 204 decreasing utility far as the patient is concerned. Unfortunately, as far as the medical-industrial complex is concerned, "expensive treatment for the duration of the patent" is the primary goal, with cures and vaccinations to be avoided if possible. We'll be stuck with that as long as medical research is paid for out of drug company profits. If, on the other hand, we had a "single payer" health care system, the federal government would have an incentive to fund research into cures and prevention.

Comment earthquakes are not necessarily bad (Score 1) 264

The notion that pumping water underground causes earthquakes has been around quite a while. What bothers me is the knee-jerk reaction that this is necessarily a bad thing. The choice is not between an earthquake or no earthquake. Rather, it's between an earthquake now, or a bigger earthquake later. Remember that the energy of the earthquake comes from strain in the rocks, which in general is continually building (due to shifting tectonic plates, moving magma, etc.). If it's not released now, then the strain will just build until it's released later - and you get a bigger earthquake.

I will grant there might be a few cases where I'd rather reduce the chances of an earthquake in the short term, even if it made the eventual earthquake worse (say, if I just discovered a weakness in a dam, and will be spending the next two years madly strengthening it). But in general I would rather have more, smaller earthquakes.

Comment Re:Chemical battery efficiency is quite poor (Score 1) 347

Li-ion batteries in laptops and cell phones don't last long, but for automotive use they're using a different electrode (lithium manganese oxide instead of lithium cobalt oxide - see which they think will last a lot longer. I'd like to know when I can get the longer-lasting kind for my laptop. Or would they rather design in a short product life?

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