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Comment Re:That's exactly right (Score 1) 645

There is at least one other option that could scale up to take over not only the electrical load, but the whole fossil energy use of the human race.

It's power satellites. In the last couple of years we got the cost down to where they can undercut coal. This is a little out of date

  https://www.youtube.com/watch?...

The updated version of it put the beamed power plants in space.

Comment Meta comment (sort of) (Score 1) 129

"that people wouldn't sacrifice for their strongly held beliefs?"

In an evolutionary context, why would people ever have beliefs strong enough they would die for them? Genes that contribute to such behavior should quickly vanish from the gene pool! But they clearly don't. The key to this is that the suicide bombers (or in times gone by tribal warriors) were not the only ones to carry the "die for the cause" genes. Their children did and if you work out the math, it turns out that genes for getting so wrapped up in a cause as to kill and be killed for it did better under reoccurring situations of ecological crisis than doing nothing. The main reason is that the young women who carried copies of the genes of defeated warriors were taken into the victorious tribe as wives and the warrior's genes marched on. Statistically, the effect was about 37% better survival for genes to get hyped up to kill neighbors--under some circumstances. If you work the model the other way, where circumstances did not favor this behavior, the bias was 45% against. So both the tendency to sacrifice and judging when it was effective were strongly selected over the past few million years.

It's weird, but it looks like both wars and religions (i.e., strongly held beliefs) are closely related and both stem from young women being booty in past human environment of evolutionary adaptedness.

Comment Incidental contacts (Score 1) 99

I met Theremin about a year before he died. It was at Stanford, at an electronic music celebration for him. Just about all of the big names in electronic music were there. I went because my wife is a big fan of radical music.

Many years before that, my father had Theremin's spy gadget in his office in the Pentagon when he was chief of the scientific section of G2. It was dead simple, a resonate cavity with a diaphragm to pick up sound and modulate the outgoing signal.

Comment Re:Another example (Score 1) 728

That close.

The chronicler Robert the Monk put this into the mouth of Urban II: ... this land which you inhabit, shut in on all sides by the seas and surrounded by the mountain peaks, is too narrow for your large population; nor does it abound in wealth; and it furnishes scarcely food enough for its cultivators. Hence it is that you murder one another, that you wage war, and that frequently you perish by mutual wounds. Let therefore hatred depart from among you, let your quarrels end, let wars cease, and let all dissensions and controversies slumber. Enter upon the road to the Holy Sepulchre; wrest that land from the wicked race, and subject it to yourselves ... https://en.wikipedia.org/wiki/...

The problem is "large population" in relation to resources.

This is more or less standard human response far back into the stone age. You can always fix the problem of not enough resources by killing the neighbors, and humans are wired to respond that way when they sense things are getting tight.

Comment Re:Stupid article (Score 2) 226

Thanks for the compliment, AC. Perhaps I can do the same for you some day.

But let's analyze the case (if any) for power satellites. Electricity is a commodity; like all commodities you have to be competitive on price if you want a significant market share. That means you want to undercut electricity from coal at around 4 cents per kWh. If you set 75% of coal (3 cents per kWh) as the target, then you can back calculate how much you can spend for a levelized cost of electricity of three cents. For generally accepted life and discount rates that's about $2400/kW.

The mass for ground based solar power is around 500 kg/kW. This article, http://spacejournal.ohio.edu/i..., make a case for 6.5 kg/kW. Not having to support the collectors against gravity and wind, plus the near 24 hr sunlight cuts the mass to about 1%. Parts and the rectenna are currently estimated at around $1100/kW, leaving $1300/kW for transport cost. If we can't get the mass lower than 6.5 kg/kW, then the cost of lifting the power sats to GEO can't exceed $200/kg. At high flight rates, Reaction Engines thinks the cost will get to $120/kg. Electric propulsion from GEO to LEO powered by 25 GHz microwave beams in the hundreds of MW, looks like it will cost under $80/kg.

This article goes into the transport cost analysis. http://ieeexplore.ieee.org/xpl...

It was peer reviewed.

If you don't have easy library access, there is a preprint here:

https://drive.google.com/file/...

AC, if you would like to be anything but a blowhard, go through the documents and see if you can find fault with them.

Comment Re:When I see "could" in a headline ... (Score 2) 226

"and just for mach 5 seems a heavy cost'

As important, Skylon is at 26 km, which is to say 96% or so of the atmosphere is below it. Also, you *start* with 150 untouched tons of LOX and enough hydrogen to burn all of it in about a 6 to one ratio. The 15 ton payload is only 5% of the 300 ton takeoff mass, but the design goal is to fly it every other day or perhaps every day with a low turn around cost. The heat exchangers are not that big a piece of the mass budget.

To solve the carbon/energy problem in 7 or 8 years would take a construction rate of 400 five GW power sats a year. This takes around a million Skylon flights. That's a reasonable number considering that we get a million commercial aircraft flights in ten days.

It's not even close to reasonable if you try to do it with rockets.

Comment Re:Stupid article (Score 1) 226

" Exactly how low is a messy calculus problem"

I have spent a lot of time with the spreadsheets that define a Skylon atmospheric ascent. It's not complicated at all. What they do is fly up the constant pressure line. By the time they switch to rocket mode, they are above atmosphere thick enough to cause Qmax problems. Forces on the vehicle are really mild.

Comment Re:When I see "could" in a headline ... (Score 5, Interesting) 226

I have followed Skylon for several years now. The engines are very interesting, in fact, the whole design, including the wings is very cool. The wings take the gravity load off, which for something that takes that long to get to orbit is quite an advantage.

They actually get more energy out of the hydrogen than they would get from just burning it. The reason is that they run the compressor on the temperature difference between ram air and the LH2 flowing to the engines. Burning hydrogen gives about 50 kWh/kg, it takes 20 kWh/kg to make it into a liquid.

You might note that everyone who has been given the full inside information, including the USAF, agrees that it will work as a SSTO. If anyone wants to build power satellites, Skylon is the only thing that is likely to get the cost to where power satellites could undercut coal.

Comment Re:Scam (Score 1) 87

I have been signed up with Alcor for 30 years. Was on the board of directors for several years and have known the major people for a long time. They now pay reasonable wages to the people who work there, but that's relatively new. In the long run, cryonics may not work, but the people who are involved are as sincere as you can find, with most of them being members as well.

Personally, I signed up after reviewing and commenting on several drafts of Eric Drexler's first work, _Engines of Creation_. It just seemed like a rational thing to do. Still does. Drexler is signed up, and so is Marvin Minsky and Ray Kurzweil plus a bunch of major players in Silicon Valley. Hal Finney was frozen a year ago. If it works, there will be some interesting company on the far end.

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