dietz@SLB-DOLL.CSNET (Paul Dietz) (02/03/86)
An additional comment on using antimatter for rocket fuel: As Forward points out, the way to use antimatter as fuel is to use it to heat much larger quantities of normal matter. In large spaceships there's another way: use it as an igniter for small fusion explosions. It might be possible to implode DT fuel onto a tiny antimatter pellet and get (almost) completely clean fusion explosives. The fusion reaction products can be directed magnetically (as in Daedalus or Hyde's fusion rocket) and can be mixed with normal matter (water, say) to vary the exhaust velocity. I think the US energy consumption in 1940 was somewhat larger than you say. A modern US power plant produces (say) 2 gigawatts of electricity. If running that plant for a decade produces 1000 years worth of electricity at 1940 rates, the power production then was only 20 MW! This is clearly false; we already had some pretty big hydroelectric plants back then. Electricity consumption had been (until recently) growing at about 7% a year, so over 50 years would go up only about thirty times.
henry@utzoo.UUCP (Henry Spencer) (02/06/86)
> I think the US energy consumption in 1940 was somewhat larger than you > say... I'll have to check the numbers; I may have to revise the dates somewhat. My point remains intact, though, I think: our ability to control and manipulate energy has expanded enormously in the very recent past. > ...Electricity consumption had been (until recently) growing > at about 7% a year, so over 50 years would go up only about thirty times. Beware of backward extrapolation of numbers that are quite recent (on the scale I'm speaking of). Even if 7% is accurate 50 years back, it cannot be accurate much beyond that. We haven't had major power plants for more than 75 years or so. A factor of 30 in 50 years gives us 250MW in 1886! -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry
henry@utzoo.UUCP (Henry Spencer) (02/06/86)
> I think the US energy consumption in 1940 was somewhat larger than you > say... Sigh, it is blush-and-packpedal time... I badly misremembered a discussion that wasn't very quantitative to begin with. But as I mentioned earlier, this only changes the time scales a bit. US power generation in 1940 was, if I've got the conversion factors right (a pox on people who cite power generation in Btus!), about 19 GW. That is, about half the power output of a Saturn V, or about the same output as a Shuttle just after booster separation. The discussion I was originally thinking of was referring to 1920, not 1940. 1920 power generation was under 2 GW, although I don't have precise numbers back that far. Fifty years of that would be, by modern standards (a big modern power plant is circa 2 GW), a handful of power plants running for a handful of years. Not a lot for a serious purpose like starflight. Volume production of solar power satellites could quite easily give a major starflight project several hundred gigawatts to work with. Not cheap, but not utterly impractical either. Our neophyte civilization, which has had electrical technology for only about a century and serious science and technology of ANY kind for only a few centuries, is fairly close to having terawatt quantities of power available for big important projects. Arguing the impossibility of starflight on the basis of energy demands simply is not realistic, especially if we are discussing more advanced civilizations. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry
phil@sivax.UUCP (Phil Hunt) (02/20/86)
> > I think the US energy consumption in 1940 was somewhat larger than you > > say... > > Sigh, it is blush-and-packpedal time... I badly misremembered a discussion > that wasn't very quantitative to begin with. But as I mentioned earlier, kjhkjhkjhkjkjh