Well, with fusion reactions you always get less gain as you go up the table. Iron is where the gain becomes less than one. Beyond that, fission gives you more gain than fusion.
HE-HE will not. In fact, it only gives off alpha (electrons),
For one, electrons are beta, not alpha. Alpha's are helium nuclei, so if He-He really gave off alpha, you'd be right back where you started.
And yes, it is possible to get He to fuse. Routinely happens in supernovas and even novas, and presumably if you slam two high energy beams of alphas together. The thing is, as you go up the table you get less gain on the amount of energy you put in.
Whatever they hit, it becomes radioactive and more fragile.
An exaggeration. Hydrogen atoms, for example, merely become deuterium atoms, which are not radioactive.
Which is why neutron shielding tends to be made of things like lightweight polymers that contain lots of hydrogen atoms. (In the early days before modern plastics, they used paraffin wax.)
There are other materials that can happily absorb a neutron and go from one stable isotope to another.
However, as a geek, I know that the Dark Ages were as much caused by the change in the fuel economy from wood to coal as the retreat of the Roman Empire.
Or in other words, "as a geek, my knowledge of history is really skewed".
The Dark Ages were hundreds of years before the switch to coal. Coal mining started around the time the dark ages were ending (circa the 11th century), and the fuel economy didn't switch wholesale until hundreds of years after that.
I wouldn't necessarily want a fusion reactor in my car, but I'd like to tell my friends that my car is nuclear powered.
Good news! Your car is nuclear powered.
That fossil fuel you put in the tank, the stuff made from long-dead vegetation, is just a very long term storage mechanism for the sunshine that made the plants grow. And that sunshine comes from -- ta da! -- nuclear fusion.
(Indeed, there are only two forms of energy in use that are not derived (ultimately) from sunshine: tidal (ultimately gravitational energy), and nuclear fission (which is storing the energy of the supernova that created those heavy elements). Geothermal is arguably a third form but it too stems from radioactive decay of elements formed in the supernova.)
I think you're using a different definition of efficiency, where "100%" is defined as converting all the mass of the weapon to energy.
In which case your figures are way high. Fission bombs only convert about 0.001% of their mass to energy, early fusion bombs about 0.007%. The latter figure may be higher for modern weapons, but no where near 20%, or even 2%. I might believe 0.02%.
You're right. Firefly is not Sci-fi. It is SF. It's not space opera, either.
If you like skiffy and space opera, but not SF (eg, you don't read any of the magazines, or science fiction books that aren't TV/movie tie-ins), you probably won't like Firefly.
(There's a great scene in "Objects in Space" where they're discussing River's possible psychic abilities. Wash says something like "I don't believe that science fiction stuff". Zoe gives him a look and says "You're living on a space ship". Wash looks at her, "so?")
To me, the holodeck episodes in ST were lazy writers' mental masturbation, barely a step up from "and it was all a dream" story endings. And Data is a toaster.
Didn't get past the first two episodes, did you? Try the third and fourth discs. Or even the third episode (on the discs, not by air date).
Oh, and you probably didn't notice that little motor or turbo spool up whine as they cock one of those "6 shooters". Not that it matters -- slug throwers can be manufactured and maintained with the low tech infrastructure you'll find on a frontier planet, and they'll kill you just as dead as the laser pistols more prevalent on the core planets. (Inara has one too, come to think of it.)
At least they don't have Wesley saving the day by reversing the graviton flux polarity on the plasma conduits every other episode.
See my reply to your parent message. At least half the shows are straight SF, with several of the others more SF than western.
Well, at least what passes for SF on TV. If you're a purist (in which case you won't like almost any self-proclaimed SF TV series), then I might limit it to "Objects in Space", "Bushwhacked", and "The Message". Probably "Trash", too; that's mostly a "heist" story but the SF elements (eg the trash pickup system from the flying island) are essential to the story line.
As for self-described geeks raving about the show, that's as much -- or more -- about the intelligent writing (plot, setting, dialog, characterization) as about technogadgetry. The days of SF being "astounding tales of super science" without regard to good writing died in the early 1940s.
Cows, horses, and train robberies aside, it ain't a western.
Was "Objects In Space" a western? "Trash"? "Ariel"? "The Message"? "Shindig"? "War Stories"? "Out of Gas"?
Yeah, several of the frontier planets (moons?) they've set down on have a decided "old west" flavor, but if you look at the chronology the series was getting away from that after the first couple of episodes.
Not that I mind the "western" flavoring, although I've never been a big fan of the straight western genre. If you prefer straight SF, try some of the above named episodes.
No, only smaller solid boosters are made from composites. Especially 20+ years ago. Prior to the Shuttle SRBs, the biggest solid boosters were the ones used for the Titan 34C and follow-ons, which were both smaller diameter and shorter. Even those were made up from multiple welded segments.
Building the tube is only part of the problem. Casting the propellant -- and ensuring no voids or cracks that could cause sudden pressure surges due to increased burn area -- is also problematic.
(And the star shaped cross section on the core gives a high surface area = high thrust at first, with the thrust tapering off as the core rounds out as it burns. Just the thrust profile you want to limit maximum acceleration as the total mass is reduced as fuel is consumed.)
Mind, going to SRBs at all on a manned vehicle was bloody stupid, and NASA by its very nature has to pork-barrel.
The winning contractor (Morton Thiokol) had to fabricate the boosters in sections so they could be shipped by barge,
By rail, actually. If all the shipping had been by barge they could have welded the joints. (No way could they have been fabricated in one piece -- the existing segments have several welded sections between each O-ring-requiring "field joint".) The SRB diameter was determined by the narrowest/lowest tunnel or underpass that the train would have to pass through.
When the they designed the lunar lander, they had to have something that would work 100% to get off the moon, and they used... a solid fuel rocket.
Not.
They used hypergolic liquid fuels (nitrogen tetroxide and unsymmetrical dimethyl hydrazine, if I remember right). Open the valves, the liquids mix, and vooom!. Pressure fed, so no finicky pumps to worry about. The problem with solids is, yeah, you light it and it goes.. but it doesn't stop until it's good and ready (or the casing bursts). And you better hope the igniter works.
Why we have this complex, unbelieveably expensive shuttle, I will never know.
Because the NASA bureaucrats responsible want to make sure that some part of it is manufactured in every congressional district out there -- helps encourage the congresscritters to approve the NASA budget to support jobs at home. Market economics (and common sense) doesn't apply to government projects.
If anyone cares, the 1986 Byte review of the AT&T Unix PC is also available.
Not quite the historic impact of the Mac, but interesting in its own right. It was certainly the first and may still be the only "Unix PC" ever offered (discounting various Linux offerings and the current MacOS X as "not really UNIX®").
The role of commercial TV is to deliver to the advertisers an audience too indiscriminating to not buy their products. Can't do that with intelligent shows.
No, I got the point, I just didn't think it worth remarking on. It might happen, but the actual lawsuit will be over copyright infringment, just like all the suits that don't care about the competition angle.
What would be interesting (but unlikely) is to see the CEO of TW hauled off in handcuffs for running an information service that provides (thanks to some subscriber) kiddie porn. If they're not a common carrier they're an active participant.
I need to sell the New York Times some stories about Norway's WMD program..
Hey, don't laugh. Norway has been making heavy-water since the 1930s. Useful for reactors that produce plutonium, or for making lithium deuteride for fusion weapons. I think you're on to something there...
(For the humor-impaired, I'm joking. Norway puts inspection requirements on its D2O exports.)
Slashdot Mirror
The morning after the Norse gods' orgy, Thor wakes up, looks around, spies a female.
"I'm Thor!" he announces, thumping his chest.
"You're Thor?" she says, "I'm tho thor I can hardly pith."
Two words:
"thorium", and "breeders"
Ah. I haven't played Doom3. I tend to ignore that whole genre as being "too silly".
;-)
I did wonder what on Earth that had to do with Mars.
is moving to Toronto really "off shoring". I think last I checked Canada was still on the same continent as the US ;)
;-)
Well yeah, but it (Toronto) is on the opposite shore of Lake Ontario.
Yeah, that's because they hire on at HP (India) for a month or two, gain some experience, then go work for IBM (India) at a slightly higher salary.
I'm joking (in that I don't know this to be true), but I have heard that turnover is pretty high there.
Well, with fusion reactions you always get less gain as you go up the table. Iron is where the gain becomes less than one. Beyond that, fission gives you more gain than fusion.
HE-HE will not. In fact, it only gives off alpha (electrons),
For one, electrons are beta, not alpha. Alpha's are helium nuclei, so if He-He really gave off alpha, you'd be right back where you started.
And yes, it is possible to get He to fuse. Routinely happens in supernovas and even novas, and presumably if you slam two high energy beams of alphas together. The thing is, as you go up the table you get less gain on the amount of energy you put in.
Whatever they hit, it becomes radioactive and more fragile.
An exaggeration. Hydrogen atoms, for example, merely become deuterium atoms, which are not radioactive.
Which is why neutron shielding tends to be made of things like lightweight polymers that contain lots of hydrogen atoms. (In the early days before modern plastics, they used paraffin wax.)
There are other materials that can happily absorb a neutron and go from one stable isotope to another.
However, as a geek, I know that the Dark Ages were as much caused by the change in the fuel economy from wood to coal as the retreat of the Roman Empire.
Or in other words, "as a geek, my knowledge of history is really skewed".
The Dark Ages were hundreds of years before the switch to coal. Coal mining started around the time the dark ages were ending (circa the 11th century), and the fuel economy didn't switch wholesale until hundreds of years after that.
I wouldn't necessarily want a fusion reactor in my car, but I'd like to tell my friends that my car is nuclear powered.
Good news! Your car is nuclear powered.
That fossil fuel you put in the tank, the stuff made from long-dead vegetation, is just a very long term storage mechanism for the sunshine that made the plants grow. And that sunshine comes from -- ta da! -- nuclear fusion.
(Indeed, there are only two forms of energy in use that are not derived (ultimately) from sunshine: tidal (ultimately gravitational energy), and nuclear fission (which is storing the energy of the supernova that created those heavy elements). Geothermal is arguably a third form but it too stems from radioactive decay of elements formed in the supernova.)
I think you're using a different definition of efficiency, where "100%" is defined as converting all the mass of the weapon to energy.
In which case your figures are way high. Fission bombs only convert about 0.001% of their mass to energy, early fusion bombs about 0.007%. The latter figure may be higher for modern weapons, but no where near 20%, or even 2%. I might believe 0.02%.
You're right. Firefly is not Sci-fi. It is SF. It's not space opera, either.
If you like skiffy and space opera, but not SF (eg, you don't read any of the magazines, or science fiction books that aren't TV/movie tie-ins), you probably won't like Firefly.
(There's a great scene in "Objects in Space" where they're discussing River's possible psychic abilities. Wash says something like "I don't believe that science fiction stuff". Zoe gives him a look and says "You're living on a space ship". Wash looks at her, "so?")
To me, the holodeck episodes in ST were lazy writers' mental masturbation, barely a step up from "and it was all a dream" story endings. And Data is a toaster.
Didn't get past the first two episodes, did you? Try the third and fourth discs. Or even the third episode (on the discs, not by air date).
Oh, and you probably didn't notice that little motor or turbo spool up whine as they cock one of those "6 shooters". Not that it matters -- slug throwers can be manufactured and maintained with the low tech infrastructure you'll find on a frontier planet, and they'll kill you just as dead as the laser pistols more prevalent on the core planets. (Inara has one too, come to think of it.)
At least they don't have Wesley saving the day by reversing the graviton flux polarity on the plasma conduits every other episode.
I watched 'Our Mrs Reynolds' three times, you know why
Come on, fess up. The third time it was just the scene with Saffron in Mal's cabin.
(This is where we lament the much under-used* "angle" feature on DVDs.)
*Well, on mainstream discs, anyway.
See my reply to your parent message. At least half the shows are straight SF, with several of the others more SF than western.
Well, at least what passes for SF on TV. If you're a purist (in which case you won't like almost any self-proclaimed SF TV series), then I might limit it to "Objects in Space", "Bushwhacked", and "The Message". Probably "Trash", too; that's mostly a "heist" story but the SF elements (eg the trash pickup system from the flying island) are essential to the story line.
As for self-described geeks raving about the show, that's as much -- or more -- about the intelligent writing (plot, setting, dialog, characterization) as about technogadgetry. The days of SF being "astounding tales of super science" without regard to good writing died in the early 1940s.
Cows, horses, and train robberies aside, it ain't a western.
Was "Objects In Space" a western? "Trash"? "Ariel"? "The Message"? "Shindig"? "War Stories"? "Out of Gas"?
Yeah, several of the frontier planets (moons?) they've set down on have a decided "old west" flavor, but if you look at the chronology the series was getting away from that after the first couple of episodes.
Not that I mind the "western" flavoring, although I've never been a big fan of the straight western genre. If you prefer straight SF, try some of the above named episodes.
No, only smaller solid boosters are made from composites. Especially 20+ years ago. Prior to the Shuttle SRBs, the biggest solid boosters were the ones used for the Titan 34C and follow-ons, which were both smaller diameter and shorter. Even those were made up from multiple welded segments.
Building the tube is only part of the problem. Casting the propellant -- and ensuring no voids or cracks that could cause sudden pressure surges due to increased burn area -- is also problematic.
(And the star shaped cross section on the core gives a high surface area = high thrust at first, with the thrust tapering off as the core rounds out as it burns. Just the thrust profile you want to limit maximum acceleration as the total mass is reduced as fuel is consumed.)
Mind, going to SRBs at all on a manned vehicle was bloody stupid, and NASA by its very nature has to pork-barrel.
The winning contractor (Morton Thiokol) had to fabricate the boosters in sections so they could be shipped by barge,
By rail, actually. If all the shipping had been by barge they could have welded the joints. (No way could they have been fabricated in one piece -- the existing segments have several welded sections between each O-ring-requiring "field joint".) The SRB diameter was determined by the narrowest/lowest tunnel or underpass that the train would have to pass through.
When the they designed the lunar lander, they had to have something that would work 100% to get off the moon, and they used... a solid fuel rocket.
.. but it doesn't stop until it's good and ready (or the casing bursts). And you better hope the igniter works.
Not.
They used hypergolic liquid fuels (nitrogen tetroxide and unsymmetrical dimethyl hydrazine, if I remember right). Open the valves, the liquids mix, and vooom!. Pressure fed, so no finicky pumps to worry about. The problem with solids is, yeah, you light it and it goes
Why we have this complex, unbelieveably expensive shuttle, I will never know.
Because the NASA bureaucrats responsible want to make sure that some part of it is manufactured in every congressional district out there -- helps encourage the congresscritters to approve the NASA budget to support jobs at home. Market economics (and common sense) doesn't apply to government projects.
If anyone cares, the 1986 Byte review of the AT&T Unix PC is also available.
Not quite the historic impact of the Mac, but interesting in its own right. It was certainly the first and may still be the only "Unix PC" ever offered (discounting various Linux offerings and the current MacOS X as "not really UNIX®").
Of course.
The role of commercial TV is to deliver to the advertisers an audience too indiscriminating to not buy their products. Can't do that with intelligent shows.
This surprises you?
No, I got the point, I just didn't think it worth remarking on. It might happen, but the actual lawsuit will be over copyright infringment, just like all the suits that don't care about the competition angle.
What would be interesting (but unlikely) is to see the CEO of TW hauled off in handcuffs for running an information service that provides (thanks to some subscriber) kiddie porn. If they're not a common carrier they're an active participant.
Oh, I'm sure it will happen. After all, who has the bigger pockets, Time-Warner (or Comcast, or whomever) or Joe User?
Ah, would this be the same Office XML format(s) that Microsoft has been filing patents for in various patent offices around the world?
"Sure it's open, anyone can use it. Oh, there is the matter of patent royalties..."
I need to sell the New York Times some stories about Norway's WMD program..
Hey, don't laugh. Norway has been making heavy-water since the 1930s. Useful for reactors that produce plutonium, or for making lithium deuteride for fusion weapons. I think you're on to something there...
(For the humor-impaired, I'm joking. Norway puts inspection requirements on its D2O exports.)