I like your airplane example- early attempts at flight did attempt to emulate the motions of birds' (and other flying animals') wings, and they were all unsuccessful. Fixed wing aircraft (a design quite unlike how birds fly) turned out to be what would actually work for man, unlike the natural example.
No one is saying that you can't do chemistry to make small molecules. But the existance of a biological enzymes does not mean that the very different process of putting molecules together with "molecular machinery" will work. (or "Smalley arms" or whatever the current buzzword for a mechanical method is)
The biological case works because all the other interactions not at the site are favorable, often attracting the two molecules with hydrogen bonding and electrostatic interactions- enzymes are therefore very specific, and work to do one reaction(or, occasionally, a few very similar ones.) Drexler thinks he can ignore all the other interactions to make an unreactive assembler work in a general case, but Smalley has shown that these other interactions are too large to ignore.
There are a lot of things that can act as catalysts, but nearly always it involves a chemical reaction with the catalyst, so that a reaction like
A+B--- / ---> AB
where A and B don't react (or react too slowly) with each other becomes something like:
A+B+C ---> AC+B---> AB+C
where both of the above reactions are faster and C ends up the same as the start. The net effect is A+B--> AB, even though that doesn't happen directly. C does undergo chemical reactions- as almost all catalysts do- it's just that the net amount of C is unchanged that makes us call it a catalyst instead of a reactant or product. I have gotten into the nitty gritty of designing catalysts and it indeed involves all of the factors you mention- but the chemistry at the site is generally most important and decided first, with the other factors also important but more easily adjustable.
Drexler has focused on one aspect of the problem and decided that it can do everything. When your only tool is a hammer all problems look like nails.
The whole "fat/sticker" fingers thing is a gross over generalization of how atoms behave. Sure, some are very "sticky" (e.g. charged, or radicals, or just highly reactive due to unfilled orbitals), but it is also possible to design very non-reactive surfaces. Likewise, some structures are very "floppy" and therefore "fat" when you try to position them, but others are far stiffer (or actively track) and can be used for fine positioning.
Smalley demonstrated that this is false. Perhaps you can avoid having highly reactive groups near your active site, but hydrogen bonding, Van der Walls forces, dipole-dipole interactions, etc. and other 'weak' interactions simply cannot be ignored on this scale. There exists no atom with properties like this for 'fine positioning'. All atoms near other atoms interact... that's fundamental.
It's true that proximity and steric effects can allow reactions to happen- but that's a far cry from the molecular machinery that Drexler claims is possible.
Well, the process must be one where enthalpic(potential energy held in chemical bonds, etc.) gains exceed entropic losses (and putting two molecules together is pretty much guarenteed to be entropically unfavorable.) The reactants have to be that much more enthalpically unstable than the products are for the reaction to proceed. This is true for 'normal' chemistry, and will also be true for nanomachine chemistry.
This is doable in the abstract, we know how to make higher energy reactants as building blocks, but it does make selection of reactants and products for hypothetical nanomachines trickier.
If I had to bet, I'd say that Smalley was right. Drexler adamantly refuses to address the issue. Smalley points out a fundamental flaw in all mechanical methods, which Drexler then says was about only a subset of mechanical methods.. those which he's not using. When Smalley points out his claim was general, Drexler pretends the original arguement applied only to the subset and is therefore a strawman.
If you strip away the fancy words (and shamelessly simplify), this becomes much more obvious:
Drexler: We can build structures with atoms exactly where we want them, within reasonable limits.
Smalley: Your fingers are too big and sticky. Any possible apparatus you can build will inherently have fingers too big and sticky. It won't work.
Drexler: We wouldn't use "fingers," we'd use a apparatus of molecules designed for the purpose that are not named "fingers".
Smalley: You're just renaming your apparatus to avoid the issue. Any mechanical apparatus will have these problems regardless of what you name it.
Drexler: I didn't call my apparatus "fingers" and your original arguement mentioned "fingers", so that is a strawman argument. Besides, living cells do something sort of like this all the time.
Smalley: Ah, but that's chemical, not mechanical, and reactions are very specific. The mechanical part of your proposal is where the problem is- you can't just shove things together and expect to get what you want.
And so forth...
The argument is about putting molecules together mechanically, as Drexler proposes. Drexler repeatedly refuses to address this point. I agree with Smalley that mechanical positioning, as Drexler advocates, is an inherently very limited method.
When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
His Third Law is more well known, "Any sufficiently advanced technology is indistinguishable from magic."
However, there's also Asimov's Corollary to Clarke's First Law (1977):
When, however, the lay public rallies round an idea that is denounced by distinguished but elderly scientists and supports that idea with great fervor and emotion -- the distinguished but elderly scientists are then, after all, probably right.
The man has a Nobel Prize and you're worried about what school he got his PhD from? Yeesh. And Feynman certainly didn't give Drexler a 'Drexler is always right, even 15 years after my death' card. Why the focus on intellectual dicksizing?
No, chemical reactions don't happen like that. Molecules do not randomly appear in product positions, nor do they follow nice straight lines to form products. They follow complicated, n-dimentional reaction coordinates involving deformations of both product and reactant. Drexler mumbles something about mechanical arms and ignores this point. Using a different name for something that is functionally identical to a "Smalley Arm" does not mean that you can cavalierly ignore all the problems which have been shown to exist for a "Smalley Arm".
In what way was Feynman less responsible than Drexler?
Unlike Drexler, Feynman typically responded to valid criticism of his work. Drexler ignores a glaring problem which was pointed out and instead rehashes a tired summary of a method which has just been shown to be flawed. That's real scentific irresponsibility, and lip service to the topic of avoiding possible negative uses of the science will not change that.
After the first person does this, the companies will have to come up with a new, much improved licensing system:
Instead of selling you an actual license, you'll get a license to make a license to make a Ferrari. Problem solved!
Re:Decreasing air pressure...
on
Eating in Space
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· Score: 1
Using your numbers but converting to calories instead of Calories, just above two hours.
Re:Decreasing air pressure...
on
Eating in Space
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· Score: 1
Er, reverse those comparisons... 4.18 Joules is a calorie; 4180 Joules are in a Calorie. The citation has it correct.
Re:Decreasing air pressure...
on
Eating in Space
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· Score: 1
A Joule is about 4.18 calories (the scientific measurement.) It is also about 4180 Calories (the food serving measurement.) Why are there two units with the same name which are three orders of maginitude off? I think nutritionists just like to make things confusing. Anyhow, you mixed the two up, so your estimate is a factor of a thousand larger than it would be without that error.
Re:Decreasing air pressure...
on
Eating in Space
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· Score: 1
In the shade, check out this tool. To use it, we need to make some big assumptions:
Turkey does not lose mass to the vacuum (even water).
Turkey is a 11 cm radius sphere of density 1.0 (about the density of water) which puts it at just over 12 pounds.
Molar mass is 25: Water has a molar mass of 18, and in humans is about 65% of the body. use this as a guess as to the Turkey's water content, neglecting all other molecules the molar mass would be 18/.65=27.6. Subtract a fudge factor for other molecules (which are mostly much bigger, but there are some more molecules in there) and call the total molar mass 25. (smaller numbers here mean a larger total number of molecules estimate.)
Temperature of a cooked turkey should be about 355 K, as any cook who uses a Kelvin thermometer will tell you.
The emissivity is.5. This wild-assed guess is made because cooked turkey should be brown, but not black (which would be emissivity 1)
In addition, this computation in general assumes that the ambient temperature can be neglected, conduction and convection can be neglected (probably reasonable assumptions in earth orbit) and that the temperature of the turkey remains uniform throughout- this last is most problematic and is expected to result in underestimation of cooling time required.
Anyhow, this massive approximation results in:
After an hour (3600 seconds) our turkey is near room temperature (295 K)
After an hour and a half or so, our turkey reaches the freezing point of water and stops there for a while- it takes a lot of energy for water go from liquid to solid. (Our first assumption that the water did not escape as a gas implies some sort of airtight seal; water freezing near 273 K makes sense if the internal pressure is roughly 1 atmosphere)
The value of that content as a whole has gone down, it's just become concentrated in fewer existing copies.
The value to the producers is what will dictate the decisions of those content producers- who are definitely relevant to making DRM decisions about their new releases. Consumers can affect this value to the producers via buying habits- but we shouldn't lose sight of who's actually deciding what formats to offer.
If your only point was that particular collectable physical items can increase in value... well, that's true but irrelevant to the discussion.
It's not much more reassuring to think that there is no conspiracy at all- and the machines make random, unpredictable errors in the amount of 16,000 votes. For all we know, they did just that in precinct(s) with a population of 100,000 and no one caught it because it wasn't blatantly obvious.
I still don't find that to be an acceptable voting tabulation method, even given the large assumption that no one is guiding the 'errors'.
Brian: Hola! Um...me, me llamo es Brian. Ahh, uh, um lets see, uh, nosotros queremos ir con ustedes.
Mexican: Hey, that was pretty good! But actually when you said, "Me llamo es Brian," you don't need the "es." Just, "Me llamo Brian."
Brian{relieved}: Oh, you speak English!
Mexican: No, just that first speech and this one explaining it.
Brian{confused}: You...you're kidding right?
Mexican: Que?
(Evil genius toddler attempting to phone home)
Stewie: Hello, operator, hello? Oh that's right, you have to dial in the numbers these...hmmm, I should know this, oh yes, 867-5309, that's it! No wait, that's not right...DAMN YOU TOMMY TWOTONE! *sigh* Well, I guess there's only one way to find out... 111-1111, Lois?... DAMN! 111-1112, Lois?... DAMN! 111-1113, Lois?... DAMN! {commercial break}
No, it's much less than 1/6. The moon's surface gravity is about 1/6 of that of the earth, but that doesn't directly translate into escape velocity.
Earth's escape velocity is about 11km/sec, while the velocity required to go from the surface of the moon to the earth is only about 2.3km/sec. Energy is proportional to velocity squared, so it works out to take only about 1/21 of the energy. (leaving the Earth/moon system entirely from the surface of the moon is somewhat more expensive, but still only about 1/16 of the energy cost as that needed from the Earth's surface.)
That'd be the right sort of thing to do with a real global conspiracy. Accumulation of vast amounts of money and power is the sort of goal which can hold such a conspiracy together. Also crucial is the avoidance of making falsifiable statements, and vigorous defense of initially safe claims which centuries later turn out to be falsifiable and/or blatantly wrong.
Making up a falsifiable claim in a field where everyone is in competition for meager grant money is not a good way to start a conspiracy. This is particularly true when substantial publicity and prestige (as measured on physicists' scale of such) would be given to anyone blowing the whistle and demonstrating the errors of the claim.
Clearly, if you believe that physicists have substantial control over politics or broadcasting, their own country, or claim infallible knowledge of morality- you need to adjust your tin-foil hat.
If you're referring to that particular group of researchers, if you RTFA you can see that
Its discovery was recently confirmed by researchers at the Fermi National Accelerator Laboratory in Illinois, US
That's the beauty of actual science, other people can duplicate your results.
If you were suggesting a vast, global conspiracy of physicists has organized itself to fraudulently claim the existance of a particle which is of interest mostly only to them- then I think you need to adjust your tinfoil hat.
No, he'd just demand that pesky 'evidence' that snake oil peddlers worldwide have so much trouble coming up with. The nerve of him, to actually expect people making wild claims to substantiate them! It's ever so much easier to lie to people if you're never asked for, you know, evidence.
I'm quite in favor of debunking the likes of John "the biggest douchebag in the universe" Edward.
Slashdot Mirror
No one is saying that you can't do chemistry to make small molecules. But the existance of a biological enzymes does not mean that the very different process of putting molecules together with "molecular machinery" will work. (or "Smalley arms" or whatever the current buzzword for a mechanical method is)
The biological case works because all the other interactions not at the site are favorable, often attracting the two molecules with hydrogen bonding and electrostatic interactions- enzymes are therefore very specific, and work to do one reaction(or, occasionally, a few very similar ones.) Drexler thinks he can ignore all the other interactions to make an unreactive assembler work in a general case, but Smalley has shown that these other interactions are too large to ignore.
Drexler has focused on one aspect of the problem and decided that it can do everything. When your only tool is a hammer all problems look like nails.
Smalley demonstrated that this is false. Perhaps you can avoid having highly reactive groups near your active site, but hydrogen bonding, Van der Walls forces, dipole-dipole interactions, etc. and other 'weak' interactions simply cannot be ignored on this scale. There exists no atom with properties like this for 'fine positioning'. All atoms near other atoms interact... that's fundamental.It's true that proximity and steric effects can allow reactions to happen- but that's a far cry from the molecular machinery that Drexler claims is possible.
This is doable in the abstract, we know how to make higher energy reactants as building blocks, but it does make selection of reactants and products for hypothetical nanomachines trickier.
If you strip away the fancy words (and shamelessly simplify), this becomes much more obvious:
The argument is about putting molecules together mechanically, as Drexler proposes. Drexler repeatedly refuses to address this point. I agree with Smalley that mechanical positioning, as Drexler advocates, is an inherently very limited method.However, there's also Asimov's Corollary to Clarke's First Law (1977):
No, chemical reactions don't happen like that. Molecules do not randomly appear in product positions, nor do they follow nice straight lines to form products. They follow complicated, n-dimentional reaction coordinates involving deformations of both product and reactant. Drexler mumbles something about mechanical arms and ignores this point. Using a different name for something that is functionally identical to a "Smalley Arm" does not mean that you can cavalierly ignore all the problems which have been shown to exist for a "Smalley Arm".
Unlike Drexler, Feynman typically responded to valid criticism of his work. Drexler ignores a glaring problem which was pointed out and instead rehashes a tired summary of a method which has just been shown to be flawed. That's real scentific irresponsibility, and lip service to the topic of avoiding possible negative uses of the science will not change that.
Instead of selling you an actual license, you'll get a license to make a license to make a Ferrari. Problem solved!
Using your numbers but converting to calories instead of Calories, just above two hours.
Er, reverse those comparisons... 4.18 Joules is a calorie; 4180 Joules are in a Calorie. The citation has it correct.
A Joule is about 4.18 calories (the scientific measurement.) It is also about 4180 Calories (the food serving measurement.) Why are there two units with the same name which are three orders of maginitude off? I think nutritionists just like to make things confusing. Anyhow, you mixed the two up, so your estimate is a factor of a thousand larger than it would be without that error.
Turkey does not lose mass to the vacuum (even water). .5. This wild-assed guess is made because cooked turkey should be brown, but not black (which would be emissivity 1)
Turkey is a 11 cm radius sphere of density 1.0 (about the density of water) which puts it at just over 12 pounds.
Molar mass is 25: Water has a molar mass of 18, and in humans is about 65% of the body. use this as a guess as to the Turkey's water content, neglecting all other molecules the molar mass would be 18/.65=27.6. Subtract a fudge factor for other molecules (which are mostly much bigger, but there are some more molecules in there) and call the total molar mass 25. (smaller numbers here mean a larger total number of molecules estimate.)
Temperature of a cooked turkey should be about 355 K, as any cook who uses a Kelvin thermometer will tell you.
The emissivity is
In addition, this computation in general assumes that the ambient temperature can be neglected, conduction and convection can be neglected (probably reasonable assumptions in earth orbit) and that the temperature of the turkey remains uniform throughout- this last is most problematic and is expected to result in underestimation of cooling time required.
Anyhow, this massive approximation results in:
After an hour (3600 seconds) our turkey is near room temperature (295 K)
After an hour and a half or so, our turkey reaches the freezing point of water and stops there for a while- it takes a lot of energy for water go from liquid to solid. (Our first assumption that the water did not escape as a gas implies some sort of airtight seal; water freezing near 273 K makes sense if the internal pressure is roughly 1 atmosphere)
... but you're not allowed to have two copies of yourself running at the same time.
The value to the producers is what will dictate the decisions of those content producers- who are definitely relevant to making DRM decisions about their new releases. Consumers can affect this value to the producers via buying habits- but we shouldn't lose sight of who's actually deciding what formats to offer.
If your only point was that particular collectable physical items can increase in value... well, that's true but irrelevant to the discussion.
How many dollars worth of that orbital record were traded on eBay last year? THOUSANDS
How much money did the copyright holder of that orbital record get from trades on eBay? NOTHING
Which transaction do you think producers of new content will care about?
... and Number 48 - WETA Digital New Zealand/2003 BladeCenter Cluster Xeon 2.8 GHz, Gig-Ethernet / 1180 IBM Counted together they'd be Number 16.
I still don't find that to be an acceptable voting tabulation method, even given the large assumption that no one is guiding the 'errors'.
The velocity required does depend on air resistance, but it's a minor component.
Earth's escape velocity is about 11km/sec, while the velocity required to go from the surface of the moon to the earth is only about 2.3km/sec. Energy is proportional to velocity squared, so it works out to take only about 1/21 of the energy. (leaving the Earth/moon system entirely from the surface of the moon is somewhat more expensive, but still only about 1/16 of the energy cost as that needed from the Earth's surface.)
Shh! ixnay on iscussingday the oomsdayday achinesmay!
That'd be the right sort of thing to do with a real global conspiracy. Accumulation of vast amounts of money and power is the sort of goal which can hold such a conspiracy together. Also crucial is the avoidance of making falsifiable statements, and vigorous defense of initially safe claims which centuries later turn out to be falsifiable and/or blatantly wrong.
Making up a falsifiable claim in a field where everyone is in competition for meager grant money is not a good way to start a conspiracy. This is particularly true when substantial publicity and prestige (as measured on physicists' scale of such) would be given to anyone blowing the whistle and demonstrating the errors of the claim.
Clearly, if you believe that physicists have substantial control over politics or broadcasting, their own country, or claim infallible knowledge of morality- you need to adjust your tin-foil hat.
If you were suggesting a vast, global conspiracy of physicists has organized itself to fraudulently claim the existance of a particle which is of interest mostly only to them- then I think you need to adjust your tinfoil hat.
They recently got renewed for a second season. Also, the first season is scheduled to be released on DVD.
I'm quite in favor of debunking the likes of John "the biggest douchebag in the universe" Edward.