Is Molecular Nanotechnology "Scientific"?

by Eliezer Yudkowsky2 min read20th Aug 200760 comments


NanotechnologyPractice & Philosophy of Science
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Prerequisite / Read this first:  Scientific Evidence, Legal Evidence, Rational Evidence

Consider the statement "It is physically possible to construct diamondoid nanomachines which repair biological cells."  Some people will tell you that molecular nanotechnology is "pseudoscience" because it has not been verified by experiment - no one has ever seen a nanofactory, so how can believing in their possibility be scientific?

Drexler, I think, would reply that his extrapolations of diamondoid nanomachines are based on standard physics, which is to say, scientific generalizations. Therefore, if you say that nanomachines cannot work, you must be inventing new physics.  Or to put it more sharply:  If you say that a simulation of a molecular gear is inaccurate, if you claim that atoms thus configured would behave differently from depicted, then either you know a flaw in the simulation algorithm or you're inventing your own laws of physics.

My own sympathies, I confess, are with Drexler.  And not just because you could apply the same argument of "I've never seen it, therefore it can't happen" to my own field of Artificial Intelligence.

What about the Wright Brothers' attempt to build a non-biological heavier-than-air powered flying machine?  Was that "pseudoscience"?  No one had ever seen one before.  Wasn't "all flying machines crash" a generalization true over all previous observations?  Wouldn't it be scientific to extend this generalization to predict future experiments?

"Flying machines crash" is a qualitative, imprecise, verbal, surface-level generalization.  If you have a quantitative theory of aerodynamics which can calculate precisely how previous flying machines crashed, that same theory of aerodynamics would predict the Wright Flyer will fly (and how high, at what speed).  Deep quantitative generalizations take strict precedence over verbal surface generalizations.  Only deep laws possess the absolute universality and stability of physics.  Perhaps there are no new quarks under the Sun, but on higher levels of organization, new things happen all the time.

"No one has ever seen a non-biological nanomachine" is a verbalish surface-level generalization, which can hardly overrule the precise physical models used to simulate a molecular gear.

And yet... I still would not say that "It's possible to construct a nanofactory" is a scientific belief. This belief will not become scientific until someone actually constructs a nanofactory.  Just because something is the best extrapolation from present generalizations, doesn't make it true.  We have not done an atom-by-atom calculation for the synthesis and behavior of an entire nanofactory; the argument for nanofactories is based on qualitative, abstract reasoning.  Such reasoning, even from the best available current theories, sometimes goes wrong.  Not always, but sometimes.

The argument for "it's possible to construct a nanofactory" is based on the protected belief pool of science. But it does not, itself, meet the special strong standards required to ceremonially add a belief to the protected belief pool.

Yet if, on a whim, you decide to make a strong positive assertion that nanomachines are impossible, you are being irrational.  You are even being "unscientific".  An ungrounded whimsical assertion that tomorrow the Sun will not rise is "unscientific", because you have needlessly contradicted the best extrapolation from current scientific knowledge.

In the nanotechnology debate, we see once again the severe folly of thinking that everything which is not science is pseudoscience - as if Nature is prohibited from containing any truths except those already verified by surface observations of scientific experiments.  It is a fallacy of the excluded middle.

Of course you could try to criticize the feasibility of diamondoid nanotechnology from within the known laws of physics.  That could be argued.  It wouldn't have the just plain silly quality of "Nanotech is pseudoscience because no one's ever seen a nanotech."  Drexler used qualitative, abstract reasoning from known science; perhaps his argument has a hidden flaw according to known science.

For now, "diamondoid nanosystems are possible" is merely a best guess.  It is merely based on qualitative, abstract, approximate, potentially fallible reasoning from beliefs already in the protected belief pool of science.  Such a guess is not reliable enough itself to be added to the protected belief pool.  It is merely rational.


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I'm not impressed. The burden of proving it is science lies with the claimant. Drexler's site appeals to physical scaling laws, which to me makes it pseudoscientific speculation, or perhaps scientific speculation (with a little more convincing). Thorne and Braginsky's massive LIGO paper is an example of one that progresses to scientific status. It follows curves already established experimentally, and so is much more believable.

It's not scientific to say "all flying machines crash"; the scientist must (and is usually more than willing) to provide physical laws and scaling suggestions that back up the assertion. Peter Woit had a good point these last few days--real science is hard work.

Drexler seems to be proposing a microscopic cooperation of molecules which has no precedent. I have no reason to believe his scaling is obeyed into this regime until he can show "curves already established experimentally" that extrapolate to his complex motors. Real successes in nanotech have been incredible: nanotube resonators, SETs, self assembling DNA--very real, and (except for the third) very useful.

There's a standard picture in a bunch of experimental presentations. It's a log plot that has an up-right diagonal line. Towards it, a line burrows to the bottom-right, until it curves upward, "repelled" by the line. This represents a scaling law which is eventually foiled by backaction, the tradeoff response. New techniques approach the line from a different height/width, or pass below the line before being repelled by another limit.

Warning signs here are: PhD 30 years ago. Not associated with a university. Lack of published progress. Any fool can tell you the consequences of such a technology, which is what he wastes most keystrokes on.

Compare four situations: 1) Space flight in 1950, 2) Heavier than air flight in 1900, 3) Heavier than air flight in 1200, 4) Drexler nanotech today. Since the science was lacking - no one had ever built the relevant technology, we have to approach the question indirectly. The best questions to ask are:

A) Does something like X already exist? For 2) and 3) yes (birds flying using mechanical force), for 4) yes (enzymes doing similar roles). For 1), no.

B) If something like X exists, do we understand it? For 2), yes, for 4), partially, for the other, not at all.

C) Do current technologies exist that can approach X without new conceptual ideas? 1) yes, (rockets), 2) yes (lifting surfaces and models of gliders), 3) no, 4) probably (larger scale nano and medical manipulations of enzymes, proteins and retro-viruses).

So I'd put Drexler's nanotechnology in with flight in 1900 - the signs are that something like what he describes (certainly not exactly as he describes) will be coming in the forseable future.

(Unfortunately, I'd put AI down with flight in 1200 - intelligence exists, but we don't understand it to any real extent, and current technologies are not approaching proper intelligence; they need new conceptual ideas)

(Unfortunately, I'd put AI down with flight in 1200 - intelligence exists, but we don't understand it to any real extent, and current technologies are not approaching proper intelligence; they need new conceptual ideas)

Interesting. Do you still agree with Stuart_2007 on this?

Less. My personal opinion hasn't changed much, but I know other people disagree, so my total opinion has moved quite a bit.

Do you still agree with Stuart_2012 on this?

Nope! Part of my own research has made more optimistic about the possibilities of understanding and creating intelligence.

From Google:

Your search - "nanotech is pseudoscience" - did not match any documents.

Again, I'm looking for examples. I have heard many criticisms of nanotech - specific, science-based criticisms. You can't be talking about those. But I'm not aware of others. Google was no help. (That wasn't my only search term BTW, the other ones I tried also failed, that particular search term simply makes the point.)

What I want to guard against is tarring valid criticisms of nanotech and nanotech advocates by associating them with a made-up, straw man attack.

[+][anonymous]10y -6
[+][anonymous]10y -28

This example seems further support for my suggestion that talking about whether something is "scientific" mostly obscures the key issues.

Notice of censorship: I've begun deleting comments from Jonathan vos Post.

Eliezer Yudkowsky: may I ask why?

I'm making what I thought was a rational, polite summary, thread by thread, of my credentials in the field, since one of the issues was whether or not Bostrom was properly citing his sources.

Is there something about my behavior, my language, or my prolific publications that you feel is inappropriate?

Also, I have not made copies of those comments which I'd submitted. If you are to delete them, would you be so kind as to email the text to me, or back them up? I did take some time to read the threads in question, and to attempt a short comment that cited by background and bias, for the sake of genuine conversation.

Is Tom McCabe asserting that I have NOT done what is claimed in some part of my CV, or published something which is, in fact, a matter of record? I'd rather not be punished for being very productive.


Prof. Jonathan Vos Post

may I ask why?

Tom nailed it.

I have forwarded you your comments. Please don't post further comments to any more threads I've authored, or they will be deleted without archival.

"Is Tom McCabe asserting that I have NOT done what is claimed in some part of my CV, or published something which is, in fact, a matter of record?"

If you want something specific, a quick check of your website shows a picture of you (on your personal homepage!) holding two Hugo awards to your head. A quick Google reveals that you have never won the Hugo; this is dishonest at best.

This example seems further support for my suggestion that talking about whether something is "scientific" mostly obscures the key issues.

I disagree; I think this example clarifies the issue. The point is that statments about nanotechnology aren't scientific (not dervived from replicated experiments) but despite this, they aren't meaningless or empty of rigour.

Setting aside a special domain that is "scientific" clarifies those domains that aren't. And demonstates why answering the statement "nanotechnology will do such and such in a few years" with "show me a replicated experiment that proves what you've just said, or I won't believe it" is the wrong response. Though it would be the proper response for a scientific statment.

I have unpublished a comment by Tom McCabe on Jon Post, and I declare this conversation over - please, neither of you comment about each other anymore here at Overcoming Bias.

I've deleted both comments. Tom, please don't respond to comments that I'm going to delete anyway.

[Edit: Unpublished comments from JVP aliases "John Sokol" and "Dr. Philip V. Fellman".]

Again, I'm looking for examples. I have heard many criticisms of nanotech - specific, science-based criticisms. You can't be talking about those. But I'm not aware of others. Google was no help. (That wasn't my only search term BTW, the other ones I tried also failed, that particular search term simply makes the point.)

What I want to guard against is tarring valid criticisms of nanotech and nanotech advocates by associating them with a made-up, straw man attack.

Here's an example of what we have to deal with.

[-][anonymous]10y -3

I went to school at my family's Kingdom of Oyotunji Royal Academy where we learn about the ancient science of astral physics.

This is sad. Shoga, your teachers have taken advantage of you, and filled your head with nonsense and confusion. If you want to truly understand the world, you must start over with new teachers.

It's an improvement, but I suspect you still won't receive a particularly welcome reception. Most people on this website are fairly firmly grounded in mainstream Western science, so if you want to advocate something called "the ancient science of astral physics" then you'll need to display a significantly higher degree of intellectual clarity and scientific and philosophical literacy than is typical among commenters here, which is a fairly high standard. You'll have an uphill battle, is what I'm saying.

Also, I really recommend against using all-caps.

No, no, I appreciate when people with great insights type in all caps. Otherwise I might miss truly important ideas, like that the earth has a 4-corner simultaneous 4-day TIME CUBE.

I think we're probably too far behind you for us to have a useful exchange; you should probably look elsewhere for smarter people who are ready for your enlightenment.

[-][anonymous]10y -2

Well I think your not being honest. In a community of people who seem to think of themselves as highly intelligent and wants to keep it that way, then you would not send me to look for smarter people who are ready for enlightenment. I guess your assuming that I'm a flower child that spend all day speaking philosophies and not hard practical science, if so now that would be sad. I deal with the physics of astral physics. I deal with the calculable astral dimension of time and space. Of course in the village they throw shells as you may see on some voodoo type movie, but don't let Hollywood fool you, the binary numbers used in calculators and everywhere else came from practice of throwing cowrie shells that based on math's 10,000 year old binary calculations as proven by the count of binary notches in the 10,000 year old Shango bone. However, I do not throw shells, unlike everyone else in my village I have taught myself to convert and formulate astral physics on paper in calculable mathematics. For your information, when I say astral physics and when you say astral physics we are certainly talking about two different things. I don't deal with myths, philosophies, numerology, and speaking from an amateur point of view. I'm dealing with my divine interface and sacred technology. As I have said, your science in the real world of possibility is primitive. You should never put down what you don't understand.

Please go away.

[-][anonymous]10y -4

For you information the royal academy was challenged by America's public school system and lost

(Insert obvious cheap shot here.)

However, it seems apparent that you are claiming that I'm lieing or a nut case, but because you know nothing about me, you would agree that your claims are based in ignorance are they not?

Your original post is all the evidence needed to assign a high probability to the hypothesis that you are a nutcase.

[-][anonymous]10y -3

To be blunt, you sound like a crank. You misspell things frequently, allude to weird, pseudo-scientific sounding theories, imply that your enemies are trying to suppress you, claim you are much more intelligent than all the ignorant people who surround you, talk about how famous, successful work was secretly based on your theories, and so on. All of these things are generally associated with cranks.

I forget who this commonly used quote is taken from, but I find it useful when discussing potential future technologies with people. "If a celebrated scientist says something is possible he [unfortunately the quote does use only 'he'] is almost certainly right. If he says something is impossible, he is almost certainly wrong."

I, as a lowly college student, would hesitate to call almost anything impossible. Speaking with the benefit of reading lots of dead smart people saying how impossible things that are trivial to us now are, I feel comfortable saying that future technology will likely surprise a lot of us. How surprised we'll be, however, depends on how much we underestimate ourselves and how much we constrain our imaginations.

The quote is Clarke's first law:

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.

What is the relationship between saying that doing something is impossible and that understanding something is impossible?

Is saying that understanding something is impossible simply thinking that mysteriousness is a property of objective rather than subjective reality? In this case, it would be infinitely worse than simply saying that doing something is impossible, as it is a type error.

At the same time, the two seem related as they both may involve mistaking the limits of imagination for the limit of possibility.

Perhaps claims that understanding is impossible are sometimes from the first, more fundamental mistake, and sometimes from the latter. Alternatively, perhaps in practice all such claims draw from both errors.

Existing molecular nanomachines (proteins) tend to be extremely unreliable. They work, but only on average. Someone recently issued a challenge to prove that Quantum computers are thermodynamically impossible So I'm wondering if anyone has done serious work with statistical mechanics, trying to figure out if the kind of nanotechnology so enthusiastically proposed in "engines of creation" runs afoul of more subtle laws around reversibility or thermal noise.

I would point out that molecular dynamics simulations are known to be inaccurate, and that by choosing the atomic force fields you can get essentially any result you want. For most materials simulations, these parameters are tuned to some experimentally realized system. It is not obvious to me that such tuning is being done in the case of these molecular gear assemblies, and even less obvious to me what would constitute an appropriate system to tune towards.

Missing the point...

Please state your disagreements instead of insinuating that they exist.

This reminds me a bit of arguing about words and definitions.

Really the question is whether nanotech is an idea worth pursuing. It is relevant how much of a stretch it is from what it known to what is claimed to be possible. There is nothing that is against science in Drexler's writings. The slow progress speaks against the most optimistic claims. Chemists talk about the sticky fat fingers problem. Biology has lots of repair mechanisms that make it look like the problem is hard. But I think given the enormous benefits it looks worth following up on.

You could say similar things about hot fusion, and the claims that we can support 11B people on first world living standards on renewable energy.