[Question] Why won’t nanotech kill us all?

[Yarrow B.]

Fifteen years ago, nanotech run amok was one of the top feared existential risks. Nowadays, nobody really talks about nanotech x-risk. What changed? Why did people decide nanotech was no longer scary?

[titotal]

I did a deep dive into the state of nanotech research here, including correspondence with the experimentalist who worked on the nanofactory project.

Essentially, research into molecular nanotech hit a wall in like 2010. They did not get very far: all they were trying to do was place two carbon atoms onto a carbon surface, and they failed, as they didn’t have the means to reliably image diamond surfaces. To my knowledge, there hasn’t been another major attempt since.

We are just nowhere close to even beginning to succeed with drexler-style nanotech, and the whole thing might just be impossible or impractical, or turn out to not be as impressive as previously thought.

On the other hand, there have been some more recent advances with DNA based robotics and DNA origami, so there may be some successes on engineered biology based bots in the future.

[Robi Rahman]

they were trying to do was place two carbon atoms onto a carbon surface, and they failed, as they didn’t have the means to reliably image diamond surfaces

Has this limitation been ameliorated by advancements in imaging? I used to work in materials science and don’t anymore, but my understanding is that scientists have very recently refined needles to one-atom width at the point, which should improve the resolution of scanning tunneling microscopy. Someone correct me if I’m wrong.

[titotal]

I asked professor Moriarty about the imaging thing, his response was:

Diamond is a very, very difficult surface to work with. We spent ten months and got no more than a few, poorly resolved atomic force microscopy (AFM) images. We’re not alone. This paper—https://​​journals.aps.org/​​prb/​​cited-by/​​10.1103/​​PhysRevB.81.201403 (also attached)-- was the first to show atomic resolution AFM of the diamond surface. (There’d previously been scanning tunnelling microscopy (STM) images and spectroscopy of the diamond (100) surface but given that the focus was on mechanical force-driven chemistry (mechanosynthesis), AFM is a prerequisite.) So we switched after about a year of that project (which started in 2008) to mechanochemistry on silicon surfaces – this was much more successful, as described in the attached review chapter.

A key issue with diamond is that tip preparation is tricky. On silicon, it’s possible to recover atomic resolution relatively straight-forwardly via the application of voltage pulses or by pushing the tip gently (or not so gently!) into the surface – the tip becomes silicon terminated. Diamond is rather harder than silicon and so once the atomistic structure at the end is lost, it needs to be moved to a metal sample, recovered, and then moved back to the diamond sample. This can be a frustratingly slow process.

Moreover, it takes quite a bit of work to prepare high quality diamond surfaces. With silicon, it’s much easier: pass a DC current through the sample, heat it up to ~ 1200 C, and cool it down to room temperature again. This process routinely produces large atomically flat terraces.

So it wasn’t about the imaging tech in general, but specifically the difficulty of working with diamond. It’s possible you could do something with another material, but diamondoid was chosen for a reason, as it is much stronger and more stable than other materials, which i think could be a requirement for atomically precise atom placement.

I haven’t seen any uptick in citations for drexler papers recently, so I don’t think any advancements have been made on this front.

[PeterMcCluskey]

Nanotech progress has been a good deal slower than was expected by people who were scared of it.

[Robi Rahman]

I agree, however, isn’t there still the danger that as scientific research is augmented by AI, nanotechnology will become more practical? The steelmanned case for nanotech x-risk would probably argue that various things that are intractable for us to do now, have no theoretical reasons why they couldn’t be done if we were slightly better at other adjacent techniques.