Misleading aspects in animations of diamondoid molecular machine elements
There are at least two quite misleading artifacts stemming from
very high simulation speeds of ~100m/s to ~1km/s or so
(possibly even exceeding the ~3km/s of the unsupported rotating ring speed limit)
Why simulate so fast:
Simulations need to make the time-steps smaller than thermal atomic wiggles.
Reasonably slow nanomachinery speed would mean unreasonably many time-steps to compute.
Thus molecular dynamic simulations of nanomachinery is typically simulated at unreasonably high speeds.
Contents
[hide]No, nanoscale diamondoid (and gem based) parts are not floppy and jelly-like (at the nanoscale).
See also page: A better intuition for diamondoid nanomachinery than jelly
Misleading jelly like floppiness.
Relative deflections from motions are scale invariant. (See: Same relative deflections across scales)
Thus intuition for expectable degree of bending and deflections can be 1:1 directly applied from macroscale.
Macroscale comparison
– proposed speeds are mere few mm/s (intentionally deviating a bit from same absolute speeds for smaller machinery) and …
– material is solid diamond or some similarly good gemstone.
=> Thus expectable deflections from machine motions are way below even
macroscale metal robots typically operating around m/s speeds.
At the extreme speeds of simulations though even spring steel parts would flex just as much
(actually even more) when slammed together.
Here's a contrived analogy example:
If one only ever saw spring steel colliding as colliding rods at hundreds of meters per second in videos
and never ever saw macroscale machines our of steel operating at "normal" machine speeds (meters per second or less),
then of course one would likely be mistaken in thinking that steel always behaves like floppy jelly
and one would quite likely mistakenly conclude that spring steel is an awfully jelly soft matrial
that would not at all make for good machines. Let's stick with stick & stone as we know that works.
This could be spun furter but I'll better stop here before everstretching the analogy too much.
Caveat: Thermal motions
This does not apply to thermally excited deformations.
Goes to show how violent these are at the nanoscale.
Structures must be thick enough to not flail around from thermal motions.
Accidental heatpump dissipation mechanism?
Terminology accident
The choice of the term gem-gum for gemstone based metamaterials and gem-gum technology
may be a bit unfortunate potentially corroborating a false intuition here.
The author will keep it, but maybe more consciously use it.
No, machine motions are not near thermal motions (causing strong coupling and high losses).
See: Stroboscopic illusion in animations of diamondoid molecular machine elements
Actually even though here the effort might be taken to simulate very many timesteps,
showing just random snapshots instead of doing a proper motion blur leads to its own problems.
(wiki-TODO: Find and link a specific work on "multi stage motion blur" for molecular motions)
Exceptions
Assuming …
– Very sharply pulsed in time and/or …
– just one single nano-device active in an otherwise inactive macroscale heat-conductor
As may occur i some rare exotic situations,
then in this special case extreme speeds may quite likely actually be possible
with all the jelly wobbling and massive losses being a real thing to accept.
Trying near km/s operating speeds with macroscale machinery it would just self-destruct as
there is no way to run it in a short enough pulse or run it isolated enough.
It is "too much for itself" already.
Macroscale physics just has a too small a surface to volume ratio for cooling for that.
Related
- Stroboscopic illusion in animations of diamondoid molecular machine elements
- A better intuition for diamondoid nanomachinery than jelly
- Intercrystolecular snapping modes – Violent unconstrained spaps are one exception case where speeds and forces can become high enough to cause intermittent jelly like wobble. Just like a steel plate wobbles like jelly in slow motion footage when hit by a bullet, but here (nanoscale gemstome like materials) the materials survives with zero damage so long it gets sufficient cooling as is possible with snaps being either sparse in time or sparse in space (or both).
