Theoretical physicists at Trinity College Dublin are among an international collaboration that has built the world’s smallest engine—which, as a single calcium ion, is approximately ten billion times smaller than a car engine.
![](https://scx1.b-cdn.net/csz/news/tmb/2019/2-physicistscr.jpg)
Source:
https://phys.org/news/2019-08-physicists-world-smallest.html