 And the final big story of recent developments in quantum mechanics is that we're starting to really use the quantum properties of things in engineering. We're trying to build quantum devices that really use this wave-like nature to do things that you can't do with classical devices. So for many decades, we've needed to understand quantum mechanics in order to understand the properties of materials and things like that. But now we're using the stranger properties of quantum mechanics as fundamental parts of our design. Hello, I'm still Kyle Hardman and we're in the Quantum Sensors Lab at ANU. And in here is still the coldest place in Canberra, possibly Australia. Hi, Kyle. Hello, Joe. Hi. It seems like there's a lot of effort going here to make these atoms really cold. Why do you do that? Well, we go through all that effort so that the wavelength of the atoms become very, very large. We can then take the atoms and make them go through two separate paths and interfere them at the bottom. The interference pattern is strongly correlated to the acceleration of gravity. And because of that, we can make a precision measurement of the acceleration of gravity. Right. So using quantum mechanics for good? Using quantum mechanics for good. Great.