9 Things To Say About Quantum Physics That Will Make You Sound Clever At Parties

So, birds can navigate using quantum mechanics, but that's just weird nature stuff, right?

Wrong.

In the ever expanding world of quantum physics, more and more of it is spilling over into the unlikely fields of biology and the natural world.

It used to be thought that our nose detected smell by detecting the shapes of the molecules that came into it. If a molecule had a specific shape, it would fit snugly with a certain type of receptor, signalling to the brain what kind of smell it was. This is different to how we detect light and sound, which we do by detecting waves as opposed to particles.

However, scientists noticed that some molecules with completely different smells had exactly the same shapes, but produced a different signal in the brain. This means that just the shape of the molecule alone is not enough to tell us what the smell is, and the actual chemical make up of it is also important on a quantum level.

When a hydrogen atom in a "smell particle" is changed to a slightly heavier form of hydrogen called deuterium, it affects the weight but not the shape of the molecule, but produces and entirely different smell. One the flip side, the smell particles of both almonds and cyanide smell the same to the human brain, despite the fact that the shape of their molecules are very different, so it's not all about shape.

It is thought that it is the chemical bonds between the particles that is more important as they vibrate in a different way. These vibrations are more like a wave than a particle, just like light and sound.

The wave-like behaviour of particles is a purely quantum effect, but somehow our noses and brains are able to pick up on this seemingly contradictory behaviour, sensing smells in its wave and particle forms.

So, slightly poetically speaking, if we experience smells in their wave form, your nose is listening to smell in the same way that your ears listen to sound.