Indecisive? So is Quantum Mechanics.A atom walks into a bar. Bartender says ‘What will you have?’ The atom says ‘I’m uncertain’.
Or my personal favorite Heisenberg gets pulled over by a police officer, officer says ‘Do you have any idea how fast you were going?’ Heisenberg replies ‘No, but I know EXACTLY where I am.’
Ever have one of those days where you just cannot make up your mind? Well thankfully you have got one thing going for you, neither can anything at a quantum level.
Particles, waves, most people hear quantum mechanics and decide to run the other direction before shooting someone. But most of the underlying principles are fairly easily explained.
Let’s use light in this example, it is a wave [hence light wave]. Until you ‘look’ at it, then it acts like a particle.
Whats the difference?
The best experiment showing the crazy way that [in this case] photons act, is the ‘famous’ double slit experiment. Photons of light are shone through two slits in a box [or whatever barrier you prefer] and if the photon is a particle it should hit the wall as, two slits.
If light is a wave it should have multiple bands, like waves in the water.
The odd thing about it? If you are trying to measure the photons of light, [either before or after the slits] they act like a particle. If you just see where they hit on the wall, then they will act like a wave.
Am I confusing anyone yet?
Good, that means you are up to speed with the rest of science.
Strange things happen at the subatomic level. So because particles act like waves when no one measures them, there are certain equations to help describe how they act. Every particle in the universe has a wave “attached to it” even the ones that make you up.
This ‘wave’ gives us a probability of where a certain particle will be at any given time, in this room, in the country, even on this planet. Because of this you can do interesting things with the math that you couldn’t ‘really’ do. For example, if you could gently tap on a wall over and over again for all of time. Eventually, you would pass through the wall unhurt, like nothing ever happened.
That is called quantum tunneling and it happens all the time at a subatomic scale with individual particles, but when you start to scale upwards to hundreds of thousands of atoms, the strangeness of the subatomic realm wears off, so to speak.
Einstein once said ‘God doesn’t play dice’ in regards to the idea that we could never know with certainty where a particle is and the speed of that particle. He thought that there was some unknown variable at play that, once found would allow us to explain the wave/particle duality mathematically.
Unfortunately, it looks like God does play dice and we cannot with certainty know the speed or the location of a particle.
Hence, particle and wave.
So which one is it, light a particle or wave?
Too much to take in? Well, how about this super cool video made completely of individual atoms.