Question: what is a photons?

Euan Allen answered on 13 Jun 2016:

Hi xXmadscientistibrahimXx,

Ooooh, good question – that’s a tough one.

When we talk about light in every day life, and most of the time in school, we can take about light as a wave. This description of light is actually pretty good for most things, and it describes everything from colours, to how rainbows are made, why your legs look funny in a swimming pool, and lots of other things we see in the world.

However there are some times when light doesn’t act like a wave at all, and in fact it begins to act like a particle. You can imagine it as a small football that carries energy. So when we talk about light that exits a laser, we can imagine the light as a stream of footballs carrying energy that exit the laser, and fly across the room. These balls of energy we call photons. A typical light bulb with emit around 10,000,000,000,000,000,000 photons per second, so they really don’t carry much energy at all.

In the experiments I perform, it is much better to consider light as a photon rather than a wave. We actually work on trying to produce and work with individual photons. This is really difficult, as it’s really hard to know when you have one because your eyes aren’t good enough to see them!