Question: Can humans touch light?

Euan Allen answered on 20 Jun 2016:

Well, in a sense yes we can, but we need to be careful what we mean by ‘touch’.

Most things we touch don’t get destroyed when we touch, or sense that they are there. If you touch sand, then the sand is still around after touching it. The weird thing with light is that we can’t see it without destroying it in the first place.

When you shine light on your hand for example, the light you see on your hand is the light that has bounced off your skin, entered your eyes and been absorbed by the light sensitive cells at the back of your eye. In that sense the light has bounced off of your skin and so you have ‘touched’ it, but you only realise it because it has gone into your eyes and been absorbed (destroyed).

Another way to feel light is via the heat that it generates, like when you sit in the sun. This light doesn’t bounce off your skin, but actually gets absorbed by it (destroyed again). This causes energy to be deposited onto your skin and for it to heat up.

So in those two ways we can ‘feel’ light, but it’s maybe a bit different to the traditional sense of touch.