# Can particles feel hot to the touch? [closed]

The other day, I got a tiny splash of hot cooking oil on my hand. But I could barely feel it because it was so small.

That made me wonder: how hot would a small collection of atoms need to be for me to feel it on my skin?

And how hot would it need to be to burn me?

Or maybe it’s too small to feel, no matter how hot (or cold)?

• Temperature as you know it is a collective property of many atoms together, it doesn't make sense to talk about the temperature of a single atom. Commented Jul 10 at 18:50
• @Triatticus I had a feeling that might be the case. See edit. Commented Jul 10 at 18:51
• If you're talking about particles which have sizes on the order of atoms, you probably won't feel a thing, no matter how hot they are. At these scales, your skin is basically an ideal thermal bath to these particles. I conjecture that for you to actually be able to feel the particle, it would be so hot that atoms could not even exist. But that is another question for another day. Commented Jul 10 at 19:07
• What do you mean by "a small collection of atoms?" How small? How many?
– hft
Commented Jul 10 at 19:41
• "...for me to feel it..." How are we supposed to know anything about your particular nerve endings, skin thickness, state of distraction, and so many other things that could contribute to whether or not you "feel it?"
– hft
Commented Jul 10 at 19:42

About the types of effect that atoms can have:

An alpha particle is the nucleus of a Helium atom. In the case of a typical nuclear decay event the emitted alpha particle have a very low energy. Those alpha particle hardly penetrate the skin. The amount of energy that is transferred to the skin (as the particle is decelerated) is so small, that is way below the sensitivity of the skin.

Heat is kinetic energy of atoms/molecules.

So, what happens if an atom with a very large kinetic energy is headed for you? Would you feel it hitting you?

You would not feel that. Even though a single atom can definitely have an amount of kinetic energy that when dumped all at once would hurt significantly, the atom does not have the opportunity to dump it all at once.

That high kinetic energy atom will pass through you completely. On its way it will disrupt molecules; the high kinetic energy atom will knock atoms off molecules, that sort of disruption. That is damage that the body will need to repair, but the amount of energy that is transferred to the body will still be very, very low.

To get an idea of just how high of a kinetic energy is possible, for a particle, check out the wikipedia article about: Ultra-high-energy cosmic ray