Scientifically speaking, there is no such thing as 'touching' something. When objects with mass – any objects with mass – touch each other, they aren’t physically in contact at all. There are two reasons for this.
Firstly, atoms consist of positively charged protons and negatively charged electrons. The protons, often with electrically neutral neutrons, are within the central nucleus of the atom. The electrons are ‘orbiting’ around the nucleus.
Opposite charges attract while like charges repel – this is known as an electromagnetic force. So, if two atoms approach, they’ll generally repel each other, since the electrons are on the outside of the atom.
The other factor at play here is known as the ‘Pauli exclusion principle’. Simplistically, this states that no two electrons in an atom can have the same quantum state – their ‘orbits’ must be different.
This creates a short-range repulsive force, called ‘Pauli repulsion’, between electrons, and hence the atoms. Combined with the electromagnetic force, these two phenomena mean that atoms will generally repel each other.
So, what happens when you ‘touch’ an object? Assuming you don’t chemically react with it, your atoms or molecules will generally be repelled by those of the object.
Each imparts a tiny repulsive force, the combined effect of which is to prevent you and the object ‘touching’.
If you sit on a chair, for example, you’re basically floating on a cushion of repulsive force, operating at the sub-atomic level.
In reality, things are a little more complicated than this, because when you touch something, you will, to a very small degree, chemically combine with it.
Some of your atoms or molecules will overcome the electromagnetic repulsion, exchange or share their electrons with those of the object, and form a bond. This means there are other forces at play, such as ‘friction’, operating at the atomic level.
But ultimately, Pauli repulsion is preventing you and the object from actually making contact with each other.
Of course, you certainly ‘feel’ something when you ‘touch’ it. This is because your body contains sensory mechanoreceptors that respond to mechanical stimuli such as pressure and vibration. Those receptors send electrical signals to the brain, which responds with the perception of ‘touch’.
But ultimately, those receptors are just detecting the tiny repulsive forces between atoms and molecules. You aren’t in physical contact with the object, however. In that sense, ‘touch’ is an illusion.
This article is an answer to the question (asked by Josh Greene, Leeds) 'Have I ever technically touched anything?'
To submit your questions, email us at questions@sciencefocus.com, or message our Facebook, X, or Instagram pages (don't forget to include your name and location).
Check out our ultimate fun facts page for more mind-blowing science
Read more:
