Our sense of touch is a fundamental aspect of our everyday interactions, enabling us to manipulate various tools and devices. However, from a physics perspective, this everyday notion is technically inaccurate, with only a few exceptions.
Before delving into the specifics, it is crucial to establish a clear definition of what it means to touch or be touched by something. While we commonly associate touch with physical contact between objects, like the sensation of your fingers on the screen of your phone or gripping a doorknob to open a door, the concept takes on diverse meanings at the atomic level.
Touch at the Atomic Level
One of the first things we learn in a physics class or from a physics tutor in Singapore is that everything we see is made up of small particles called atoms. Atoms have a centre called a nucleus, and around it, there are three particles: positively charged protons, negatively charged electrons, and neutral neutrons. When things have microscopic contact, it is effectively the atoms of one item interacting with those of another.
Now, let us delve into a practical example. Imagine you are about to tap the screen of the device you are currently reading on. During this action, the atoms of your fingers and those of the screen, specifically their electrons, engage in a fascinating interplay. As they draw near, a repulsive force comes into play, driven by one of the fundamental forces in our universe – electromagnetic force.
This force dictates that when two electrically charged particles approach each other closely, they will exhibit either an attractive or repulsive force, depending on the charges involved. Repulsion occurs if the charges are the same, preventing a physical touch, while attraction arises when the charges differ.
Zooming back to the microscopic level, let us consider what transpires when two atoms approach each other. Given that every atom in the universe has negatively charged electrons orbiting its nucleus, as atom A approaches atom B, their respective electrons gradually repel each other, maintaining a constant distance.
Another reason atoms cannot physically touch is explained by Pauli’s Exclusion principle, which explains that two or more quantum particles cannot occupy the same space. Therefore, the electrons of two different atoms need to be in the same energy state to touch each other, which, according to Pauli’s exclusion principle, is impossible.
Going back to the screen tapping scenario, the electrons of your fingers repulse the electrons of the screen’s glass surface as you press on it. This force of repulsion makes up our sense of touch, and while it may seem that your finger is making physical contact with the screen, there are nanometres of distance between them at the atomic level.
Then, Can We Not Actually Touch Anything?
Despite the explanations above, there are still ways to meet the definition of “touching” at the atomic level, such as chemically reacting with an object. A perfect example of this is eating food, wherein your digestive system processes the things you eat and turns them into matter that your body can chemically combine with and use for energy. Thus, it is correct to say that our sense of touch is a grand illusion created by our brains to interpret interactions between our body’s electrons and the electromagnetic field.
If you really want to get into the technicalities of touch, physics says that the only thing you have ever touched is your parents when you were conceived. This is because, during that time, your father and mother’s DNA reacted chemically and shared electrons to create you.
With the fundamental scientific truth that not everything is as it seems or how we perceive it to be, there are certainly many discoveries that await that can help us see our known universe in a new light. If you want to be among those who make such discoveries, polish your fundamentals first by signing up at Tuition Physics. With the help of our highly regarded programmes for IP and O-level physics tuition, you can build the strong foundation you need to excel in this impactful branch of science.