Half Full or Half Empty?

There is a cup half filled on the table, and I ask my mother; 'Is the cup half full, or half empty?'

This is a question most of us have come across, and usually the most logical answer would be to say that it is half full. The diligent observer and thinker would then argue that it depends on your viewpoint. This individual would say that an optimist considers the cup half full, while the pessimist sees it as half empty, even though, the significance of the contents of the cup are really not important, and so this argument is quite irrelevant in my opinion.

Later on you ask this question to a keener observer, a scientist. The scientist replies, to your astonishment, that the cup is mostly empty, around 90% to be more precise, and you remain puzzled. What does he mean by the cup being mostly empty, when it is clearly filled by half? You ask the scientist to explain, and he replies, rather proud of being aware of such details.

Everything in the universe is made up of atoms, little tiny particles that can form a solid, let's say a chair, when they are moving very slowly or a gas, like the one we breathe in, when they are moving fast. Atoms can also have an intermediate phase, a liquid, to form something like water. Well, it doesn't stop there. For you see, an atom is made up of tinier denizens. There is the pessimistic, negatively charged electron, the optimistic, positively charged proton, and the neutral passive neutron. These are the three particles that make up each atom in everything around us, from the shirt you are wearing, to the skin it is covering, to the moon in the night sky.

There is more to the story, however, and it comes to a big surprise to know that an atom, is mostly empty space. You see, an atom is always made up of protons and neutrons clustered up together as a group in the middle and an electron, or electrons, running around them in circles. Let's say you are standing in the middle of an Olympic stadium. You are the proton, a happy guy talking to neutrons in the middle of the pitch. Then there are the energetic little electrons zipping by, running around the course track. The size of the atom, or its radius, is defined by how far the electron is, from the group in the middle of the stadium. That means, that everything which is made up of atoms, which is, ironically, everything, is defined, or made up of electrons running around, and at a large distance away from, the middle of atoms. The space in between the electron and you, the proton in the middle, is empty space.

This empty space, is nothing like the air we can wave our hands through. Air is made up of gaseous atoms,  spaced apart from each other, moving fast between your fingers. The space in between the electron and the proton, on the other hand, is really empty. This empty space, amounts to around 90% of the total volume of atoms. This means, that the tip of a pencil, made out of carbon atoms, is 90% empty space, and this applies to every thing around us. So, you ask, how come we do not fall through our chair, into the Earth and through all this empty space which is in every thing.

Well, you have to consider that every thing is made up of atoms, and as such, has electrons, buzzing around it. Electrons are pessimists, negatively charged dudes that don't like talking very much to each other. When the atoms at the tip of my finger, and the electrons they are made up of, are pressed to a wall, my finger does not pass straight through the wall, because it meets other pessimistic electrons on the atoms of the wall, who repel my finger electrons. Similarly, the electrons on my bum repel those on the chair, and I can safely 'hover' on the chair, and never fall through it. So much for flying, we do it all the time. About those superhero fans that prefer their characters to pass through walls...well, I'm sorry for them.

And so we can come to the conclusion of our story. When my mother replied with 'Half Full', to the question imposed about the mythical dilemma of the cup, she wasn't wrong, but she wasn't exactly right. To the scientist, or those people who have wondered and had the time to ponder and learn the marvellous mysteries of our universe, the answer is, it is mostly empty. And what would be the coolest answer to give in a bar as a pick up line? You decide.

Edit 14/10/12 - Typos