The Big Bang theory can satisfyingly explain the creation of the cosmos, but it fails to explain the interaction among various types of energy in the universe. Why did shortly after the Big Bang some elementary particles join to make protons and neutrons? And what made electrons bind to them later to create atoms? Why did these atoms then go on to build glaring stars and vibrant galaxies?
It turns out that all events in the universe can be blamed on four fundamental interactions (four fundamental forces) – gravity, electromagnetism, strong interaction and weak interaction. I am sure everybody has at least a basic overview of the first two forces, the last two, however, might be entirely foreign to some. But it is crucial to understand these interactions, since they govern the whole universe.
Take your own body as an example. First, let us dive deep into the microworld, where we can see the basic building blocks of everything. Your body is, just like everything else in the universe, made up of energy. It is of course present in many various forms, but fundamentally, it is simply energy.
The energy of the human body is concentrated mainly in the form of elementary particles – the same particles that were created just a moment after the Big Bang. These particles then form composite particles – protons and neutrons. But what keeps elementary particles together? The answer lies in the strong interaction. If we jump one level up, we can see collections of protons and neutrons – atomic nuclei. Again, we can blame the strong interaction. Going another level up, we can see electrons, devoutly whizzing around the nuclei. Here, we observe the token of another fundamental force – electromagnetism. Individual atoms then go on to form molecules – electromagnetism shows itself once again.
And finally, unless you are currently at the international space station or reading this text in a distant future on a faraway planet (most likely on Mars, as explained in one of the following chapters), it is quite likely that you are finding yourself on our tiny blue planet. And the only “force” keeping your feet on the ground instead of flying off to space is gravity – another of the four forces.
Our demonstration is over now. We have seen the essence of three of the four interactions using only the human body on Earth. If you are interested in the fourth force as well, you will have to wait a while – it manifests itself the least of the four forces. But now, let us analyse the interactions in detail, one by one. And we will start with the most sneaky and peculiar one – gravity.
Keishinrei 