There is not much stranger than physics and this is a good lecture if you have the time. If not, here are my notes:
What do we know about the fabric of the universe? You may have learned that all matter is made of atoms which differ in their numbers of sub-atomic particles.
These 118 different kinds of atoms are the chemical elements known to modern chemistry. Interestingly, there are only three particles that make up every kind of atom: electrons, up-quarks and down-quarks. The up and down quarks make protons and neutrons. This model is not the best we have, however.
Even more fundamental building blocks are fluid-like structures which spread across the entire universe and which ripple in interesting ways.
There are fields. For example, light is composed of electromagnetic field waves. But the fields aren’t smooth and continous. The fields have little particles of light we call photons. They are spread everywhere, the electron field, a fluid that fills the entire universe. The ripples get tied into bundles of energy and these are called the electron particle. The electrons are all waves of the same underlying field.
Energy is not continuous, it is bundled up into packets or quanta. There are two quark fields, these fields give rise to the up-quarks and down-quarks, which are all connected as waves of the same fields.
What does it mean that we are made of fields instead of particles? If you take away all particles from a given space, you will still have fields constantly fluxuating in a very complicated way.
Nothing is a busy place. The simplest thing we can imagine in the universe is extremely complicated. It is filled with twelve (12) fields that give matter, and four (4) other fields that give forces. Space and time (space-time) itself is a field itself, the one responsible for gravity. The world we live in is a combination of the 16 fields interacting in interesting ways.
This is the greatest theory in the history of human civilization, although it is referred to by the boring name “The Standard Model”. There is one more field, the final building block, the Higgs field, which is responsible for all mass. From all of this, we have one equation that correctly predicts the results of every experiement we’ve ever done in science:
This amazing Standard Model equation does not cover everything, however. There are invisible particles in space like dark matter and there is the field of dark energy that causes everything in the universe to repel everything else, so we need to do better than the standard model which does not account for these two things.
The universe is 13.8 billion years old. In the first 380,000 years, the universe was a flickering fireball which we now see as cosmic background radiation. What caused the flickering was something that took place in the first few fractions of a second after the big bang. Tiny quantum vaccuum fluctuations were caught and stretched 20 billion light years across the sky. These are the ripples in the fireball.
It may be that all of the forces and matter can be unified. This is the theory of super-symmetry. String Theory combines and contains all of the forces and types of matter.
According to our best theories of physics, the fundamental building blocks of matter are not particles, but continuous fluid-like substances known as ‘quantum fields’. David Tong explains what we know about these fields, and how they fit into our understanding of the Universe.
I’m grateful that we can pretend to understand this much of the universe, but I don’t really get what a field is. One current view is that a field is a physical quantity, represented by a number or tensor, that has a value for each point in space and time. A physical quantity. Hmmm.