 When it comes to explaining the building blocks of matter and how they interact, the standard model does a fairly good job. However, there are problems in the standard model which physicists try to patch with an idea called supersymmetry. So what exactly is this theory of supersymmetry? In the 1970s, physicists proposed a theory called the standard model, a theory explaining the most fundamental particles in our universe, as well as their properties and interaction. All the particles in the standard model can fall into two categories, fermions and bosons. Fermions are fundamental particles, aka particles which serve as the building blocks for matter. Fundamental particles which are fermions include quarks, which make up the protons and neutrons of atoms. Neutrinos, which are subatomic particles emitted from stuff like exploding stars or gamma ray bursts. Muons, which can be found in cosmic rays that hit earth. Electrons, which make up atoms. And last but not least, Taus, which are massive, unstable subatomic particles that can decay into other subatomic particles like muons. In addition, fermions have a spin of an odd half number like one half. Also, two fermion particles cannot be in the same place at the same time in the same quantum state, which explains why electrons exhibit the phenomena demonstrated in the Pauli exclusion principle. Bosons are the fundamental particles which govern the forces of our universe. Fundamental particles which are bosons include gluons, which are the carriers of the strong nuclear force, which holds together the protons, neutrons in the nucleus of atoms. Photons, which carries the electromagnetic force that helps us to see. W and Z bosons, which carry the weak nuclear force. And the Higgs boson, which is responsible for giving mass to all the matter. In addition, bosons have a spin that is classified with an integer, and multiple boson particles can be in the same place at the same time in the same quantum state. So, now that you kinda know what the standard model is, you're probably wondering what could be wrong with the standard model. After all, it seems like a pretty good explanation of our universe, right? Well, for starters, physicists claim the standard model is unfinished. So, physicists proposed the idea of supersymmetry, saying that for every particle in the standard model, there was a heavier partner particle with the spin varying about one half, with the goal of filling in some of the holes of the standard model. But there are some other problems which supersymmetry can help us solve. But unfortunately, due to time constraints, we can only look at two of the most arguably important issues in physics, which supersymmetry helps us solve. The first problem supersymmetry helps solve is the issue of the Higgs boson. But first of all, what is the Higgs boson? Well, throughout the universe, an entity called the Higgs field permeates. When particles move through this field, they interact with it, and this interaction with this field is what gives particles and matter its mass. The Higgs field consists of a subatomic particle known as the Higgs boson. Physicists say the Higgs boson is not very heavy. However, this seems surprising as physicists also state that the interaction between the Higgs and the subatomic particles in the standard model would mean heavy Higgs boson. However, to quote an article from CERN, which explains it perfectly, the extra particles predicted by supersymmetry would cancel out the contributions to the Higgs mass from their standard model partners, making a light Higgs boson possible. Now, let's take a look at the second problem supersymmetry solves, the issue of grand unification theory. Today, it seems that the fundamental forces seem separate. However, just a fraction of a second after the Big Bang, the four forces that we know today were unified into a single force. However, as the universe cooled down, the forces separated into the four distinct forces we know and love today. Well, the same article from CERN also claims, and I quote, if supersymmetric particles were included in the standard model, the interactions of its three forces, electromagnetism and the strong and weak nuclear forces, could have the exact same strength at very high energies as in the early universe. This aspect of supersymmetry, which unites three of the fundamental forces, brings a giant glimmer of joy to physicists everywhere. So you're probably wondering, what exactly do physicists have to gain from unified forces? The answer is simple, to gain a better understanding of the cosmos. You see, naturally, general relativity and quantum mechanics aren't really that compatible. So theories such as grand unification theory offer physicists a bridge between the two ideas, bringing us one step closer to our goal of understanding the cosmos. And on a final note, unification goes far beyond than just some theories and physics. Everything in nature is connected. From the four nitrogenous bases, all life forms share, to the atoms in your body which came from the stars long ago. So the day we understand how everything in nature is interconnected is the day we truly become one with the cosmos. That concludes today's lesson. I hope you really enjoyed this video, and if you did, be sure to leave a like and subscribe. Last but not least, let me know in the comments below if there's anything in astronomy or physics you wish to learn more about.