The author receives a phone call in the middle of the night, showing how hard it is to work with CERN at the large hadron collider. The fact that there are so many people working so hard just to find the answer to fundamental questions without any other motivation is a proof that science by itself is something extremely interesting. The author feels obliged to share this interest with a more general audience, especially now (as of 2013) that a particle that resembles the Higgs boson has been found and that is the objective of this book: To explain how we reached this moment, why it is important, and to try to share this feeling with the readers.
Chapter 1. The mass of fundamental particles that defines the shape of the universe.
We talked about a particle that has been discovered in 2013 which could be the Higgs boson but, what is the Higgs boson? In order to explain this, we will see how particle physics is related to the whole picture of the universe, introducing the importance of mass, which is believed to exist thanks to the Higgs boson, and how experiments in particle physics are carried out.
Part 1. The relation between particles and the universe.
Many fundamental questions about the origin of the universe used to be answered by philosophy, but now they belong to cosmology. In order to answer these questions, however, we must also understand particle physics.
But, how come such a small thing as subatomic particles is related to the universe as a whole? Sheldon Glashow, who received the Nobel Prize in Physics in 1979, introduced the idea that there is a hierarchy in the study of nature which depends on the size of things and can be represented by an ouroboros; a snake that swallows its own tail. It is obvious that different fields study things of different sizes. If we look for bigger stuff, we enter fields such as geology, space science, astronomy and, finally, cosmology. If we look in the opposite direction we go from biology to particle physics, passing through chemistry and nuclear physics.
The most widely accepted model of the origin of the universe is the Big Bang, the idea that everything that exists within the universe originated from a single point. Three minutes after the Big Bang, the first hydrogen and helium nuclei were formed, but it was not until 380,000 years later that these got together with their corresponding electrons to become atoms. During that time, the universe existed as a plasma of charged particles. Photons (light) could not travel freely in that environment since they would constantly interact with those charges. When atoms were formed (a phenomenon known as recombination, fig. 2), photons were finally “released.” If we consider that the universe at that time must have had a temperature of about 3000 K, due to the expansion of the universe these photons must have an energy equivalent to approximately 3 K nowadays. The—accidental—discovery of this radiation, known as the cosmic microwave background earned Wilson and Penzias a Nobel Prize in Physics, and it is one of the biggest proofs for the Big Bang: a radiation signal that comes from every direction with the same energy.
In order to see back in time we need see further, since light from further places took more time to reach us. However, since recombination occurred only 380,000 years after the formation of the universe and it took much more time for the first stars to be formed, we cannot see the conditions at the beginning of the universe, since before that it was just a plasma of particle that did not emit any light. Then, how can we observe the initial conditions of the universe? The answer is in particle physics: in particle accelerators we can recreate those conditions (pressure and temperature) by colliding particles at a speed close to the speed of light. That is how our ouroboros bites its own tail.
Part 2: The universe and the origin of mass.
On chapter 3 we will see in more detail what the Higgs boson is, but now we just need to know that it is a particle that gives their mass to other particles. Mass is a decisive factor that defines the shape of the universe. If particles did not have mass, everything would move at the speed of light (as explained by the theory of special relativity) and atoms would not exist. We would have a very boring universe in which all particles exist infinitely in that state. We have to consider, however, that it is wrong to say that the Higgs boson is “the origin of the mass of everything”. It is only the origin of the mass of all particles, but not of all things. Although this might make no sense at first sight, it is part of the mystery of the world of particles and we will understand it better after the fourth chapter.
Part 3: The discovery of a new particle: A revolution begins.
Almost forty years have passed since the Higgs boson was theorized and we could say that its discovery is one of the most—if not the most—important topics in particle physics. This, however, does not mean that there is nothing else to study. On the contrary, proving its existence allows us to decide how to keep going. The reason is that a phenomenon called the “hierarchy problem” takes place in case the Higgs boson actually exits and there are many proposed ways to solve it such as the multiple dimensions and supersymmetry theories. This is why the Higgs boson is a key point that defines the future of physics and we could say that it is the beginning of a revolution in that field.
Thank you for reading. You can follow The Relearner on Facebook, Twitter, and Instagram to see our latest posts right on your news feed. The Relearner works for you and also thanks to you, so please check the “Support Us” section of our blog. Share this entry on Facebook, Twitter or Instagram with the hashtag #TheRelearner and tell us what your favorite scientific book is. You’ll have the chance to get a souvenir from Nagoya University. A winner will be chosen every month. Thank you and see you next time!
Figure 1. Sheldon Glashow, sketch reproduced in T. Ferris, New York Times Magazine, Sept. 26, 1982, p. 38.
Figure 2. Official site of chronological scientific tables
(The featured image was made by NASA).