Even though it surrounds us every day, physics is not something we think about often. Sure, we can appreciate the universe or how atoms are the building blocks of our very existence, but how much of this do we really understand? Although you may think that physics can only be understood by physicists, in actuality, physics can be understood by anyone if it’s explained right.
This is where Seven Brief Lessons in Physics comes in. Author and theoretical physicist Carlo Rovelli gives readers a unique look at physics. Starting from where it all began, the great breakthroughs of our time and what awaits us in the future, this summary will take you on a journey that you never know you needed.
In this book summary readers will discover:
- The theories that propelled physics into the spotlight
- Quantum mechanics
- The big parts of the universe
- The little parts of the universe
- General relativity versus Quantum mechanics
- The Science of heat
- Where do humans fit in?
Key lesson one: The theories that propelled physics into the spotlight
There are few people in physics who stand out as much as Albert Einstein. We all know his story, his genius and his theory of relativity but do you know what it actually means? Einstein’s theory of special relativity was first submitted in 1905 and described how time is relative and depends on the conditions surrounding the person experiencing it. This may sound a bit confusing at first but it basically means that you will experience time depending on what you are doing or what is happening around you. So, if you were travelling at the speed of light, time would pass by slower for you as compared to others not doing anything.
At the time of its release, Einstein’s theory spread through scientific circles like wildfire. There was just one hiccup. It was in direct conflict with Isaac Newton’s theory of gravity which had been around for almost two hundred years before his. Newton’s theory stated that gravity was a force that controlled how the planets moved through space and interacted with one another. Newton’s theory of gravity had everyone thinking about the universe and how it all worked together.
Newton inspired the studies of physicists Michael Faraday and James Maxwell. They introduced electromagnetic fields into the discussion about the forces in space. Their theory stated that these radio waves could transport electrical forces and was published about ten years before Einstein’s theory of relativity. Einstein considered this electromagnetic field in his studies and thought that if one exists, then surely a gravitational field exists as well. But, he didn’t just leave it at that, he further theorized that the gravitational field did not fill space – it is space. This just means that the gravitational fields didn’t just exist in the space between planets, it curved around them and exerts a force that holds them in place.
Everything that we know about space is based on these theories. They remain as relevant today as they did when they were first released.
Key lesson two: Quantum mechanics
Quantum mechanics, also known as quantum theory refers to the study of atoms and particles. Understanding the universe at an atomic level may not be high on your priority list but research in this field has opened our eyes to many new discoveries and has even contributed to computing.
How? Well, it’s best to start at the very beginning. Quantum mechanics was introduced by Max Planck in 1900. Planck was actually trying to make an equation simpler so he decided to represent energy as having distinct values and in the form of small packets. This assumption of specific values led to Planck’s calculations being much more precise. Turns out, energy packets are real! Einstein further proved that light is made up of these energy packets five years later. He named these energy packets of light, photons.
Approximately twenty years later, Niels Bohr discovered electrons and how they move around the nucleus of an atom. Bohr also discovered that electrons could move from one orbit to another. This movement was named quantum leaps. The concept of electrons launched physicists into research once more and the next great quantum theory was put forward by Werner Heisenberg. He tried to understand the strange way electrons behave and theorised that it may take interaction for an electron to exist. If there were no interactions, the electron had no fixed position and only the probability of where it would be could be calculated.
It is with this last theory that you can see how quantum mechanics and its probability equations can have an influence on not only physics, but engineering, chemistry, biology.
Key lesson three: The big parts of the universe
The universe still remains a topic of hot contention. Even though Greek philosophers openly discussed the possibility of the earth being a sphere almost 26 centuries ago, there are some people who still believe the world is flat today.
Copernicus was the first person to put forward a heliocentric theory 500 years ago. This stated that the sun was in the centre of the solar system and that the Earth, stars and other planets rotate around it. The universe was coming into clearer view with the development of powerful telescopes and the one thing everything could agree upon was that the universe was much bigger than anyone had ever anticipated.
In the early twentieth century, physicists finally discovered how just how small our galaxy really is and what the true expanse of the universe meant. It was at this time, that Einstein’s theory of relativity shaped our views of the universe. How space works in terms of the force it exerts and even the concept of black holes. It is with this foundation of knowledge that physicists were able to determine that the universe is slowly expanding.
Key lesson four: The little parts of the universe
Understanding the universe in terms of quantum mechanics just means that you look at it from a particle point of view. Everything in the material world is made up of elementary particles – more specifically, atoms. Atoms contain a nucleus and a nucleus is associated with electrons, protons and neutrons. Looking at these more closely, protons and neutrons contain quarks which are held together by gluons. Then there are photons, neutrinos and bosons. These are a lot of names that you are not going to remember but it just shows you just how diverse elementary particles are. And although these particles make up all matter, quantum mechanics teaches us that our world is not made up of things but rather by events.
Just consider a rock. It seems like it is a simple configuration of particles to make up a solid object. However, if you consider it as a physicist, this configuration is only temporary, it will be broken down over time. Quantum mechanics has remained an area of debate with the closest agreement of the behaviour of particles being theorised by Murray Gell-Mann and Richard Feynman. It’s called the standard model of particle physics and as much as it works, it is not as solid as Einstein’s theories. This is why it is still debated. However, to physicists, this just means that there’s room for improvement and someone has yet to develop a groundbreaking quantum mechanics theory.
Key lesson five: General relativity versus Quantum mechanics
As much as general relativity and quantum mechanics make up the two major parts of modern physics, they are in a constant battle. If you try to bring both theories together, all you get are contradictions.
There are physicists who are working to solve this though. Their field is called quantum gravity and looks to find a way in which quantum theory and general relativity can be compatible. If successful, this would lead to a unified theory of nature. So far, the closest theory is called loop quantum gravity and theorises that space is made up of loops or atoms of space. This somewhat brings both theories together by allowing space not to be continuous. It also suggests that time is not continuous either and that the big bang was more likely a ‘big bounce’ because there was a universe before the current one. This has raised more questions than answers, so we will await the next theory to clear it up in future.
Key lesson six: The Science of heat
The next branch of physics is thermodynamics or the science of heat. The study of heat was first done under calorics, which refers to different kinds of fluids. You might wonder what heat has to do with fluids, but it was more to do with a state of a heated object. If the atoms of an object move around, it generates heat and this heat increases as the movement of the atoms increase. In terms of the transfer of this heat, it is completely by chance. No law states heat must be transferred between two objects and whether it is from hot to cold or cold to hot. It happens by pure chance.
Also discussed in thermodynamics is how heat influences our perception of time. If there were no friction and therefore no heat created by moving objects, it would not lose energy and therefore never stop. So, the whole concept of time is lost.
Key lesson seven: Where do humans fit in?
Physics plays an all-important role in understanding the universe and, as much as human curiosity results in the development of theories, humans are also part of this universe. We are also made up of atoms, much like everything that surrounds us.
Physics is about the laws of nature and to study physics is to attempt to predict how events will occur. As humans, we may have free will and think that our actions cannot be predicted but this is not entirely true. We are also bound by the laws of nature. Our actions and in fact, our very existence, much like the universe, can be theorised.
Physicists are often too busy trying to solve the mysteries of the universe to realize that they are a part of it too. But with continued research, who knows how the next big theory pulls us all together.
The key takeaway from Seven Brief Lessons on Physics is:
Since its emergence, the area of physics has been the source of awe and mystery. As much as there were great discoveries made by famous physicists in history, many areas still require attention and refinement. With each passing year, we are one step closer to understanding more about our universe and how it really works. But then again, we may just be at the tip of a giant iceberg!
How can I implement the lessons learned in Seven Brief Lessons on Physics:
Spread the word! Now that you have had a crash course in physics, you can explain it to others. Physics may not seem like a topic of discussion outside of the scientific community but it’s sometimes nice to know the basics. You never know where it may lead!