I was listening to the On Being podcast where Krista Tippett was interviewing Carlo Rovelli. Rovelli is an Italian physicist working with the Quantum Gravity research group at Centre de Physique Theorique in Marseille, France.
As soon as the episode was over, I went over to Amazon and ordered the book he had been talking of – Seven Brief Lessons on Physics. This is an English translation of Rovelli’s Sette brevi lezioni di fisica written in 2014. The book was translated into English by Simon Carnell and Eric Segre in 2015.
In his discussion, I felt that there were still parts of Physics that I would like to explore and read up more on. Although the book does not have footnotes that would help me to learn more. It is an intense book packed with information. I read this book between March 17, 2020 and finished it on May 26, 2020. The book is 79 pages long.
The first lesson of the book explores Einstein’s theory of general relativity published in 1915. But, before we get there we have to realise that in one of his three papers written in 1905, Einstein suggested that time is not the same for everyone. The Theory of General Relativity suggests that gravity is the curvature of space.
In the second lesson, Rovelli deals with Quantum Mechanics. In 1900, Max Planck conducted an experiment to measure the electric field in a hot box. For calculations, he considered energy to be lumps of energy that he called quanta. While the results agreed, it disagreed with what was known till then about Energy.
In 1905, one of the three papers that Einstein submitted showed that Planck’s view of the world is true. He showed that light is made of similar packets, called photons. This paper birthed the field of Quantum Physics. The rest of the second lesson explores how Niels Bohr and Werner Heisenberg flesh out the field of Quantum Physics with Einstein objecting and rejecting the results that the field proposed.
The 1905 introduction to the paper begins with “It seems to me that..”. Rovelli suggests that genius hesitates and great scientists doubt till the end.
The third lesson is a chapter filled with diagrams. The reason why is explained beautifully by Rovelli, thus:
This lesson is made up mostly of simple drawings. The reason for this is that before experiments, measurements, mathematics and rigorous deductions, science is above all about visions. Science begins with a vision. Scientific thought is fed by the capacity to ‘see’ things differently than they have previously been seen.
Carlo Rovelli, Seven Brief Lesssons in Physics, Third Lesson, pp 21-22, 2015, translated into English by Simon Carnell and Eric Segre
The diagrams refer to how our view of our world changed from Earth below to sky above to us being in an ordinary solar system in an ordinary galaxy. The diagrams describe the structure of our universe.
The fourth lesson talks about particles. It goes into the development of quantum physics and then ends up discussing the various issues related to the Standard Model. The Model is a series of equations that has “never been taken entirely seriously by physicists” and seem to them “piecemeal and patched together”. The Model when applied directly leads to nonsensical predictions. A process called re-normalization is used to make them sensible. One of its limitation is an inability to explain dark matter. However, this Model provides the best answers to the phenomena we witness in the universe.
The fourth lesson also introduces an important concept. It introduces us to a “world of happenings, not things”. He explains:
The nature of these particles, and the way they move, is described by quantum mechanics. These particles do not have a pebble-like reality but are rather the ‘quanta’ of corresponding fields, just as photons are ‘quanta’ of the electromagnetic field.
Carlo Rovelli, Seven Brief Lesssons in Physics, Fourth Lesson, pp 30, 2015, translated into English by Simon Carnell and Eric Segre
The fifth lesson introduces us to a conundrum in the world of physics. General Relativity is our best theory that explains things at the cosmic scale and which led to the development of fields like Cosmology and Astrophysics. Quantum Mechanics provides our best theory that explains things at the quantum scale and led to the development of fields like atomic physics, nuclear physics, physics of condensed matter, etc. However both these fields do not agree with each other.
Many theories are being postulated to try and bring these two laws together and fit them together. The author himself is part of such an effort called Loop Quantum Theory. He is part of one of several groups trying to integrate the two theories.
The sixth lesson deals with concepts of heat that I was not aware of. The nature of time is dependent on nature of heat.
The difference between past and future only exists when there is heat. The fundamental phenomenon that distinguishes the future from the past is the fact that heat passes from things that are hotter to things that are colder.
Carlo Rovelli, Seven Brief Lesssons in Physics, Fourth Lesson, pp 51, 2015, translated into English by Simon Carnell and Eric Segre
He then says that the answer to why heat flows from hot bodies to clod bodies is very simple. It is just probability. The rest of the chapter flows from probability towards the concept of the heat of black holes. This still unanswered question brings together the field of quantum mechanics, general relativity and thermal science.
The book is a lot of information to take in about 79 pages. Even writing this review of the book took me more than a week. I don’t think I have done justice to the book. But, writing more would have become the equivalent to just writing the book here. What I have sought to do here is to try and build an outline of the book and introduce you to the mysteries that pulled me towards reading the book.
This is a book that provides a simple, deep understanding of the Physics of the twentieth century. It helps you understand where we stand and throws a light on where we are headed.
[It took me well over a week to write this all down. The best way to digest this information is to consume it in podcast form and read the transcript for clarity. I thought the podcast was so information-packed that it took me 19 revisions and 2785 words to put this all down. I started with in-depth exploration in the beginning but took to compressing ideas into paragraphs later. There’s still a lot that I don’t understand about the subject. Writing this also kept me away from writing any other post in the meanwhile. My thanks to Mat Kaplan for this wonderful interview. – Pradeep]
Paul Davies is the Regents’ Professor of Physics and Director of the Beyond Center for Fundamental Concepts in Science at Arizona State University. He is a physicist, cosmologist, astrobiologist and author who has written thirty books.
Kaplan first tries to understand the context in which this book is written. There is a fundamental difference that we see in Living Matter and Non-living Matter. Davies suggests that this fundamental difference is information. He gives us an equation to understand this:
Life = Matter + Information
Davies suggests that the present Physics cannot provide a solution for helping us understand this issue. We need or need to discover a new Physics to understand the problem. We need to dive back into some history for this context.
History of Context
The hero of this story is Erwin Schrodinger (famous more for his thought experiment with a cat). Schrodinger is an Austrian who succeeds Max Planck in 1927 in Berlin. In 1933, he leaves Germany and moves to England. He is invited to Ireland to establish Institute for Advanced Studies in Dublin by the then Prime Minister of Ireland, Éamon de Valera. He moved to Clontarf, Dublin as Director of the School for Theoretical Physics in 1940. He stays here for another 17 years. Ireland is neutral during World War II. He gives what are a string of lectures about life (in the biological sense). Davies calls Biology the next frontier of Physics.
Schrodinger is the architect of Quantum Mechanics. His theory works really well for non-living matter. It explains almost everything from atoms to stars. Where it does not explain things is when it comes to living matter. In 1944, these are compiled into a book called What is Life? This book has an immense influence on the field of molecular biology.
In 1944, he wrote What Is Life?, which contains a discussion of negentropy and the concept of a complex molecule with the genetic code for living organisms. According to James D. Watson’s memoir, DNA, the Secret of Life, Schrödinger’s book gave Watson the inspiration to research the gene, which led to the discovery of the DNA double helix structure in 1953. Similarly, Francis Crick, in his autobiographical book What Mad Pursuit, described how he was influenced by Schrödinger’s speculations about how genetic information might be stored in molecules.
Davies says that biologists however got distracted and involved in the field of molecular biology and lost track of the bigger picture. In the past two decades, the focus has gone back to the bigger picture.
Information is the secret sauce…
What differentiates non-living matter and living matter is the information. Davies says that the use of the word information here differs significantly from the way we talk about information in our daily life. He says that when defined in Physics, information becomes a part of the laws of physics much like energy does. Information enters Physics through the Laws of Thermodynamics.
Here, we go further into the past. We go to the mid-nineteenth century. James Clerk Maxwell who was working on concept of heat at King’s College in London. In a letter he sent to a friend, he asked that his friend consider a diminutive being that could see and follow molecules. The being could then use a shutter mechanism to sort fast and slow moving molecules. Slow and fast moving molecules determine temperature. So, by sorting the molecules, the being has created a difference in temperature. An engineer could, in principle create an engine that could do work. This being that Maxwell discusses is called Maxwell’s Demon. It is this demon that the title of Davies book references in the title of his book.
Maxwell’s suggestion created a perpetual motion machine, in effect and went against the First Law of Thermodynamics. In the podcast, Davies says it goes against the Second Law but then describes it as, “We can’t get something for nothing”. I think he’s going after the First Law. Maxwell’s thought stood as a thorny issue in Physics for a long time.
However, in the last two decades, scientists have been able to create these Maxwell demons at the nano level. However, they have not yet been able to scale it up. However, this introduces information into the realm of Physics.
The Laws of Thermodynamics predicts that entropy (the level of chaos or disorder) in a system goes on increasing. However, information seems to reverse this trend in living systems. In the words of Schrodinger, “Order from order, evermore order.” This, is used as an example of a miracle.
However, Davies suggests that order in living systems is paid for by disorder in the environment. And so, overall, things are balanced. He says living beings are open systems. In Thermodynamics, that means a system that allows transfer of energy and mass.
Davies then jumps to the life at molecular level where Davies says that Maxwell demons are working to get the most thermodynamic efficiency in living systems. He now gives examples of this nearly 100% efficient Maxwell demons enabling replication of the DNA. The most exciting example that Davies cites for this efficiency is the human brain. A megawatt capability supercomputer is operating at such efficiency that it works at the energy level of a dim light bulb.
Original World Wide Web
In Biology, Davies says, information also plays a managerial or supervisory role. Information flow scales up from signalling (chemical, mechanical and electric) mechanisms between cells, to decision making among insects, to co-ordination between birds in a flock all the way up to the planetary scale. Another key Davies line spoken here is,
And I like to say that the biosphere is the original worldwide web.
A New Physics
Davies says that the information flow in biological systems is more than just simple information flows. He says that information is encrypted and has to be decrypted for use by cells. Information has to be read and expressed in a certain way and biological systems express this. Physicists have not found a way to incorporate this into Biology and hence, this is where Davies think the New Physics that he thinks is required will come from. Information makes a difference to the way that an organism behaves. Davies thinks this has a physical effect.
Davies now arrives at the topic of complexity of biological beings. Kaplan discusses his high school biology experience of the complexity involved in a single cell. Davies responds by saying that scientists don’t have a way to measure the complexity at say the level of the biosphere or even the organism. He says we don’t yet know if the complexity increased with time or is there a fundamental law that defines the growth of complexity and other problems related to Complexity. However, he says at the root of it all are atoms, whose Physics we know well.
[To me personally, there seems to be a relationship between Complexity and Entropy.]
Davies says however that talking about things at the molecular level and then seeking to get answer about complexity has a parallel in the world of computer science. A scientist trying to explain complexity in terms of molecules would be like a software engineer trying to explain his code at the level of electrons flowing through computer hardware. Davies says that there are people like Paul Nurse who are seeking to explain Complexity in a language and precise terms of code that software engineer uses.
Kaplan asks about the change in our understanding genes express themselves as the understanding of DNA not as a ROM but as a read/write memory. Davies says that there has been a change in Biology in the last 30 years. He says that people have moved away from the assumption that genetics alone explains life. Expression of the genes also plays an important role. This is explored in the field of Epigenetics.
Things like an external physical force, physical environment, growth of cell in space, etc. seem to affect how the genes express themselves and this has an impact on how cell structure or the organism grows and develops. So, genes are somehow expressing themselves differently based on the information about their surroundings.
Davies cites the work of Cheryl Nickerson at Arizona State University in the impact of gut bacteria in astronauts. He says that the bacteria that are passive on Earth’s surface somehow get active in the environment of weightlessness and makes an astronaut throw up.
Davies also cites the work of Mike Levin at Tufts University who works with planaria worms. He says that planaria worms are cut at different parts of the body and they grow back up in the correct way. He says that using electrical patterning, they are able to grow worms with two heads, two tails etc. He says this proves that something more than just genes has a role to play in the way genes express themselves.
Davies says that Physics inherently has a bottom up structure of explaining things. Biology, on the other hand, explains things both ways, in terms of bottoms up and from the up down to the bottom. He says that Physics needs a way to do this. Davies says that thinking of information flows may be the simplest way of doing this. A cell gets information about its environment from the organism and changes the way it expresses itself. Things like electronics and gravity seem to affect the expression of the genes of a cell.
As an example, Davies says that in eukaryotic cells, the genes are in the chromosomes. There is complex structure and mechanism within the chromosomes that switches on and off the genes that get expressed depending on the environment.
Darwin suggested that the mutation in the organisms that evolved was random. Davies suggests it is not. He says that at the cellular level, that the way cells edit their genes have been shown to be statistically non-random. He says that Epigenitics explains the new biology much better than Darwin’s theory. He says Epigenetics is to Darwin’s theory what Einstein’s Physics is to Newton’s Physics. He says that Science replaces with even more approximate views of the World.
Davies has a special interest in our ways of curing cancer. He says that in the beginning about 2 billion years ago, only single cell organisms existed. Their only job was to replecate endlessly. At some point in time, multi-cellular organisms came into existence. There is a contract of sorts between the cell and the organism. Cells perform specialised functions and in exchange the organism exists. He says Cancer is a return to single cellular nature of the cell, a breaking of the contract in multi-cellular organisms.
He says current treatment of Cancer targets the uncontrolled replicability of the cells. However, cells have learnt over 2 billion years how to overcome obstacles placed in the replicability of the cells. They learn to overcome radiation and there could possibly be chemotherapy resistance.
Davies suggests the ideal way to think of treatment of cancer is to “reason” with the cell. The cell does not realise that its replication while good for the cell, is bad for the host and could eventually lead to it getting killed. Davies suggests that one has to download a patch or reboot the system in order to manage the Cancer, in a way similar to Diabetes. In the end, its a way of making the cells behave better. This hasn’t been done in practice. It’s still all theory.
Quantum Biology is a field that has come into existence in the last 10-20 years. Life exploits quantum mechanics for little quirks. Davies sits on the fence about whether there is space for quantum biology. They’re currently at a place where they could be at the tip of the iceberg or it could be just small quirks of living beings.
The issue with quantum biology is the lack of ease of doing experiments. Davies says that there is a lot of thermodynamic noise in systems at room temperature. He says that’s the reason why quantum mechanics experiment happen at very low temperature. Here the effects are clearly visible. Not so much at room temperature. Also quantum mechanics involves simple systems but life is a very complex system.
Photosynthesis as an example of Quantum Biology
Photosynthesis is the process by which plant uses sunlight to break water molecules to create energy for the plant. However, what has been noticed is that there is some molecular distance between the place where solar energy is captured and where the break of the water molecule happens. Energy to break the molecule has to be transported with minimum loss of energy. It has been found that this transmission takes place using a principle called quantum coherence. Study in this field was begun and is ongoing under Graham Fleming at UC Berkley.
Consciousness and Quantum Mechanics
It is thought that Quantum Mechanics will either explain consciousness or it will not. Thinking currently is that at the quantum level, atoms live in a universe of multiple possibilities and parallel universes. However, when one brings in the act of observation, these multiple possibilities are brought into one defined reality by consciousness. There is also another school of thought that is looking at things from outside in and asking the question whether quantum effects exist in the brain. People like Roger Penrose at Oxford University and Stuart Hameroff at the University of Arizona are working to figure out whether there are quantum goings-on in cells and more importantly in the human brain that explains consciousness. Davies says that personally he is skeptical but open-minded about the possibilities.
Davies suggests that a quantum pathway could be a possibility for explaining the link between non-living molecules to living molecules.
It is believed that one of the possible origins of life on Earth is in the depths of the ocean. It is kilometers below the surface of the ocean where perhaps even sunlight would not reach it. Davies suggests that life discovered the use of quantum coherence discussed above in these depths and improved and perfected it when it reached the surface. Other possibilities include origin of life outside Earth with comets and meteorites seeding the planet.
Phylostratigraphy is a new field of study where it is believed that genes can be dated. There are ancient genes and some recently evolved genes. It sheds light on how life evolved on the planet.
Miller Urey experiments
Chemists have been trying to cook up life in laboratories by mixing various organic chemicals but without any luck. Stanley Miller tried to experiment using simple organisms from chemical substances. Davies thinks this is a stretch and the wrong way to do things.
How does life code?
Davies says that the real question is how does life code. Going back to the computer analogy, he thinks that life is the software which codes. It’s the way which life processes information. He believes that this is the boundary between non-life and life. But there is no answer as to how these cells learn how to code. Cells store information, process information and encodes this information and passes it on.
New ways of thinking
Davies suggests that life is so complex that we need new ways of thinking about life to break this code. His way of thinking is to think about parallels with the world of computers.
His craziest paper has been a submission to a journal Nature on the quantum origin of life. He suggests that the original code existed on an interstellar dust of grain existing at 3 degrees above absolute zero, the temperature that existed in the cosmic microwave background. He suggests that life code existed here and coded in q-bits. It made copies that got stored in organic molecules that seeded Earth and is possibly seeding other planets as we speak.
Davies suggests that such crazy ideas are necessary as we think about that jump from non-life molecules to living organisms.