Reality Is Not What It Seems by Carlo Rovelli
Rating: 9/10
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One Sentence Wrap-Up
The nature of our reality made easier to understand, with complex concepts explained ranging from special relativity; general relativity; blackholes; spacetime; quantum mechanics to loop quantum gravity, as developed by renowned philosophers and / or scientists Aristotle, Albert Einstein, Michael Faraday and Higgs, etc.
Summary Notes
After reading this book, I regretted that I did not consider the 'why' when I was studying my engineering degree. I have come across a lot of the theories from the book but I was so focused in cramping in the 'how' that I failed to appreciate the 'what' - i.e. the wonders of the ways in which the theories linked together, over time, to provide our current view of reality.
This book provided me the 'what' by consolidating the seemingly separated scientific theories into one coherent landscape.
The author dives into theories that the general readers would have heard of, but would not understand exactly what they are or their contributions to the progress of science. The best part is that he does so without getting entangled with mathematics! Despite that mathematics IS the language of nature it could get overly complex, thus losing the interest of the general readers very quickly (including myself). I appreciate that the theories were explained in a concise and clear manner such that I could grasp the significance of their findings and understand how they relate to our world.
Philosophers / Scientific theories touched upon include (not an exhaustive list):
- Plato / Aristotle
- Democritus
- Brownian motion
- Newtonian physics
- Electromagnetism
- Special relativity
- General relativity
- Bohr's atomic model
- Quantum mechanics
- Loop quantum gravity
In addition, the author attempts to link the theories and denote the key scientific developments over time, back from the ancient Greek philosophers and the Roman poet Lucretius to the present day. Who would have thought that the formulation of an atomic theory was done by the Greek philosopher Democritus back in ~400 BC! I held the view that we as a specie knew very little about our world before the scientific revolution, which to some extent still stands, however I understand now that we would not get to where we were without the work by the ancient thinkers. This brings me back to the famous myth by Plato in The Republic, in which some men are chained to the bottom of a dark cave facing the wall, and could only see shadows cast upon the wall by a fire behind them. They think the shadows are reality, when in fact, there is a wider world just outside the cave. The chained man is me, or us, with our limited capacity to understand the world around us due to the lack of knowledge; our preconceptions; and the restrictions of our senses.
Key Lesson Learnt #1 - Science is not based on certainty: it is because we can falsify theories or prove them to be uncertain that science has its merits
Science is never certain and that is why it is valid. We developed our scientific approach which consists of building a hypothesis; proving them via repeatable and numerous experiments and questioning ourselves of its validity even after it has been accepted widely. This approach is the reason why we have such accelerated progress in understanding the nature of our reality.
In the case of myths and stories, they cannot be falsified and can be quickly altered depending on the circumstances, unlike scientific theory in which a slight alternation could render it inapplicable.
Key Lesson Learnt #2 - The constructs of our world is beyond our limited knowledge and experience
This screen-cap is lesson #2 in a nutshell...
Special mentions to the following, which threw me out of my comfort zone as they changed how I should see the world, and how much my senses fool me.
- Space and time are not separate dimensions. Spacetime is one. There is the possibility that time does not exist but is in fact, our approximation of the world around us.
- The earth is traveling at 227 km/s as it orbits around a supermassive blackhole at the centre of the galaxy. The blackhole itself is ~4 million times the volume of our sun!
- The sci fi nature of blackholes and the bizarre facts behind them (e.g. having a point of no return or event horizon; acting as time machine to the future).
- Time stops once we reach the speed of light, but mass increases to infinite given Einstein's equation E = mc2.
- We do not know how big our universe is, or whether there are multiple universes. We know the size of our observable universe (~45 billion light years), but there is an unobservable universe in which light has not reached earth yet, thus we could not observe them.
- We are limited in our senses. We cannot see many of nature's phenomena (e.g. moving particles with their protons, electrons, etc.) Instead, we observe averages (e.g. heat). Mathematics is the language of nature.
- The beginning of the universe might be a result of a Big Bounce instead of a Big Bang based on quantum gravity.
Favourite Quotes (Or Sections!)
But the leap made by Einstein is unparalleled: space-time is a field; the world is made only of fields and particles; space and time are not something else, something different from the rest of nature: they are just a field among the others.
What is a wave, which moves on water without carrying with it any drop of water? A wave is not an object, in the sense that it is not made of matter that travels with it. The atoms of our body, as well, flow in and away from us. We, like waves and like all objects, are a flux of events; we are processes, for a brief time monotonous…
To the very last, the desire to debate, to understand more. To the very last, doubt. This permanent doubt, the deep source of science.
These quantum fields make up atoms, light and the full contents of the universe. They are strange objects: their quanta are particles that appear when they interact with something else; left alone, they unfurl into a 'cloud of probability'. The world is a swarming of elementary events, immersed in the sea of a vast dynamical space which sways like the water of an ocean.
These fields do not live in spacetime; they live, so to speak, one on top of the other: fields on fields. The space and time that we perceive in large scale are our blurred and approximate image of one of those quantum fields: the gravitational field.
The bounce of a collapsing star can be very fast, if watched from down there. But - remember - time passes much more slowly there than outside. Seen from the outside, the process of the bounce can take billions of years. After this time, we can see the black hole explode. In the end, basically, this is what a black hole is: a shortcut to the distant future.
In this space - between the size of the minute quanta of space, up to quarks, protons, atoms, chemical structure, mountains, stars, galaxies (each formed by one hundred billion stars), clusters of galaxies, and right up until the seemingly boundless visible universe of more than 100 billion galaxies - unfolds the swarming complexity of our universe; a universe we know only in a few aspects. Immense. Finite.
The only truly infinite thing is our ignorance.
The search for knowledge is not nourished by certainty: it is nourished by a radical distrust in certainty.
It is a world which does not exist in space and does not develop in time. A world made up solely of interacting of interacting quantum fields the swarming of which generates - through a dense network of reciprocal interactions - space, time, particles, waves and lights.
A world without infinity, where the infinitely small does not exist, because there is a minimum scale to this teeming, beneath which there is nothing. Quanta of space mingle with the foam of spacetime, and the structure of things is born from reciprocal information which weaves the correlations between the regions of the world. A world which we know how to describe with a set of equations. Perhaps, to be corrected.
