Max Tegmark is a very interesting person, obviously very intelligent, interested in mysteries and the unexplainable, and has a great deal of open-minded imagination. That makes him a machine of ideas and theories about our universe. His determination is impressive. When he finds an obstacle, he writes a new computer program to be able to analyze data, or builds a groundbreaking kind of telescope - an omniscope, involving a method called 21 cm cosmology - to be able to continue his research.
This book brings out the physicist in you. Tegmark mixes equations and explanations with the big, existential questions. Sometimes the book is on the verge of philosophy, which only makes physics more beautiful. What are we, really? What makes us aware of everything and ourselves? Do we exist or are we just Boltzmann brains? (A self aware entity, existing due to fluctuations in space, according to quantum mechanics). What is reality? Is time an illusion? In which universe do we live? What does the world really look like? How accurate is our view when we depend on photons? (In the dark, we see nothing. Different materials absorb different light waves and the colour we see seems to be the one not absorbed. Much of the reality is hidden from us, like other dimensions).
This is some of the themes discussed in the book.
* Time is a fascinating dimension, belonging to the four dimensions of our universe. The speed of time moves differently depending on the whereabouts of the observer. Near a black hole, it goes faster. We are able to see almost 14 billion years back in time, when viewing the cosmic radiation created 400 000 years after the Big Bang.
* Hydrogen gives off radio waves with a wavelength of 21 centimeters. Since the waves reaches earth are stretched out by the expending universe, the length of them reveals how far away they come from. Since distance is a factor of time, that also reveals how old they are. It's called 21 cm tomography. It's a current scientific activity and physicists around the world are trying to track the signal from the places farthest away.
* Without three dimensions and time, woven together in a cosmic fabric of spacetime, life wouldn't exist, but according to Tegmark, we are not unique. Because of his theory about multiple universes, everything that can happen, will happen somewhere.
* According to Tegmark, there are universes on four levels. Our universe is on the first level, and is represented by how far we are able to see, or the light that has reached us in 14 billion years. Beyond that, there are other universes that we can't see. The universes on level two are a consequence of a great expansion happening before Big Bang, called the inflation theory. These universes have different physical rules depending on inflation and early fluctuations. Universes on level three are coming from quantum physics. Universes on level four are made of every mathematical structure there is. Every equation happens somewhere, and imagination is the limit.
* According to quantum physics, there are endless copies of you that have your memories and think they are you. When you gamble, somewhere one of you win, and one of you loose. There are no luck, there are only different outcomes. When you feel immortal, it means the number of you have diminished. When you feel lucky, the number of you have increased.
In one chapter, the apocalypse is discussed and five alternatives for the universe apocalypse are introduced. They are called Big Chill, Big Crunch, Big Rip, Big Snap and Death Bubbels. The theories have to do with the expanding or eventual compressing of the universe. When considering an apocalypse within a billion years, Tegmark thinks the sun is the big threat. He almost dismisses the idea of an invasion from intelligent life in our galaxy, since the probability of a planet with intelligent life existing within our galaxy, considering the immense size of the rest of the universe, is almost non-existent. (In the same way, one could argue that mankind will not live for billion years. The probability of us being born so early in that kind of time-line is very small). Many planets are inhabitable, but are still not inhabited. Many planets are older than earth, and if there were intelligent life somewhere in our galaxy, some of them would probably already have colonized the universe. Or, perhaps they already have?
In the near future, however, the existential risks are the biggest threat, considering nuclear weapons and the fact that we eventually might build an intelligent computer, which earns some egoistical person much money and leaves the rest of the world in poverty. The artificial intelligence might be well beyond ourselves, and learn how to evolve without us, which makes us superfluous and ultimately might lead to our extinction. We should be grateful to what we have and not waste it. We should be able to save ourselves and our planet with knowledge. Tegmark thinks that scientists have failed to educate people and have to improve their information distribution. Many people still think that mankind is only 10000 years old, and in 2012, twelve people were burned to death for witchcraft in Haiti. The lack of knowledge is dangerous and certain companies strive to maintain ignorance to profit.
Despite his successful career, Max Tegmark seems to be a very modest and humble man, fully aware of the risks of theories, and that research has turned out to be wrong before. That is why he has an open mind. His attitude and love for his work, his collegues and previous scientists is admiring. Perhaps scientists have to really love their work, be their work, to succeed. Often, they work day and night, struggling with their thesis and experiments, to be able to finally reach a conclusion.
Tegmark's view of the world is fascinating and very inspiring. He mentions facts that are very romantic, almost like poetry. Gold is produced when a star dies in a supernova explosion so violent and rare that, during a fraction of a second, it releases about the same amount of energy as every other star in our observable universe, together. The world needs school teachers like that. The only criticism might be the sometimes fast deductions in his arguments. It would have been nice with a few more sentences with distinct explanations about the consistency in some of the chapters.
The gigant distances, mystery, beauty and elegance of the universe often make us feel small and insignificant. We are not. First, we have a big decision to make. During our lifetime, the future of our planet is most likely to be decided, according to the book, and we will be remembered for it in the future. Second, as Tegmark so delicately puts it, the universe – which is a true art - is only beautiful because a conscious being can perceive it. We are probably the only intelligent beings in our galaxy, and if we weren't here, the beauty of the universe would be a waste of space. Instead of thinking the universe is giving meaning to us, we should think that we are giving meaning to the universe.