Max Tegmark

"(…) the bottom line is that if you believe in an external reality independent of humans, then you must also believe that our physical reality is a mathematical structure. Nothing else has a baggage-free description. In other words, we all live in a gigantic mathematical object—one that’s more elaborate than a dodecahedron, and probably also more complex than objects with intimidating names such as Calabi-Yau manifolds, tensor bundles and Hilbert spaces, which appear in today’s most advanced physics theories. Everything in our world is purely mathematical—including you."

"Here... is the Schrödinger equation [i \hbar \frac{d}{d t}\vert\Psi(t)\rangle = \hat H\vert\Psi(t)\rangle]... and what its actually saying is that the state of the world, thats this Greek letter Ψ there with the bracket around it... Its saying that the rate of change of it... depends on the current state of the world, when you do this operation on it and for the math nerds, this is a linear operation... and what that just means is, as Everett has pointed out and many others have known for a very long time is that, in some circumstances, two different solutions to this can do their parallel thing. We can talk at... length about the discoveries... about decoherence and why it is that sometimes these different parallel branches are unaware or each other, but my point is... if you give a science nerd colloquium... at a physics department... ideally, you should also start in the same way you start discussing this with your grandma. Just at a very high level... here are the cool ideas, and then you can go as deep as the audience or the listener wants, from there."

"(…) no spectator is needed, because your consciousness basically is your reality model. I think that consciousness is the way information feels when being processed in certain complex ways. Since the different parts of your brain interact with each other, different parts of your reality model can interact with each other, so the model of you can interact with your model of the outside world, giving rise to the subjective sensation of the former perceiving the latter."

"Evolution endowed us with intuition only for those aspects of physics that had survival value for our distant ancestors, such as the parabolic orbits of flying rocks (explaining our penchant for baseball). A cavewoman thinking too hard about what matter is ultimately made of might fail to notice the tiger sneaking up behind and get cleaned right out of the gene pool. Darwin’s theory thus makes the testable prediction that whenever we use technology to glimpse reality beyond the human scale, our evolved intuition should break down. We’ve repeatedly tested this prediction, and the results overwhelmingly support Darwin. At high speeds, Einstein realized that time slows down, and curmudgeons on the Swedish Nobel committee found this so weird that they refused to give him the Nobel Prize for his relativity theory. At low temperatures, can flow upward. At high temperatures, colliding particles change identity; to me, an electron colliding with a and turning into a Z-boson feels about as intuitive as two colliding cars turning into a cruise ship. On microscopic scales, particles schizophrenically appear in two places at once, leading to the quantum conundrums... On astronomically large scales... weirdness strikes again: if you intuitively understand all aspects of black holes... put down this book and publish your findings before someone scoops you on the Nobel Prize for quantum gravity… [also,] the leading theory for what happened [in the early universe] suggests that space isn’t merely really really big, but actually infinite, containing infinitely many exact copies of you, and even more near-copies living out every possible variant of your life in two different types of parallel universes."

"... I would rather have questions that I cant answer than answers that I cant question. (variation of a remark by Richard Feynman)"

"Eratosthenes... knew that the Sun was straight overhead in... Syene at noon on the summer solstice, but that it was 7.2 degrees south of straight overhead in , located 794 kilometers farther north. He concluded... 794 kilometers corresponded to 7.2 degrees out of the 360 degrees... around Earths circumference, so that the circumference must be... 39,700 km..."