barney@napier:~/books$ cat seven-brief-lessons-in-physics.md
Seven Brief Lessons in Physics
Carlo Rovelli
★ ★ ★ ★ ☆ 4/5
read: 2017-06-28
non-fiction · #physics
A modern take on the fundamental lessons of the physical world.
Most beautiful Theory
- Einstein discovered that the gravitational field IS the space Newton talked about
- Cosmic background radiation from the big bang (explosion of a small overheated universe that made our large ever expanding one) is proof of the big bang
Quanta
- The idea of light as photons (packets of energy)
- Werner Heisenberg devised the idea that electrons only exist when being interacted with, and that when not so, they are simply a calculable probability, this helped with the quantum leap theory/idea
- Quantum mechanics is using the idea that no object has a definite position unless colliding with something else
- To this day we cannot prove why this theory holds, we just accept it
Architecture of the Cosmos
- Corpernicus proved the earth wasn’t the centre of everything
- The universe began as a small ball and exploded into its current cosmic dimensions
- There are billions of planets out there just like Earth, as our galaxy is one of billions
- A grain of sand on a beach has more significance than our galaxy in the universe
Particles
- Quarks are glued together by gluons to make protons and neutrons
- Electrons quarks photons and gluons are the elementary particles that make up everything around us, they fluctuate between existence and non existence according to quantum theory
- “Standard model of elementary particles”
- There is a large cloud of dark matter surrounding every galaxy
- Dark matter is just something we know is there but don’t know what it is, and the standard model doesn’t explain it
Loop Quantum Gravity Theory
- Quantum mechanics and general relativity conflict each other but are both such good theories
- Loop quantum gravity theory says that space is made up of minute particles (atoms of space) that link together to give the texture of space
- The atoms of space are not in space because they are space
- This theory does not include time, everything moves on its own time scale and there is no universal passing of time
- A black hole is a rebounding Planck star that is expanding in extreme slow motion, if you were on the star of would seem fast as the lack of gravity speeds up time
- This theory says that the big bang was actually a bounce outward following a previous universe collapsing in on itself like a black hole for universes
Probability, Time and The Heat of Black Holes
- Heat is atoms vibrating more quickly
- Heat proves that time exists, without friction (heat transfer) a pendulum would fluctuate forever and if you played it in reverse would seem the same, but with friction you can tell the future (small fluctuations) from the past (larger fluctuations)
- Boltzmann discovered that heat moves from hot to cold due to probability. It is much more likely a fast vibrating particle hits a still one than vise versa, and due to the conservation of energy it gives energy to the still one
- We don’t know how gravitational field are affected by heat. How does space-time change with heat? It must vibrate but what does vibrating time look like
- We do not say that things not ‘here’ don’t exist so why do we say things not ‘now’ don’t exist? This confuses physicists
- Hawking proved black holes are always hot using quantum mechanics
- His theory combines all 3 main physics approaches, quantum mechanics, general relativity and thermodynamics
Ourselves
- “Integrated information theory” - theory about the structure of a system that makes it concious. What changes when we sleep etc
- To be free means to make decisions based on what’s going on in your mind. Not externally
- “Homo” species are characterised by being curious (humans, chimps, Neanderthals)
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