## Posts Tagged ‘7lessons0mg’

### iPad Notebook export for Seven Brief Lessons on Physics

December 10, 2016

Quotes from the book I particularly liked:

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In his youth Albert Einstein spent a year loafing aimlessly. You don’t get anywhere by not wasting time on something, unfortunately, that the parents of teenagers tend frequently to forget. He was in Pavia.

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The sun bends space around itself, and Earth does not turn around it because of a mysterious force but because it is racing directly in a space that inclines, like a marble that rolls in a funnel. There are no mysterious forces generated at the center of the funnel; it is the curved nature of the walls that causes the marble to roll. Planets circle around the sun, and things fall, because space curves.

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The difference between past and future exists only when there is heat. …

Boltzmann’s idea is subtle and brings into play the idea of
probability. Heat does not move from hot things to cold things due to an absolute law: it does so only with a large degree of probability. The reason for this is that it is statistically more probable that a quickly moving atom of the hot substance collides with a cold one and leaves it a little of its energy, rather than vice versa. Energy is conserved in the collisions but tends to get distributed in more or less equal parts when there are many collisions. In this way the temperature of objects in contact with each other tends to equalize. It is not impossible for a hot body to become hotter through contact with a colder one: it is just extremely improbable.

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### Georgi–Glashow model – Wikipedia

December 10, 2016

https://en.wikipedia.org/wiki/Georgi%E2%80%93Glashow_model

SU(5) theory predicting proton decay

### Quark – Wikipedia

November 24, 2016

https://en.wikipedia.org/wiki/Quark

QT:{{"
For some time, Gell-Mann was undecided on an actual spelling for the term he intended to coin, until he found the word quark in James Joyce’s book Finnegans Wake:

–Three quarks for Muster Mark!
Sure he hasn’t got much of a bark
And sure any he has it’s all beside the mark.

— James Joyce, Finnegans Wake[49]
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### Anaximander – Wikipedia

November 24, 2016

https://en.wikipedia.org/wiki/Anaximander

QT:{{"
Anaximander was the first to conceive a mechanical model of the world. In his model, the Earth floats very still in the centre of the infinite, not supported by anything. It remains "in the same place because of its indifference", a point of view that Aristotle considered ingenious, but false, in On the Heavens.[30] Its curious shape is that of a cylinder[31] with a height one-third of its diameter. The flat top forms the inhabited world, which is surrounded by a circular oceanic mass.

Anaximander’s realization that the Earth floats free without falling and does not need to be resting on something has been indicated by many as the first cosmological revolution and the starting point of scientific thinking.[32][33] Karl Popper calls this idea "one of the boldest, most revolutionary, and most portentous ideas in the whole history of human thinking."[34] Such a model allowed the concept that celestial bodies could pass under the Earth, opening the way to Greek astronomy.
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### Seven Brief Lessons on Physics: Carlo Rovelli: 9781524723385: Amazon.com: Books

November 20, 2016