SEVEN BRIEF LESSONS ON PHYSICS

 스티븐 호킹의 책을 읽고 물리학, 특히 천체물리학에 관한 책을 찾다가 발견한 책이다. 사실 이 책의 선전에는 상당히 난해한 주제를 상당히 쉽게 설명한 책이라는 문구가 있다. 어느 정도는 맞는 얘기이지만 이 책도 만만치는 않다. 다만 100% 이해했다고는 말할수는 없지만 작가의 노력에 맞추어 나름 열심히 읽은 책이다.. 새롭게 배울수 있는 내용들이 많았다.

내용은 The Most beautiful of Theories, Quanta, The Architecture of the Cosmos, Particles, Grains of Space, Probability, Time and the Heat of Black Holes 다.

 

- It isn't only space that curves ; time does too. Einstein predicted that time passes more quickly high up than below, nearer to the Earth. This was measured and turned out to be the case. If a man who has lived at sea level meets up with his twin who has lived in the mountains, he will find that his sibling is slightly older than him .........

-Light is made of packets ; particles of light. Today we call these 'photons'.

- The theory describes a colorful and amazing world where universes explode, space collapses into bottomless holes, time sags and slow near a planet, and the unbounded extensions of interstellar space ripple and sway like the surface of the sea ........ cosmic background radiation ... Big bang ..

- Genius hesitates.

- Without quantum mechanics there would be no transistors. Yet they remain mysterious.

- To the very last, the desire to challenge oneself and understand more. And to the very last ; doubt.

- Scientific thought is fed by the capacity to 'see' things differently than they have previously been seen.

- Light is made up of photons, the particles of light intuited by Einstein.

- Everything we tough is therefore made of electrons, and of these quarks.

- Loop quantum gravity is an endeavour to combine general relativity and quantum mechanics.

- Why does heat go from hot things to cold things, and not vice versa ? It is a crucial question, because it relates to the nature of time. In every case in which heat exchange does not occur, or when the heat exchanged is negligible, we see that the future behaves exactly like the past.

-As soon as there is heat, however, the future is different from the past.

- It is not impossible for a hot body to become hotter through contact with a colder one ; it is just extremely improbable.

- What is the 'present' ? We say that only the things of the present exist ; the past no longer exists and the future doesn't exist yet. But in physics there is nothing that corresponds to the notion of the 'now'.

- Physicists and philosophers have come to the conclusion that the idea of present that is common to the whole universe is an illusion and that the universal 'flow' of time is a generalization that doesn't work. People like us, who believe in physics, know that the distinction made between past, present, and future is nothing more than a persistent, subborn illusion.

- Our thoughts and our speech exist in time ; the very structure of our language requires time ..

- The German philosopher Martin Heideger emphasized our 'dwelling in time'.

- The universe would be a single block of past, present, and future.

- Using quantum mechanics Hawking successfully demonstrated that black holes are always 'hot'. They emit heat like a stove.

- In the big picture of contemporary science there are many things that we do not understand, and one of the things which we understand least about is ourselves.

- As our knowledge has grown we have learnt that our being is only a part of the universe, and a small part at that.

- on the edge of what we know, in contact with the ocean of the unknown, shines the mystery and the beauty of the world. And it's breathtaking.