# Strangeness

In particle physics, strangeness S is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic reactions, which occur in a short period of time. The strangeness of a particle is defined as:

where represents the number of strange quarks (s) and represents the number of strange antiquarks .

— Wikipedia on Strangeness

2010.07.18 Sunday ACHK

# The Time Traveler’s Wife

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The Time Traveler’s Wife, published in 2003, is the debut novel of American author Audrey Niffenegger. It is a love story about a man with a genetic disorder that causes him to time travel unpredictably, and about his wife, an artist, who has to cope with his frequent absences and dangerous experiences. Niffenegger, frustrated in love when she began the work, wrote the story as a metaphor for her failed relationships.

She has said the story is a metaphor for her own failed love affairs and that “I had kind of got the idea that there’s not going to be some fabulous perfect soulmate out there for me, so I’ll just make him up.”

Instead, as critic Marc Mohan describes, the novel “uses time travel as a metaphor to explain how two people can feel as if they’ve known each other their entire lives”.

— Wikipedia on The Time Traveler’s Wife

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2010.07.18 Sunday $ACHK$

# Displacement-distance graph 2

「Longitudinal wave」（縱波）的意思是，wave medium（波介質）的物質粒子的振動方向，和該個 wave （波動）本身的移動方向，互相平行。例如，假設這個 wave 是向右移動的話，粒子 A 就會左右振動。

the wave itself

「位移 – 距離 圖」的意思是，把 wave 上的每一粒粒子的「位移」和「距離」畫成一個 xy 圖（座標圖）。

x 座標 的讀數為「距離」。「距離」的意思是，「wave 中的 一粒粒子 和 第一粒粒子 的距離」。對於粒子 A 來說，「距離」是 ，因為 是粒子 A 和第一粒粒子（粒子 O）的距離。

y 座標 的讀數為「位移」。「位移」的意思是，「wave 中的一粒粒子 當時的位置 和 它自己的平衡位置（equilibrium position）的差別」。對於粒子 A 來說，「位移」就是 ，因為 是粒子 A 當時的位置 和 它自己的平衡位置（ ） 的差別。

displacement-distance graph

the wave itself

displacement-distance graph

— Me@2010.07.17