CHAPTER 6

Implementing at Pace

The Speed of Light at the Center of the Sun

It takes a photon of light a little over 8 minutes to reach the earth after it leaves the sun’s surface. In the vacuum of space, the photon literally travels at the speed of light over the 150-million-kilometer journey. But doesn’t light always travel at that velocity? Well, not quite, as it turns out.

The center of the sun is incredibly densely packed with hydrogen and helium atoms—even more densely packed than shoppers at Macy’s at the start of the seasonal sale!—and this means that the photon cannot escape quickly at all. Each photon’s energy is repeatedly absorbed and released by these atoms, creating a path of travel that scientists call a “drunkard’s walk” of 700,000 ...

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