Endnotes
Note 1: The number of colors in a rainbow
- Quote: Because different frequencies of visible light are reconstructed by our brains as different colors, the circlet of light has varying color; the outside of the band of light appears red-orange, the inside is violet-blue, and yellow-green is in the middle.
- Endnote: The rainbow phib is that it contains six colors, or seven colors, or five colors, depending on whom you ask and what country they are from. But in fact, when we divide the rainbow into a finite set of colors, we are using a combination of language and perception to create categories that exist only in our brains. The rainbow itself has an infinite set of frequencies without divisions; in no sense is the set of colors finite.
- Discussion
Note 2: Infrared vs. heat
- Quote: This infrared light is easily absorbed by your body, causing your skin to become warmer and your heat-sensitive nerves to fire.
- Endnote: Any form of light causes heating if absorbed; heat is not uniquely connected with infrared light, despite what some schoolbooks may say. It’s true, however, that most warm objects around us, including people, coffee, and engines, are too cool to glow in visible light but glow readily in infrared frequencies.
- Discussion
Note 5: More on the Cosmic Microwave Background
- Quote: For these reasons, I will mostly relegate the CMB to side comments and endnotes. We shouldn’t forget about it, but it doesn’t affect the main conceptual points of this book.
- Endnote: I don’t want the CMB to become a distraction, but I also don’t mean to sweep the issue under the rug. I’ve put a thorough discussion of the CMB and its interplay with relativity, explaining why it doesn’t affect this book’s lessons, elsewhere.
- Discussion (same as for chapter 3, endnote 1)
