I’m a liar. I can’t help it. One or two things I write each week is wrong to some degree. For example, I’ve said that light moves at the constant speed of 186,282.4 miles per second. But if I had more space, I might mention that this is only true in a vacuum, like in space. Light moves 25% slower through water and glass.
That’s why a spoon seems bent in a half-glass of water and why coke bottles were designed to make it seem to be holding much more than it really does. But is light really slower then? Well, it does take longer to pass through water. However, light photons actually still move at their previous superfast speed between water molecules. It’s just that each photon gets absorbed and then re-radiated each time it hits an atom, and this takes a bit of time. So is light really moving slower within water, or not? The answer is yes and no. If we fully explain such facts, we’ll never get to the point.
Since childhood, we’ve each “known” that Earth spins in 24 hours. But we actually rotate in 23 hours, 56 minutes and 4.1 seconds if we use any distant star as a nice stationary reference for our motion. Clocks are built to add an extra four minutes to compensate for Earth’s curved orbital path because the Sun appears in a slightly different direction each day, and what we most care about is how fast we rotate relative to the Sun. If we want the Sun to always be highest and due south when clocks say noon, we must let Earth spin around a bit more than a full rotation and that’s why clocks’ hands make a complete circuit in 24 hours on the nose. Don’t imagine that clocks register our true spin.
The overhead sky is blue, right? Well, it looks blue. But go to e-bay and buy a spectroscope, which reveals what’s really in light. Point it at the sky. Wham — all the colors of the rainbow. Vivid greens and oranges come from the sky. Its composition resembles sunlight, but with four times less red than blue, making blue dominate our vision when we look up. So it’s not strictly correct to say “the sky is blue.” It would be better to say, “the sky looks blue.”
Excessively condensed science is everywhere. We’ve always heard that “humans breathe out carbon dioxide.” In truth, we exhale 20 times more nitrogen and four times more oxygen than carbon dioxide. Our out-breaths are only 4% CO2. It’s downright misleading to say our exhalations are carbon dioxide. If true, then breathing into a drowning victim’s mouth to try to revive them would be pointless. In fact, breathing into another person’s lungs gives them just a bit less oxygen (16% vs. the 20% in fresh air) they normally receive. Yet science writers never clarify this.
And how many people are aware that meteorites are never hot when they land? Or that every visual image is an experience occurring within the skull, not something happening outside the body? And that the night’s visible stars are truly still there, since the odds of even a single one having died while its light was on route is 200-to-one against. (Stars live for billions of years whereas the time required for their light to travel to Earth is never more than a few thousand years.)
So be aware that science is almost always simplified, often to the point of being misleading. And that’s the truth. Sort of.
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