From the July 2012 issue

Believe it?

September 2012: Sometimes the truth is just what you have the space and time to explain.
By | Published: July 23, 2012
I’m a liar. I can’t help it. Each page I write has something wrong to a degree and — no surprise — readers often catch on. “Two months ago, you wrote that the solar system is heading toward the star Deneb in Cygnus. But my textbook says we’re actually moving toward Vega in Lyra.”

That person was right. But so was I. How can two conflicting statements both be correct? That’s this month’s subject.

The Milky Way’s rotation swiftly carries the Sun and Earth toward Deneb. However, if one merely considers the 200 nearest stars around us in space, we have a separate little motion relative to them. This slow sideways drift is toward Vega; some say the constellation Hercules. Years ago, scientists only knew that local motion.
The problem — and it never ends — is limited space. If science writers pause to fully explain such facts, we’ll never get to the point of the article. Hence, much that appears in science magazines is true in just one sense. Falsehoods include the simplest “facts” everyone thinks they know.

For example, we say Earth rotates in 24 hours. However, our planet actually spins in 23 hours, 56 minutes, and 4.1 seconds. The discrepancy isn’t caused by rounding off. Clocks are deliberately built to include an extra few minutes of spin. This compensates for Earth’s orbital path, which places the Sun toward a new direction each day. If we want Sol to always be highest when clocks say noon, we must let Earth spin once completely and then add an extra 3 minutes and 55.9 seconds of rotation. Only then will we face the Sun at the same clock time the next day. Timepieces were thus designed to keep our lives aligned with the Sun. Don’t imagine that they register our actual rotation.

The sky is blue, right? Well, buy a spectroscope on eBay. This wonderful instrument reveals what’s really in the light we see. Point it at the daytime heavens. Bam — all the colors of the rainbow. Vivid greens and oranges come from the sky. Its composition resembles sunlight, but with red scattering four times less than blue, the latter color is visually dominant. So it’s not strictly correct to say, “The sky is blue.” It would be better to say, “The sky looks blue.”

But that’s probably too picky. After all, we happily say, “The Sun is rising,” despite knowing that “the horizon is falling” would be more accurate. We don’t want to sound stilted or obnoxious. Still, shouldn’t we draw the line when a statement is more wrong than right?

Much that appears in
science magazines is
true in just one sense.

Consider the expanding universe. Cosmic expansion would seem as straightforward as blowing up a party balloon. Actually, it’s not like that at all. Turns out, the cosmos inflates only on the largest scales, which itself is odd. Within solar systems, star clusters, individual galaxies, and among all the stars visible in the night sky, there’s no expansion whatsoever. You could travel 3 million light-years and not encounter the slightest hint of expansion. As a result, people are seriously puzzled. They ask how galaxies can possibly collide if the universe is expanding. Such confusion arises because we rarely mention that an “expanding universe” doesn’t apply to each cluster of galaxies and all its contents.
In water, light travels 25 percent slower than it would in a vacuum, making a spoon appear bent in a glass of the liquid. But does that mean light doesn’t have a constant speed? Hemera/Thinkstock
Another oft-repeated fact is that light has a constant speed. It’s true in a vacuum. But it goes 25 percent slower through most liquids, which is why a spoon seems bent in a half-glass of water. But is light really slower then? Kind of. It does take longer to pass through water. However, light photons still move at their previous superfast speed between water molecules. They’re absorbed and then re-radiated only when they hit atoms, and this process takes a bit of time. So are photons really moving slower within water or not?

Such nuances can’t be clarified in a few words. If I fully explain, any article will read like the legalistic “don’t use your new laptop in a hot tub” part of an instruction booklet. The alternative is to be flat-out wrong in some way. There’s no good solution.

Does Jupiter orbit the Sun? Actually, it orbits the barycenter where the jovian and solar gravities balance. Have you ever seen a meteor? Actually, you’ve seen only the glowing air around the seed-sized meteoroid.

Excessively condensed science is everywhere. You’ve always read that humans breathe out carbon dioxide. Turns out, we exhale roughly 78 percent nitrogen, 17 percent oxygen, 4 percent carbon dioxide, and 1 percent argon. We exhale far more oxygen than carbon dioxide. Performing mouth-to-mouth to fill someone’s lungs with our air would be pointless if there wasn’t a lot of oxygen in that offering.

It’s downright misleading to say, “Out-breaths are carbon dioxide.” Yet no science writer has ever to my knowledge taken the time to clarify this.

So next time you spot something suspicious, be aware that science prose is simplified for brevity and filled with trade-offs. (And, on this page, designed to sneak in some cool little-known facts.) Is everything totally true?

Yes, sure. Also, no.

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