Zoom: From Atoms and Galaxies to Blizzards and Bees: How Everything Moves (37 page)

3. The former chairman of Columbia University’s astrophysics department, David Helfand, told me that he has used the waving fingers technique to “freeze” and observe the famous pulsar at the heart of the Crab nebula. It blinks on and off thirty times a second, far beyond a person’s ability to perceive it as anything but steady light. Yet Helfand made it blink by rapidly oscillating his hand—making a motion like that of fan blades—in front of the telescope’s eyepiece. Low tech, but it worked.

4. Modern movies display three of the same frame in a row, with moments of darkness between, then three images of the next frame, and so on, for a total of seventy-two images along with seventy-two momentary periods of darkness per second—even if there are only twenty-four different images presented each second. When this method is used, no one complains of seeing any flickering.

5. Iron rusting is a leisurely process because it requires fast-moving colliding atoms. In ordinary real-life situations, the average speed of iron atoms is too leisurely for reactions with oxygen to proceed. But at any given moment, a few atoms move faster than the group average, and it is these that continually create the oxidizing.

6. If increasingly heated metal glows red, then orange, yellow, and white, and if blue would be the next color if the substance didn’t first boil into gas, what happened to green? All the rainbow colors are represented except for green. Why? The answer, which also explains why there are no green stars, is that when green light is being maximally emitted the human eye sees it as white. That’s because, at that point, there are still copious red and blue emissions in the mix, and our retinas perceive white whenever those three primary hues hit us simultaneously. White is our green, in these cases.

1. One’s home is not always a safe house when it comes to lightning. I once carefully assembled firsthand accounts for a safety article published in 1984. The first was from a friend whose extended family gathered for Thanksgiving in Catskill, New York. Through the bay window, several of them saw lightning strike a large tree at the far end of the lawn. Immediately, a “ball” of lightning appeared at the base of the tree. It started to “roll” along the grass toward the window, coming right toward them. It briefly vanished from sight below the glass, but then, to their horror, all the seams in the drywall started to glow. Suddenly the dazzling ball was inside the wall and resumed its “rolling” across the living room. My friend said that his elderly aunt who hadn’t walked for years leaped out of its way as it went directly into the TV set, which exploded in a shower of sparks. For many long seconds, all was silent. Then his characteristically laconic father finally spoke. “I guess that takes care of that TV,” he said.

My second story involves a woman in the village of Saugerties, New York. This was a well-known incident in 1983. She said it happened on a day with a clear blue sky, before any storm could be seen. She was in her house when lightning explosively struck the roof, flinging a rain of asphalt shingles down the block. She was struck in the head in her living room, and the electricity exited her big toe, leaving a black burn. Though many of her teeth were shattered and she required months of rehabilitative care, she attributed her survival to the fact that she’d been wearing rubber flip-flops. I asked her if she was now afraid of lightning. “No; of course not!” she assured me. “It was a one-in-amillion event. I merely take the same precautions everyone does. I make sure I’m wearing flip-flops all the time, no matter what.”

2. None of the other sense-propagation velocities mattered. Or even earned attention. Few wondered how fast smells travel. (Actually, we have—in chapter 7. Along with the speed of neural impulses conveying the senses of touch and of pain, in chapter 11.)

3. When Galileo telescopically observed Saturn between 1610 and the 1630s, he described that planet—in words and pictures—as having handles on either side, like those of a sugar bowl. It took until Christiaan Huygens’s later observations, a full half century after Galileo’s, for the rings’ true nature to come to light. Why? Probably because here on earth there is not a single example of a ball surrounded by unattached rings. It lay outside human experience. Observers had a hard time seeing something that was without precedent. The same impediment may have prevented anyone from regarding lightning as preceding thunder. In the prefirecracker era, no one knew of any lights that produced sounds. Lightning would have been the first to do so.

4. Through air, sound moves only one way—by compressing and then decompressing the gas. In effect, it pushes along a disturbance in the air, which dampens down in time, thus explaining why sounds get fainter and less distinct as the distance increases. Sound’s so-called longitudinal waves, moving only in the direction of travel, are also present when sound goes through solids. However, in the latter case, a second wave exists, too. This is the up-and-down, or elastic, deformation of the material, usually called a shear wave or transverse wave, and it can actually travel at a different speed from the longitudinal wave—letting the listener receive two separate noises. The speed of shear waves in solids was calculated accurately by Isaac Newton in his all-purpose 1687 masterpiece, Principia. The speed is determined by the solid’s density, stiffness, and susceptibility to compression.

5. The wave-versus-particle furor reminds me of the old joke about the agreeable judge who never wanted to make anyone feel bad. After one side argued its case in his courtroom, he said, “You’re right.” Then the opposing side made strong antithetical arguments, to which the judge said, “You’re right!” Hearing this, the first plaintiff rose with exasperation and said, “But Your Honor, we’ve made opposing points. We can’t both be right!” The judge just smiled and said, “You’re right!” In the same way, the wave and particle evangelists are all correct.

6. Actually, for us to see white, the mix only has to include equal amounts of the primary colors—red, green, and blue. Unequal mixtures of any two or all three of these can create every other imaginable color. But the primary colors of paint and pigment are cyan, magenta, and yellow. Artists create other colors by mixing these, but unlike light, which requires only that more light of different wavelengths be added in order to change color, paint requires the subtraction of some of the light being reflected from the mixture in order to change color. A canvas doesn’t glow on its own. Rather, a picture is viewed in white light, and each of its pigments absorbs one or more colors present in the room’s light, so that what reflects to your eyes is the hue the artist wanted that spot to be. Thus adding further pigments subtracts more of the ambient light. In point of fact, each primary color of paint is composed of an equal mixture of two of light’s primary colors. That is, red and green light combine to create yellow light, and yellow is a primary color of paint. Similarly, red and blue light make magenta. Blue and green make cyan.

7. Could we have any advance warning of something arriving at light speed? No. In Star Wars–type movies, the hero’s spaceship skillfully dodges and weaves to avoid laser weapons and photon torpedoes. In reality there’s no way to anticipate the arrival of a light-based weapon’s pulses or rays, no way to “see them coming.” However, we would be able to detect reflections. So say the sun suddenly went dark. Although we wouldn’t see this happening ahead of time, we could see the various planets blink off one by one as light reflected from their surfaces no longer arrived. Mercury would vanish first, then Venus. Saturn would keep shining for more than an hour after Earth’s sunlit hemisphere lost its light. Thus if the sun’s demise occurred at night, we’d have advance notice of it without having to wait for the sunrise that never arrives.

8. If this doesn’t yet seem bizarre, imagine if baseballs behaved as photons do. Imagine driving a pickup truck at ninety miles per hour directly toward a batter while a pitcher standing in the flatbed hurled his best one-hundred-mile-per-hour fastball. The ball should logically reach the batter at an unhittable 190 miles per hour. But what if the ball arrived at the strike zone at the same speed regardless of the vehicle’s motion, even if it were speeding away from the plate? Would that not be odd? Yet that is exactly how photons behave.

9. To ponder more logical behavior, consider sound waves. When we approach the source of sound, as when a wailing ambulance is racing toward us, its siren’s waves hit us at a faster speed. This scrunches them up, and the pitch audibly rises. It’s the famous Doppler shift. But when we approach a light source, its waves do scrunch up to change the observed color (since blue light waves are closer together than red ones), yet the speed of each photon never budges. This is bizarre and counterintuitive.

1. The 1908 Tunguska intruder is usually characterized as a meteor. This is merely the generic term for any object that arrives on Earth from space. An asteroid made of metallic rock and a comet made largely of ices are both termed a meteor or meteorite when, respectively, they’re zooming across the sky or hitting the ground. There is a small-minority view that the Tunguska event (and, for that matter, the “great dying,” the Permian extinction event that took place 251 million years ago) was caused by trapped gas escaping from deep within the earth and then igniting high in the air. But the vast majority of scientists are confident that it was an air-bursting meteor that did not survive its passage through the atmosphere. This would also explain the absence of any crater or meteoric debris. Moreover, air-bursting meteors have been chronicled in the past, whereas an escaping glob of methane that did not explode until it rose miles into the atmosphere would be a unique event in world history.

2. NASA and the Russians also left spent landers on Venus, Mars, and the Saturnian moon Titan. A probe also parachuted into Jupiter, but it was swallowed up and crushed by the planet’s thick gases, so we won’t count that as an example of littering, because it could be argued that the probe is “out of sight, out of mind.”

3. For millennia, one of the permanent frustrations for astronomers was the inability to observe the moon’s hidden side. Yet everyone expected it to look more or less like the face we do see. That’s why the Russian Luna 3 probe, which whizzed past the far side in October of 1959, its television cameras whirring, created such a shock. The hidden hemisphere was a different world! It had virtually none of the large, dark blotches—the so-called seas—that give the familiar side its characteristic, chauvinistically named man-in-the-moon appearance. Obviously that more distant portion escaped the period of volcanism the near side underwent. This is supported by the fact that the moon’s center of mass is not in its geographical middle but rather a mile closer to Earth. Meanwhile, the Russians exercised their prerogative as discoverers and gave Russian names to every mountain and crater and almost every pebble, an embarrassment that has kept that lunar hemisphere out of many Western textbooks.

1. Actually, FitzGerald couldn’t believe that light is always a constant regardless of one’s motion toward or away from the light source. He assumed that observers and their measuring tools had their length squashed in the direction of travel in such a way that light would merely appear constant. He thought that fast speed introduced an experimental distortion.

Sleepy Village in an Exploding Universe

1. Because the speed of the expanding universe increases with distance, weird stuff happens to truly faraway objects. Consider a galaxy at the edge of the visible universe. We can say it’s old because we see it as it was when its light started traveling to us thirteen billion years ago. Its image is ancient. We can also say it’s young because we’re viewing a picture of a newborn galaxy; after all, everything back then was newly hatched. But is it really thirteen billion light-years away, as news articles claim? Does it even make sense to compare where we are now with where that galaxy was situated thirteen billion years ago? When the image we’re seeing left that galaxy, we were much closer together. It was then only 3.35 billion light-years from us. So it should logically display the size of a galaxy at that nearer distance—its location when its light left—rather than the size of a galaxy located as far away as it is now. A photograph’s dimensions don’t change just because it took a long time to get delivered.

Amazingly, that galaxy indeed looks much larger than we’d expect for something so far away. It’s like a fun-house mirror. The galaxy appears much closer than it is!

In terms of its size, that is. But it’s far dimmer than we’d expect an object at that distance to be. Space has been stretching while the image traveled, dramatically redshifting and weakening it. It now exhibits the ultrafaintness of a galaxy at the impossible distance of 263 billion light-years.

Let’s put all this together. It’s the oldest galaxy image we’ve ever seen, but it’s of a newborn galaxy, so we can also say it’s the youngest. It looks way too big for its distance, but also way too faint. Could things get any weirder? You bet. Science articles say it’s thirteen billion light-years from here because distance is often expressed that way—as how many light-years of space the image had to traverse to arrive here. And thirteen billion years is also how long its light took to reach us. However, during all that time the galaxy has meanwhile been madly receding. This galaxy is now actually thirty billion light-years away. Its recession speed today is far faster than that of light.

2. Every astronomer in the early 1990s would have told you with absolute certainty that the universe’s expansion is slowing down. There was even a name for this: the deceleration parameter. But just a few years later, the cosmos had flipped. Then it was obvious that the expansion is speeding up. Cosmologically we are clearly in our infancy. Despite TV specials carrying on about the overall universe being such and such, the scarcity of hard data makes virtually nothing we “know” immune from revision and reversal tomorrow. Those knowledgeable in astrophysics greet all the popular speculative models with a smile.