what produce suntans and sunburns. But why didn’t we ever get any from a campfire? Classical physics said that UV should be present, and hanging out long enough around a campfire should deliver a tan. But it never did.
The answer had to do with electrons, which were discovered in 1897. They were immediately assumed to orbit around an atom’s nucleus like planets around the Sun. But here’s the thing: In 1900 Max Planck surmised that electrons can absorb energy from a hot environment, and then radiate it back in the form of bits of light, which ought to include some ultraviolet light. But if electrons—unlike planets, which can orbit the Sun at any distance at all—could only orbit their atom at specific, discrete locations, then they would only be able to absorb or emit specific quantities of energy, called quanta because it takes a precise amount or quantum of energy to move an electron a specific distance. If the environment wasn’t energetic enough, electrons would only be able to make easy jumps, like those in the atom’s outer fringes. They’d never be able to make a powerful jump from the innermost orbit to the next highest, which is what’s required to create a UV photon when the electron fell back down again.
Planck’s idea, soon called the Planck postulate, was that electromagnetic energy could be emitted only in specific quanta. It wasn’t long before Niels Bohr, the brilliant Danish physicist, confirmed that all atoms indeed behave like that. Only by falling back inward from one allowable, higher orbit to another one closer to the nucleus do atoms emit packets of light, called photons. This is the only way in which light is born. If an atom is not stimulated, its electrons remain in stable orbits, and it produces no light at all.
That high-energy drop from the second orbit to the innermost one—needed to create a sunburn-producing UV photon— requires a more powerful initial energy boost than a campfire can provide. Quantum theory—the idea that electrons can make only specific moves between allowable orbits and thus absorb or emit only specific quanta of energy—explained previously enigmatic facets of nature. So far, so good. But weirdness was already lurking in the closet. According to Bohr, an electron cannot exist in any intermediary position outside a precise, allowable orbit; anytime it changes position it must go from one specific orbit to another, and never be anywhere between them. So here’s what’s odd: As an electron changes orbits, it does not pass through the intervening space!
Imagine if the Moon behaved like that. It used to be much closer to us, and is still moving farther away at the rate of almost two inches a year. It’s spiraling away like a bent skyrocket. Also, physics allows the Moon to be any distance from us. Now imagine if the Moon didn’t budge in its separation from us for millions of years, but then, in an instant, suddenly vanished and rematerialized in a new location fifty thousand miles farther away. And imagine, too, that it accomplished that jump in zero time without passing through any of the intervening space.
Well, that’s what electrons do. Needless to say, this opened bizarre new implications and set the stage for earthquakes that rocked classical physics forever. Even Planck unsuccessfully struggled to understand the meaning of energy quanta. “My unavailing attempts to somehow reintegrate the action quantum into classical theory . . . caused me much trouble,” he wrote with exasperation many years later. Ultimately he gave up trying to make logical sense of it, or even trying to convince his most stubborn doubters. “A new scientific truth does not triumph by convincing its opponents and making them see the light,” he said presciently, “but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”
But it was hard for anyone to get too familiar with quantum mechanics because strange new revelations kept arriving. Physicists learned that light, as well as bits of matter, are not just particles but also are waves, and how they exist depends on who’s asking—meaning, the method of observation determines how these objects appear! Actually it’s worse than that. These entities can also exist in two or more places at once, in a kind of blurry probabilistic fashion. We might say that electrons acting as waves are really wave packets, and where the packet is densest is where an individual electron is most likely to materialize as a particle. But it may also, upon observation, pop into existence in an unlikely place, on the almost totally empty fringes of that packet. Over time, a series of observations will show electrons or bits of light materializing according to probability laws.
This means the electron or photon doesn’t enjoy any independent existence as an actual object in a real place, with a real motion. Instead, it exists only probabilistically. Which is to say it doesn’t exist at all—until it’s observed. And who observes it? We do. With our consciousness.
Suddenly, consciousness and the cosmos—which had parted paths way back with Aristotle, and whose divorce seemingly was made more permanent by Cartesian and Newtonian credos—might not be such totally separate entities after all.
Slowly, in the opening decades of the twentieth century, classical physics and the common-sense gospel of locality were eroding. After all, some “motion” unfolded without the object penetrating through any space or requiring the slightest bit of time.
Objectivity was melting, too, because the observer alone made these tiny objects materialize. Causal determinism was vanishing as well, because nothing palpable or visible caused the entities to assume one position instead of another. And as for the “physical monism” that made consciousness a random offspring of the material cosmos, it now gained interest and was reexamined. It suddenly seemed like consciousness might enjoy some central importance in the universe’s overall reality. After all, the observer’s awareness was now seen to determine what physically occurs.
And yet despite these profound oddities being increasingly perceived in the 1920s, the real quantum strangeness was just beginning.
3 It didn’t have to be stated, but another element to this classical physics model was what Einstein later called locality. Nothing budges unless acted upon by a nearby object or force. Einstein famously showed that the ultimate speed, that of light at 186,282.4 miles per second, imposes a limit of how quickly anything could affect anything else.
Einstein explained that nothing with any mass (i.e., that weighs anything) can quite attain lightspeed, because its mass would grow until, for instance, even a feather at just below lightspeed would outweigh a galaxy. And the amount of force needed to accelerate such a huge mass further would be impossible to obtain—it would exceed all the energy in the universe. Indeed, at the speed of light, a zooming mustard seed would outweigh the entire cosmos. (This change of “weight” that automatically accompanies speed was part of Einstein’s first, special relativity theory of 1905. It happens because motion always involves energy, and energy and mass, he said, are two sides of the same coin. They’re equivalent, as per his famous E = mc2, where the E is energy and the m is the object’s mass. So if you increase an object’s inherent energy by increasing its speed, you’re also increasing its equivalent mass.) See chapter 7 for a wider discussion on the implications of locality.
THE END OF TIME
6
Stand still, you ever-moving spheres of Heaven,
That time may cease, and midnight never come.
—Christopher Marlowe, The Tragical History of the Life and Death of Doctor Faustus (1604)
When we grow up watching our loved ones age and die, we assume that an external entity called time is responsible for the crime. But as we’ve seen, many lines of science and logic cast doubt on the existence of time as we know it. We must repeat that, although we do observe change, change isn’t the same thing as time.
So
