by Marcus Chown
In Song of Myself, Walt Whitman wrote: “Let your soul stand cool and composed before a million universes.” Of course, he never meant it literally; he was using poetic license. But, remarkably, today, we know it is actually possible to stand cool and composed before a million universes. In my hand I am holding a 1-gigabit flash memory drive. You will have to trust me about that! A moment ago I fished it from my pocket and now it dangles on my key-ring. Believe it or not, it has the capacity to store the information for 1 million universes.
I too was pretty incredulous to discover this. But, before I explain, I should say that one consequence of all this is that Einstein was wrong when he declared: “God does not play dice with the universe.” In other words, atoms did not do things unpredictably—completely at random—as the widely accepted theory of the microscopic world maintained. In fact, Einstein could not have been more completely, utterly, spectacularly wrong. And it is not often you can say that about the great man.
Enough of these teasers. Some essential background. The universe is currently expanding. Its basic building blocks—galaxies like our own Milky Way—are flying apart from each other like pieces of cosmic shrapnel in the aftermath of the big bang explosion from 13.7 billion years ago. Imagine, if you can, this expansion running backwards like a movie in reverse. Of course, the universe gets smaller and smaller.
However, it turns out that, as the universe gets smaller, there is less and less room for all the stuff within it. This is because we live in a fundamentally grainy universe. Ultimately, everything comes in tiny, indivisible chunks, or “quanta.” Matter comes in quanta, energy comes in quanta, time comes in quanta—and so does space. Imagine the space of the universe, then, as a giant chessboard, with the spaces as locations for putting stuff like matter or energy. Because the squares cannot get any smaller, in the past, when the universe was tinier, there were less of them.
Here we come to the crux of the matter. The universe is believed to have begun in epoch of super-fast expansion called “inflation.” And, prior to that, according to calculations by Stephen Hsu of the University of Oregon in Eugene, there were a mere 1000 locations—1000 chessboard squares, if you like—for stuff. Each of those 1000 locations could either contain energy or no energy. Describing its exact state would take just 1000 binary digits, or “bits,” of information. A gigabit flash memory drive, like the one on my key-ring, can store 1000 million bits. Hence, if Hsu is right, my key-ring drive can store the information describing the initial state of 1 million universes.
You might reasonably ask, where does all the information to describe today’s universe come from? After all, it takes a lot more than 1000 bits to describe the world around us. You are right. Actually—and you will have to trust me on this one—it takes about one followed by 89 zeros bits!
The explanation as to where the universe’s information came from is that some process must have “injected” it since the big bang. The likely suspect is the minuscule activities of matter and energy that are dictated by quantum theory. Quantum theory is our very best description of atoms and their subatomic constituents. It is a fantastically successful theory. It has literally made the modern world possible, giving us lasers and microchips and nuclear reactors, not to mention an explanation for why the Sun shines and why the ground beneath your feet is solid.
One feature of quantum theory already mentioned is that it describes a fundamentally grainy rather than continuous world. But another feature is that it stands in marked contrast to all other theories of physics—“classical” theories, as physicists call them. Such theories are recipes for predicting the future with 100 percent certainty. For instance, if the Moon is over here at midnight tonight, using Newton’s law of gravity, we can predict where it will be tomorrow night at midnight with 100 percent certainty. In quantum theory, it is possible to predict only the chance, or “probability,” of something happening. For instance, if an atom is flying past an obstacle of some kind, it can go to the left or the right, but the path it actually takes is utterly random, utterly unpredictable.
Now randomness, believe it or not, is synonymous with information. If you have 1-million digit number whose digits are random, to remember the number you have to write down every single digit. This is because a random number contains a lot of information. By contrast, a 1 million digit number that consists of 9 repeated over and over—that is, a non-random number—is easy to remember. It contains hardly any information at all.
So it is the randomness of quantum theory that explains where the information of our universe comes from. Since the big bang, every quantum event—every atom randomly deciding to go along one path or another, every photon deciding to be spat out by an atom not spat out—has injected information into the universe. A fantastically enormous amount of information.
I happen to be looking up at my bookshelf at the moment. The ultimate reason why Stephen Hawking’s A Brief History of Time is next to Dan Brown’s Angels and Demons is because of countless quantum accidents since the big bang. Recall Einstein’s famous declaration: “God does not play dice with the universe.” Well, not only does God play dice with the universe but, if He did not, there would be no universe of the complexity necessary for us to be here. Look around you—at a rose, a newborn baby, a plane riding a vapor trail across the blue sky. We live in a world of boundless complexity. But all the complexity you see is merely the result of a long sequence of quantum “coin tosses” since the end of inflation. Like it or not, we live in a random reality. You, me, and everyone you know—we owe everything to randomness.
Formerly a radio astronomer at the California Institute of Technology, Marcus Chownis now cosmology consultant for the science magazine, New Scientist. The subject of our random reality—and many other mind-blowing topics—is covered in his new book, The Matchbox that Ate a 40-Ton Truck: What Everyday Things Tell Us About the Universe. You can follow Marcus on Twitter.
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