Aladdin's Lamp


The most incomprehensible thing about this world is that it is comprehensible.
— Albert Einstein

Given three wishes from Aladdin's lamp or some other magical device, the hero always makes a disappointing choice: a pile of gold, a castle, a princess. How selfish! Why not wish for universal health care (or universal good health)? Or material prosperity for all? Or that everyone could lead a full and rich life of the mind and the spirit? It may be overstepping the bounds of politeness to ask so much of the genie of the lamp.
     My curiosity is such that, given three lamp-wishes, I'd be tempted to spend at least one of them on a physics experiment. What would our world be like if the gravitational constant, which specifies how strongly each bit of matter is attracted to each other, were ten percent less? Apparently, in this case, our universe would be destined for infinite expansion. Would life exist? Would it be very much different? There are a number of physical constants that seem fine-tuned for life: if they were changed a little either way, life (at least on earth) wouldn't have come about.
     In my Aladdin's-lamp physics experiments, I wouldn't limit myself to changing constants in existing physical laws. I could enact new laws of physics and repeal old ones. What would it be like if I repealed relativity and quantum mechanics and returned to a universe governed by Newton's laws? Would the people be friendlier? Are there rules for universe design? Is it difficult to invent a consistent set of laws of physics? It certainly is difficult to envision the effect a change in physics would have on the world around us. What we need is a way to simulate the universe, another sort of Aladdin's lamp.
     There is a game called Life, which has simple rules and yet produces complex and life-like phenomena. A flat playing surface is divided by a grid into small squares, each of which may contain a cell or be empty. The player selects an initial pattern of cells, the first generation, and the rules take over from there, deriving the second-generation pattern from the first generation. If a square has empty spaces all around, or just one neighbor cell, it will be empty in the new generation. If it has 2 neighbors, it stays as it is. If it has 3 neighbors, it will contain a cell, even if it was empty in the first generation. If a square has cells in 4 or more neighboring squares, it will be empty. These rules may be interpreted in a life-like way: cells die from isolation or overcrowding, cells are born and flourish with moderate population density. Applying these rules to every square of the first generation gives the second generation. Applying them to the second gives the third generation, and so on. Generations are usually calculated by computer, with the playing surface displayed on the computer screen, several generations per second. The game produces amazingly complex and lifelike phenomena, starting from very simple initial patterns.
     I picture our universe as like this game. The laws of physics are the rules of the game. There was an initial state at the moment of creation of the universe, 10 to 20 billion years ago. It's open to conjecture whether there is an interpretive mechanism for the universe, analogous to the computer and the game-of-life program. Maybe so, or maybe the universe simply is, a direct implementation of those physical laws.
     There is no way we can ever know the answer to this question. Imagine that we are playing a game like the game of Life on a very large playing surface with a very fast computer, and that we selected just the right rules and initial condition so that, after the game had been running a long time, a set of sentient beings arose in the changing patterns of the cells. Imagine that these beings conducted scientific research and figured out the rules of their game, the size of the playing surface, and the initial configuration that gave rise to their universe. As part of their research, they might have constructed their own games of life, running at a slower speed, with smaller playing surfaces, simulating their own universe and its “physical” laws. They would know essentially everything there is to know about themselves in low-level physical terms; they would have the recipe for their own creation. They might ask the question that we just asked: is there an interpretive mechanism that is the substratum for their “physical” universe? The answer, of course, would be “yes,” and there is no way they could ever know it.
     (If this analogy seems impossibly far-fetched to you, it may be that you're not a materialist, as I am. I don't believe in Gods or spirits or life forces or ghosts or anything else that doesn't follow the laws of physics, whatever they are. I believe that human beings are complicated mechanisms that have developed out of billions of years of evolution. I am a materialist because it is the simplest plausible explanation of the observed facts.)
     Could we, in principle, simulate our own universe on some future souped-up computer? The simulation would start with the universe's initial condition, and follow every subatomic particle, every ray of light, every stray electromagnetic field in minute detail, instant by instant, in all their interactions with one another. It would require a tremendous amount of computation, many orders of magnitude more than we get from our present-day machines.
     If the universe is deterministic, and if the initial condition was simple and well enough defined, a complete and perfect universe simulator running faster than real-time would be like a time machine, with all its paradoxes. It would allow us to simulate the past and the future, to make changes and see the consequences — how the French Revolution would have sorted itself out without Napoleon, or what life would be like now if Germany had beat us to the finish line in the race to develop the atomic bomb. This simulator would be an Aladdin's lamp, allowing us to alter our universe at will and see the results.
     The operators of the game, running the simulations of our universe, would be Gods in their own right. They would be omnipotent, able to change anything in their universes, even the rules of the game, at any time. They could create and destroy, punish and reward the beings in their simulations. They would be omniscient in the sense that the whole simulated universe, with all its space and time, matter and energy, would be open for their inspection. They would be omniscient in this sense, though they wouldn't know any more than you or I. Humans or other beings in these simulated universes would believe in God if the operators were constantly and heavy-handedly interfering. Rational beings in universes without interference would not. There would be no way they could detect us or our world.
     These simulated beings would be as real as we are. Their world would look the same to them as our does to us. They would behave as we do, feel as we do, live, die, learn, love, go to war. The only difference would be that their physical world would be simulated in our simulation machine, at another level of existence. How far can this go on? Our physical reality could be, in turn, simulated by a still higher-level interpretative machine, and so on.
     A simulation of our universe, running at real-time speed or faster would be impossible since the simulation would have to include the computer running the simulation, since it's part of the universe. It would take all of the computer's power (and probably more) just to simulate itself, with none left over for simulating the rest of the universe. This problem would be avoided if the simulation ran slower than real-time; this also avoids the paradoxes of time travel into the future. With our present technology, we are nowhere near this massive scale of simulation — our fastest computers are inadequate to simulate the weather on a small part of our little planet.
     Another prerequisite for exactly simulating the universe is perfect knowledge of the laws of physics. Will we ever know, perfectly and completely, the rules that determine how the material objects in our universe behave? It seems quite possible. I can imagine that, with a few key insights and breakthroughs, we come up with a final, complete, self-consistent theory that explains all the low-level physical phenomena that we can observe, and that we can reconcile it with cosmology so that the theory explains how the universe got to be as it is, starting from a simple initial condition. I can imagine this theory withstanding the test of time, so that it remains unchanged for a few centuries, and we come to realize that this is it, we've really learned the rules of the game, there's no need to do more physics research. I can imagine that the final and true laws of physics can be written as equations on ten sheets of paper. There is something paradoxical about the recipe for creating the universe being so simple when the universe contains such complication.
     It would not mean that we understand everything about everything; we would understand just the physical level of our universe. We would understand the low-level interactions between the matter and energy that make up our brain, but wouldn't necessarily know the brain's chemicals, or how cells are constructed from them, how the cells are organized into larger structures such as nerves, how these integrate as a thinking machine, or what makes us conscious.
     We may never know all there is to know about physics. Toward the start of the twentieth century, prominent physicists were saying that 90% of the work of physics was done, and the other 10% would involve just cleaning up certain nagging details. This was in the days when electrons, protons and neutrons were the smallest known particles (it having been realized that the “atoms” they make up were not the primitive, indivisible components of matter that the name implies). This view seems ludicrous now that we've gone on to discover relativity and quantum mechanics and another level of subatomic particles. It's possible that this will continue, so that every time we break through to another level of understanding, we come to realize that there's more, and we still have only an approximation. Maybe there are an infinite number of rules in our game. And maybe not.
     It would make a big difference for us to completely understand the physical laws of the universe. Our science has made us bigger than the earth upon which we grew up, something that was inconceivable just a thousand years ago. We can now contemplate building ourselves new places to live, away from the earth. In the same way, knowledge of physical laws would give us mental mastery over the universe. We would know the recipe for constructing the universe and our selves, even if we didn't have the physical means to realize it.
     On the other hand, it would increase our sense of a frustrating circumscription in the universe, a feeling I have now when I read about cosmology; our universe is made cramped by our dawning understanding of its limits since our minds can surpass these limits to imagine something greater, or at least something else. Why is the gravitational constant not ten percent less? Why do we have this set of physical laws rather than another? It seems so arbitrary that this can't be all there is. What is there at a higher level that we can probably never know?


Copyright © 2000 - 2007 by Dean Wallraff. All rights reserved.