Slate eBook Club - Best of 2003
Page 21
Before getting to why you should or should not believe in multiple universes, there's a semantic point we ought to deal with. If the universe is, as the dictionary has it, "all existing things ... regarded as a whole," then isn't it true by definition that there is only one such thing? (After all, uni- is built right into the word itself.) Well, yes. But when physicists and philosophers talk about different space-time domains being "two universes," what they generally mean is that those regions are 1) very, very large; 2) "causally isolated" from each other (meaning that an event in one cannot have an effect in another); and hence 3) mutually unknowable by direct observation (since observing something means causally interacting with it). The case for saying the two domains are separate universes is further strengthened if 4) they have very different characters: if, say, one of them has three spatial dimensions (like ours), whereas the other has 17 dimensions. Finally—and here is the existentially titillating possibility—two domains might be called separate universes if 5) they are "parallel," meaning that they contain somewhat different versions of the same entities, like your own alter ego.
Thinkers who entertain the possibility that there are lots of universes have invented a new term for the entire ensemble: "the multiverse." Why believe in the multiverse? The "pro" camp has essentially two kinds of arguments.
One—the good kind—is that the existence of other universes is logically implied by the theories that best explain features of our own universe. For instance, measurements of the cosmic background radiation (the echo left over from the big bang) indicate that the space we live in is infinite and that matter is spread randomly throughout it. Therefore, all possible arrangements of matter must exist out there somewhere—including exact and inexact replicas of our own world and the beings in it. The idea is a bit like that of monkeys in front of typewriters eventually typing out all of Shakespeare: Quantum theory says that nature is discrete, so the visible universe we inhabit is characterized by a finite amount of information; if space is infinite, this informational pattern is bound to repeat at vast enough distances. A back-of-the-envelope calculation shows that there should be an exact copy of you around 10 to the 10 to the 28th light-years away.
A more extravagant kind of multiverse is entailed by the theory of "chaotic inflation." Proposed by Andrei Linde to explain why our universe looks the way it does—big, uniform, and flat—inflation theory also predicts that big bangs should be a fairly routine occurrence, giving rise to an eternal network of universes tied together by impassable "wormholes." These universes, according to the theory, would have different physical characteristics. This kind of multiverse has become the bane of natural theologians.
Here's why. One reason for believing in God is that our own universe seems improbably fine-tuned for life. It's as though a cosmic designer had carefully adjusted the physical laws to ensure that beings like us would eventually shimmer onto the scene. But if our universe is one among a vast ensemble of universes with randomly varying physical constants, then it is only to be expected that a few of these universes should be life-fostering. Add to this the fact that if we exist at all, we are bound to find ourselves in a universe that is congenial to us—the so-called "anthropic principle"—and the presumed fine-tuning of our universe seems wholly unremarkable. No need to invoke the God hypothesis to answer the question, why are we here?
But some thinkers want to turn this reasoning around. They insist that other universes must exist precisely to make certain conceptual mysteries go away. This is the second kind of argument for the multiverse—the bad kind, since it has nothing to do with empirical observation.
One version of this argument derives from attempts to make sense of quantum theory. Take the famous paradox of Schrödinger's Cat—the unfortunate feline, who, because of the quantum superposition of possibilities, is simultaneously alive and dead. According to the "many-worlds" interpretation of quantum theory, Schrödinger's experiment splits the universe into two parallel copies, one with a live cat, the other with a dead one (and each with a version of you). Physicists who buy into this interpretation—and many distinguished ones do—claim that each universe splits into something like 10 to the 100th copies every second, all of them equally real. Yet, since quantum theory forbids these parallel worlds from interacting, there is no experimental way to confirm their reality.
Another version of this backward argument for multiple universes was championed by the late Princeton philosopher David K. Lewis. Lewis believed (or at least pretended to) that all logically possible universes are as real as the one we call the "actual" one. Why? Because their existence would neatly solve a wide range of philosophical problems. Take the problem of counterfactuals. What does it mean to say, "If JFK hadn't gone to Dallas, the Vietnam War would have ended earlier"? According to Lewis, the counterfactual statement is true only if there is an alternative universe in which JFK didn't go to Dallas and the Vietnam War did end earlier. His "modal realism" entails that there is even a universe containing the Greek gods and is primarily a linguistic philosophical argument rather than a scientific one.
As for the arguments against the multiverse, they boil down to these three.
1) It's not science. Both Paul Davies and Martin Gardner claim that the proposition "the multiverse exists" has no empirical content and hence amounts to empty metaphysics. But the hypotheses that imply it do lead to testable predictions, some of which jibe with the evidence collected so far. In the next decade, as Max Tegmark points out, improved measurements of the microwave background radiation and of the large-scale distribution of matter may fortify or knock down two pillars of the multiverse: the infinitude of space and the theory of chaotic inflation.
2) Alternative universes should be shaved away by Occam's Razor. Both Davies and Gardner complain that the multiverse notion is too extravagant. "Surely the conjecture that there is just one universe and its Creator is infinitely simpler and easier to believe than that there are countless billions upon billions of worlds," Gardner writes. Is it? Our universe came into being with the big bang, and (as the Canadian philosopher John Leslie has observed) it would be exceedingly odd if the mechanism behind this event bore the label "THIS MECHANISM OPERATED ONLY ONCE." A computer program that prints out the entire sequence of numbers is much simpler than one that prints out only a single number of any length. And besides, why should simple theories be more probable than extravagant ones?
3) The multiverse, if real, would reduce our own world to a Matrix-like simulation. This objection, voiced by Davies, is surely the most bizarre of the lot. If there really were myriad universes, Davies argues, then some would contain advanced technological civilizations that could use computers to simulate consciousness and create endless virtual worlds. So, he continues, taking the multiverse theory at face value means "there is no reason to expect our world—the one in which you are reading this right now—to be real as opposed to a simulation." This is a terrible argument for at least two reasons. If it were valid, it would rule out technologically advanced civilizations in this universe since they, too, would presumably create such simulations. And the hypothesis that we are living in a simulation itself has no empirical content. We cannot even talk about it coherently, as Hilary Putnam has pointed out, since our words could refer only to things "inside" the alleged simulation.
How seriously should you take multiple universes? That depends on how scrupulous you are about your ontological commitments. I know people who still regard atoms as theoretical fictions. I have friends who claim to doubt the reality of the past, of the future, of other minds. I have heard of academics—though I cannot believe they actually exist—who think that the cosmos is a social construction. But I am a robust scientific realist. If an empirically sound theory entails that unobservable entities exist, then I take them at face value. After all, reality has over and over again turned out to be much more inclusive than we've given it credit for being. Just a century ago, our puny Milky Way was thought to comprise the entire cosmos.
What Fuel Does Voyager 1 Use?
Plus, why it will run out in 2020.
By Brendan I. Koerner
Updated Thursday, Nov. 6, 2003, at 12:49 PM PT
Voyager 1, launched in 1977, has reached the edge of the solar system, 8.4 billion miles from the sun. NASA says the spacecraft and its trailing twin, Voyager 2, have enough fuel left to keep operating until 2020. What sort of fuel are the Voyagers running on?
The spacecraft actually carry two types of fuel—one to power the thrusters, the other to keep the electricity humming. The propellant is hydrazine, a simple concoction of nitrogen and hydrogen that smells like weak ammonia. It was chosen—and remains favored today—because it's cheap and has a very low freezing point. The Voyagers' jets are used to orient the vessels; the geek term for the hydrazine is "attitude control propellant." (There's no need for constant propulsion, of course, because space is gravity-free, so the initial boost went a long way; the spacecraft additionally took advantage of the outer planets' gravitational fields, which act like slingshots to increase speed.) NASA estimates that the Voyagers' fuel efficiency is upwards of 30,000 miles per gallon of hydrazine.
Voyager 1 has enough hydrazine to keep going until 2040, while Voyager 2's juice can keep it hurtling along until 2034. (Though the spacecraft are identical, Voyager 2 has had to expend more hydrazine visiting Uranus and Neptune.) The real limiting factor is the other fuel, plutonium-238 dioxide. This is what powers the Voyagers' scientific instruments and communications equipment. The plutonium is converted into electricity by onboard radioisotope thermoelectric generators (RTGs), which feed off the heat generated by the radioactive fuel's decay. The fuel spheres are encased in a special iridium alloy, to prevent contamination in the unlikely event that the Voyagers crashed shortly after takeoff in 1977.
The plutonium's radioactive decay means that the fuel is generating less and less heat as the years go by, and consequently the RTGs are producing less and less power. At launch, the RTGs were cranking out 470 watts worth of electricity; now it's more like 315 watts. NASA is trying to combat the problem by shutting down non-critical systems, and alternating which instruments are on and off. But come 2020 or so, there won't be enough plutonium left to keep the heaters working, and everything of value will shut down.
Geomagnetic Storms
By Brendan I. Koerner
Posted Friday, Oct. 24, 2003, at 11:24 AM PT
A strong geomagnetic storm is slated to hit Earth today, and experts warn that power grids and satellites could suffer. What's a geomagnetic storm?
Think of it as an electrical kick in the pants, courtesy of the sun. Geomagnetic storms like today's begin with an event called a coronal mass ejection, a geyser of solar gas. A CME can spout billions of tons of this ionized gas, also known as plasma, traveling at upwards of 3 million miles per hour. That discharge is carried the 93 million miles toward Earth by the solar wind, a constant stream of particles emitted by the sun.
Normally, when solar particles reach the Earth, they're deflected by the magnetosphere, the magnetic field produced by the planet. But in the wake of a major CME, the solar wind carries far too many ionized particles for the magnetosphere to handle. Charged particles slip through the defenses, so to speak, causing the magnetosphere to fluctuate. This produces an intensified ring current, an electrical current trapped within the magnetosphere. The intensity is so strong, in fact, that it can create electrical current in voltage transformers and other power-grid hardware. That's bad news for whomever manages those grids, as the resulting power surge can knock out service to millions of customers. Geomagnetic-storm watchers warily mention March 13, 1989, when 6 million customers of Hydro-Québec lost power for an extended time.
The good news is that geomagnetic storms can also produce brilliant light shows akin to the aurora borealis, or "northern lights." (Or, in the southern hemisphere, the aurora australis.) These lights are caused by milder, more common versions of today's storm and are visible in areas relatively close to the two magnetic poles. The abundance of charged particles that will be pounding the magnetosphere today should make for some great skywatching, at least for those lucky enough to live near the roof or the basement of the globe. However, the intensity of this particular storm may mean that people farther south may get a peek, too; the infamous 1989 storm was reportedly visible in Mexico.
Bonus Explainer: A few fringe scientists have speculated that there's a link between geomagnetic activity and mental health, arguing that psychiatric admissions increase during heavy storms. The mainstream dismisses this correlation as no more substantiated than reports that the full moon causes people to act strangely.
Why Don't Hurricanes Hit L.A.?
By Andy Bowers
Posted Thursday, Sept. 18, 2003, at 11:59 AM PT
East Coast residents bracing for Hurricane Isabel today are old hands at fending off violent storms—an average of two make landfall each year. Why is the Eastern Seaboard consistently plagued by hurricanes, while the U.S. West Coast almost never suffers a direct hit?
Two reasons, really. The first is that hurricanes form in the tropics, where (thanks to the Earth's rotation) winds tend to blow from east to west. That means tropical cyclones—including hurricanes—in the waters near the United States almost always move toward the west-northwest. So when they form in the Atlantic region, they head straight for the American mainland. But in the Pacific, they head farther out to sea. However, that path does take cyclones over Mexico and Hawaii from time to time. And of course, their westward movement also takes them toward land masses in Asia.
The other reason hurricanes almost never hit California, Oregon, or Washington is that cyclones feed on warm sea water—preferably over 80 degrees. But the ocean temperature in the northern Pacific is usually under 75. In fact, there's no record of a tropical hurricane ever hitting the West Coast.
By the way, the words hurricane and typhoon both refer to the same thing—a severe tropical cyclone. The difference is that hurricane is used for storms in the northeastern Pacific, on the American side of the International Date Line, and typhoon is used on the western—or Asian—side.
Bonus Explainer: What's the origin of those interesting proper names given to hurricanes? Most people know that each hurricane season, tropical cyclones are named in alphabetical order to help scientists tell them apart. This year's storms in the Atlantic have ranged so far from Ana to Isabel. The practice began in earnest in the '40s and '50s with all female names. Male monikers were added in the late '70s. But according to the book Atlantic Hurricanes, it was an Australian forecaster in the early 20th century who first used proper names for cyclones. The names he chose belonged to politicians he disliked.
Trick or Treatment
Teen drug programs turn curious teens into crackheads.
By Maia Szalavitz
Posted Friday, Jan. 3, 2003, at 10:38 AM PT
America loves its quick fixes. Think your child might be on drugs? Test him. Think your child's school is full of addicts? Test them all. Institute a policy of zero tolerance: One strike and it's off to a drug treatment program. Get those rotten apples out and clean them up before they can poison the whole batch. Last year's Supreme Court decision in Board of Education v. Earls allowed for a massive expansion of drug testing in schools. And increases in drug testing increase the numbers of offenders. As a result, schools and juvenile courts are increasingly turning to both "zero tolerance" and "treatment, not punishment" as a remedy.
The number of teenagers in drug treatment as a result of court coercion and school diversion increased by nearly 50 percent between 1993 and 1998 accordi
ng to the U.S. Department of Health and Human Services' Substance Abuse and Mental Health Services Administration, and the number of teen admissions to treatment programs in general rose from 95,000 in 1993 to 135,000 in 1999. But what if drug "treatment" doesn't work for teens? What if, rather than decreasing drug use, teen treatment actually encourages it by labeling experimenting kids as lifelong addicts? What if it creates the worst sorts of peer groups by mixing kids with mild problems with serious drug users who are ready and willing to teach them to be junkies? What if suggestible kids respond poorly to the philosophies that have made Alcoholics Anonymous and Narcotics Anonymous successful for many adults? Then we'd be using "treatment" to turn ordinary adolescents into problem drug abusers.
That's precisely what we're doing. A 1998 study of nearly 150 teenagers treated in dozens of centers across the country found that there was 202 percent more crack abuse following treatment and a 13 percent increase in alcohol abuse. In other words, recent research suggests that parents and schools may be sending binge-drinking/social marijuana smokers off to treatment and getting back crackheads in their stead.
Michael's case illustrates some of the dangers inherent in shipping youngsters off to treatment programs. An 18-year-old marijuana smoker and cocaine user I interviewed regarding drug treatment, Michael was recently sent by his parents for drug treatment at the respected Caron Foundation. But his $11,000 one-month treatment program degenerated into a fruitless debate when his counselor wanted him to admit that he was "powerless" over drugs. Michael, who didn't use daily, wouldn't accept that. What teenager would admit to being "powerless" over anything? Michael used again within four hours of leaving treatment.