How the Higgs Boson Was Found A famous story in the annals of physics tells of a 5-year-old Albert Einstein, sick in bed, receiving a toy compass from his father. The boy was both puzzled and mesmerized by the invisible forces at work, redirecting the compass needle to point north whenever its resting position was disturbed. That experience, Einstein would later say, convinced him that there was a deep hidden order to nature, and impelled him to spend his life trying to reveal it. Although the story is more than a century old, the conundrum young Einstein encountered resonates with a key theme in contemporary physics, one that’s essential to the most important experimental achievement in the field of the last 50 years: the discovery, a year ago this July, of the Higgs boson. Let me explain. Science in general, and physics in particular, seek patterns. Stretch a spring twice as far, and feel twice the resistance. A pattern. Increase the volume an object occupies while keeping its mass fixed, and the higher it floats in water. A pattern. By carefully observing patterns, researchers uncover physical laws that can be expressed in the language of mathematical equations. A clear pattern is also evident in the case of a compass: Move it and the needle points north again. I can imagine a young Einstein thinking there must be a general law stipulating that suspended metallic needles are pushed north. But no such law exists. When there is a magnetic field in a region, certain metallic objects experience a force that aligns them along the field’s direction, whatever that direction happens to be. And Earth’s magnetic field happens to point north. The example is simple but the lesson profound. Nature’s patterns sometimes reflect two intertwined features: fundamental physical laws and environmental influences. It’s nature’s version of nature versus nurture. In the case of a compass, disentangling the two is not difficult. By manipulating it with a magnet, you readily conclude the magnet’s orientation determines the needle’s direction. But there can be other situations where environmental influences are so pervasive, and so beyond our ability to manipulate, it would be far more challenging to recognize their influence. Physicists tell a parable about fish investigating the laws of physics but so habituated to their watery world they fail to consider its influence. The fish struggle mightily to explain the gentle swaying of plants as well as their own locomotion. The laws they ultimately find are complex and unwieldy. Then, one brilliant fish has a breakthrough. Maybe the complexity reflects simple fundamental laws acting themselves out in a complex environment—one that’s filled with a viscous, incompressible and pervasive fluid: the ocean. At first, the insightful fish is ignored, even ridiculed. But slowly, the others, too, realize that their environment, its familiarity notwithstanding, has a significant impact on everything they observe. Does the parable cut closer to home than we might have thought? Might there be other, subtle yet pervasive features of the environment that, so far, we’ve failed to properly fold into our understanding? The discovery of the Higgs particle by the Large Hadron Collider in Geneva has convinced physicists that the answer is a resounding yes. Nearly a half-century ago, Peter Higgs and a handful of other physicists were trying to understand the origin of a basic physical feature: mass. You can think of mass as an object’s heft or, a little more precisely, as the resistance it offers to having its motion changed. Push on a freight train (or a feather) to increase its speed, and the resistance you feel reflects its mass. At a microscopic level, the freight train’s mass comes from its constituent molecules and atoms, which are themselves built from fundamental particles, electrons and quarks. But where do the masses of these and other fundamental particles come from? When physicists in the 1960s modeled the behavior of these particles using equations rooted in quantum physics, they encountered a puzzle. If they imagined that the particles were all massless, then each term in the equations clicked into a perfectly symmetric pattern, like the tips of a perfect snowflake. And this symmetry was not just mathematically elegant. It explained patterns evident in the experimental data. But—and here’s the puzzle—physicists knew that the particles did have mass, and when they modified the equations to account for this fact, the mathematical harmony was spoiled. The equations became complex and unwieldy and, worse still, inconsistent. Read more: smithsonianmag/science-nature/How-the-Higgs-Boson-Was-Found-213876841.html#ixzz2Y5ehPQyE Follow us: @SmithsonianMag on Twitter
Posted on: Thu, 04 Jul 2013 15:16:09 +0000
Trending Topics
Recently Viewed Topics
© 2015