The Wall Street Journal

• OPINION
• DECEMBER 16, 2011

The 'God Particle' and the Origins of the Universe

The search for a unifying theory is nowhere near over.

By MICHIO KAKU

Physicists around the world have something to celebrate this Christmas. Two groups of them, using the particle accelerator in Switzerland, have announced that they are tantalizingly close to bagging the biggest prize in physics (and a possible Nobel): the elusive Higgs particle, which the media have dubbed the "God particle." Perhaps next year, physicists will pop open the champagne bottles and proclaim they have found this particle.

Finding this missing Higgs particle, or boson, is big business. The European machine searching for it, the Large Hadron Collider, has cost many billions so far and is so huge it straddles the French-Swiss border, near Geneva. At 17 miles in circumference, the colossal structure is the largest machine of science ever built and consists of a gigantic ring in which two beams of protons are sent in opposite directions using powerful magnetic fields.

The collider's purpose is to recreate, on a tiny scale, the instant of genesis. It accelerates protons to 99.999999% the speed of light. When the two beams collide, they release a titanic energy of 14 trillion electron volts and a shower of subatomic particles shooting out in all directions. Huge detectors, the size of large apartment buildings, are needed to record the image of this particle spray.

Then supercomputers analyze these subatomic tracks by, in effect, running the video tape backwards. By reassembling the motion of this spray of particles as it emerges from a single point, computers can determine if various exotic subatomic particles were momentarily produced at the instant of the collision.

The theory behind all these particles is called the Standard Model. Billions of dollars, and a shelf full of Nobel Prizes along the way, have culminated in the Standard Model, which accurately describes the behavior of hundreds of subatomic particles. All the pieces of this jigsaw puzzle have been painstakingly created in the laboratory except the last, missing piece: the Higgs particle.

It is a crucial piece because it is responsible for explaining the various masses of the subatomic particles. It was introduced in 1964 by physicist Peter Higgs to explain the wide variation. Until then, a theory of subatomic particles had to assume that the masses of these particles are zero in order to obtain sensible mathematical results. This was a puzzling, disturbing result, since particles like the electron and proton have definite masses. Mr. Higgs showed that by introducing this new particle, one could preserve all the correct mathematical properties and still have non-zero masses for the particles.

While physicists cannot yet brag that they have found the Higgs particle, they have now narrowed down the range of possible masses, between 114 and 131 billion electron volts (over a hundred times more massive than the proton). With 95% confidence, physicists can rule out various masses for the Higgs particle outside this range.

Will finding the Higgs boson be the end of physics? Not by a long shot. The Standard Model only gives us a crude approximation of the rich diversity found in the universe. One embarrassing omission is that the Standard Model makes no mention of gravity, even though gravity holds the Earth and the sun together. In fact, the Standard Model only describes 4% of the matter and energy of the universe (the rest being mysterious dark matter and dark energy).

From a strictly aesthetic point of view, the Standard Model is also rather ugly. The various subatomic particles look like they have been slapped together haphazardly. It is a theory that only a mother could love, and even its creators have admitted that it is only a piece of the true, final theory.

So finding the Higgs particle is not enough. What is needed is a genuine theory of everything, which can simply and beautifully unify all the forces of the universe into a single coherent whole—a goal sought by Einstein for the last 30 years of his life.

The next step beyond the Higgs might be to produce dark matter with the Large Hadron Collider. That may prove even more elusive than the Higgs. Yet dark matter is many times more plentiful than ordinary matter and in fact prevents our Milky Way galaxy from flying apart.

So far, one of the leading candidates to explain dark matter is string theory, which claims that all the subatomic particles of the Standard Model are just vibrations of a tiny string, or rubber band. Remarkably, the huge collection of subatomic particles in the Standard Model emerge as just the first octave of the string. Dark matter would correspond roughly to the next octave of the string.

So finding the Higgs particle would be the beginning, not the end of physics. The adventure continues.

Mr. Kaku, a professor of theoretical physics at CUNY, is author of "Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by 2100" (Doubleday, 2011).