Associate Professor of Physics Eric Carlson, who joined the faculty in 1995, explains what happens when protons collide — and why it could be important to our everyday lives.
Interview on WXII-TV »
When protons collide
Associate Professor Eric Carlson answers questions about the Large Hadron Collider
The Large Hadron Collider is the world's largest and highest-energy particle accelerator complex, intended to collide opposing beams of protons with very high kinetic energy. On Sept. 10, the first beams were circulated through the collider, located at the European Organization for Nuclear Research (CERN) near Geneva, Switzerland. Associate Professor of Physics Eric Carlson, who teaches modern and quantum physics, answers questions about this latest scientific breakthrough.
For the non-scientists out there, what exactly is being done at the Large Hadron Collider?
The Large Hadron Collider, or LHC, is designed to help us learn more about the universe, how it was born, where it is going, and how everything works. It does so by studying the debris created when tiny sub-atomic particles called protons are collided together at high energy. This allows us to create new, more massive fundamental particles according to Einstein's famous formula E=mc2.
One of the particles scientists hope to discover is the predicted-but-never-seen Higgs particle, which is believed to be the cause of the masses of all the other particles, including you, me, the Earth, and everything else around us. But the real hope is that we will discover even more interesting things, such as a host of particles predicted by a theory called supersymmetry, or the mysterious dark matter that seems to pervade outer space, or best of all, something that no one predicted. It is the unexpected discoveries that are the most valuable.
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Why does the LHC facility have to be so large?
To reach such fantastic energies, the protons must be accelerated to very high speed, nearly the speed of light. This is done by making them go repeatedly around a circular track, 17 miles in circumference, and increasing their speed each time, like a race car with the driver steadily pressing on the accelerator. But at such high speeds, the particles can't turn quickly, just as a race car can't make a hairpin turn when its going 200 miles per hour. The only way to have the protons turn is very gradually, which means the accelerator must be a very large circle.
It is truly ironic that to study the smallest particles in the universe, we must use the largest machines.
On a scale of one to 10, how earthshaking is this endeavor, and why?
Particle physics is the most fundamental of all the sciences, and the LHC will be the premier machine for studying particle physics for several decades, if not the rest of the 21st century. As an endeavor, I would rate it a nine, but as for its results, no one knows yet. Certainly it will discover something, and I expect several Nobel prizes will be awarded, but whether it will lead to truly groundbreaking discoveries, we will simply have to wait to find out.
The events of Wednesday, Sept.10, when they first sent particles around the machine, are only baby steps, however. They have sent protons one direction once around the track, but to produce interesting data, they must make the protons stay on track for billions of revolutions, and then they have to send a second set going around the other direction at the same time, so that the two beams can collide, much like runners racing in opposite directions around a racetrack. These events can be likened to the early Apollo missions, which of course did not reach the moon, but we never would have made it to the moon without them.
How do scientists draw conclusions about the origin of the universe from watching subatomic particles collide?
There is very strong evidence that the universe started with a cataclysmic explosion called the Big Bang. During the first fraction of a second, particles were colliding with more energy than we have ever witnessed, until now. By studying the way they collide in the LHC, scientists can figure out what happened during this very early era of the universe. As for the origin, that is still a mystery — but it may be that the discoveries of the LHC will point the way.
How will scientists such as yourself and your colleagues, and ultimately our students, benefit from these experiments?
Scientists want to know how the universe works, and the LHC provides the opportunity to peek at its mysteries in a domain we have never seen before. The results will advise and guide our thinking about particle physics for a generation or more. Ultimately, we want to understand, and this machine will help us understand.
Will these experiments make a difference in our everyday lives?
When Ben Franklin experimented with electricity, he did it for the purpose of understanding how it worked. Now more than half of our nation's GNP is based on electrical devices that Franklin could never have imagined. Will the LHC bring such transformation to the world? Who knows?
On the shorter term, spin-off technologies will doubtless result from a scientific endeavor of this magnitude. The computing demands alone will require significant advances in data processing. Let us not forget that it was at CERN, the very laboratory where the LHC is located, where the World Wide Web was born. Without particles physics, we might never have discovered the Web.
