Constructing the Large Hadron Collider

Fabrice Coffrini/AFP/Getty Images

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Can scientists recreate the big bang?

­­According to the big bang theory, billions of years ago the entire universe spanned an area of zero volume and infinite density. Then, this area expanded, doubling in size hundreds of times in less than a second. During those earliest­ moments, the universe was filled with energy, much of it in the form of intense heat. As the universe grew and cooled, some of this energy transformed into matter.

­When we talk about the building blocks of matter, we usually concentrate on atoms. Atoms consist of a nucleus that contains at least one positively-charged subatomic particle called a proton. The nucleus might also contain one or more neutrally-charged particles called neutrons. Negatively-charged particles called electrons surround the nucleus, moving quickly around it within the confines of an energy shell.

But in the earliest stages of the big bang, atoms couldn't form. The universe was too dense and hot. In fact, in the earliest moments of the first second of the big bang, even protons and neutrons couldn't form. Big bang theorists believe the universe was full of subatomic particles like neutrinos, particles with no mass, or quarks, elementary particles that bond together to create larger particles like protons or neutrons.

Scientists call the force that holds quarks together to form larger particles the strong nuclear force. It's so strong that under normal circumstances, we can't observe quarks at all. That's because the quarks bind together so tightly that we can't separate them easily. For many years, the only proof that quarks even existed came from mathematical models of how the universe works. The models required the presence of particles like quarks in order to make sense.

­Today, scientists have managed to take particles like protons and neutrons and break them down into quarks and gluons -- particles with no mass that mediate the force between quarks. The quarks and gluons stay separated for only fractions of a second before decaying, but that's long enough for scientists to observe them using powerful equipment.

How do scientists do this, and are they really recreating the big bang? Keep reading to find out.

An aerial view of the Fermi National Accelerator Laboratory

Courtesy Fermilab

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The Big Bang in the Lab

The world of subatomic particle studies is paradoxical. Scientists use some of the world's largest­ machines to study some of the smallest particles we know about. The devices they use are extremely sophisticated and precise, yet they rely on an almost violent approach. These methods and devices allow scientists to catch a glimpse of what the early universe might have looked like.

The way scientists look at the tiny particles of matter that make up subatomic particles like protons and neutrons is both elegant and primitive. They smash subatomic particles against each other really hard and look at the pieces that are left over. To do this, they have to use powerful machines called particle accelerators.

­Particle accelerators shoot opposing beams of subatomic particles like protons at each other. Some accelerators are circular, while others are linear. They can be very big -- circular accelerators can measure miles across in diameter. The accelerators use banks of magnets to accelerate the proton beams as they travel through tiny tubes. Once the proton beams reach a certain velocity, the accelerator guides them into a collision course. When the particles collide, they break apart into their component parts -- such as quarks.

These subatomic particles decay in fractions of a second. Only by using powerful computers can scientists hope to detect the presence of a quark. In 2006, a team of scientists at the University of California, Riverside reported detecting a top quark, the most massive of the six kinds of quarks. The team had used a particle accelerator to cause a collision between a proton and an anti-proton. They detected the presence of the quark after it had already decayed. The decay process left an identifiable electronic signature [source: University of California, Riverside].

Does this mean scientists can recreate the big bang? Not quite. Instead, scientists hope they can simulate the condition of the earliest moments of the universe. That involves creating a hot, dense area of matter and energy. By studying these conditions, scientists might be able to learn more about how our universe developed. But they can't recreate the period of rapid expansion that we call the big bang.

At least, not yet.

To learn more about the big bang and other scientific theories, take a look at the links on the next page.

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Lots More Information

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Sources

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  • Hawking, Stephen. "A Brief History of Time." Bantam Books. New York. 1998.
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