So far, the Large Hadron Collider (LHC) has destroyed billions of protons by colliding them head-on inside its super-chilled detectors. Soon, however, the protons won’t be alone, lead ions — whole atomic nuclei — will be smashed up. Why? To recreate the conditions immediately after the Big Bang.
Yes, you read that correctly, scientists working on the most powerful particle accelerator in the world are on the verge of generating their own micro-Big Bangs in an effort to study a state of matter that hasn’t existed in the Universe for 13.75 billion years.
“Matter exists in various states: you can take a material like water and if you deep freeze it, it’ll be solid, and if you put it on a table, it’ll turn into a liquid, and if you put it into a kettle, it’ll turn into a gas,” CERN’s spokesman James Gillies told BBC News reporter Katia Moskvitch.
“It’s all the same stuff, but those are different states of matter. And if you take materials into laboratories, you can pull the electrons off the atoms and you have another state of matter which is called plasma.”
Although plasma might sound pretty exotic, the majority of matter found in the cosmos is in a plasma state. So what do LHC scientists hope to find?
Starting this month — and continuing for four weeks — the particle accelerator will be speeding lead ions around its superconducting electromagnets. So far, only protons have had this dubious pleasure.
When accelerated to relativistic speeds and collided head-on with other protons powering in the opposite direction, the resulting explosion of energy has caused the production of brand new particles. Some of these particles may not have been witnessed by scientists before.
After collision, the energy condenses to create new particles that can be measured and tracked inside the complex particle detectors around the accelerator ring. The very nature of the quantum world can then be probed.
So far, the proton-proton collisions have been designed to generate energies that might produce exotic phenomena like the Higgs boson. But the LHC is also designed to collide heavy lead ions relativistically to help physicists peer back into the beginning of time.
Through ion-ion collisions, higher energies can be generated (because lead ions have more mass — and therefore more kinetic energy — than single protons), thus making these short-lived collisions very hot.
In fact, these fleeting micro-Big Bangs will generate the hottest temperatures yet, replicating the temperature conditions just after the Big Bang. At these temperatures, matter is thought to take on an entirely different state; a state called a “quark-gluon plasma.”
“And this is the state of matter you have if you’re able to effectively melt the nuclear matter that makes up atoms today, releasing the things that are inside, which are quarks and gluons,” said Gillies.
Similar experiments have been carried out in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory where temperatures of 4 trillion Kelvin were measured after colliding gold ions (that’s 250,000 times hotter than the center of the sun, in case you were wondering). It is thought the Universe was as hot only a fraction of a second after the Big Bang.
And soon, for fleeting moments in the LHC’s detectors, the basic components of matter could soon be floating freely as a primordial quark-gluon “soup” giving physicists a glimpse at the extreme conditions that existed at the dawn of time.
Image: A simulation of lead ion collisions in the LHC’s ALICE detector (CERN)