LHC Back Online

Scientists at CERN turned the Large Hadron Collider back on and injected protons into the particle stream on Friday, resuming operations for the first time in a year.

Last year, shortly after it became operational for the first time, the LHC experienced a failure in one of the containment magnets that keeps the particles within their track and going around in circles. Because of the tremendous forces required, these magnets are extremely powerful, and if they become misaligned by even a tiny amount, they can fail catastrophically, destroying themselves.

That's what happened last year, and resulted in repairs and replacement of the magnet. It took a while to complete the repairs because the LHC is kept at a brisk -271°C and had to be warmed up slowly, repaired, and cooled back down slowly, but the work is finally done and science is once again underway at the world's most powerful particle collider.

And, in case you hadn't noticed, it still hasn't destroyed the world.

New Research on Quantum Entanglement

The idea of faster-than-light—even instantaneous—communication has been around for a long time. Pretty much ever since the concept of quantum entanglement was proposed. Albert Einstein, notably, did not believe in such behavior, as his Theory of Relativity showed that faster-than-light travel and even communication were impossible. He mocked quantum entanglement, famously calling it "spooky action at a distance."

Nevertheless, recent studies have confirmed the presence of this "spooky action" and now, for the first time, placed a limit on how quickly it happens. The experiment, conducted in Switzerland, confirmed that the entangled particles had exactly the same properties at the same time, even though they were 11 miles apart. In doing so, the research determined that the minimum speed at which the quantum information could be passing between the two particles was at least 10,000 times the speed of light.

There are several possible explanations, but a great deal of new work would need to be done before we really know what's going on. It's possible that some exotic particle that travels faster than the speed of light (a tachyon) could be emitted by one of the particles and absorbed by the other. Indeed, the theory of tachyons shows that a tachyon with no mass would have an infinite velocity, which in a way means that it would exist completely outside of time, capable of traveling to any (and every) point in the universe instantaneously, and would never exist in time (which is why we have never detected them directly).

It is also possible that nothing is traveling that fast at all, but rather that the act of observing the particles causes their wave functions to collapse, and because the particles are entangled they share the same wave function. If the collapse of the wave function happens instantaneously, then it would happen for both particles at the same time.

In any event, researchers are still quite a ways away from being able to give us a reliable ansible.

LHC Won't Destroy the World

Good news! It seems that, when the Large Hadron Collider at CERN is turned on, it won't actually destroy the Earth. Of course, physicists were already sure of this, but now a new safety review conducted by CERN's governing council has confirmed the fact.

The main argument for why the high-energy reactions won't destroy the Earth is that they haven't so far. Since the Earth gets bombarded with highly-energetic cosmic rays all the time, they point out, the types of interactions that will happen within the controlled confines of the LHC have already happened 10³¹ times since the universe began. And none of those reactions destroyed the Earth. So since we're still here, these types of reactions aren't going to destroy the Earth. Pretty good logic from where I'm sitting, but it probably won't stop the conspiracy-theorists and doomsday prophets from continuing to predict the end of the world, and it almost definitely won't stop the lawsuit that is attempting to prevent CERN from activating the LHC.

At last, I can relax and stop worrying about the world ending. Until the next over-hyped doomsday scenario, at least.

Falling Up

Does antimatter fall up? It turns out, we don't know. Our scientists have too little experience with the stuff, as it tends not to last very long once we produce it. But a series of new experiments being planned at Fermilab and CERN could provide some insights.

The experiments involve testing the effect of gravity on antimatter by producing beams of antihydrogen and measuring how gravity affects the beam. The experiments are highly challenging, as the detectors that we would use to identify the position of the antihydrogen beam are made of normal matter, which tends to react rather violently with antimatter.

Most scientists seem to think that the antimatter beams will behave exactly the same as normal matter beams of the same mass and electrical charge would. But they're hopeful of seeing something that they don't expect. After all, results that do not conform to expectations are where newer, more advanced scientific theories come from.

A Test for String Theory?

Researchers at University of California, San Diego, Carnegie Mellon University, and University of Texas at Austin have developed what they believe will be a means of testing String Theory, the leading candidate for unifying the laws of physics into a single theory.

The process involves testing one of the three underlying mathematical assumptions used by String Theory, that there is a smoothness criteria for the scattering of high-energy particles after a collision. They propose to test this assumption by using the Large Hadron Collider to investigate the scattering of W bosons. If the W bosons do not scatter according to the predictions made by String Theory, physicists will know that there is a flaw in the theory.

“If the bounds are satisfied, we would still not know that string theory is correct,” said Jacques Distler, a professor of physics at The University of Texas at Austin.

One of the main criticisms of String Theory has been that it is largely untestable. And while this test is not a perfect test, it will allow researchers to test at least a part of the theory, and that's at least progress toward a better understanding of our universe.