Beyond the speed of light


With potentially groundbreaking data published in the last few weeks, Conor O’Nolan talks about the experiments that could change physics forever

Two weeks ago scientists at OPERA in Italy, working in collaboration with CERN in Geneva, published a paper which suggested that they have observed neutrinos travelling faster than the speed of light. News of their apparent discovery went viral instantly, and the findings were published on a number of news websites before the CERN website was even updated. Should these results be verified, a large proportion of physics will have to be completely rewritten.

In the seventeenth century, Issac Newton invented Newtonian mechanics. This worked perfectly for a few hundred years, but as physics progressed it became apparent that this paradigm did not work when it came to the very fast and the very small.

In 1905, Albert Einstein published his theory of special relativity, which allowed particle physics to be better understood than if classical mechanics was used. One of the central equations in this theory was the equation describing mass energy equivalence, or more succinctly E = mc^2. This equation is considered so important that Steven Hawkins chose it as the only equation to include in his best selling A Brief History Of Time. The basic and fundamental thing that can be taken from this equation is that nothing can travel faster than the speed of light.

Wolfgang Pauli postulated the neutrino in 1930 to explain the observed discrepancies in beta decay (A type radioactive decay). It took twenty-six years for it to be experimentally verified by Clyde Cowan and Frederick Reines in 1956, who together won the Nobel Prize in Physics for this work a mere thirty-nine years later. Neutrinos have no charge and almost no mass (it is important to note that they do have some mass, but it is minute). It was also thought that they travel almost at the speed of light. The earth is continually bombarded with neutrinos from the sun, which are a product of nuclear fusion. However, neutrinos react with almost nothing, so they just pass though the earth and carry on their merry way.

The experiment that was conducted involved sending a beam of neutrinos from Gran Sasso Laboratory in Italy, 732km through the earths crust. While this seems like a massive distance, it took the particles less than 3 milliseconds. Neutrinos were produced by focusing a high-energy beam of protons onto a fixed target; this caused a variety of particles to be released, but the other particles were affected by atomic material within the earth. Neutrinos made the target 732km distance as a result of their negligible mass and no charge. The particles reached the detectors in Geneva a minute fraction of a second before they were expected to arrive. The experiment was conducted over three years and the data for over 15,000 neutrinos was collected.

The results published are completely unexplained as of yet. The Italian scientists want other labs conducting similar experiments to run this experiment in the hope of either repeating, or falsifying, these results.

This is also not the first time that experiments have hinted that neutrinos can travel at the speed of light. The MINOS experiment run by Fermilab in Chicago shot beams of neutrinos 450 miles underground to a former iron mine with a 6,000 tonne detector in it. The findings of this experiment do not contradict the results published by OPERA.

However, the scientific community as a whole do not seem entirely convinced by the results. A professor from the University of Surrey, Jim Al-Khalili, said that he would eat his boxer shorts on live television if the experiment’s outcomes were proven correct. Despite the rigorous repetition involved in the experiment, instrument error is still cited as a potential explanation for the unusual data.

If these groundbreaking results are true, Einstein’s theory of special relativity will no longer be completely correct, as a lot of it is based on the fact that nothing is thought to be able to travel faster than light. Famous physicists have offered alternative explanations using somewhat non-mainstream physics theories. Brian Cox mentioned in an interview with the BBC that there is a possibility of our world consisting of more than just three dimensions (or four, if time is included) and that the neutrinos could have taken some sort of dimensional shortcut.

On a slightly lighter note, should these results be proven to be correct, and scientists subsequently come up with an explanation for the results, it should be possible to determine whether time travel is actually a possibility. Up until now, physicists have been unable to give a definitive answer because there is a disparity between quantum mechanics and general relativity, but if general relatively is proven to be partially incorrect, a unified theory might be possible.

Regardless of the outcome, this is an exciting time for physics. A key part of science is proving and disproving theories that might nullify thousands of peoples lives’ work, but the pursuit of a final model that explains everything we have observed up until now is fruitless – something new, such as a better understanding of neutrinos, is always bound to turn previous research on its head.