Faster than light
It's all over the news: scientists from CERN, the European Organization for Nuclear Research, may have found particles which travel faster than light. (See the New York Times Article Tiny Neutrinos May Have Broken Cosmic Speed Limit.) Why is this a big deal?
A group of scientists set up an experiment in which they shot neutrinos, special elementary particles, from the CERN laboratory in Switzerland to the OPERA detector in Italy, roughly 700 km (450 miles) away. To measure the speed, they clocked the time and measured the distance. Their result is that the neutrinos were faster than light.
This result is a big deal because it contradicts Einstein's statement that the speed of light in a vacuum (roughly 300 000 km or 186,000 miles per second) is the absolute maximum speed of anything. The speed of light as a maximum speed limit is a crucial part of his special theory of relativity, which includes his famous formula E=mc2. If something can travel faster than the speed of light, E=mc2 would become useless.
Einstein's theory had and still has a big impact on physics. When he came up with the theory of relativity in 1905, existing theories about speed and time had to be changed. The last hundred years, this speed limit was assumed to be fact, and a lot of experiments supported Einstein's theory. So far, all claims of speeds faster than light could not be verified.
So now, the CERN researchers have asked the greater scientific community to help them verify their results. Everyone is looking for errors in the measurements from the experiments. And there is plenty of room for error. Here are the main problems:
- Neutrinos are hard to detect. They go through nearly everything without interaction.
- It is difficult to measure the exact distance accurately.
- Because of the extremely short time intervals and large distances (the neutrinos needed only 2.4 milliseconds to travel the 450 miles), it is difficult to clock the time accurately enough.
GPS is used to measure the distance, and the theory of relativity is used to determine position with a GPS device. It's ironic that the scientists depend on the theory of relativity in order to disprove the theory.
I bet that it turns out that the neutrinos didn't travel faster than light. Stay tuned...