It's by far the hottest news in physics and astronomy right now: neutrinos were found to move faster than the speed of light!
What are neutrinos and where do they come from?
Neutrinos are a subatomic particles. They are essentially the building blocks of atomic particles such as protons and neutrons which are inside atoms. Neutrinos come in different types (or flavors as particle physicists call it) and are often the result of nuclear reactions or radioactive decay of an atom. They are created in stars and supernova explosions, and we can also create them here on Earth using particle accelerator labs. Neutrinos are electrically neutral which means that they don't interact with things often and can therefore travel far distances and through thick objects without ever being bothered. As an example, the sun creates so many neutrinos that every square cm of our body is being hit with 65 billion neutrinos every second! That's right every second! And we never feel anything.
How do you measure the speed of neutrinos?
The first task at hand is to build a device that can detect neutrinos. It's very hard to stop a neutrino, but particle physicists have figured out a way to detect there presence. I'm not going to go into the details here, so you'll just have to take my word for it. The next task is measuring their speed, and that theory is simple. Velocity, or speed in a given direction, can be calculated by taking the distance traveled and dividing by the time it took to move that distance. It's the same concept as driving a car. The distance from point A to point B, divided by the time I took to get there, gives me my average traveling speed in miles per hour. Now imagine a very long underground vacuum tube like the one particle physicists have at CERN. Neutrinos are created at point A at a given time, travel down the tube, and are detected at point B some amount of time later. We know how long the tube is, and we know the departure and arrival time of the neutrinos, so we can calculate a speed!
Faster than light?
Assuming that neutrinos travel at the speed of light (which is the current theory), particle physicists knew how long it should take for the neutrinos to get form point A to point B. When they looked at the timestamps given by the computers, the neutrinos actually arrived at point B ~60 nanoseconds too early! (That's 0.000000060 seconds) This implies that they traveled faster than the speed of light! (By a very tiny amount, but still measurable). The team that conducted the experiment has been checking for any possible errors that they may have made, and have yet to find any.
If no mistakes were made, what does this mean?
Attempting to interpret this result has some pretty cool implications in the world of physics. What does it mean if a neutrino travels faster than the speed of light? Well it sort of means that the neutrino traveled backwards in time! Our sense of time is defined around the speed of light, so if something moves faster than light, it can be observed before it even occurs. Very weird to think about! Another option is that the neutrinos took "short cuts" through higher dimensions during their travels. In this sense, the neutrinos didn't travel faster than light, they just took a shorter path from point A to B that we as humans can not perceive. The final option is that certain parts of the theory of relativity are incorrect and objects can move faster than the speed of light, without traveling back in time or entering different dimensions. Which one of these solutions is right? Well we will have to wait for the next Einstein to come along and figure it out!
