Faster than the Speed of Light.
CERN laboratory has a quandary. It appears that in one of their experiments that they had found particles travelling faster than the speed of light. According to Einstein's special theory of relativity, this is impossible.
A stream of neutrinos were measured travelling between two points and appear to have made the distance faster than is possible. They have been over the results several times and are opening up all the details to other scientists to try and confirm what may or may not have just happened.
What is good, is that a lot of the scientists are being very, very cautious about the result. This isn't like room temperature fusion, where it was announced and swiftly debunked. This is a group of people trying to understand what the hell just happened.
But if true, this could mean cause and effect is no longer certain.
Of course, the neutrinos could have been moving faster than light and were heading towards their destruction instead of their creation.
More details here for starters.
Even XKCD has picked this one up quickly.