What Happens when Pushing Light Past its Speed
One of the more famous consequences of the Theories of Relativity is that the speed of light is a universal constant and impossible to exceed. While the former has been proven many times over, the latter has some loopholes to it. NIST researchers decided to test the loopholes by pushing part of a light wave past the fastest speed possible.
To say that nothing can travel faster than the speed of light is actually not a completely accurate interpretation of physics. The real limit is on how fast information can move, and as it turns out there are certain properties of light waves that do not carry information. Researchers discovered two years ago that it is possible to exploit that and nudge the leading edge of a light pulse ahead of the wave, causing it to arrive nanoseconds earlier. As it does not contain information in a traditional sense, this does not violate any physical laws, but what about quantum mechanical information? This is the question the NIST researchers decided to investigate and they did so by entangling two photons, and only nudging one of them. Because the photons are entangled, their states are strongly correlated and measuring one will reveal information about the other.
When the researchers measured the photons they found that the entanglement weakened as the nudging increased the amount of noise present, which means that even quantum information obeys the speed limit. This work should prove very useful as researchers develop the systems to transfer information within the systems of quantum computers.