Light is the fastest anything in existence. Unless we say otherwise. It's fairly easy to stop light (you can do it by closing your eyes), but a team at the University of Darmstadt stopped light, held it motionless for over a minute, then sent a signal to let it continue on its way.
They reversed the polarity of traffic lights.
A probe laser pulse was frozen in a supercooled Praseodymium-ion-doped Yttrium Orthosilicate crystal, because all laser-based scientific research is required by law to sound like exposition dialogue from a 1950s B-movie. How did we make this material freeze lasers? With more lasers, because that's always the most awesome solution. Preparation laser pulses set up the crystal's quantum states, then a "write" pulse induced Electromagnetically Induced Transparency (EIT). Our laser tells the material to be transparent, allowing the probe pulse to pass into the material. We literally fire lasers at matter until it does what we say. Then the "write" pulse is turned off while the probe is still inside, removing the transparency, and the probe pulse is trapped.
But instead of being destroyed, the probe is encoded into the quantum energy levels of the atoms. External magnetic fields hold them stable for over a minute, which in quantum terms is infinity plus a zillion years. A "read" pulse from the control laser renders the material transparent again, and probe light shines out. They were able to recover probe pulses and images sixty seconds later this way. The light should have moved 18 million kilometers in that time. We held it inside a three millimeter crystal.
Science is often lots of tubes and glowy things.
Stopping light like this could be useful for quantum computation and communications, if you're the sort of person who could see people stopping light and then need another reason to be impressed.
We've always been told that someone powerful once said, "Let there be light."
Humanity's response? "When we say so."
Continue your education with The Focal Length of Whiskey and Mario's Terrifying Implications For Physics.
Light up your mind with 9 Badass Lasers That Prove The Death Star Isn't Far Off and The 5 Smartest Things Humanity Has Done (Recently)
Luke has a website, tumbles, and responds to every single tweet.