While conducting fusion research, scientists at the Imperial College London realized that they’d accidentally created a machine that can convert energy into light! From Geek:
They were attempting to work with a fusion power component called a hohlraum, or a small, empty gold container, when they realized they were inadvertently creating the perfect conditions for a Breit-Wheeler reaction. More than 80 years after the fact, these scientists believe they have developed a way of turning the Breit-Wheeler hypothesis into the Breit-Wheeler theory. Though physicists seem extremely certain their model will be upheld by the data, that data could still reveal a lot about the physics of existence.
That’s important for a number of reasons. Over and above the fact that science has thought of this idea as fact for some time, the mass-energy conversion process was a major player in the very earliest moments of the universe. High-level physics and cosmology today can look back into time at the Big Bang though remaining evidence like cosmic background radiation, and through measured experiments like these proposed photonics collisions. Basically anything that pushes the boundaries of understanding of energy, from the Big Bang to black holes to gamma ray bursts, could be illuminated by a better understanding of exactly how energy and mass are related to one another.