This Exotic State of Light Acts Like a ‘Liquid’


This Exotic State of Light Acts Like a ‘Liquid

Light has been a favorite subject of study since pretty much forever and it still has more amazing hidden properties waiting to be discovered. Recently researchers found that under the right conditions, light can behave like a liquid with particles that flow in unison. That’s right—liquid light. Well, that’s not quite right. “Liquid” is a useful analogy…but it implies the light is in a liquid state, when really it’s in a more exotic state of matter, namely a Bose-Einstein condensate, or BEC.

Sometimes called the 5th state of matter, after solids, liquids, gasses, and plasma, a BEC is created when a group of particles acts as one giant superparticle. This can be done using entire atoms like rubidium and potassium cooled to near absolute zero.

Like photons, atoms behave like both waves and particles, and as they cool to extreme temperatures they lose momentum and their wavelengths blur together. Pioneering Indian physicist Satyendra Nath Bose and Albert Einstein predicted they could exist nearly a century ago. Because they require such low temperatures, Einstein thought it would be impossible to actually observe one. Turns out the impossible became possible in 1995, when the first Bose-Einstein condensate was created using roughly 2,000 rubidium atoms. A different technique for creating Bose-Einstein condensates out of light was discovered in 2010, and interestingly, it involves much more reasonable temperatures. When cooled, photons have a tendency to vanish into the walls of whatever is containing them.

Like it? Share with your friends!