Subtitles section Play video Print subtitles Time travel to the past is basically impossible without breaking some laws of physics and acquiring plutonium from some Libyans. But time travel to the future is easy; we're all doing it right now. So why does time go forward and not back? The idea that time only flows in one direction is called the Arrow of Time. But, odd as it sounds, there's nothing in the equations that describe the laws of physics that says it has to be this way. The equations can tell you what will happen in the future or what took place in the past based on what's going on in the present, but they don't explicitly state that time must go from past to present to future. The math works just as well going either direction. The one thing that seems to keep driving this time bus to futuretown is the second law of thermodynamics, which states that entropy must always increase. Things must go from order to chaos ; heat must disperse from hot bodies to colder ones. This increase in entropy is what keeps the ordered past behind us and the increasingly messy future ahead. But there seems to be a loophole in the second law of thermodynamics, and scientists recently exploited it to turn entropy on its ear. Apparently the law doesn't apply to correlated particles, which are like entangled particles, but with less of a connection. When researchers observed a hot hydrogen nucleus that was next to a cooler carbon nucleus inside a trichloromethane molecule, the nuclei behaved as expected: Heat flowed from the hot hydrogen to the cool carbon. But when they tried the same thing with correlated hydrogen and carbon nuclei, the opposite happened. The hydrogen got hotter, while the carbon chilled even more. This is akin to putting a hot coffee cup in a cold room and watching it heat up as you feel the room get colder. The scientists went on to make the bold claim that this experiment shows the reversal of the Arrow of Time. But even if that's indeed what's happening, it looks like it only applies under very specific circumstances on an atomic scale. So, not that I'm a physicist or anything, but did you reverse the Arrow of Time ? Does that mean time is suddenly running backwards or is there something else at play with these atoms here? Needed is research more. I wouldn't exactly predict a future where broken coffee mugs spontaneously reform or rooms tidy themselves just yet. Special thanks to DOMAIN.COM for sponsoring this episode of Seeker. DOMAIN.COM is awesome; affordable, reliable, and has all the tools you need to build a new website. They can fulfill all of your website needs. They offer .com and .net domain names and intuitive website builders. They have over 300 domain extensions to fit your needs, from .club, .space, to .pizza! Take that first step in creating an identity online and visit DOMAIN.COM. If you've watched all our past episodes, then please subscribe for our future ones. If you haven't seen them all, check out this video on how your perception of time can alter if you speak another language. In the distant future, when the entropy is at its maximum, there will actually be no Arrow of Time, because nothing will be able to change. Thanks a lot for watching Seeker.