###### July 2, 2014

# Time-Traveling Photons

If I were to ask you what 88 miles per hour, a sporty-yet-horrendously-unreliable vehicle, Michael J. Fox, and Christopher Lloyd have in common, it wouldn’t take a bolt of lighting to come up with the answer: time travel. But you already know that. Or knew that. Or *will* know that. If there’s one concept that’s more perplexing, more confusing, more intriguing, more abused, and more fascinating than moving through the very fabric of space-time and completely changing the world around you, I couldn’t tell you what it was. It shows up in books, in video games, and in movies. I’d be lying if I said I didn’t spend a large portion of my middle-school mathematics class daydreaming about time-travel with one of my best friends at the time, and I always thought it would be fascinating if the mysterious conspiracies of the world were, in fact, the work of time-travelers desperate to fix a tragically ruined time-line. The grassy knoll? Lee Harvey Oswald? Forget it. Patsies, left to fall for the greater good of the time-space continuum. Clearly, John F. Kennedy would have led the United States to ruin.

But as much fun as it is to bang your head against the impregnable wall of complexity that is time travel, one thing has always remained consistent. It’s just not possible, for a thousand reasons that I simply don’t have the room here to explicate. From the obvious, circular “travel back in time to complete an objective whose resolution would have prevented the need to time travel in the first place” to the complex minutia of quantum physics, it’s just not really going to happen.

Right?

Martin Ringbauer, a PhD student at the University of Queensland, led a team that purportedly sent a single particle of light (known as a photon) through a pathway through space and time that returned the traveling object to the same point at an earlier time — a phenomena known as a *closed timelike curve. *While I won’t pretend to understand the full-on quantum physics, it would seem that by calculating the position of the particle at an earlier point in time using mathematical equivalencies, they were able to identify the “return” by measuring at what point the original particle of light intersected with a second photon simulating the first photon’s original position. Essentially, it went through a mathematical wormhole and bumped into itself.

“Quantum systems can exist in a mixture of existing and non-existing states. In the classical state, you can either exist or not, but quantum systems can operte in both which resolves the paradoxes and time-travel can be formulated in a self-consitent way,” Mr Ringbauer noted. Unfortunately for science-fiction buffs, big ol’ physical masses like human beings don’t really apply for the quantum exceptions that make this possible, much like an earlier success with teleportation. That tends to be the tricky part – replicating the results on a larger scale. Honestly, that’s probably good for everyone in the long run.

Still, Ringbaur is excited about the discovery. According to the article, it’s not about trying to prove whether time travel would ever be possible on a personal scale, but rather that these possibilities might help reconcile the differences between two equally valid but often clashing theories: Einstein’s general relativity and quantum mechanics.

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