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Time travel is a popular concept in movies, on TV shows and on the internet, but up until now no one has actually been able to do it in the real world.
Not that people aren’t trying to figure out how.
For example, scientists at the University of Cambridge Hitachi Laboratory have been hard at work on time travel and recently shared some of their very interesting discoveries in the journal Physical Review Letters.
Recently, they were able to simulate a form of backward time travel that enabled them to change the results of an event from the past 25 percent of the time.
“Imagine that you want to send a gift to someone: you need to send it on day one to make sure it arrives on day three,” David Arvidsson-Shukur, the study’s lead author, said in a statement. “However, you only receive that person’s wish list on day two. So, in this chronology-respecting scenario, it’s impossible for you to know in advance what they will want as a gift and to make sure you send the right one.
“Now imagine you can change what you send on day one with the information from the wish list received on day two. Our simulation uses quantum entanglement manipulation to show how you could retroactively change your previous actions to ensure the final outcome is the one you want.”
The simulation is based on quantum entanglement, which consists of strong correlations that quantum particles can share and classical particles—those governed by everyday physics—cannot.
The particularity of quantum physics is that if two particles are close enough to each other to interact, they can stay connected even when separated. This is the basis of quantum computing – the harnessing of connected particles to perform computations too complex for classical computers.
“In our proposal, an experimentalist entangles two particles,” said co-author Nicole Yunger Halpern, researcher at the National Institute of Standards and Technology (NIST) and the University of Maryland. “The first particle is then sent to be used in an experiment. Upon gaining new information, the experimentalist manipulates the second particle to effectively alter the first particle’s past state, changing the outcome of the experiment.”
“The effect is remarkable, but it happens only one time out of four!” said Arvidsson-Shukur. “In other words, the simulation has a 75% chance of failure. But the good news is that you know if you have failed. If we stay with our gift analogy, one out of four times, the gift will be the desired one (for example a pair of trousers), another time it will be a pair of trousers but in the wrong size, or the wrong color, or it will be a jacket.”
To counteract the high chance of failure, the theorists propose to send a huge number of entangled photons, knowing that some will eventually carry the correct, updated information. Then they would use a filter to ensure that the right photons pass to the camera, while the filter rejects the rest of the ‘bad’ photons.
Arvidsson-Shukur added that while they are “not proposing a time travel machine” and that the “simulations do not allow you to go back and alter your past,” they “do allow you to create a better tomorrow by fixing yesterday’s problems today.” Which is pretty darn exciting.