Physicist Claims Traveling Back in Time Creates Doppelgangers that Annihilate Each Other

Wednesday, 29 July 2015 - 3:20PM
Weird Science
Physics
Wednesday, 29 July 2015 - 3:20PM
Physicist Claims Traveling Back in Time Creates Doppelgangers that Annihilate Each Other
Traveling to the past at the risk of destroying oneself is a common staple of science fiction, not to mention the central concern behind the Grandfather Paradox. In real life, we still have no idea if time travel is really possible, but a physicist determined in a recent study that if it were possible to travel to the past, it would likely involve the creation of a pair of ghostly twins that ultimately annihilate each other.

When physicists discuss time travel, there are several proposed methods, including travel through a wormhole that serves as a shortcut through curved spacetime. But the most well-known method is faster-than-light space travel, which most physicists believe is impossible. "Time travel" to the future with a spaceship has already been proven, as NASA astronauts have been observed to age .0007 seconds slower every six months that they're in space, but traveling to the past is a different matter entirely. 

Opening quote
"It is well known - and not controversial - that you can time travel to the future by just traveling quickly in a spaceship and coming back," professor Robert Nemiroff of Michigan Technological University told the Daily Mail. "The closer one goes to the speed of light, and the longer the trip, the further into the future you can go. But what about the past? Can you get to the past simply by just traveling in a spaceship?"
Closing quote


For his thought experiment, Nemiroff assumed that faster-than-light travel is, in fact, possible. In his scenario, a spaceship launches from Earth, travel at five times the speed of light to a planet about 10 light-years away, and then returns home to the approximate location of the lift-off site. He then determined exactly what would happen if this feat were achieved, and found that two ghostly ships would be spontaneously created during the act of the time travel.

Opening quote
"The only solutions we could find involved these strange pairs of travelers popping into and out of existence," said Nemiroff. "We speculated that one member of this pair must have a strange type of negative mass, while the other has normal positive mass."
Closing quote


From the perspective of a person on Earth watching the launch pad, because the light emitted from the spaceship would travel five times slower than the spaceship, images of the spaceship on its way out and another doppelganger spaceship on its way back would appear out of thin air about five years after the embarkment. Eight years later, there would be one ship on the landing pad and two phantom ships further away, as if they were traveling backwards in time. Then, ten years later, the two ghost ships would destroy each other, leaving the ship on the landing pad.

Opening quote
"For example, if in Doctor Who, two Doctors were standing right next to each other, we found that a third Doctor must exist, of negative mass, hurtling away faster than light," said Nemiroff. "This third Doctor is destined to meet up with one of the original Doctors and, together, disappear. This superluminal Doctor would also appear to be moving time-backwards."
Closing quote


Like many thought experiments, the study brings up at least as many questions as it answers. Which is the "real" ship? And what are the phantom spaceships made of, exactly? Would the people inside survive this whole process? Would they also be duplicated? And most importantly, is any of this possible?

Sadly, the answer to the latter question may very well be "no," as Nemiroff himself doesn't believe that we will achieve faster-than-light travel, but rather conducted this thought experiment for teaching purposes:

Opening quote
"Unfortunately, it does not seem possible for physical things to travel faster than light, and that is a crucial step," he said. "We can make shadows and light spots from laser pointers appear to move that fast, but no one has ever been able to make something physical - with mass - move that fast. So time travel to the past seems impossible, at least presently."
Closing quote
Science
Science News
Weird Science
Physics

Load Comments