For as long as there has been science fiction, the concept of time travel has captured the imagination. Though it has long been dismissed as fantasy, physicists have not yet been able to prove or disprove that humans may one day be able to manipulate the fourth dimension. Apart from physical problems, several paradoxes stand in the way of time travel. These include the "grandparent paradox", which has long flumoxed physicists and philosophers. As Science Alert explains, a time traveller could in theory prevent his or her grandparents from meeting, "thus preventing the time traveller's birth". This would make it impossible for the time traveller to have set out in the first place and kept the grandparents apart.
However, cosmologists believe they have figured a way around this by suggesting that there is more than one universe in existence – the 'multiverse' model. This allows for every possible version of an event to take place. The Independent's science editor Steve Connor gives this example: "a woman who goes back in time to murder her own granny can get away with it, because in the universe next door the granny lives to have the daughter who becomes the murderer's mother." This, and other paradoxes, are situations that "give cosmologists nightmares," writes Stephen Hawking.
Physicists studying the behaviour of single particles of light say they can now discount one of the main theoretical objections to time travel. During research published in Nature Communications, scientists at the University of Queensland designed an experiment that simulated the effect of a photon – a particle of light – travelling back in time and interacting with its older self. "Time travel was simulated by using a second photon to play the part of the past incarnation of the time-travelling photon," said University of Queensland physics professor Tim Ralph.
The results revealed that time travel on a quantum level seems to be possible.
Kemo D. 7
Kemo D. 7