Grandfather Paradox

 

In the past two months, physicist and professor Tim Ralph of the University of Queensland and his PhD student Martin Ringbauer led a team that experimentally simulated Deutsch's model of CTCs. This is the first time, testing and confirming many aspects of the two-decades-old theory. A lot of their work circles around the "Grandfather Paradox" which is a hypothetical scenario in which a person travels back through time in a CTC also known as a Closed Time Curve back in time to murder their grandfather then preventing them from being born. This creates a paradox that is infinite unless there is an interjection that disrupts and solves or destroys the paradox timeline. 

    Deutsch's quantum solution to the Grandfather paradox goes something like if a girl were to go back in time using a CTC and then killing her grandfather. The girl has a probability of 50% of not traveling back and killing her Grandfather and the Grandfather has  50% chance of escaping her murderous attempt. Thus according to Deutsch, there are good enough probalistic terms to close the causative loop and escape the paradox.

    In the new simulation developed by Ralph, they studied the interaction of two polarized photons within a quantum system is arguably equal to a singular photon traversing a CTC. They made it so the second photon acts as a past incarnation of the first. Because it is currently impossible to send a person into the past, they created a stunt double of the "person" and ran them through a time-loop simulator to see if the doppelganger emerged from the CTC appearing like the original one in that moment in the past. 

    By measuring the polarization state of the second  photon after emerging from the CTC and comparing it to the original first photon before entering the CTC they found that they were the same and got a successful experiment that helps to solidify his theory. Of course they are not sending actual objects or people into the past through CTCs but it is the closest thing to it at this time.

    

Question 1: Do you think that through following this experiment, that it would be possible to traverse a CTC and resolve a paradox?

Question 2: Do you think that CTCs exist and are usable?

Question 3: Do you think people will give up on travelling back and instead travel to the future?

Patrick Young