Can You Travel Back in Time to Stop Patient Zero Getting Infected?

A turntable for playing vinyl records.

Time travel has intrigued both filmmakers and scientists alike. Though Hollywood has taken liberties and ran away with its imagination, physicists have been stumped by the issue of paradox – an inconsistency that can result from time travel.

An undergraduate, through some clever math in a peer-reviewed paper, has proven that time travel is possible – but only if it doesn’t result in a paradox.

The question has been framed in a different way. We always assumed that we have the freedom to do time travel as an arbitrary action. Turns out we can only travel in time but do nothing for a paradox to occur.

In the patient zero case, it is not possible because if you stopped patient zero getting infected then you won’t have the motivation to go back in time to do it in the first place. Or the other scenario is that you go back in time to stop patient zero getting infected but then you yourself or someone else becomes patient zero.

Salient events would “just recalibrate around you… the events will always adjust themselves, to avoid any inconsistency.”

There’s a lot of terms like “closed time-like curves,” determinism, reversible dynamics and freedom of choice. You can wrap your head around them, or they can make your head spin. Or they will add to the jargon that Hollywood writers can use to fire their imagination.

For the rest of us mortals, it means even if someone invents a machine for us to travel back in time, we won’t be allowed to change big events or mess things up. It’s a bit like playing vinyl records on a turntable — you can choose what record to play but you can’t change what’s on the record.

There’s an on-going debate among physicists whether the future is already set or is continuously being created. I am not a physicist but I want to believe that we can still determine the future by the choices we make today. That is a freedom I would like to hold on to.

In the meantime, one can always go back in time by playing one’s favourite music on a turntable. It’s as good a time travel machine as any.

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Lens-Artists Photo Challenge #116: Symmetry