“The best way to predict your future is to create it.”
- Abraham Lincoln
Okay, this is something we all might agree upon: of all the fears we face in our lives, the fear of our future is the biggest. The uncertainties associated with our personal and professional lives prompt us to make predictions about our future every now and then. Is there such a thing as precognition, or seeing the future? What does science have to say about this? Let’s find out.
In Popular Culture
I just watched Minority Report, so I thought I must mention it here. Precognition takes centre stage in this Steven Spielberg’s sci-fi action thriller. It involves three precogs capable of having visions about future crimes. This makes it possible for police to catch criminals before a crime is committed. Precrime chief John Anderton (Tom Cruise) is accused of one such crime and sets out to prove his innocence. I absolutely loved this movie and definitely recommend it for sci-fi lovers.
Arrival and Krrish are other two notable movies based on precognition.
Predicting the Doomsday
One of the first things we will do if we are ever able to harness the superpower of seeing the future will be to see when the world would end. As it turns out, numerous doomsday predictions have been made in the past:
Europe
In 1499, Johannes Stöffler predicted a great flood that would end the world on February 20, 1524, based on the conjunction of all the planets: Mercury, Venus, Mars, Jupiter, and Saturn. People fled their homes in a state of panic. But when the day came, there was only a slight rain. The mob burst into anger as everyone felt betrayed. A riot broke out and hundreds were killed.
Georgia
In 1648 Sabbatai Zevi in Smyrna declared that the world would end in 1666. The news spread across Europe. After his prediction failed, Zevi was imprisoned.
America
William Miller proclaimed that Jesus Christ would return to the Earth by 1844 resulting in the end of the world. A spectacular meteor shower occurred in 1833, further enhancing the influence of Miller's prophecy. But the date passed peacefully, and the reaction that followed came to be known as the Great Disappointment.
Similarly, Charles Taze Russell failed twice in predicting doomsday in 1874 and 1914.
Defying Causality
Causality is a principle which states that an effect of an action of happens after its cause and not vice versa.
Every physical law obeys this cause → effect relationship. Precognition violates causality. We are yet to discover a law that would violate causality.
Newtonian mechanics is firmly based on causality. If you know the present parameters that affect the motion of an atom (like position, velocity and the force acting on it), you can calculate its future trajectory. Here, the present parameters represent the cause and the future parameters represent the effect. According to Newtonian physics, the future is calculable but not predictable.
There is no room for precognition in Newton's theory. Forget about predicting the universe, Heisenberg’s Uncertainty Principle rules out even calculating the future with absolute accuracy.
Backwards In Time
In the 19th century, Scottish mathematician James Maxwell developed the electromagnetic theory of light. When we solve Maxwell's equations for light, we arrive at two kinds of waves: retarded and advanced. A retarded wave represents the standard motion of light travelling forward in time whereas an advanced wave travel backwards in time. Since there is no such thing as travelling backwards in time, advanced waves were considered unphysical and were abandoned.
But in recent times, physicists have started taking an interest in these mysterious advanced waves. Some physicists argued that there ought to be some physical relevance to these advanced waves. If we could learn to control these waves and send messages back in time, our past generations would achieve the power of precognition.
Richard Feynman was one of those who were intrigued by the idea of time travel. While working as a PhD student under John Wheeler at Princeton University, he studied Dirac's work on the electron. He found out that Dirac’s equation obeyed T-symmetry if it obeyed the C-symmetry as well i.e. the laws retained their form upon reversing the direction of time and charge of the electron in Dirac's equation.
Is there any physical significance of this result? Yes! It implies that an electron going backwards in time is the same as a positron going forward in time. This meant that backwards-in-time travelling wave solutions could exist in nature: they represented the motion of antimatter.
Next, he considered the process of Electron-Positron Annihilation (EPA). An electron and positron come close, collide, disappear and produce gamma rays. Remember that electrons and positrons travel forward and backwards in time respectively.
Now reverse the charge of the positron so that it becomes an electron going backwards in time. Now imagine what happens. It looks like the electron went forward in time, then suddenly reversed its direction and produced gamma rays in the process. Pause for a moment to digest this so significant result: EPA involves the same electron going forward and backwards in time! Isn’t it crazy?
If antimatter is just ordinary matter travelling back in time, is it possible to send a message into the past?
Bad news, since it has been found that antimatter doesn’t violate causality. The laws of physics remain the same whenever an experiment is performed with antimatter. Each time the electron goes backwards in time, it simply fulfils the past. Feynman showed that if we add the contribution of the advanced and retarded waves, we find that the terms that might violate causality cancel precisely. Thus antimatter is essential to preserving causality.
So as we see, precognition is ruled out by Newtonian physics. Quantum theory allows for the existence of antimatter which can travel back in time but it too doesn’t violate causality. Physicists are trying to discover Tachyons, the elementary particles which would defy causality but are yet to succeed.
So achieving precognition is a near-impossible task. But if we ever succeed, it would be at the expense of a major shake-up in our understanding of the natural laws.
Sources:
Ch 15 - Precognition, Physics of the Impossible, Michio Kaku