So many people wrote in to say how hard it is to get their minds around retrocausation – the idea that present thoughts can influence past actions - that I thought I’d share an even more mind-warping experiment.

This was simple experiment carried out by the Oxford University physicist Vlatko Vedral who decided to use Bell’s inequality, the famous test of non-locality – that spooky entanglement between quantum particles. Bell demonstrated that two quantum subatomic particles can remotely influence each other, even over vast distances, which completely ‘violates’ our Newtonian view of separation in space.

Could this same test be used to show that limits governing time can also be violated, they wondered? Brukner enlisted one of his colleagues at the University of Vienna, Caslav Brukner, to design a thought experiment (an experiment essentially just carried out mathematically).

So many people wrote in to say how hard it is to get their minds around retrocausation – the idea that present thoughts can influence past actions - that I thought I’d share an even more mind-warping experiment.

This was simple experiment carried out by the Oxford University physicist Vlatko Vedral who decided to use Bell’s inequality, the famous test of non-locality – that spooky entanglement between quantum particles. Bell demonstrated that two quantum subatomic particles can remotely influence each other, even over vast distances, which completely ‘violates’ our Newtonian view of separation in space.

Could this same test be used to show that limits governing time can also be violated, they wondered? Brukner enlisted one of his colleagues at the University of Vienna, Caslav Brukner, to design a thought experiment (an experiment essentially just carried out mathematically).

Non-locality through time

Their experiment rested on one of the most basic assumptions in science about time: in the evolution of a particle, a measurement taken at a certain point will be utterly independent of a measurement taken later or earlier. In this instance, the ‘inequality’ of Bell’s would refer to the difference between the two measurements when taken at different times.

Scientists like to give a particles names, and so Vedral and Brukner decided to call their photon ‘Alice’. The task now was to make theoretical calculations of Alice’s ‘polarization’ at two points of time.

Remember that quantum waves behave like a wriggling skipping ropes being shaken at one end. The direction in which the rope is pointed is called polarization.

First Vedral and Brukner calculated Alice’s present polarization, then measured it moments later. When they had finished their calculations of Alice’s current position, they went back and measured her earlier polarization again.
To their amazement, they discovered that, between two points of time, they got a different measurement of the first polarization the second time around. The very act of measuring Alice at a later time influenced and indeed changed how it was polarized earlier.

Entanglement between particles, or spooky action at a distance, as Einstein called it, can occur through time as well as space.

Futureshock

The implications of their astonishing discovery were not lost on the scientific community. New Scientist included their discoveries in a dramatic cover story: ‘Quantum entanglement: How the future can influence the past’ and concluded:

quantum mechanics seems to be bending the laws of cause and effect… entanglement in time puts space and time on an equal footing in quantum theory… Brukner’s result suggests that we might be missing something important in our understanding of how the world works.

For me, Vedral’s thought experiment holds a significance far greater than a simple theoretical one. It shows that instantaneous cause and effect not only occurs through space but also back and possibly forward through time. It offered the first mathematical proof that the actions of every moment influenced and can even change those of our past.

It may well be that every action we take, every thought we have in the present, alters our entire history. Time is a now, space is a here.

The power of observation

Even more significantly, his experiment demonstrated the central role of the observer in creating, and indeed changing, reality. Observing had played an integral part in changing the state of the photon’s position. The very act of measuring something at one point of time changed its earlier state.

This may mean that every observation of ours changes some earlier state of the physical universe. A deliberate thought to change something in our present could also influence our past. The very act of intention, of making a change in the present, may also affect everything that has led to that moment.

According to some scientists like Dutch physicist Dick Bierman, what appears to be retrocausation is simply evidence that the present depends upon future potential conditions or outcomes. n a sense, our future actions, choices and possibilities all help to create our present as it unfolds.

According to this view, we are constantly being influenced in our present actions and decisions by our future selves. Spooky action, indeed.