Wind up your clockwork universe, Einstein … if you can

Albert Einstein Head.

Quantum mechanics (the theory of atoms, quarks and photons) is definitely weird and, thanks to the work I’m doing, it might be getting weirder.

Allow me to throw a quantum spanner in the works.

In the early part of the 20th century, the Danish physicist Niels Bohr (referred to popularly as the father of quantum physics) said “those who are not shocked by quantum theory cannot possibly have understood it”.

To quote the comedian/musician Tim Minchin, it can blow your hippy noodle.

Because of its inherent complexity, quantum theory does not allow a picture of a clockwork universe run by simple cause and effect. Rather, it has long seemed to physicists that we must do one of two things:

1) Give up our current understanding of reality, where properties of particles exist whether or not they’ve yet been measured.

2) Allow for the possibility that signalling (literally communication) occurs between particles at a rate faster than the speed of light.

Many physicists support this option, although it does throw up many fascinating issues, such as the grandfather paradox.

Since the 1980s, a third possibility has been bubbling along beneath the surface, but hasn’t been taken very seriously until now: giving up some of our free will.

Free will

What do we mean by free will in this context? Let me give an example:

A scientist might set a voltmeter at a high scale or a low scale of sensitivity, in which case he or she may feel they are exercising free will with regards to setting.

But whatever influence may have come into play with regards to the choices they’ve made might also have influenced the voltage properties of the circuit about to be tested.

In other words, we are influenced by environmental factors, and those same factors may have influenced the voltage properties of the circuit that is to be measured.

To put this yet another way: we are not disconnected from the rest of the universe – we are physical phenomena in the same way as voltage, solar systems, you name it.

“God does not play dice” – Albert Einstein

Consider one very well known quantum light source, known as the singlet state, which emits correlated pairs of photons at roughly the same time in opposite directions.

Now imagine two fictional people: Alice and Bob, who are standing at opposite ends of a room.

For each pair of photons emitted, one travels towards Alice and one travels towards Bob.

Photons wiggle in various ways as they move (up and down, left and right, diagonally) – a property known as polarisation.

Sunglasses make use of this property, only letting through photons that are wiggling vertically.

In our fictional experiment, Alice and Bob can gauge whether their photons are wiggling in a given direction by donning sunglasses, tilting their heads at the appropriate “wiggle angle”, and seeing if a photon comes through.

The photon pairs in our fictional experiment have a remarkable characteristic.

If Alice and Bob tilt their heads at the same angle, their respective photons either both pass through the sunglasses, or both are blocked. In other words, there is a perfect and provable correlation.

How is this possible?

One obvious answer is that the photons have a predetermined destiny, almost as if they have agreed on a story beforehand (“Right, if Bob’s sunnies have a diagonal tilt, pass through, otherwise don’t bother and we’ll meet up at the pub afterwards”).

This idea of a pre-agreed story, or determinism, is exactly what Einstein was referring to when he said “God does not play dice!”.

Breaking the speed limit?

All of the above is fine. But … isn’t there always a but?

The quantum light source in the above example behaves such that, if Alice and Bob tilt their heads at different angles to each other, the correlated photons pass through both pairs sunglasses too often to be explained solely by determinism.

In 1964 John Bell showed that determinism wasn’t enough – it seemed the photons needed to be able to “communicate” somehow when they reached the sunglasses (“Hey, Alice is tilting her head diagonally; what’s Bob’s head doing?”).

Bell’s result no doubt had Einstein spinning in his grave (the great man had died nine years earlier).

Allowing communication between the photons after they had separated at source would mean sending information faster than the speed of light – which was the universal speed limit set by Einstein himself, in his Theory of Relativity.

Giving up (some) free will

I would contend there’s another possibility, a new and compelling argument which I’ve developed over the past year.

It goes like this: Alice and Bob make almost, but not quite, free choices about how they, as the “experimenters” in our fictional scenario, tilt their heads.

Suppose the same factors determining the photons pre-agreed story are also allowed to have a small statistical influence (about 14%) on Alice and Bob’s choices regarding how they tilt their heads.

In other words: Alice and Bob are choosing freely, but not quite as freely as they might believe.

This makes sense, given that Alice and Bob are part of the same physical world as the photons, and hence subject to the same set of environmental factors.

In this way, Einstein can have his cake and eat it: the behaviour of the photons is pre-determined, and there is no faster than light communication between the photons.

But would the great man be willing to give up some of his free will in return for this cake? And would he even have a choice in the matter?

 

What about you? How much free will do you have? Leave your comments and opinions below (PS: you may have little choice in this; your response may be predetermined).

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