25 March 2009

Subatomic particles have free will

Cosmos Online
If humans have free will, then so do subatomic particles such as electrons, say U.S. mathematicians.
floating atoms

It's possible that the free will we experience is a result of the free will of subatomic particles. Credit: iStockphoto

SYDNEY: If humans have free will, then so do subatomic particles such as electrons, say U.S. mathematicians.

“If experimenters have a certain freedom, then particles have exactly the same kind of freedom,” wrote mathematicians John Conway and Simon Kochen, of Princeton University in New Jersey, in a recent paper published in Notices of the American Mathematical Society.

“Indeed, it is natural to suppose that this latter freedom is the ultimate explanation of our own,” they said.

The quantum world

Quantum mechanics is a theory that uses probability to predict how particles will behave. But on a case-by-case basis, the behaviour of each particle is almost completely unpredictable.

Not accepting such unpredictable behaviour, some scientists have proposed the existence of hitherto unknown forces or properties they call ‘hidden variables’. They argue that the randomness of particle behaviour is only a mirage, and the behaviour would be entirely predictable – or ‘deterministic’ – if only the hidden variables were known.

This, the duo argue, is no longer a valid interpretation of quantum mechanics. “Any such theories must now contain some indeterminism – or ‘free will’,” said Stephen Bartlett, a quantum physicist at the University of Sydney, who agreed with the general thrust of the arguments made by the Princeton duo.

“Conway and Kochen prove that the randomness does not depend on anything. They prove that the outcomes of these quantum random events are really completely independent of anything that has happened in the past,” he added.

The free will theorem

The U.S. mathematicians based their deductions on three unassailable theorems, which also happen to rhyme: ‘spin’ – measuring a quantum property called spin of an elementary particle; ‘twin’ – that a pair of particles are correlated; and ‘min’ – that an experimenter’s choice of what to measure cannot be communicated faster than the speed of light.

If experimenters are free to choose between experiments – that is, the choice of experiments is not predetermined by past events – then the particle must also decide how to act on the spur of the moment.

Bartlett believes Conway and Kochen’s work is convincing. “It’s quite an interesting result. Their research falls into the broad category of exploring just how strange the quantum world is,” he says.

Conway is currently presenting his theorem in a series of lectures at Princeton University.


Sign up to our free newsletter and have "This Week in Cosmos" delivered to your inbox every Monday.

>> More information
Like us on Facebook
Follow @CosmosMagazine
Add Cosmos to your Google+ circles

Get a weekly dose of Cosmos delivered straight to your inbox!

  • The latest in science each week
  • All the updates on our new website launch
  • Exclusive offers and competitions

Enter your name and email address below: