In
a new paper, researchers say they've proved that two realities can exist at
once, at least when it comes to the quantum world.
To
investigate their hypothesis, researchers at the Department of Experimental
Physics at the University of Innsbrück in Austria tackled one of the world's
most confounding thought experiments, called 'Wigner's Friend.'
The
experiment, named after its progenitor, the Nobel Prize-winning physicist
Eugene Wigner, was posited in 1961 and involves two people observing the same
thing — in this case, a single photon.
When
the photon is observed, it is displayed in either a horizontal or vertical
state, but according to quantum mechanics, before that observation is made, it
exists in a state of 'superposition' meaning that it is in both states at once
— horizontal and vertical.
In
Wigner's experiment, one person in a laboratory observes the photon, sending it
to either a vertical or horizontal state, while Wigner, who is outside of the
laboratory, runs a simple test called an 'interference experiment' to prove
that the photon is still in a state of superposition.
In
the thought experiment, both observations, and therefore both the realities
they represent, can be proven to be true simultaneously.
While
Wigner's Friend has long just been an intriguing thought experiment, advances
in the field of quantum mechanics and physics have allowed researchers to put
the theory to the test — and that's exactly what Massimiliano Proietti of
Heriot-Watt University in Edinburgh and colleagues have done.
Using
six entangled photons - particles of light whose fates are tied together --
Proietti and colleagues were able to replicate the results of Wigner's Friend.
When
observed, the photons existed in a state of polarization, but when tested using
an interference experiments, it was concluded that photons still existed in a
state of superposition.
The
implications of the study not only confirm the long-discussed experiment, but
challenge the foundation of how observations are made.
'The
scientific method relies on facts, established through repeated measurements
and agreed upon universally, independently of who observed them,' say Proietti
in the paper published in pre-print journal AirXiv.
'In
quantum mechanics, the objectivity of observations is not so clear.'
However,
if those facts can neither be proved right or wrong — or both —
as Proietti's work posits, then science itself may have to change.