Credit: Public Domain.

Credit: Public Domain.

All chickens hatch from eggs and all chicken eggs are laid by chickens — and here lies the baffling conundrum. The paradox is typically used to illustrate how in certain situations it’s not clear which of two events is the cause and which is the effect. But the ancient Greek philosophers who first proposed this dilemma had no notion of quantum physics — that’s the domain of physicists at the University of Queensland, Australia and the NÉEL Institute, Frace who claim that the chicken and egg can both come first.

According to Dr. Jacqui Romero, a physicist at the University of Queensland (UQ), cause and effect are not always as straightforward as they are in the macroscopic, ‘real’ world.

“The weirdness of quantum mechanics means that events can happen without a set order,” Dr. Romero said. “Take the example of your daily trip to work, where you travel partly by bus and partly by train. Normally, you would take the bus then the train, or the other way round. In our experiment, both of these events can happen first.

“This is called ‘indefinite causal order’ and it isn’t something that we can observe in our everyday life.”

This Indefinite causal order was observed in the laboratory when the physicists measured the polarisation of photons at the output of a quantum switch. This measurement suggests that the order of transformations on the shape of light was not set, the authors reported in the journal Physical Reviews Letters. 

“This is just a first proof of principle, but on a larger scale indefinite causal order can have real practical applications, like making computers more efficient or improving communication,” said UQ’s Dr. Fabio Costa.

Is this the last word on the matter? Perhaps, perhaps not. Quantum physics is often weird and confusing, but there is some more ‘concrete’ research that investigated the chicken or egg dilemma.

In 2010, researchers from Scotland and England used a supercomputer called HECToR to analyze in high detail a chicken eggshell, determining the vital role of a protein used to kick-start the egg’s formation. The protein was known to be linked to egg formation, but the analysis showed it is an important catalyst. It’s also a protein only found in a chicken, which some see literally as scientific proof that the chicken definitely came before the egg.