Study shows how gravity affects quantum behaviour

Gravity may play a significant role in quashing bizarre quantum behaviour in our everyday world, a new international study has found.

Dr Magdalena Zych from the ARC Centre of Excellence for Engineered Quantum Systems (EQuS) and the School of Mathematics and Physics (SMP) at The University of Queensland, said that to date, scientists have been puzzled as to why quantum phenomena are never observed in our daily lives.

“Our work investigates whether gravitational time dilation can be responsible for that,” Dr Zych said.

Gravitational time dilation -- a consequence of Einstein’s theory of general relativity -- is a phenomenon whereby time runs slower near massive objects.

The phenomenon affects everything and everybody -- people working on the ground floor age 10 nanoseconds less each year than their colleagues a floor above.

In results published this week in Nature Physics, the researchers have now shown that once small quantum building blocks form larger, composite objects – such as molecules, microbes or dust particles – time dilation can suppress their quantum behaviour.

“As a result, these composite objects behave as we expect in everyday experience, unless they are at extremely low temperatures,” Dr Zych said. 

Lead author Dr Igor Pikovski (now at the Harvard-Smithsonian Center for Astrophysics) said that it is quite surprising that gravity can play any role in quantum mechanics.

“Gravity is usually studied on astronomical scales, but it seems that it also alters the quantum nature of the smallest particles on Earth,” he said.

The results reveal a fascinating interplay between the two great theories of the 20th century -- quantum theory and general relativity.    

Other authors of the research are Dr Fabio Costa from EQuS and SMP, and the head of the research team Professor Časlav Brukner from the University of Vienna and the Institute of Quantum Optics and Quantum Information in Vienna.

More information regarding this research can be found here.

Media Contact: Dr Magdalena Zych,+61 7 334 67348,

Image: A composite quantum object under gravitational time dilation: The object is initially in a quantum superposition - a quantum phenomenon never observed in our everyday life. Time dilation suppresses this quantum behaviour. As a result, the object behaves as we expect from our daily experience.

Image credit: Magdalena Zych

Major funding support

Australian Research Council

The Australian Research Council Centre of Excellence for Engineered Quantum Systems (EQUS) acknowledges the Traditional Owners of Country throughout Australia and their continuing connection to lands, waters and communities. We pay our respects to Aboriginal and Torres Strait Islander cultures and to Elders past and present.