A new quantum thermometer has been designed to measure minute changes in temperature in the fabric of space-time. The device will enable scientists to, for the first time, observe the consequences of a physical theory related to Einstein’s Relativity.

A team of physicists, led by Dr James Q Quach while he was working at the University of Adelaide, published its findings in the journal *Physical Review Letters*.

Einstein’s Special Theory of Relativity tells us that the speed at which an observer is moving dictates how that observer perceives time. The effects are noticeable only when observers approach the cosmic speed limit: lightspeed (300,000 kilometres per second).

Throwing gravity into the mix, Einstein broadened his theory to derive the General Theory of Relativity which tells us that space and time form the fabric of the universe which can warp and flex.

It turns out that, much like the relationship between speed and time, observers moving at different *accelerations* will perceive *temperature* differently. These differences, albeit minute, are a consequence of the same relativistic relationships that Einstein formulated in his famous theories.

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“In 1976 Canadian physicist William Unruh combined Einstein’s work with the other fundamental theory of modern-day physics, quantum mechanics, and predicted that fabric of space-time has a very low temperature,” Quach says. “Intriguingly this temperature changed depending on how fast you are moving.”

Quach explains that these changes in the temperature of the fabric of the universe, depending on acceleration, have been unobservable up until now.

“To see this change in temperature, you would have to move extremely fast. To see even one degree change in temperature you would have to move close to the speed of light. Up until now, these extreme speeds have prevented researchers from verifying Unruh’s theory.”

Not only does the quantum thermometer not require close to lightspeed acceleration, it is completely stationary.

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“In theory a quantum thermometer does not need to physically accelerate, instead it uses a magnetic field to accelerate the internal energy gap of the device,” says Quach.

And Quach explains that such a device can be built with current technology. “The theoretical design of the quantum thermometer is based on the same technology used to build quantum computers.”

The team’s work on designing a quantum thermometer has implications for future research, allowing physicists to measure ultracold temperatures with precision for the first time.