Decoded: How particles 'fall' in love this Valentine's

Washington: Here is a love story at the smallest scale imaginable: particles of light.

It is possible to have particles that are so intimately linked that a change to one affects the other, even when they are separated at a distance.

This idea, called "entanglement", is part of the branch of physics called quantum mechanics, a description of the way the world works at the level of atoms and particles that are even smaller.

Now, the technology used to study the "love" between particles is also being used in research to improve communications between space and Earth.

“What is exciting is that in some sense, we're doing experimental philosophy. Humans have always had certain expectations of how the world works, and when quantum mechanics came along, it seemed to behave differently,” said Krister Shalm, physicist with the National Institute of Standards and Technology (NIST), Boulder, Colorado.

In 1964, however, John Bell published the idea that any model of physical reality with such hidden variables also must allow for the instantaneous influence of one particle on another.

While Einstein proved that information cannot travel faster than the speed of light, particles can still affect each other when they are far apart according to Bell.

Scientists consider Bell's theorem an important foundation for modern physics.

“Our paper and the other two published last year show that Bell was right: any model of the world that contains hidden variables must also allow for entangled particles to influence one another at a distance," explained Francesco Marsili from NASA's Jet Propulsion Laboratory in Pasadena, California.

The design of the new experiment can potentially be used in cryptography -- making information and communications secure -- as it involves generating random numbers.

Cryptography is not the only application of this research. Detectors similar to those used for the experiment could eventually also be used for deep-space optical communication.

Information can never travel faster than the speed of light - Albert Einstein was right about that.

“But through optical communications research, we can increase the amount of information we send back from space," Marsili said.

"The fact that the detectors from our experiment have this application creates great synergy between the two endeavours,” he pointed out in a paper published in the journal Physical Review Letters.

And so, what began as the study of "love" between particles is contributing to innovations in communications between space and Earth.

“Love makes the world go 'round'", and it may, in a sense, help us learn about other worlds.