The 'atomic fountain' is used to measure the space-time curvature.

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Researchers have used time dilation to detect gravity.

In 1797, Henry Cavendish, an English scientist, used a device made of lead spheres, wooden rods, and wire to measure the strength of gravity. Similar work is being done in the twenty-first century, but with even more powerful tools: atoms.

No matter how often it's been taught, scientists are still working to understand better gravity and the forces that influence it. It has now been accomplished by using the effects of time dilation — the slowing of time induced by increasing velocity or gravitational force — on atoms by a group of scientists. It was revealed today in the Science journal that scientists have accurately quantified the curvature of space-time.

The experiment is part of atom interferometry, a branch of physics. As a light wave can be represented as a particle, so can an atom (or any particle) be described as a "wave packet," according to quantum physics. In the same way that light waves can interfere with each other, matter-wave packets can as well.

As a result, it is possible that an atom's wave packet is divided in two and then recombined, resulting in a shift in the phase of the waves.

"One tries to extract relevant information from this phase shift," Albert Roura, a physicist from the Ulm Institute of Quantum Technologies in Germany who was not involved in the current work, told Space.com. Science released Roura's "Perspectives" paper on the new study today, which you can read online.

Detectors of gravity waves follow a similar path. To better grasp how electrons behave and how powerful gravity is, scientists can analyze particles in this fashion and fine-tune the mathematics behind some of the universe's most fundamental workings.

In the latest study, Chris Overstreet and his colleagues at Stanford University looked at the last effect. They constructed an "atomic fountain," a 33-foot (10-meter)-tall vacuum tube adorned with a ring at the very summit.

A series of laser pulses steered the atomic fountain. Two atoms were propelled from the bottom with a single pulse. When the second pulse hit, the two atoms had risen to separate heights before being lowered again. A third pulse grabbed the wave packets and recombined them in the bottom atoms.

There was a phase difference between the two wave packets, indicating an irregularity in the gravity field of the atomic fountain.

When asked about Einstein's famous theory of space-time curvature, Roura said: "That... in general relativity, may truly be interpreted as the effect of space-time curvature."

The ring's gravity accelerated the atom that went higher since it was closer to the ring. In an entirely uniform gravity field, these effects would be eliminated. Instead, the atoms' wave packets were out of phase, and the atom that experienced more acceleration was ever so slightly out of time with its counterpart because of the effects of time dilation.

Atom interferometry is sensitive enough to detect the resulting change, despite its microscopic size. As a result, "the scientists can detect and examine these impacts," Roura said because they can regulate the ring's positioning and mass."

Researchers have claimed that atom interferometry, the technology behind this finding, could one day be used to detect gravitational waves and help us travel more effectively than GPS.

Reference : https://www.livescience.com/curvature-space-time-atomic-fountain

Image source : https://pixabay.com/id/illustrations/banner-header-waktu-jam-ekspansi-1240822/

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Using 'atomic fountain' to determine the space-time curvature.