Scientists have just discovered the smallest unit of time ever. They made it through measuring how long it takes for a photon to cross an atom of hydrogen.

The time is 247 zeptoseconds, for the record. A zeptosecond is a trillionth of a billionth of a second, followed by 20 zeroes and 1, or a decimal point. That's one femtosecond equals 0.000000000000001 seconds or 10-15 seconds.

Researchers had previously submerged themselves in the zeptosecond realm. In 2016, scientists publishing in the journal Nature Physics used lasers to quantify time in intervals down to 850 zeptoseconds.

This measuring unit is a huge leap from the study that first measured time in femtoseconds, which are millionths of a billionth of seconds, earning the 1999 Nobel Prize. 

The scientists classified their discovery as the shortest time ever measured. It amounted to approximately 247 zeptoseconds (or 10-21 seconds, a trillionth of a billionth of a second).

Chemical bonds take femtoseconds to break and shape. A single molecule of hydrogen, on the other hand, takes zeptoseconds for light to pass over.

Physicist Reinhard Dörner of Goethe University in Germany and his colleagues fired X-rays from PETRA III at the Deutsches Elektronen-Synchrotron (DESY), a Hamburg particle accelerator, to measure this very short journey.

The researchers fixed the X-ray intensity such that the two electrons were knocked out of the hydrogen molecule by a single photon or particle of light. That's around two protons and two electrons in a hydrogen atom.

Shortest Measurement Ever

One electron was bounced from the atom by the neutron, and then the other, a little like a pebble rolling across the surface of a sea.

These interactions produced a wave pattern called an interference pattern, which could be calculated by Dörner and his colleagues with an instrument called a reaction microscope called Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS). 

In essence, this instrument is a very sensitive detector of particles that can capture incredibly rapid atomic and molecular reactions.

"Since we knew the spatial orientation of the hydrogen molecule, we used the interference of the two-electron waves to precisely calculate when the photon reached the first and when it reached the second hydrogen atom," Sven Grundmann, a study co-author at the University of Rostock in Germany, said in a statement.

The time? Two hundred and forty-seven zeptoseconds, with some wiggle space depending on the gap within the molecule between the hydrogen atoms at the same time the photon winged. In essence, the calculation captures the speed of light within the molecule.

"We observed for the first time that the electron shell in a molecule does not react to light everywhere at the same time," Dörner said in the statement. "The time delay occurs because the information within the molecule only spreads at the speed of light."

The findings were detailed in the journal Science on October 16.

Check out more news and information on Time in Science Times.

ALSO READ: 

NASA Would Create The 'Coldest Spot In The Universe' At International Space Station, With Laser-Powered Atom Freezer [Video]

'Time Crystals' May Be The Breakthrough Of The Millennium: Scientists Create New Form of Matter