Scientists have measured the shortest unit of time ever: the time it takes for a particle of light to traverse a hydrogen Molecule.
This time is 247 zeptoseconds. A zeptosecond is a trillionth of a billionth of a second, or a decimal point, followed by 21 zeros and a 1. Previously, researchers were immersed in the zeptosecond range. in 2016 researchers report in the journal Natural physics used lasers to measure time in steps of up to 850 zeptoseconds. This accuracy is a big leap from the 1999 Nobel Prize-winning work, which was the first to measure time in femtoseconds, which corresponds to millionths of a billionth of a second.
It takes femtoseconds for chemical bonds to break down and form, but it takes zeptoseconds for light to travel over a single hydrogen (H2) molecule. To measure this very short trip, the physicist Reinhard Dörner from the Goethe University in Germany and his colleagues shot X-rays from PETRA III at the German Electron Synchrotron (DESY), a particle accelerator in Hamburg.
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The researchers adjusted the energy of the X-rays so that a single photon or light particle knocked the two electrons out of the hydrogen molecule. (A hydrogen molecule is made up of two protons and two electrons.) The photon bounced one electron out of the molecule and then the other, a bit like a pebble jumping over the top of a pond. These interactions created a wave pattern called the interference pattern, which Dörner and his colleagues were able to measure with a tool called a COLTRIMS reaction microscope (Cold Target Recoil Ion Momentum Spectroscopy). This tool is essentially a very sensitive particle detector that can record extremely fast atomic and molecular reactions. The COLTRIMS microscope recorded both the interference pattern and the position of the hydrogen molecule during the interaction.
“As we knew the spatial alignment of the hydrogen molecule, we used the interference of the two electron waves to calculate exactly when the photon reached the first and when the second hydrogen atom,”
This time? Two hundred and forty-seven zeptoseconds, with some slack depending on the distance between the hydrogen atoms within the molecule at the moment the photon is winged. The measurement essentially records 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,” said Dörner in the statement. “The time delay occurs because information within the molecule only propagates at the speed of light.”
The results were published in the journal on October 16 science.
Originally published on Live Science.