Physicists in Germany have measured the shortest timespan ever recorded. The team measured the time it takes for a photon of light to travel the length of a hydrogen molecule, and found it to occur in just trillionths of a billionth of a second.
The microscopic world contains many mysteries, not just because everything is so tiny but because it all happens incredibly fast. At this scale, one second can seem like an eternity – chemical bonds form and break in mere femtoseconds, which are quadrillionths of a second. Over the last few decades we’ve been able to use femtosecond laser pulses to measure these ultrashort events.
But the new measurement zooms in much further, making a femtosecond seem sluggish in comparison. The researchers found that a photon will cross a hydrogen molecule in around 247 zeptoseconds.
For reference, a zeptosecond is a million times shorter than a femtosecond, or one sextillionth of a second. That’s 0.0000000000000000000001 seconds. There are the same number of zeptoseconds in one second as there are seconds in 31.7 trillion years, which is 2,365 times longer than the universe has even existed. There's just no way to overstate how short a zeptosecond is.
This groundbreaking measurement was made by researchers at Goethe University Frankfurt, the DESY accelerator, and the Fritz-Haber Institute. It’s not actually the first measurement made on the zeptosecond scale – that honor belongs to a team in 2016 that found that after a helium atom is struck by a photon it takes 850 zeptoseconds to eject an electron. That means the new measurement is about 3.4 times shorter than the previous record.
The new experiment was similar. The team irradiated a hydrogen (H2) molecule with X-rays at a particular energy level that sent both electrons flying out of the molecule. By measuring the interference patterns of the two electrons, the researchers were able to precisely calculate how long it took the photon to reach the first hydrogen atom, then the second, in the molecule. The answer, it turns out, is up to 247 zeptoseconds.
“We observed for the first time that the electron shell in a molecule does not react to light everywhere at the same time,” says Reinhard Dörner, lead author of the study. “The time delay occurs because information within the molecule only spreads at the speed of light.”
The research was published in the journal Science.
Source: Goethe University Frankfurt
