Heavyweights successfully measure up the lightweights

Scientists deliver new more accurate mass of the electron

Scientists in Germany have done something remarkable that has physicists excited, but leaves the rest of us dumbfounded. They have come up with a new, more accurate mass of a single electron.

Think back to science class in secondary school to remember that electrons are the little balls that whiz round the nucleus of an atom. Those working in fundamental physics use the mass of an electron in calculations that help them do the maths and explain the basic building blocks of matter.

The German scientists didn’t just improve the measure by a bit, they delivered a result that is 13 times more accurate than the figure currently being used.

But how can such a small number be expressed in human terms? The measurement is so small that its mass might just as well have been given as zero.

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It doesn’t help at all to know that you would need 1.1 times 10 to the 30th electrons to add up to the mass of a bag of sugar. Or that it would take 2.7 times 1024 electrons to equal the mass of a skinny mosquito. Or that one single average human cell weighs about the same as 1.1 times 1018 electrons.

Even so it is a big deal for the physicists. If they didn’t know the mass of an electron then it would make very difficult to predict how atoms and molecules work and how they all fit together to make matter and to bind together the far-flung universe.

In typical German understatement they acknowledged in their research report published this evening in the journal Nature , that "the low mass of the electron considerably complicates its precise determination".

Of course how they did it is also hugely complicated. They stuck a single electronic onto the side of a single carbon nucleus and used “quantum electrodynamics” to figure the whole thing out. “This result lays the foundation for future fundamental physics experiments and precision tests of the standard model,” they write.

And so say all of us.

Dick Ahlstrom

Dick Ahlstrom

Dick Ahlstrom, a contributor to The Irish Times, is the newspaper's former Science Editor.