Deciphering the mystery of the number 137: Why is this number so important?

aMathematician de la Soule He famously saidThree is a magic number. But if we are to believe physicist Richard Feynman, that number is off by a factor of about 400. For Feynman, you see, the “magic number” is about 1/137 — specifically, it is 1/137.03599913.

Physicists know it as α, or the fine structure constant. “It has been a mystery since its discovery,” Feynman said books In his 1985 book QED: The Strange Theory of Light and Matter. “All the good theoretical physicists put that number on their walls and worried about it.”

It is incredibly mysterious and incredibly important: it appears to be a random, dimensionless number, and yet it holds the secret of life itself.

“It is a measure of the strength of the interaction between charged particles and the electromagnetic force,” explained SUNY Stony Brook astrophysics professor Paul M. Souter in an article for space.

“If it had any other value,” he wrote, “life as we know it would be impossible.” “Yet we have no idea where it came from.”

Normally, this would be the part where we give you some examples of where the value appears – but the answer to that, quite literally, is “everywhere.” He was It was first discovered in 1916by physicist Arnold Sommerfeld, but they already appeared in equations for Decades before that. It lies in the formulas that describe light and matter, governing everything from the smallest hydrogen atom to the formation of stars.

“In our everyday world, everything is either gravity or electromagnetism,” said Holger Müller, a physicist at the University of California, Berkeley. Quanta Magazine. “That's why alpha is so important.”

Of course, physics is no stranger to constants – there are CThe speed of light; g, gravitational constant; In quantum physics there are both H And ħ To describe Planck's constant. If you are a true lover, you might be aware of this KBoltzmann constant. But α has something that none of those other constants have – or, to be more precise, it does no They have something to have Do.

“There is no dimension or unit system beyond a value [fine structure constant] Depends on,” books Sutter. “Other constants in physics are not like that.”

Take the speed of light for example. Search for it in the search engine, and you will find that it is equal to 299,792,458 meters per second. Or is it 670615200 mph? Our mistake: It's actually 1,802,600,000,000 furlongs every two weeks. Fuck it – let's just say it's one light year per year.

Get the picture yet? The value of the constant is not actually a constant, it depends on the units you use. But the fine structure constant does not have this property: it is a completely dimensionless constant.

“If you met an alien from a distant star system, you would have a very difficult time communicating the value of the speed of light. Once you determine how to express our numbers, you will then have to define things like meters and seconds,” Sutter explained.

“But the fine structure is fixed? You can just spit it out, and they will understand it.”

But perhaps the strangest thing about these seemingly pure constants is that they may not, in fact, be constant. Some physicists have suggested that the α that exists today is actually… A little bigger than it was before – Only one part in about 100,000 over six billion years, but that's enough to cause some huge long-term repercussions. Change that from 137 to 138, for example, and you reduce the value of α by 0.00005 – enough, Some scholars sayTo prevent stars from creating carbon, thus stopping the creation of life as we know it.

As Feynman put it“It is one of the great mysteries of physics: a magic number that comes to us without human understanding.

“You can say that the hand of God wrote this number, and 'we do not know how he pushed his pen.'”

A previous version of this article was published in June 2022.