PITTSBURGH — For one hundred and forty-seven years, the Hall effect has been a thing you can do math with. It was discovered in 1879 by a twenty-eight-year-old named Edwin Hall, and it has, since then, been the backbone of a very large number of calculations, the kind of calculations that go into the kind of devices that go into the kind of things you are holding right now. This week, a team at Carnegie Mellon did the thing that has been done to physics exactly a handful of times in its history: they found the thing was wrong, in the specific, in the corner of it that everyone had been using.

The Hall effect is, in the specific, the effect a voltage has when a current runs through a material in a magnetic field, and it is, in the specific, one of the most reliable numbers in all of applied physics. It is the number you put in when you need a number. It is the number that lets you build a sensor, a compass, a chip, a screen, a thing. The CMU team, as reported by Phys.org, did not break the number. The CMU team broke the assumption that the number worked the way everyone thought it worked, in a specific class of material, and the specific class of material is the class of material that the industry is, in the specific, building the next generation of things out of.

"You put the number in when you need a number. This week, a team found that the number, in the specific corner, was not the number. The math still works. The math just works differently, which is the worst kind of math news."

This is not the kind of physics news that has a headline. It does not have a particle. It does not have a black hole. It has an equation, and the equation, in the specific, is one that a very large number of people have, in the specific, been using for a century and a half, and the equation, in the specific, was right in most of the places where it was used, and wrong in the place that was being used next. That is the precise shape of the news. It is not “the thing was wrong.” It is “the thing was right everywhere except where it was about to be used a lot.”

THE 147: A TALLY

  • The number: 1879. The year Edwin Hall, at twenty-eight, found the effect.
  • The use: The backbone of a very large number of calculations. The number you put in when you need a number.
  • The break: Not the number. The assumption about where the number works. The specific corner. The corner that's about to be used.
  • The mood: "The math still works." The math just works differently. That is the worst kind of math news.

There is a tradition, in the tradition of science, of a result that is so boring it is only interesting to the people who use it, and the tradition is not kind to the result, because the result does not get a headline, and the result does not get a photo, and the result gets a paper in a journal that a very specific number of people will read, and the very specific number of people who will read it are, in the specific, the people who were about to build the next thing out of the number that was just shown to be, in the specific, a little bit off. The next thing, for its part, has not been built yet. The next thing, in the specific, is now being re-mathed. The re-math, in the specific, is the whole story, and the re-math, in the specific, does not get a headline.

At press time, the CMU team had not said when the re-math would be finished, and the industry had not said which of its next things would be affected, and the equation, for all that has been done to it, was still, in every way that mattered, just an equation, only now, in the specific, a different one.