What was this precious cargo? A scientific instrument that the researchers hoped would shed new light on the field of physics once it reached its new home in a new laboratory.
Eight years later, this equipment has done just that. Wednesday, a scientific measurement
, recorded by this device, has been made public. It may not seem like much, but this unique measurement tells scientists that their theory on what’s called the standard model of particle physics
is incomplete – and needs to be rethought.
As counterintuitive as it may sound, this is not bad news. The goal of science is to seek the truth. With this goal in mind, researchers constantly come back to their data and check whether the measurements and theories agree or not. If the agreement is still satisfactory, it is in disagreement that we progress. When a theory is proven to predict something other than what a valid measurement has revealed, scientists rethink their theory and adjust it.
The Standard Model of Particle Physics, at the center of this news story, explains the world of atoms and smaller things, and it was developed in the 1960 and 1970
. It has been universally accepted in the scientific world as the most precise subatomic theory devised to date. But this venerable model may well need to be changed because of this new measurement, which gives us reason to believe that the Standard Model is incomplete.
What the Standard Model predicts – and what this new measurement evaluates – are the magnetic properties of an ephemeral subatomic particle called muon,
which is very similar to the familiar electron, but with a few differences. The muons are on 200 times heavier
than electrons and they decay into little more than one millionth of a second
. Otherwise, electrons and muons have a lot in common.
They both, for example, electric charge and they turn
. A rotating electric charge becomes a magnet. And if you generate a magnetic field and put a spinning charge in it, the charge precedes like a spinning top does, making a circle with its tip as it spins.
Scientists can use accepted laws of physics to predict how fast the muon should precede. Thus, more than two decades ago, researchers working at Brookhaven National Laboratory
in Long Island, New York, conducted what is known as the Muon g-2 experiment (gee minus two).
These scientists measured the muon’s actual precession velocity and the Standard Model’s prediction and measurement disagreed. When the data and theory disagree, one (or both) must be wrong. And if the theory is wrong, it’s because scientists forgot something when they designed it.
To give a practical example, introductory physics says that a thrown baseball will follow a perfect parabolic arc. However, this prediction ignores real world air resistance and therefore the simple prediction and the real path of baseball do not agree. To be precise, the theory must be broadened to include the effects of air drag.
The disagreement between the measured and predicted precession properties of muons could have meant that our better understanding of the subatomic world is forgetting something. Or it could have meant that the original experiment was flawed in some way or another. A second more precise measurement, hopefully, was needed.
However, Brookhaven’s equipment had been pushed to its limit. A more precise measurement required the participation of another laboratory. Enter Fermilab,
America’s flagship particle physics laboratory, located just west of Chicago. (Full disclosure: I am a Fermilab scientist, but I am not involved in the g-2 research effort.)
So the experimental equipment of the g-2 – a ring of hoop-shaped magnets, 50 feet wide and 6 feet high – made this long boat and truck trip from Long Island to Fermilab, just in outside of Chicago.
Fermilab researchers combined the g-2 measuring device with that of Fermilab stronger muon beams
and repeated the measurement. And they just released their first experimental results
. Not only does the new and improved prediction and measurement of muon magnetic properties still disagree, but the increased accuracy further suggests that something important is overlooked in Standard Model Theory.
And the researchers haven’t finished. The recently published measure is based on only about 6%
of the total expected data. Scientists report on this small fraction of the data because they always record and validate the rest. When the rest are available, carefully reviewed, and published, it will dramatically improve the accuracy of the final measurement. It is likely that the measurement using the dataset proves without a doubt that the best theory scientists have for the subatomic world – a theory that has been tested and validated for more than half a century – is incomplete and will have to be. be rephrased.
In truth, this is why I love science so much. It is never complete. It is never absolute. He is always open to new data and new ideas. It is constantly challenged and tested by people who know it best. And sometimes actions are taken that tell experts that the theory they have known for years needs to be reconsidered. The recently published results are one such measure.
When you recognize that finding out the truth is more important than proving you’re right, you realize that being wrong teaches you something new. And if you accept and embrace this novelty, you have a much better chance of being right. This is science.