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The universe is vast, complex and awesome.
Despite hundreds, if not thousands of years of scientific endeavour, there’s still so
much we don’t know about it.
And that point was hit home this week with results out of Fermilab — a particle physics
lab in the US state of Illinois.
In their experiments, tiny subatomic particles called muons disobeyed the laws of physics
as we know them.
And if the results hold, the only logical explanation is that there are kinds of matter
and energy out there that physicists either don’t fully understand or don’t yet know
about.
The way physicists currently explain how the universe works is mostly through something
called the Standard Model.
This model explains three of the four fundamental forces of the universe — like how electricity
works and why particles stick together to make atoms, and elements, and us.
The only one it doesn’t cover is gravity… because, well, gravity doesn’t seem to matter
to subatomic particles.
Besides, we have the whole theory of general relativity for that.
The Standard Model also describes 17 building blocks — called fundamental particles — that
make up everything.
These include things like the quarks which make up protons and neutrons in the central
nuclei of atoms, as well as even weirder things, like muons.
They’re essentially the heavier cousin of electrons — the small, negatively-charged
particles that buzz around atoms.
Now, the particles and forces described in the Standard Model have been pretty great
at explaining what we see happening here on Earth and in the universe in general.
But physicists keep seeing more and more stuff that doesn’t quite fit.
And that’s where this news comes in.
Fermilab researchers ran an experiment where they measured how muons wiggle while they’re
spinning around inside a giant magnetic ring.
You see, muons have their own little magnetic fields.
And that means when they move through the stronger magnetic field generated by the ring
in the experiment, they wobble a bit, kind of like a top spinning on a table.
How fast they wobble depends on how strong the muon’s mini magnetic field is and what
other particles or forces they’re interacting with.
Which means they can give scientists an exciting glimpse into the subatomic world.
Now, the Standard Model provides an estimate for how fast they should wobble based on how
muons interact with the particles and forces that we know about.
But researchers noticed their muons were wobbling faster than that estimate.
See, the wobble is measured by a unit called a g-factor, which gives the strength and orientation
of the muon.
And the muons should have had a g-factor of 2.00233183620... but their actual one was
2.00233184122.
That might seem like a pretty tiny difference.
But, it’s almost enough to totally table-flip physics as we know it.
Particles simply shouldn’t deviate from predictions.
Not if the universe works how we think it does!
So even that teeny shift suggests there are other forces or particles out there that were
able to influence the muons’ wiggling.
To put it another way, the scientists say there’s only a one in 40 thousand chance
that this finding was a fluke.
Now this isn’t the first time researchers have seen muons acting strangely.
Using the same magnet, a team at Brookhaven National Laboratory in New York got a similar
result back in 2001.
But physicists aren’t tossing out their textbooks quite yet.
That’s in part because the result was from just one “run” of the experiment, which
only represents about 6% of that data the researchers are hoping to collect.
The team plans on doing this test several more times over the next several years — and
they may end up getting a different answer when they do.
It’s also possible the theoretical Standard Model estimate both they and the Brookhaven
team compared their measurements to was off.
That estimate requires such complex calculation and extrapolation of data that more than 130
scientists worked together to get it!
In fact, just last week, researchers from Penn State announced a different prediction
for the Standard Model value that took supercomputers hundreds of millions of CPU hours to calculate.
And their number is actually closer to the one seen in the Fermilab experiment!
Still, there seems to be mounting evidence that there’s something fundamental to the
universe not being captured by the Standard Model.
Some experts even think it’s time for a new theory — one that explains everything,
including gravity.
Though, to actually figure out what would look like, physicists will need even more
precise measurements from the subatomic world — so they can be totally sure that discrepancies
between reality and the current model actually exist.
And that means the Standard model will likely stick around a little while longer.
[outro] Thanks for watching this episode of SciShow
News!
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They look so cool!
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