Some scientists at the Pierre Augin Cosmic Ray observatory have a question about muons. Like, why are there as many of them as there are when the Standard Model of physics says there shouldn't be. Trouble is, they can't really answer that question yet.
Muons are among the subatomic particles produced when atoms or other subatomic particles collide at great speeds. When those collisions happen in the Large Hadron Collider, then all the measurements show the proper amounts of leftovers. But cosmic rays strike the Earth's atmosphere at much greater speeds than those created by the LHC, meaning the collisions have much greater energy. They also happen out in the wide-open spaces rather than conveniently amidst a number of detectors and instruments.
The latter situation means that it's pretty tough to get exact measurements of what kind of leftovers a cosmic ray collision produces -- including a solid figure of how many muons it dumps out. A guesstimate procedure described in the blog entry at BackRe(Action) which is completely opaque to me offers a possible amount of muons and muon energy these high-velocity collisions produce. And it's more than it should be, compared with other kinds of energy coming from them.
The Standard Model of physics says how atoms and subatomic particles behave when certain things happen, and describes what all of those things are made of. Its strength is that things which it has predicted have often been shown to be true once measuring capabilities have advanced as far as the predictions. But this estimate does not match the Standard Model, meaning that either the method of producing it is flawed (possible) or there's something going on the Standard Model doesn't account for. Since it will be pretty dang difficult to create laboratory conditions in the upper atmosphere where the cosmic rays collide with air molecules, that means that scientists either have to massively upgrade the LHC or build a collider that can duplicate the energies of cosmic-ray speed collisions. It may take awhile for the technology and money to meet that need, but it is likely to happen someday.
What's interesting is that this problem is the kind of thing that often happens when scientists learn their frame of reference has been either too small or too slow. The geocentric universe blew up when Galileo saw Jupiter's moons and Saturn's rings. Isaac Newton's clockwork universe blew up when Albert Einstein started asking about things that moved faster than Newton could have considered. Could this be about to happen again? Who knows? But I imagine it may make a generation of physicists a little jealous of those who will come after them who have the opportunity to find out.