Slashdot Mirror
Bizarre Particles Keep Flying Out of Antarctica's Ice, and They Might Shatter Modern Physics (livescience.com)
There's something mysterious coming up from the frozen ground in Antarctica, and it could break physics as we know it. From a report: Physicists don't know what it is exactly. But they do know it's some sort of cosmic ray -- a high-energy particle that's blasted its way through space, into the Earth, and back out again. But the particles physicists know about -- the collection of particles that make up what scientists call the Standard Model (SM) of particle physics -- shouldn't be able to do that.
Sure, there are low-energy neutrinos that can pierce through miles upon miles of rock unaffected. But high-energy neutrinos, as well as other high-energy particles, have "large cross-sections." That means that they'll almost always crash into something soon after zipping into the Earth and never make it out the other side. And yet, since March 2016, researchers have been puzzling over two events in Antarctica where cosmic rays did burst out from the Earth, and were detected by NASA's Antarctic Impulsive Transient Antenna (ANITA) -- a balloon-borne antenna drifting over the southern continent.
ANITA is designed to hunt cosmic rays from outer space, so the high-energy neutrino community was buzzing with excitement when the instrument detected particles that seemed to be blasting up from Earth instead of zooming down from space. Because cosmic rays shouldn't do that, scientists began to wonder whether these mysterious beams are made of particles never seen before. Since then, physicists have proposed all sorts of explanations for these "upward going" cosmic rays, from sterile neutrinos (neutrinos that rarely ever bang into matter) to "atypical dark matter distributions inside the Earth," referencing the mysterious form of matter that doesn't interact with light.
Sure, there are low-energy neutrinos that can pierce through miles upon miles of rock unaffected. But high-energy neutrinos, as well as other high-energy particles, have "large cross-sections." That means that they'll almost always crash into something soon after zipping into the Earth and never make it out the other side. And yet, since March 2016, researchers have been puzzling over two events in Antarctica where cosmic rays did burst out from the Earth, and were detected by NASA's Antarctic Impulsive Transient Antenna (ANITA) -- a balloon-borne antenna drifting over the southern continent.
ANITA is designed to hunt cosmic rays from outer space, so the high-energy neutrino community was buzzing with excitement when the instrument detected particles that seemed to be blasting up from Earth instead of zooming down from space. Because cosmic rays shouldn't do that, scientists began to wonder whether these mysterious beams are made of particles never seen before. Since then, physicists have proposed all sorts of explanations for these "upward going" cosmic rays, from sterile neutrinos (neutrinos that rarely ever bang into matter) to "atypical dark matter distributions inside the Earth," referencing the mysterious form of matter that doesn't interact with light.
Low-energy neutrinos = pass through
High-energy neutrinos = bounce off everything, BUT we are seeing them coming from our planet. So if they are not bouncing off things, then are they being generated? or what is the mechanism that makes them appear to be coming from the planet.?
Direction of travel is determined similar to following a traveller who has a strobe light attached. When you identify the spot you see the light initially, then the same light shows up awhile later at another spot, you can determine the back-azimuth to the originating dot. (collector is large enough to see 2 or more interactions within the collection material)
but it was aliens
Neutrinos are leptons (like the electron) but have no charge. This means that they cannot interact via the electromagnetic force like every other matter-like particle (fermion). Instead, they can only interact via the weak interaction.
We have known for several decades that the electromagnetic and weak interactions are really two aspects of the same electroweak force. What makes the weak force different from the electromagnetic force is that the carriers of the weak force, the W and Z bosons, have large masses ~90 times that of a proton whereas the electromagnetic force is transmitted by massles photons.
At low energies when particles collide there is not enough energy to create "real" (on-shell) W and Z bosons and so it is extremely rare that particles will interact via the weak force at low energy. So, if this is the ONLY way you have to interact you basically hardly every interact at all. This is what happens for low energy neutrinos.
However, at _really_ high energy - about 10,000 times or more the energy of a proton in the Large Hadron Collider - collisions of neutrinos with matter have enough energy to create real W and Z bosons. When this happens the chance of a weak interaction starts to become similar to that of an electromagnetic interaction and neutrinos can no longer pass through the Earth.