Unidentified High-Energy Particles Detected Passing through the Antarctic Ice
The IceCube Observatory carries the distinction of being the most remote astronomical facility on Earth. Anchored deeply in the ice of Antarctica, in the very definition of the middle of nowhere, the IceCube installation features a high-tech particle neutrino detector designed to search for one of the most elusive particles in the universe.
Neutrinos are the subatomic cousins of electrons. They’re ghostly shadows with no electric charge and an infinitesimal mass. They avoid interactions with matter, which makes them extremely difficult to detect.
Nevertheless, we are swimming in an invisible soup of them every moment of our lives. They are one of the essential elements of creation and have been here since the start. Many astrophysicists believe that dark matter is comprised of primordial neutrinos left over from shortly after the Big Bang, which if true would make them the most common type of particle in the universe.
Electrons and neutrinos both belong to a class of particles called leptons. Leptons are involved with the weak nuclear force, which governs decay in atomic nuclei and creates brand new particles as a result of the transformation. It is in these patterns of decay that neutrinos are formed, and detecting their presence gives scientists a glimpse into the fundamental processes of creation and destruction.
Unlike light particles, neutrinos can escape from even the densest environments. For example, neutrinos from a supernova called 1987A reached the Earth three hours before the light particles emitted, carrying enormous energies harvested from that space-time-ripping event.
The arrival of these types of neutrinos was expected at the IceCube Observatory, and hunting for such particles was one of the main reasons why the facility was erected. But IceCube researchers were not prepared for what they found during a routine survey of data in 2012.
While analysing data collected between 2010 and 2012, scientists stationed at IceCube were surprised to discover that two neutrinos with extremely high energy levels had been detected. They were among 28 neutrinos detected overall, many of which had higher-than-usual energies. But none could compare to the prodigious energies carried by the two neutrinos that their discoverers named “Bert” and “Ernie.”
Stars (including our Sun) and supernovas emit significant numbers of neutrinos, as does the Earth’s atmosphere. It is these neutrinos that detectors would normally find. But the two standout neutrinos were measured as having 100 million times more energy than neutrinos emitted by supernovas, which made it clear they had different origin than anything discovered before.
“We’re pretty excited about it. They’re the highest energy neutrinos that have ever been seen,” said Thomas Gaisser, an IceCube researcher from the University of Delaware-Newark, speaking in 2013.
Active Galactic Centers
This discovery was unexpected, and the search for explanations began immediately.
Much speculation centered on active galactic centers. Massive black holes are believed to form the center of many galaxies, and they would have the potential to emit huge jets of super-energetic materials, including neutrinos, that could travel long distances through space.
The Earth is bombarded by ultra-high-energy cosmic rays, which many astronomers conclude must come from these active galactic nuclei. Since the energies were similar, connecting them to high-energy neutrinos made sense. Because neutrinos have so little interaction with matter, they could emerge from even the thickest galactic cores with their energies intact.
If this theory was correct, it meant these neutrinos must have come from outside the Milky Way galaxy. No neutrinos with energy levels approaching this had ever been detected in our cosmic neck of the woods before, and it seemed unlikely they would have come from the center of this galaxy.
Other suggestions were offered to explain the energy levels of Bert and Ernie. Some scientists theorized that the neutrinos may have been accelerated somehow by powerful astronomical bodies located in our own galaxy, such as pulsars, neutron stars or small, invisible black holes. These ideas were highly speculative, however, and most were convinced that these wispy subatomic particles actually had begun their journey outside the Milky Way.
The debate continued for a few years, but in 2017 new data obtained at the IceCube Observatory seems to have settled the question. Once again, neutrinos with ultra-high energy levels were detected. But this time, they were traced to a particular spot in the sky, within the constellation Orion.
The source of the neutrinos was positively identified as a type of black hole known as a blazar, which produces flaring jets of neutrinos and particles that in this case were pointed directly at Earth. This particular blazar is located an astonishing 3.7 billion light-years from Earth, which means the neutrinos detected here now were emitted almost four billion years ago from a place far distant from our Milky Way.
The discovery of such neutrinos is the very definition of a rare event. But that is based on the nature of the detection technology and not on the limitations of the phenomenon itself.
In actuality, we are being bombarded by a virtually infinite supply of neutrons here on Earth, which come from the Sun, other stars, supernovas, black holes, galactic centers, our own atmosphere, and possibly from sources we have yet to discover. They are found infrequently only because of how rarely they interact with matter and not because they are few in number. These ghostly particles literally move through matter as if it weren’t there, and they are constantly passing through everything and everyone at all times.
The Solar Neutrino Problem and What it Means for Reality
One of the purposes of studying rare or exotic particles is what they might reveal about the true nature of the universe. Their existence and activities can help confirm or falsify current theories about cosmology, and neutrinos may in fact be doing the latter right now.
After studying neutrino activity in relation to our Sun, astronomers have been confronted with a conundrum. While neutrinos have been detected coming from our closest star, their numbers have not approached the expected level. The processes of nuclear fusion that are believed to power our Sun should be producing far more neutrinos than are being found, even given the limitations in detection technology.
Up to two percent of the Sun’s energy should be carried away by neutrinos, as a side effect of fusion, But the prodigious quantities of neutrinos necessary to complete such a task are not being detected. This is called the solar neutrino problem, and it could have profound consequences for our understanding of the universe if no solution is forthcoming.
In order to preserve the standard model of how the Sun functions, some astrophysicists have postulated that neutrinos may change their form in ways that make them more difficult to detect. Obviously, another possibility is that current consensus ideas about how the Sun produces its energy are simply wrong, and neutrinos only appear to be missing because the predictions are based on false assumptions.
In science, contradictory data could conceivably nullify any hypothesis, no matter how popular or widely believed. Consistent neutrino shortages from the Sun could mean that stars don’t function the way we’ve been told they do, as hard as that might be for mainstream cosmologists to accept or admit.
One increasingly popular alternative to Big Bang-based cosmology is the Electric Universe Theory. Proponents of the Electric Universe claim the Sun produces its energy by acting as an enormously powerful electrical conductor, or point of discharge. If this is true there would be no nuclear fusion occurring inside the Sun or any other star, which could explain the variance between neutrino populations observed and the predictions of the standard model.
As of now, the Electric Universe Theory remains unproven and confined to the margins of scientific debate. But if it were one day to be confirmed, the solar neutrino problem might be identified as one of the first clues that ultimately led to a revolutionary change in the scientific consensus.
Cosmological theories could indeed rise or fall based on the behavior and characteristics of the smallest, lightest, and most elusive bits of matter in the universe. From subatomic particles to human beings to far-off galaxies, everything that exists is interconnected in some way, and our study of the nature of that interconnection may someday yield some amazing discoveries.
Top image: Abstract illustration of high energy particle. Credit: LanaPo / Adobe Stock
By Nathan Falde