Tyler Christensen

Tyler graduated from MIT in 2014 with a Bachelor of Science degree in physics and electrical engineering. After graduation, he moved to Washington State to pursue a career in electrical engineering. In his spare time on weekends, he usually goes climbing in the mountains.

Some 13.8 billion years ago, according to the big bang theory, the universe was devoid of matter and existed only as a point of energy. Then in an instant, that energy converted into matter and antimatter. Ever since, the universe has been expanding outwards. Although it's hard to imagine such vast scales of time and space, the theory has significant credibility in the world of science. However, scientists still need to answer one big question: why do we still exist? According to the theory, the big bang would have created equal amounts of matter and antimatter from that point of energy. The problem is, matter and antimatter annihilate one another on contact, so why didn't all the matter and antimatter immediately annihilate back to energy in the moments after the big bang? And why is there so much more matter than antimatter in today's universe if they were made equally? These are exactly the questions that the DAEdALUS experiment could answer by observing neutrinos.

Neutrinos are particles which come in three different types, often called flavors. Think of these as three different types of balls: a baseball, a football, and a soccer ball. They're all balls, but they're all a little different in their physical makeup. The biggest difference between a ball and a neutrino is that when you throw a baseball, it will remain a baseball while flying. Neutrinos on the other hand exhibit an extremely unintuitive property of "oscillations"—that as one flavor of neutrino is traveling through space, it will evolve into a different one! It is as strange as you throwing a baseball, but your friend catching a football.

A concept in physics called CP-symmetry says that neutrinos should oscillate, or transmute, with the same probability as antineutrinos (the antimatter counterpart of a neutrino). That is, if we imagine one out of every hundred baseballs we throw will turn into a football, then CP-symmetry suggests one out of every hundred anti-baseballs thrown will turn into an anti-football. We don't know if neutrinos follow CP-symmetry, but the scientists behind DAEdALUS are interested in finding the answer. If neutrinos violate CP-symmetry, it could explain why today there is so much more matter than antimatter.

The obvious way to study this phenomenon would be to make a bunch of neutrinos and measure how many changed flavor after a given time or distance from the production point, and then repeat the test with anti-neutrinos for comparison. If CP-symmetry is violated, different numbers will be found in the two cases. However, this requires experimentation with both neutrinos and antineutrinos, which can take a very long time. Instead, DAEdALUS will perform the test while looking at only antineutrinos, measuring the flavor changes at various distances and comparing the results to predictions with no CP violation. The detector will analyze the presence of a certain flavor of neutrino at three different distances and find the probability of flavor changing over each of those distances. From that information, physicists will be able to extrapolate whether neutrinos violate CP-symmetry and possibly help to explain the imbalance between matter and antimatter in today's universe!

Although much of the theoretical groundwork is already established, it will still be many years before the DAEdALUS experiment will be ready to answer the mystery. Since neutrinos are so hard to detect, the experiment requires a very high rate of neutrino production in order to carry out the investigation in any reasonable length of time. These neutrinos are created using high-power particle accelerators which will need to be more powerful than any existing similar accelerators. Jose Alonso is an accelerator physicist working on the neutrino sources for the experiment and points out that the particle accelerators used to produce the neutrinos for DAEdALUS need to be powered "about a factor of 10 higher than what's been done before." Although the accelerator technology exists, it will take significant work to increase their power to sufficient levels to run the experiment. Dr. Alonso believes that it would still be about five years before the power necessary for the experiment could be achieved.

Despite the hard work that lies ahead in the construction of the experiment, it is exciting that physics has reached a point in which we can experimentally explain events that took place billions of years ago.