Apr 15 2019
When Matthew M. Szydagis, an assistant professor of physics at the University at Albany, State University of New York, watched YouTube videos of supercooling a bottle of water and stimulating it to freeze by striking it, he got a concrete impression of this idea, particularly when he saw it again during the Disney movie “Frozen.”
At the 2019 American Physical Society April Meeting in Denver, Szydagis will explain how this inspired him to investigate whether a subatomic particle, such as dark matter, can initiate the freezing of supercooled water.
“All of my work is motivated by the search for dark matter, a form of matter we’re sure is out there because we can observe its indirect gravitational effects,” stated Szydagis. “It makes up a significant fraction of the universe, but we have yet to uncover direct, conclusive and unambiguous evidence of it within the lab.”
If water is clean enough—low in impurities, such as dust particulates—and placed in a smooth enough container, Szydagis explained, it can be cooled below its freezing point of 0 C (32 F) without freezing.
This is called ‘supercooling’ and is similar to how water can be easily superheated in the microwave, essentially heated above its boiling point without actually boiling. It’s simply the reverse. The water ends up, in either of these cases, in a state known as ‘metastability’, neither unstable nor quite stable either.
Matthew M. Szydagis, Assistant Professor of Physics, University at Albany, State University of New York.
In this case, a disturbance can set off the phase transition, freezing, and crystallization. “This isn’t ordinary freezing, and it forms white snow instead of clear ice,” he added. “We cooled liquid water to as cold as −20 °C (−4 °F). in our lab without it freezing. It isn’t the same as freezing point depression, like when you salt your sidewalk, because the water was pure and not contaminated with impurities on purpose.”
The team showed that specific forms of particles that hit the water have the ability to microscopically (subatomically) cause it to freeze in case it is supercooled first.
Some particles like neutrons can even scatter multiple times within the water. We were able to show this not only with commercially available sources of particles, but also a Fiestaware ‘radioactive red’ plate with orange uranium-based paint from the 1950s.
Matthew M. Szydagis, Assistant Professor of Physics, University at Albany, State University of New York.
They developed an innovative detector based on the supercooled water, called the “snowball chamber” since that goes well with “bubble” and “cloud” chambers—technologies from the early- to mid-20th century that involve the use of boiling and condensation.
Most certainly, supercooled water is not a new concept; it has been explored for a number of decades by condensed matter physicists and chemists, down to −40 °C (−40 °F). There even exist publications related to it dating back to over100 years.
But we managed to discover a new property of supercooled water. To our great surprise, we found that some particles (neutrons) but not others (gamma rays) trigger freezing. Since this is basic research that has never been done before, there was no guarantee it would work. It was a ‘let’s try it and see’ approach—the scientific method in its most basic form. Not only do we have a new detector of fundamental particles, but potentially of dark matter because neutrons are thought to emulate it.
Matthew M. Szydagis, Assistant Professor of Physics, University at Albany, State University of New York.
The researchers predict a number of other prospective implications for their discovery, such as gaining insights into cloud formation, the detection of nuclear weapons in cargo for homeland security, and offering hints as to how some mammalian species hibernate, somehow supercooling their blood.