TRADITIONAL notions of data collection invoke the idea of empiricism, the notion that all knowledge comes from sensory experience. Today, we still refer to our work as empirical science, even though, at this point, there is often quite a distance between human sense-based experience and how data is collected. In both astronomy and physics, data collection typically involves complex equipment that is connected to extensive computer-based algorithms that convert the signals in the equipment into data that humans then analyse. Even so, we still treat this as a sensory process, with a heavy emphasis on what we can “eyeball” on our computer screen.
But there is a tendency to overemphasise certain sensory processes in how we practise science: what we see matters more than what we can hear or feel. Empirical practice is, after all, not just “vibes”. Thus in astronomy, observing the sky using light has, for a long time, been the central practice. For most of our existence, this happened exclusively with optical observations – data collection in wavelengths that the human eye is sensitive to.
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In 1800, astronomer William Herschel (who usually worked with his sister Caroline) showed that infrared heat radiation was, in fact, light at a frequency beyond the red end of the visible light spectrum. Thanks to quantum mechanics, we can now also understand that these different wavelengths of light have photons with different energies, with infrared at a lower energy than ultraviolet. Today, humans around the world observe the cosmos in a variety of apparently invisible wavelengths, from ultra-high-energy gamma rays to extremely long wavelength radio waves.
And we have learned that light isn’t the only gateway to the cosmos. Over the last few decades, subatomic elementary particles known as neutrinos have become an important window on the cosmos. Neutrinos are produced in radioactive decays, which can seem pretty far out. But actually, bananas – which are high in potassium – emit neutrinos from potassium decay. (Don’t worry, it is totally safe!) This same kind of process occurs in stars, star deaths like supernovae, and stellar collisions, which means that all of these phenomena emit neutrinos. Neutrinos don’t interact with other matter very much, which makes observing them difficult. For this reason, the South Pole has become an important neutrino astronomy site, taking advantage of the extensive ice to house experiments like the IceCube Neutrino Observatory.
Neutrinos allow us to map the cosmos using particles that aren’t photons, making the entire universe an ongoing particle physics experiment that simultaneously gives us insight into the nature of neutrinos and the events that produce them. Regular readers might recall a cosmic neutrino mystery that I have mentioned before. Neutrinos come in three types – electron, muon and tau – and when they travel over long distances, they randomly oscillate between type. The non-trinary nature of neutrinos was first discovered by comparing observations of neutrinos emitted by the sun with theoretical predictions of neutrino production there.
As exciting as neutrinos are, they aren’t the only non-photon game in town. In 1974, astronomers studying a binary star system observed that it was losing energy at a rate consistent with the emission of gravitational waves. Predicted by general relativity, which posits that space and time are a single entity that can curve, gravitational waves are literally ripples in space-time. The 1974 observations remained the only evidence for this phenomenon until 2015, when the Virgo Collaboration and the Laser Interferometer Gravitational-Wave Observatory (LIGO) directly detected gravitational waves from a black hole binary for the first time using vibrations in carefully designed instruments called interferometers.
So maybe at least some of science is vibes after all! Virgo and LIGO’s 2015 detection inaugurated a new era in astronomy, where we now look at the universe through not just light waves and particle emissions, but also by feeling for vibrations in space-time itself. The success of LIGO also provided a strong case for the development of gravitational wave facilities. The next stop? We are going to space!
On 25 January, the European Space Agency (ESA) announced it will be moving forward with the development of LISA, the Laser Interferometer Space Antenna. ESA will work with NASA and an international group of scientists to develop this exciting new mission, which will get away from the vibrations of Earth’s surface. In space, after all, no one has to wonder whether the instrument is vibrating because two black holes are colliding or because a truck drove by.
Chanda’s week
What I’m reading
Geraldine Heng’s The Invention of Race in the European Middle Ages is fascinating.
What I’m watching
I was thrilled by the classic John Carpenter movie about physicists doing things they shouldn’t, Prince of Darkness.
What I’m working on
I have got a major grant proposal due at the end of the month!
Chanda Prescod-Weinstein is an associate professor of physics and astronomy, and a core faculty member in women’s studies at the University of New Hampshire. Her most recent book is The Disordered Cosmos: A journey into dark matter, spacetime, and dreams deferred
