One popular type of ghost story involves a phone call from the past from a loved one, or perhaps even from one’s younger self, sending a warning or some other message. These are limited to the invention of the telephone or recording devices, but there are also cases of letters from the past with hidden messages. As our radio telescopes and signal detectors get ever stronger, astronomers can listen further back into the past of the universe. What if they could pick up a message from the beginning of time … just moments after the Big Bang? A never-before-seen type of gravitational wave picked up by a new kind of detector may have done just that. What’s the warning?
“A ground-breaking detector that aims to use quartz to capture high frequency gravitational waves has been built by researchers at the ARC Centre of Excellence for Dark Matter Particle Physics (CDM) and The University of Western Australia. In its first 153 days of operation, two events were detected that could, in principle, be high frequency gravitational waves, which have not been recorded by scientists before. Such high frequency gravitational waves may have been created by a primordial black hole or a cloud of dark matter particles.”
In a press release touting the results of a new study published in the journal Physical Review Letters, lead author Michael Tobar, a physicist at the University of Western Australia in Perth, explained how a new small detector built by him and his colleagues from crystal quartz 1 inch (3 centimeters) in diameter and a resonant chamber that produces an electrical signal whenever it vibrates at certain frequencies. By cooling it to extremely low temperatures to minimize thermal vibrations, they were able to pick up two new signals. At the time, they had no idea what the signals might be.
Since then, Tobar and the team narrowed their list of probable causes to normal cosmic rays, a previously-unknown type of thermal fluctuation in the crystal, a type of dark matter known as an axion spinning around a black hole and giving off gravitational waves, and some off-the-wall ideas that require suspending the Standard Model of physics. One of those ideas was proposed recently in Live Science by Francesco Muia, a theoretical physicist at the University of Cambridge in the U.K., who was not involved in the work.
Muia says shortly after the Big Bang, the universe went through a period called inflation, followed by a phase transition. During that time, large amounts of energy may have been sent into the fabric of space-time, generating gravitational waves. Those waves from the beginning of the universe may be what Tobar’s device picked up.
Tobar says he’d love for his unknown signals to be messages from the beginning of time, but he wants more proof. That requires more detectors to be built in hopes that two or more pick up the same signals.
In the meantime, if these signals are indeed messages from our ancestors at the beginning, what do you think they might say? Welcome to the universe? Hurry up and find another dimension before it’s too late? Don’t take the blue pill?