Rest assured that as everything seems to be falling apart on Earth, it also appears that the rest of the universe is on a downward trajectory, too.
In new research that gauged several vital signs of the cosmos, a team of 175 astronomers found that our universe is already well past its prime, creaking its way into a dismal future in which fewer and fewer stars will be born, until the process eventually stops entirely. There’s no light at the end of the tunnel — just the inevitable revenge of darkness.
“The universe will just get colder and deader from now on,” lamented Douglas Scott, a cosmologist at the University of British Columbia and a coauthor of the resulting yet-to-be-peer-reviewed study, in a statement.
Scott and an army of astronomers analyzed a trove of optical data collected by the European Space Agency’s Euclid space telescope and its Herschel satellite, which probed far-infrared wavelengths. Combined, the observatories’ measurements formed the largest sample of galaxies so far: 2.6 million, the researchers said.
“In the past, researchers wouldn’t have a large enough sample, or might be missing key populations of cold or hot galaxies,” lead author and UBC researcher Ryley Hill explained in the statement. “Since Euclid is so comprehensive, you can really measure dust temperatures in a way you can’t argue with.”
Dust temperatures are a key barometer of a galaxy’s health. Astronomers have observed that galaxies with higher star formation also tend to have hotter dust on average, as those higher temperatures indicate the presence of more massive stars. And stars are good, we like to think: they bring light into the cosmos and facilitate the formation of planets, on which puny lifeforms like us can form. Even stellar deaths are fruitful; the epic supernovas that completely obliterate a star at the end of their life also seed the universe with heavy metals, not to mention the dust grains measured in the study.
“Dust grains are connected with star formation, and when stars burn up, they make a whole bunch of dust grains in the process,” Scott said.
What the researchers found, grimly, is that the universe has gotten gradually colder. Ten billion years ago, the average dust grain temperature in the sampled galaxies was warmer by about 10 degrees Celsius, for a resulting temperature of -238 degrees Celsius.
That sounds cold — and it is — but a more useful metric here is Kelvin, in which zero Kelvin represents the absolute lowest temperature in the cosmos. In those days of yore when the universe was a little over three billion years old, the average dust temperature was 35 Kelvin, which is a fairly significant departure from zero.
Now that the gap has closed, it doesn’t bode well for stars. If things aren’t hot, then stars aren’t forming.
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