Carl Sagan’s famous quote, “We are all star stuff,” is important to keep in mind when hearing that scientists have just indirectly observed, for the first time ever, the very first stars born in the universe’s past. Sagan’s quote reminds us that these scientists haven’t only glimpsed the first stars ever ignited, but have also given us insight into our most ancient origins as living creatures.
In terms of how the antenna was able to identify the very first stars, that all comes down to the way the ultraviolet light from the first stars was absorbed by the very cold clouds of hydrogen surrounding them. In other words, the scientists weren’t directly detecting the light emitted by the stars, they were measuring the hydrogen’s absorption of surrounding radio waves (left over from the big bang) after being hit by the UV light coming from the stars that had just “turned on” (become enormous balls of plasma powered by nuclear fusion reactions at their cores).
Detecting that absorption of radio waves in the primordial hydrogen clouds was extraordinarily difficult, however, due to the immense amount of electromagnetic radiation propagating throughout the universe; to the point where, according to the speaker in the above video, “Finding the impact of the first stars in that cacophony… [was] like trying to hear the flap of a hummingbird’s wing from inside a hurricane.”
The hydrogen clouds’ absorption of the surrounding radio waves was detected however, and now these scientists say that the first stars probably emerged around 180 million years after the big bang.
As a massive side note to the findings, it seems that the hydrogen gas was much cooler than scientists originally theorized. As Rennan Barkana, an astrophysicist at Tel Aviv University, says in a related paper published in Nature, this could be due to its interacting with much colder dark matter. So on top of observing the first stars ever, these findings may have also just given us a new way of studying dark matter.
“This is a huge milestone,” said Judd Bowman, the astronomer from Arizona State University who led the research effort. “If you really look at our cosmic origins as humans, what are all the events in the universe that had to happen for us to be there? The first rung in that ladder is these first stars.”
Here’s a little more Carl too, just as a reminder of how profound all of this is:
What do you think about this indirect observation of the first stars in the universe? Let us know your stellar thoughts in the comments below!
Images: National Science Foundation
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