Speaking to an Astrophysicist Who Just Discovered a Five-Billion-Year-Old Galaxy

Yes, we asked her about aliens.

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Jul 8 2015, 2:06pm

Image via Wikidepdia Commons

What have you done this week? Made it to work? Maybe did your laundry? Ordinarily we'd say that's pretty good, except for the fact that it's Wednesday and Australian astronomers have already announced they've discovered a five billion-year-old galaxy that predates our own solar system. The finding was made using a high-tech radio telescope setup—the CSIRO'S Australian SKA pathfinder (ASKAP)—in remote Western Australia.

Elaine Sadler is a Professor of Astrophysics at University of Sydney and part of the research team that found the galaxy. She leads the ASKAP-FLASH project that uses the radio telescopes to search for galaxies through detecting hydrogen gas in the radio frequencies they emit.

Though she was excited, Elaine's accustomed to dealing with intangible stuff that's a billion years-old on a daily basis. She spoke to us about how this could lead to hundreds more discoveries and explained they're really looking back in time.

VICE: I bet discovering a galaxy feels really good.
Elaine Sadler: It was very exciting! We've been working for two or three years to get to making this first observation. To make a detection so early was exciting because it means what we we're doing is working. We will over time find many hundreds of these galaxies in the distant universe and be able to learn about them.

How does one discover a galaxy anyway?
We look for signals at a particular radio frequency that come from cold hydrogen gas in the universe. It's like we have a receiver and we're tuning it to a radio frequency, so that every so often we get a signal.

Could you explain that again like you're talking to a complete layperson, which I am?
I'll make it as simple as I can! The hydrogen atom is a very simple atom, it's got a proton and an electron. They sit there doing not very much when the gas is cold. But every so often the electron will spontaneously flip and spin. And when it does that, it emits a very faint signal. If you look at the Milky Way galaxy that we live in, and the signals from gas in our galaxy, then convert the signal into a longer wavelength because of the expansion of the universe, you start to see the signature of hydrogen in galaxies far, far away.

Speaking of far away, this galaxy is five billion light years from Earth. That means what we're seeing happened five billion-years-ago. Does that mean it might not even exist anymore?
It probably does exist, but the light would have left the galaxy five billion-years-ago. Something may have happened to it in the meantime but mostly the stars will be there, some of them may have exploded. But the galaxy itself probably doesn't change very much over that time.

But you're effectively looking into the past?
When these radio waves set out from the galaxy, our sun and our solar system hadn't even been born yet. While those radio waves were traveling to us, the sun was formed, the planets formed, life evolved on earth, all of these things happened in the intervening time.

What's it like to study something that can never be reached?
I think it's quite inspiring actually. It's like studying the past of human civilization. We know we can never go to the Roman Empire, but it doesn't mean it's not interesting to know more about it and how people lived in those days.

What can we learn from this?
Well, what's specific about our Milky Way galaxy is that it's full of gas where new stars form. There's a constant process of stars dying and new stars being born. In other galaxies that doesn't seem to happen—they seem to run out of gas. So one of the things we want to look at is what happens to galaxies to make them either able to form new stars or not able to form new stars. The other thing that we can learn about is black holes, and why some galaxies have these very energetic events in their centers.

Does it ever feel bizarre working with something so intangible?
No. It's actually one of the questions that many, many people around the world are interested in: How do galaxies change over their lifetime or the lifetime of the universe? It's a complicated problem that people would love to have more insight into.

Is detecting life out of the picture here?
No, it's actually a very serious question. We know now many of the stars in the Milky Way have planets, some of those planets are kind of like Earth so we might imagine that life could form there. And there's a serious attempt to look for radio signals from other planets, not as far away as this five-billion year old galaxy, but around stars within our own galaxy. Nobody's found anything yet, they've had questions about what they would do if they did find something, but really the signals even from the nearest stars take years and years to reach.

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