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Astrophysicist From Maine Explains Why 'Epic Image' Of Black Hole Created Such A Stir

courtesy Dr. Grant Tremblay
Dr. Grant Tremblay.

Dr. Grant Tremblay is an astrophysicist who studies black holes. He's also a native Mainer who was back in the state last week to speak at the University of Maine in Orono about the phenomena.  Maine Public Radio’s Morning Edition host Irwin Gratz had a chance to speak with him while he was there soon after NASA released the first ground-breaking image of a black hole. Gratz asked Tremblay what an image like that can teach an expert like him.TREMBLAY: It's hard to overstate what an epic image this is. By epic I mean there's a before and an after. You think of images like the earth rising from the Apollo program. Or that pale blue dot image from the Voyager spacecraft showing Earth suspended in a sunbeam from billions of miles away. This is an image quite like that. It's been an image decades in the making. My institute - the Center for Astrophysics, Harvard & Smithsonian – effectively operate the Event Horizon Telescope project, by Shep Doeleman who's the director of the project. And I have to state honestly that when the images were revealed last Wednesday there were tears in the audience - we were all gathered to watch the press conference. Now what's interesting is that the public thought the image was blurry. And that's fair enough. The image looks kind of blurry. But it is technically the second sharpest image ever taken in all of human history. And it is a confirmation of the thing that we thought was there but never thought we could see.

GRATZ: Your talk is titled “Galaxy Scale Fountains With Black Hole Pumps” - fountains of what, I guess, was the first question.

So it turns out that black holes aren't just big vacuum cleaners. And what that means is that black holes interact with their surroundings. So it turns out that in order to grow a billion-solar mass black hole like the one observed by the event horizon telescope and released last week, you have to liberate an enormous amount of gravitational potential energy. And what that means is that as black holes grow, they output or feed back an enormous amount of energy into their surroundings. So they can drive the evolution of the entire galaxy in which they sit. By analogy, if that black hole were the size of a grape, than the galaxy that it sits in would be, relatively, the size of the earth. So we are talking about something that is the size of the grape affecting and driving the evolution of something that is the size the earth.

Credit Event Horizon Telescope Collaboration/Maunakea Observatories / via Associated Press
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via Associated Press
This image released Wednesday, April 10, 2019, by Event Horizon Telescope shows a black hole.

We tend to think of black holes as destructive because there's an event horizon, you disappear beneath it and you're gone. But do they serve a constructive purpose in the universe?

Yeah, that's a beautiful way to put it. So black holes aren't actually violent objects, right? They're not big vacuum cleaners. If you actually replace the sun with a black hole of equal mass all of the planets would orbit just as they are right now. Nothing would change - of course, OK, all life on earth would die because there would be no sun and the food chain would collapse and things like that - but the dance of the planets around this solar mass black hole would be exactly the same. What is special about that math is that it is draped in a mathematical boundary called an event horizon, which is effectively a causal discontinuity in the fabric of space time. It is destructive in that any particle or any thing or any person or any planet that crosses the event horizon is doomed forever to continue toward the singularity. So you could describe them as destructive in that sense. But I actually like to think of them as elegant. 

0422_ig_tremblay_2_way_long_edit_01.mp3
Hear more from Dr. Grant Tremblay on NASA's effort to image a black hole.

Astronomy, of course, has come a long way. What kinds of instruments are helping you today in continuing to discover the nature of black holes and their effects?

We are no longer simply bouncing photons off of shiny mirrors. We are literally listening to the ringing of the fabric of space time itself. I'm currently involved in leading one of the four NASA-funded projects for one of the next great observatories. The Lynx X-Ray Observatory would create a mirror that works like skipping stones off the surface of a pond. It would be this 37,000 piece chandelier of the most pristine segments of silicon meta-shell optics ever devised. And we would literally see the unseen universe with that sort of technology.

Thank you for the time this morning we really appreciate it.

Thank you. And it was a pleasure.

This interview has been lightly edited for clarity.