Shedding new light on black holes
Columbia astrobiologist shows what blows at the Secret Science Club
Breaking news on black holes. Within the last few years – which is quite recent when you consider that our universe is 13.7 billion years old – technological advances in telescopes have allowed scientists to determine the existence and behavior of black holes in a way that has never been possible.
Speaking to a standing-room-only crowd of over 400 at Tuesday’s Secret Science Club at the Bell House in Brooklyn, Columbia University astrobiologist and author Caleb Scharf elaborated on the subject of his recent book, Gravity’s Engines: How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Cosmos.*
An intellectual conception of the late 18th century, black holes were largely ignored until Einstein’s theory of relativity provided a mathematical framework for how space could be altered by mass. Event horizons – the edge of a black hole where light bends around it and matter can still escape – seemed theoretically possible but difficult to believe in their occurrence outside the math. However, scientists could only explain the universe’s existence if black holes were part of the equation.
Fast-forward to Tuesday and Scharf’s discussion on supermassive black holes. Relatively small and compact by outer space standards, they exist in the center of every galaxy, including our own. They’re not even really black, for as objects fall towards a black hole, the conversion of mass into energy is so great that subatomic particles shoot out, lighting up brighter than anything else in the cosmos. The Milky Way’s supermassive black hole is 4.3 million times the mass of the sun and is surrounded by dust and debris as objects fall towards the event horizon.
“Recent discoveries have allowed us to chart out the universe in an unprecedented manner,” Scharf said to the crowd. The British professor spoke confidently and articulately on his research as he moved about the stage. Telescopes such as NASA’s X-ray Chandra Observatory – around since 1999 – can detect X-ray emission from very hot regions around a black hole, an area that has been previously obscured from scientific observation because of the surrounding dust and debris.
“Now we can survey the universe, look at millions of galaxies, and pin down their characteristics,” said Scharf. “We can find galaxies that look like the Milky Way, and ask what their properties are.”
So what does this mean for our own galaxy? A lot, actually. In the past few years, scientists have discovered that our supermassive black hole hasn’t been as quiet as we once thought. In fact, it’s been blowing bubbles! Sometime within the last 100,000 years, our supermassive black hole has been blowing bubbles of hot atmospheric gas from its core, generating mega sound waves that ripple out into the galaxy. These bubbles help keep the gas from cooling and condensing to form new stars, suggesting that supermassive black holes play an important role in the development and regulation of new stars. The activity of black holes, which were once thought to be isolated curiosities, is not confined to the event horizon but instead sprawls across millions of light years.
“For the first time in human history, we are prepared to watch what happens and learn about how material gets fed into supermassive black holes,” said Scharf. And thanks to advances in telescope technology, scientists like Scharf will be watching. “After all,” he mentioned in an interview, “astronomony is a science of looking at stuff.”
*Correction: November 15, 2012
This story used to read that around 200 people attended the Secret Science Club event at the Bell House in Brooklyn. According to the event’s organizers, the actual number of attendees was over 400.