Bernie Badger: Here's another one Einstein got right
Predicted a century ago by Albert Einstein in 1916, gravitational waves have finally been detected. Just last week researchers with the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO, announced their success at a news conference and in a paper in Physical Review Letters.
The detection was of a kind of “chirp” lasting only 20 milliseconds. It is actually within the human range of hearing. Like birdwatchers who know the calls of a rare species, researchers recognized the rising pitch that matches the final moments of the merger of two stellar-mass black holes. The estimates are that one is about 29 solar masses and the other is about 36 solar masses.
Although we have detected the chirp, our current detectors only give a general idea of the direction that the signal came from. The estimate is that the source was some 1.3 billion light-years away, in a region of the sky near the Large Magellanic Cloud (LMC). The LMC is only 158,200 light years away. The signal came from one of the many distant galaxies in patch of sky just overlapping the LMC.
On this siteyou can hear the sound repeated twice, and then shifted into a higher register that’s easier to hear. The original sound repeats again two more times. Something that just moved in an orbit 1.3 billion years ago can make your eardrums move 1.3 billion light years away.
The ability to detect gravitational waves opens a new observational window on the universe. Previously, only the various forms of electromagnetic radiation have brought us information about the stars and galaxies. Scientists have exploited waves longer than light (radio, microwave and infrared) as well as waves shorter than light (ultraviolet, x-ray and gamma rays) in their search to learn more about the universe.
Gravitational waves have eluded detection for over 50 years. In theory every mass sheds a gravitational wave as it accelerates. But only the most cataclysmic events would make waves strong enough to detect. These changes in the fabric of space move out at the speed of light. If the Sun were suddenly transported to a new location on the opposite side of the Earth, for eight minutes the Earth would continue to orbit the Sun’s old location, and we would still see the Sun shining up in the sky. That’s how long it takes for the sunlight to reach the Earth, and it should be the same for gravity.
No instances of teleporting stars have been observed, so far. But the “death spiral” of two black holes could move around stellar-sized masses at high frequency. It cannot last long however, as the gravitational waves carry away energy, moving the two holes into an ever-closer embrace.
The closer the black holes get, the faster they orbit and the more energy is spent producing gravitational waves. The resulting crescendo is one of the most energetic events conceived. It is just enough for LIGO to detect.
At the planetarium
You can come to the Eastern Florida State College Planetarium exhibit hall and see a demonstration of the destructive power of a black hole. All you have to do is roll a coin into the gravitational well exhibit. As it rolls energy is radiated as sound, causing it to fall further into the well. Near the end the coin orbits so fast that you can only see a blur before the coin passes the point of no return and disappears forever.
Visit the Eastern Florida State College Planetarium in Cocoa to see the following public shows:
Friday Evening, 2/19
7:00 Skywatchers of Africa
8:15 SolarMax (IMAX)
9:00 U2 Laser Show
Saturday Evening, 2/20
7:00 More Than Meets the Eye
8:15 Antarctica (IMAX)
9:00 Jimi Hendrix Laser Show
Wednesday Matinée, 2/24
2:00 Legends of the Sky: Orion
3:15 Africa's Elephant Kingdom (IMAX)
Call the EFSC planetarium box office at (321) 433-7373 or visit https://www.calendarwiz.com/planetarium for latest show times, descriptions and prices.