Tag archives: black hole
By Tushna Commissariat
It’s not often that we come across a mention of an astronomical event measured in Earth years, let alone months or hours. So suffice to say I was pretty surprised by a recent XMM-Newton finding that talked about a star orbiting a black hole at the furious rate of once every 2.4 hours! Further investigation revealed that this has only broken the previous record by an hour, but these extremely short orbits still have me rather amazed. Certain short orbital period binary stars or pulsars do have even shorter periods of less than an hour, but this star orbits a stellar-mass black hole (it’s about three times more massive than the Sun) that is roughly a million kilometres away from it. The video below, courtesy of the European Space Agency (ESA), is an animation showing one complete orbit of the star.
By Hamish Johnston
If you are a fan of astronomy and the comedian David Mitchell, the Open University has a treat for you. Mitchell and the OU have made a series of 12 short animated videos about the physics of the cosmos.
By Tushna Commissariat
As I was looking through all that is new and exciting in the world of physics this morning, I came across this interesting paper titled “Persistence of black holes through a cosmological bounce”, recently published on the arXiv preprint server. The paper looks at the possibility of certain black holes persisting when the universe collapses in a “big crunch”, only to stick around for the universe to re-expand with a “big bounce”. The paper was written specifically for the 2011 Awards for Essays on Gravitation held by the Gravity Research Foundation. Upon investigation, I found another two submissions published on arXiv, entitled “Birkhoff’s theorem in higher derivative theories of gravity” and “Quantum gravity and the correspondence principle”.
The Gravity Research Foundation was founded by Roger W Babson, a graduate from the Massachusetts Institute of Technology, who had an interesting relationship with gravity. In his youth, his older sister drowned in a river near their home, prompting him to write an essay titled “Gravity – our enemy no. 1″ wherein he claimed that it was gravity that killed her. “She was unable to fight gravity, which came up and seized her like a dragon and brought her to the bottom” he wrote.
Later he owed a debt of sorts to the theory of gravity as it helped him to predict the 1929 stock market crash based on the principle that if there was a strong upward action, there would follow a severe downward reaction. “What goes up will come down” he said. “The stock market will fall by its own weight.”
Gravity was a neglected area of physics in the 1940s. To energize the field, at the encouragement of his colleague George Rideout, he set up the Gravity Research Foundation, which handed out the first awards for the best essays submitted on gravity in December 1949. Previous prizewinners include Stephen Hawking (who has won it six times) and British science writer and astronomer John Gribbin (who was co-author of the winning paper, with Paul Feldman, when Gribbin was only 24) An archive of all winning essays can be found on the foundation’s website.
This year will be the 62nd year of the Essay Award and they will be announcing the top five prizewinners on 15 May, so all the best to the participants. And do look out for a follow-up blog!