Why does the Universe expand the way it does? Why does it accelerate? Einstein’s equations offer an explanation of gravity that works on the scale we know, but do they work on the grandest scales of space and time? Humanity now has a way to find out. The General Theory of Relativity predicts the behaviour of gravity, and includes a term known as the cosmological constant. Einstein added this term to make the universe static and unchanging, as he believed it was. But when the expansion of the universe was discovered by Edwin Hubble, Einstein regarded it as ‘the greatest blunder...
Dark matter could be almost anything. With little data other than how much total dark matter mass exists, we can’t decode much about what individual chunks of dark matter might be made of. I’ve talked before about Massive Compact Halo Objects (MACHOs) and Weakly Interacting Massive Particles (WIMPs), but these are just two possibilities. Other theorists have talked about Modified Newtonian Gravity (MNG), where gravity may work differently on the grand scale than it does on our small Earth scales. Or perhaps it’s something I haven’t seen before. Maybe what we call dark matter is just a large population of ancient black holes....
With the recent discovery of gravitational waves, we now have a target for probing the very early universe, close to the big bang. This is because gravitational waves can travel across the universe unimpeded, meaning those created after the big bang are still bouncing around today. It’s like the big bang was the ringing of a giant bell, and the ringing can still be heard. But all of our Easter eggs are not in one basket. There is another way to probe the very early universe, one we haven’t found yet, because it involves particles that are very tiny and...
The merger of black holes proven by LIGO yesterday looks amazing in this simulated view in today’s APOD. What would normally take a third of a second has been stretched out to show the entanglement. And remember, these things are far more massive than the Sun, so to be moving this quickly and merging is an extremely high-energy interaction. And kablammo, matter converted to energy, gravitational waves aplenty, and an even bigger black hole. Happy Long Weekend!
A long time ago, in a galaxy far far away…. Two black holes, with masses 29 and 35 times the mass of the Sun, merged to form an even bigger black hole. The merger resulted in three entire suns worth of matter converted to pure energy in the form of gravitational waves. The waves travelled a billion light years before a tiny meat-filled species on a pale blue dot in space figured how to see them. Thanks to the smartest one that species had seen in a century, they knew that black holes might merge, and that they would produce these waves if...
Today, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) is expected to announce a monumental discovery that is 100 years in the making. Theorized by Einstein’s general relativity in 1915, gravitational waves are ripples in space-time, similar to sound waves, but much tinier. The search has been ongoing for decades, with no results. Until now. LIGO has the most sensitive gravitational wave detector ever conceived – in two interferometer facilities in Livingston, Louisiana and Hanford, Washington. They use a laser split along two axes to give an in-phase beam. If gravitational waves along one of the axes affect the beam, it...
You may have heard about the leaked rumour about the discovery of gravitational waves from earlier this week. It was from Lawrence Krauss, who is an amazing science communicator and author, as well as a darn good astrophysicist. My earlier rumor about LIGO has been confirmed by independent sources. Stay tuned! Gravitational waves may have been discovered!! Exciting. — Lawrence M. Krauss (@LKrauss1) January 11, 2016 It’s safe to say that as a guy with an inside scoop on a lot of the latest science news, this is something to get excited about. The ‘LIGO’ he is referring to stands...
New science has come forward from a team of astronomers who, earlier this year, discovered a pair of black holes in a close orbit, heading toward a cataclysmic merger. The new results suggest that this incredibly powerful collision will occur much sooner than previously thought, as little as 100,000 years from now (A blip on the radar of astronomical timescales). By precisely calculating the individual and relative masses of the black holes, the team was able to predict how the merger would take place, giving a time line for the collision. The astronomers, from Columbia University, saw bright flashes of light...
I’ve talked about black holes previously, and only in our own Galaxy, and only the big one in the middle, Sag A*. When I speak with the public and with kids about Black Holes, most people never really understand that there aren’t just one or two kicking around, but potentially there are as many as a Billion Black Holes in our own Galaxy! The problem is, we are not very good at finding them. It makes sense, they give off no light, and we can only find them through indirectly measuring their effects on the surrounding environment. We can sometimes see...
