Last night I went to Prof Brian Cox’s lecture at the Aotea centre. I had some predictions about what he would include in the talk; light speed as a universal constant, ‘red shift’ and the expanding universe, the moons in our solar system with water that could potentially hold life, and the new LIGO discovery that I wrote about in my last post – very exciting!
The Aotea theatre stage was completely covered in a huge hi-def screen that he used to show photos and video of various cosmological events and to explain some of the more important theories and the relevant equations. Although I would say most of the audience there were not scientists, just enthusiastic amateurs like myself and my friends, he didn’t dumb things down too much like often happens with TV series, so I felt engrossed for the whole 2.5 hours.
My favourite visuals were the Cassini images of the moon Enceldus, the video of Mercury’s transit across the face of the sun (I’d seen this before but it was incredible on the giant screen), the real data visualisation fly-through of all detectable galaxies and the computer simulation of two black holes converging (data also captured by LIGO). I’ve linked to the video below on the LIGO YouTube page, it’s fascinating how spacetime around the holes is warped and stretched as they merge. The event horizon is shown as the thin edge of light before total blackness.
Black Holes Merge video
(While I was hunting around for videos of the Mercury transit this morning, I kept coming across videos from flat-earthers ‘debunking NASA’. I find the whole thing fascinating! I still can’t quite get to grips with what they feel is to be gained by NASA pretending to the world that the earth is a sphere orbiting the sun? So curious.)
(Image:Artist’s illustration of two merging neutron stars. The rippling spacetime grid represents gravitational waves traveling out from the collision, while the narrow beams show bursts of gamma rays expelled just seconds after the gravitational waves. Ejected clouds of glowing, neutron-rich material swirl around the merging stars. Credit: NSF/LIGO/Sonoma State University/A. Simonnet)
Scientists at LIGO have detected, for the first time, spacetime ripples known as gravitational waves from the collision of two neutron stars. This phenomenon was predicted by Einstein but had not been observed until August 17 2017. All of the previously detected gravitational waves came from merging pairs of black holes which are so dense that light cannot escape their grasp, making such mergers essentially invisible to normal telescopes. While neutron stars appear to create less extreme gravitational force than that generated by black holes, these super-dense stars created by the collapse of supernova, have gravitational fields strong enough to squeeze and break down an entire sun into a ball of neutrons the size of a small city. Unlike a black hole, a neutron star’s gravity is too weak to trap light, meaning the huge burst made from two of them slamming together can be bright enough to be observed from Earth.
The collision of these two neutron stars likely produced a black hole, allowing the observation of the birth of one of these phenomena. It also provides evidence that it is neutron star collisions that forge the universe’s heavy elements including uranium, platinum and gold. The bulk of the universe’s hydrogen and helium was produced in the first moments after the big bang, and most of the lighter elements—oxygen, carbon, nitrogen etc—were formed from nuclear fusion in stars, but scientists were unsure as to the origin of the heavier elements. This new cosmic observation provides evidence that the collision of the universe’s densest stars is the true alchemical forge.
“If you think about it, the universe is sort of a cosmic particle collider, with neutron stars as the particles,” O’Shaughnessy says. “It throws them together, and we now have the opportunity to see what comes out…. This event is a Rosetta stone, giving us real data to connect disparate threads of astrophysics that previously only existed in the mind of theorists or as bits in a supercomputer simulation. It allows us to understand the cosmic abundance of heavy elements. It allows us to probe the squishiness of nuclear matter at extreme densities. It allows us to measure the expansion of the universe…. We are now reaping the reward, a mountain of gold 10 or a hundred times the mass of the Earth, that the universe just gave us.”
Richard O’Shaughnessy, an astrophysicist and LIGO team member at Rochester Institute of Technology quoted in Scientific American. (https://www.scientificamerican.com/article/gravitational-wave-astronomers-hit-mother-lode1/)