Crash from the past

This exercise is a part of Educator Guide: Neutron Star Crash Seen for First Time / View Guide

1. The article described the latest detection of gravitational waves by LIGO. Can you find an article about the first detection of gravitational waves by LIGO? What is a difference between the recent detection and the first detection of gravitational waves?

Possible student response: The article “Year in review: Gravitational waves offer new cosmic views,” published 12/24/2016, recounts how gravitational waves were directly detected for the first time in 2015 and announced to the world in 2016, after having been predicted by Albert Einstein’s theory of general relativity nearly a century earlier. The first detected gravitational waves came from the collision of two black holes, and the most recent detection was generated from a neutron star merger. The article about the first detection also describes how observing gravitational waves could tell us more about orbiting black holes, explosions of stars and other cosmic events that create sufficiently strong gravitational waves.

2. Although we cannot mimic neutron star collisions on Earth, we can at least smash heavy nuclei such as gold together at high speeds. Can you find an article about such experiments and what they discovered?  

Possible student response: The article “Smashing gold ions creates most swirly fluid ever,” published 3/4/2017, discusses how the Relativistic Heavy Ion Collider at Brookhaven National Laboratory in New York accelerated beams of positively charged gold ions to nearly the speed of light and then smashed them together in head-on collisions. During the collisions, the neutrons and protons from the gold break down into their component quarks and gluons, creating a soup called quark-gluon plasma. This plasma was similar to the state of the early universe just millionths of a second after the Big Bang, when it was still too hot for these elementary particles to condense to form neutrons and protons. Among other exotic properties, the quark-gluon plasma created at Brookhaven had a swirliness, or vorticity, measured at 9 billion trillion radians per second. For comparison, the core of a strong tornado has a swirliness of 0.1 radian per second.

3. Can you find an article about an earlier neutron star collision? 

Possible student response: The article “Gold seen in neutron star collision debris,” published 7/22/2013, discusses how the remnants of a different neutron star collision were indirectly observed in June 2013. No gravitational waves were detected from that collision, but NASA’s Swift satellite detected gamma rays from the collision and the Hubble Space Telescope detected visible light. The gamma-ray data showed that the collision produced a gamma-ray burst, similar to the one reported by the most recent neutron star merger. The visible light spectra showed that the collision produced an assortment of heavy elements, including gold, lead, platinum and uranium, but the scientists weren’t able to say whether or not the light was produced from the gamma-ray burst or the star collision.