One of the main themes of this blog is “What’s changed in the last 50 years?” — as far as our understanding of physics and the cosmos. For this post, let’s consider the last 100 years or so. There have been major changes in our cosmic perspective. Rather than adding the content of this post as a comment for a previous one on the topic (see notes), I decided that this video visualization merits its own post.
This retrospective on the SpaceRip YouTube channel contains wonderful visuals. Many comments praise the narration. The video takes us from the days of an island universe into the quest to understand distant incredibly powerful gamma ray bursts. In particular, the role that the Swift Gamma-Ray Burst space telescope (now called the Neil Gehrels Swift Observatory) has played in that understanding.
There have been times when our understanding of the universe has reached a standstill — when our grasp of the workings of time and space, the nature of matter and energy do not fully square with what we observe. In those times, opposing world views cannot be resolved. So it was in the spring of 1920 when astronomers debated the scale of the universe …
September 13th 2008, the Swift satellite recorded a burst with the power of 9000 supernovae and a jet that was clocked at 99.9999% the speed of light.
April 29th 2009, brought the second most distant object ever recorded. The journey of this gamma-ray burst started 13.14 billion years ago.
Astronomers have begun to see these beacons as probes for understanding the chemical evolution of the cosmos going all the way back to when stars and galaxies were just beginning to form. But how does nature produce a beacon of light that can reach across the entire breadth of the visible universe? One team of scientists has been looking for answers close to home in a giant galaxy some 50 million light years away known as M87.
Photographing a black hole?
Cosmological fact and fiction
Beyond the infinity of black holes
Ergosphere – what?
6 thoughts on “Cosmic retrospective — gamma ray bursts”
Regarding the origins of bursts and how the energy of gamma rays can vary tremendously, this Physics World article “Cosmic gamma-ray energy record shattered by high-altitude observatory” (06 Jul 2019) highlights that range.
Here’s an interesting article about the speed of gamma-ray jets from cosmic beacons: Forbes > “Ask Ethan: Can Gamma-Ray Jets Really Travel Faster Than The Speed Of Light?” by Ethan Siegel, Senior Contributor (Oct 5, 2019).
Remember that experiment (or video of a demonstration) in physics lab showing what happens to the speed of light when a laser beam is split into two paths, one through air (or vacuum) and one through water? (See this Fermilab YouTube video for an explanation of the actual physics.)
UCLA Physics > YouTube video (2013) “How to Measure the Speed of Light”
A multinational global project to build a new generation of ground-based gamma-ray telescopes moved forward this year with successful operation of a prototype telescope.
Science Daily > “Scientists detect crab nebula using innovative gamma-ray telescope” – First-of-its-kind telescope promises to shed new light on the physics of high-energy phenomena, from supernovae to dark matter by Columbia University (June 2, 2020).
More insight into (and a new model of) the sources of gamma rays.
• SciTechDaily > “Mysterious ‘Empty Sky’ Gamma-Ray Puzzle Solved – May Lead Astrophysicists To Unravel Dark Matter” by Australian National University (September 20, 2021)
1. when gas falls into supermassive black holes.
2. via star formation in the disks of galaxies (the majority of this diffuse gamma-ray radiation).
A cosmic flash from a powerful type of supernova? Multi-wavelength observations may answer the question.
• Space.com > “Astronomers just spotted the most powerful flash of light ever seen” by Tereza Pultarova (October 14, 2022) – The gamma-ray burst [GRB221009A] was also the nearest [2.4 billion light-years away] ever detected.
Here’s a visualization.
• NASA > APOD > GRB 221009A (2022 October 15 )
Image Credit: NASA, DOE, Fermi LAT Collaboration
Here’s another visualization.
• NASA > APOD > X-Ray Rings Around a Gamma Ray Burst [GRB 221009A] (2022 October 17)
This article is a useful recap of gamma rays. It discusses where these high-energy photons fit in the electromagnetic spectrum (compared to visible light); their energy levels, production, health hazards (protection measures), history of detection; cosmic bursts and current space observatories. As well as some useful references.
However, with a degree in physics and astrophysics, Cooper still introduces his article by using the popsci legacy characterization of photons as particles which can behave as waves. Rather than, as in quantum field theory, that all elementary so-called particles are localized excitations in fields. Packets of energy modeled as waves. (As physicist Art Hobson wrote in 2017, do radio telescopes look like they’re capturing particles? – see Point particles RIP).
• Space.com > “Gamma rays: Everything you need to know about these powerful packets of energy” by Keith Cooper (December 28, 2022) – Gamma rays can only be detected by sensors made of dense metals and takes over six feet (1.8 meters) of concrete to block.
• Humans fit for space? — NASA’s Twins Study
• Kilonovas and multi-messenger astrophysics
• Up in the sky — faster than a speeding LHC proton
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