yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Death From Space — Gamma-Ray Bursts Explained


4m read
·Nov 2, 2024

Imagine if you could gather the energy from every star within a hundred million light years. From thousands of galaxies, each with billions of stars. Imagine, you could take this kind of power, and use it to fire the biggest super-weapon in the universe. Imagine the damage you could do.

It turns out, you don't need to imagine it. These exist, and they're called gamma ray bursts. But what are these cosmic snipers? And what happens if one takes a shot at Earth? To understand gamma ray bursts, we first have to understand gamma rays.

Gamma rays are electromagnetic radiation – waves which carry energy just like visible light. Visible light is a tiny part of the electromagnetic spectrum: it's the part your eyes can see. At lower energies, there are radio waves, microwaves and infrared. And at higher energies: ultraviolet, x-rays and gamma rays.

Gamma rays are incredibly powerful. A single gamma ray photon is more energetic than a million visible photons combined. Their high energy makes gamma rays a form of ionizing radiation. Meaning they are energetic enough to break apart atomic bonds. This makes them dangerous to you and me.

Ionizing radiation disrupts the delicate biochemical machinery that keeps us alive, like a 9mm bullet through a clock. Fortunately, on Earth, the ozone layer blocks gamma rays, filtering them out before they can harm us. But if the atmosphere blocks gamma rays from space, how were gamma ray bursts (or GRBs) from space ever discovered?

During the Cold War, the USA sent up spy satellites, which could detect gamma rays from Soviet nuclear tests in space. They didn't see any bombs, but they did observe faint bursts coming from space, lasting only a few seconds. To date, this may be the only major scientific discovery made by spy satellites (that we know about anyway).

Astronomers use telescopes to see different kinds of light to make their discoveries. And these spy satellites gave them a new pair of eyes. They were a mystery for thirty years, but eventually, we discovered the source of a GRB: a galaxy six billion light years away. If a GRB can be seen from such a distance, then it must be incredibly energetic.

Releasing more energy in a second than the sun will in its entire ten billion year lifetime, making GRBs the brightest events in the universe. So, where do they come from? GRBs accompany some of the most violent, cataclysmic deaths in the universe, and the birth of black holes.

There are two types of gamma ray bursts: short and long, and each has their own source. Long GRBs last about a minute, and scientists think they are produced by supernovae: when the core of a massive star collapses to become a black hole. Short GRBs last a second and are produced when two neutron stars in a binary merge.

Over millions of years, their orbits decay by emitting gravitational waves. Once they are close enough to touch, they crash and splash into each other, forming a black hole. Both supernovae and neutron star mergers create the same thing: black holes, surrounded by a magnetized disc of gas left over from their parent stars.

In these environments, the rotation winds up the magnetic field, which funnels hot jets of particles traveling at nearly the speed of light. The gas in this funnel creates two tight jets of high-energy gamma rays, like a celestial laser gun. So, unlike other cosmic explosions, which spread out and fade, GRBs stay focused and can be seen from much further.

Any more detail would require too much mathematics for a YouTube video. The universe is full of these cosmic snipers, firing blindly and randomly into the dark, and they're hitting us all the time. On average, we detect one per day. Fortunately, most are harmless.

All the bursts we have detected so far originated outside the Milky Way, too far away to hurt us. But a nearby GRB could be disastrous. If one goes off within a few light years of us, it would totally cook the surface of the Earth, or at least, the half that's facing it. But even a more distant GRB could still end life on Earth.

And it wouldn't need to score a head-shot to kill us. If originating from a few thousand light years away, it would be a hundred light years wide by the time it reaches us, washing over the Solar System like a tidal wave. Again, the ozone layer protects us, but it's better equipped to handle the trickle of ultraviolet from the sun.

A gamma ray burst would overwhelm it, leaving us exposed to deadly solar radiation. Ozone takes years to replenish itself by natural processes, which is more than enough time for the sun to burn the Earth sterile, or at least, to kill most complex life. In fact, this may have already happened.

A GRB has been suggested as one possible cause of the Ordovician extinction 450 million years ago, that eradicated almost 85% of all marine species. Although it's pretty much impossible to prove. Gamma ray bursts could even be one reason we don't see life anywhere else in the universe. They might be wiping clean huge chunks of it on a regular basis.

It's been suggested that because of GRBs, only 10% of all galaxies might be hospitable to life, similar to us. So, are they going to kill us? Probably not. In a galaxy like ours, there may only be one GRB per millennia.

And to harm us, they must be close and directed at us. But since gamma rays travel at the speed of light, we won't know when it's headed our way until it arrives. So, there could already be a GRB on its way to kill us all, and we won't know it until it hits us, and we're dead.

More Articles

View All
WARNING: The Truth About Bitcoin
The views and opinions expressed in this video are just that: opinions. This content is for entertainment and informational purposes only and should not be taken as investment, financial, or other advice. Aka, don’t listen to some random dude on YouTube a…
Maintain | Vocabulary | Khan Academy
Ahoy word Smiths! Hold fast because this word is about keeping it steady. As she goes, “maintain” is the featured word. Oh, I maintain a steady course. Word Smith’s maintain, it’s a verb; it means to keep something the same, to provide support for someth…
Newton's second law calculations | Physics | Khan Academy
Let’s solve a couple of problems on Newton’s Second Law. Here’s the first one: we have an elevator which is moving up, and let’s say the mass of the elevator, including the passenger inside, is 1,000 kg. Now, if the force, the tension force of the cable,…
Volume with cross sections perpendicular to y-axis | AP Calculus AB | Khan Academy
Let R be the region enclosed by y is equal to four times the square root of nine minus x and the axes in the first quadrant. We can see that region R, and gray right over here, region R is the base of a solid. For each y value, the cross section of the so…
Khan Stories: Jordan
I’m Jordan. I’m a sophomore at Harvard. I’m a first generation college student. My dad works two, three jobs. My mom’s still working. My grandparents, you know, coming from Puerto Rico and that kind of thing, really not having any education. So from one,…
Meet the powerful female duo behind National Geographic’s Queens | National Geographic
National Geographic’s Queens celebrates powerful female leaders in the natural world. Behind every inspirational animal on screen is an equally gritty and determined woman. All the women on this Queen’s Journey are true leaders— all hail the Queens! Stor…