Death From Space — Gamma-Ray Bursts Explained


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 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 scientist think they are produced by supernova: 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 emmiting gravitational waves. Once they are close enough to touch, they crash and splash into each other, forming a black hole. Both supernova and neutron star mergers 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 say focused, and can been 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 chucks 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. This video was sponsored by squarespace.com/nutshell Death from the sky could come around any second. Maybe, even now! So you don’t have any time to waste. Learning to set up a website, portfolio or blog is usually hard and time consuming. Not so with Squarespace though. They let you set up a page with easily understandable tools, very quickly, and without any knowledge of web design. You can use the code “NUTSHELL” to save 10% and support Kurzgesagt. Squarespace have been a great sponsor, so give them some love. You can support us directly at Patreon or get Kurzgesagt merch here: it really helps. Over the next few months, we’d like to make more videos about cataclysmic destructive events, because, honestly, it’s a lot of fun to make these. If you have any ideas about what kind of doomsday scenario you’d like to learn about, let us know in the comments. And if you need to kill a little more time now, here are few related videos. Or maybe… NOW!




Comments
  1. 12 year old on COD vs GRB: I’ll take your bitch ass to RUST one v one me scrub and I’ll 360 no scope you and your mom with my eyes closed and no perks

  2. If life on Earth might be snuffed out at any moment, why bother with web design? I would argue we're all better off going outside and enjoying the moments we have, rather than wasting them at the computer.

  3. GF: "I don't know… maybe we should wait…"
    Me: Show this video – "So you see, this is the reason why we should have sex today!"

  4. The irony is that if a gamma ray does hit us, there will be someone somewhere arguing about how the chances of us being hit by a gamma ray burst are min—————————

  5. 5:43 Are they going to kill us?

    Why brother, we will be dead eventually.
    Just grab your beer and cigs and enjoy your life while you can. BE HAPPEEEE

  6. Wait a second, so light cannot escape a black hole but gamma rays can? Like you said it has way more energy than photons so that means that you either need way more energy to escape a black hole or gamma rays aren't affected by gravity at all.

  7. OMG gamma Ray bursts killed all the Pokemon??

    And maybe even the Green lantern corps, Pandora, Ego the living planet and most other planets that were supposed to exist!!
    The thought makes me sad

  8. In one of the kurzgesagt videos, you said that black hole bombs theoretically are the most powerful. Say if this is true, does it mean it's even stronger than gamma ray bursts and supernovas? Just curious 🙂

  9. Me: Just got done watching all of Adventure Time.
    Kurzgesagt: Flame Princess makes for a good "alien species" representative, right?
    Me: Watching Adventure Time from episode one again.

  10. Einstein's famous equation, E=mc^2 is wrong otherwise garbage also can be used to make nuclear bombs as long as it is matter or it has mass. Energy and matter can't interchange one another according to Einstein's famous equation. One must have photons before one can emit out photons. Photons are particles and they have mass. All forms of EMWs are dynamic photons per volume per time in different saturations. I do agree that long gamma burst is due to supernova explosion as a result of the nascent formation of a neutron star or a black hole where all atoms of dying dense star will be eventually reduced to quarks or preons respectively under its own tremendous weight. It will be quite awhile for entire dying star to eventually turning into a lump of quarks or preons respectively. Thus, the gamma burst will last for awhile.. On the other hand, short gamma burst is likely due to mergence of two neutron stars into a black holes. Quarks still contain some sizeable remnant of photons. When quarks reduce to preons, there are still sizeable amount of photons to be dissipated out before neutron stars turned into a black  hole. When two black holes merge to become a larger black hole, there wont be even a short gamma burst taken place because superstructures of black holes don't contain any photons at all. But sucking all celestial bodies within the accretion disk of black holes before merging them (by reducing them from atoms to preons) into a part of a larger black hole will dissipate out tremendous dynamic photons in the form of short gamma burst. Some supernova explosions had already taken place within Milky Way in the past since NASA discovered there are presence of some gigantic black holes within the center of Milky Way. Glad that we (our ancestors) still managed to survive despite of long gamma bursts near our vicinity in the past.If you are interested in real discoveries, I would recommend you to read my book, The Unification Theory- Volume One and you will be amazed with lots of new, interesting discoveries. In God I trust.    . . .

  11. me in middle school: hey ,teacher what is the radiation?
    teacher: idk
    me: how can i learn about it more?
    teacher:idk i gotta go my tea is gettin cold
    me: whaaa
    * years later *
    this video: exist
    me: finally(tears)

  12. Kurzgesagt: "we'd like to make more videos about cataclysmic events because, well, they're fun"

    Me, crying in the corner: "FUN?!?"

  13. I've never seen such a cheerful video about the potential extinction of all life on earth. Bring on the gamma ray burst!

  14. god just got turned on by someone's hot sexxy bod. Magdalene? maybe? = I hope it never happens it would take out not only Earth but 100's of light years in the midst of it.

  15. Wait till you watch strange stars that just explains that there is space Ebola running around turning planets to green goop

  16. Well, this is how to milk a franchise to get what you want, using the power of thumbnails. Cough, Star Wars, yeh…

  17. Do black holes have depth? Like, okay, they're deep. I get that. But let's say you're looking at a black hole that looks like a black empty circle in space. Is that black hole spherical, or is it like, flat?

  18. I’ve heard a ‘negative velocity’ theory, that if we were to go negative speed we would travel to maybe another dimension, because we would be traveling in a way that no one has ever done, like traveling down on a flat 2d dimension, you would be on another different flat 2d dimension theoretically right?

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