nuclear, physics, science

Drop and Run

(Cheers to @lukeweston on Twitter, whose wrote the post that inspired this one.)

Radiation therapy is a lifesaver, because, unfortunately, cancer still exists. And sometimes cancers grow in places doctors can’t reach without poking a hole in something important. (The brain and pancreas are good examples. Don’t poke holes in those.) Luckily, instead of going after the cancer with pointy sharp things, a doctor can instead shoot the tumor with a radiation gun. (It’s weird that that counts as lucky, but it does.) If the radiation beam is swiveled properly, rest of the body only gets the beam swept over it briefly. The tumor, on the other hand, at the center of the beam’s pivot, gets the radiation constantly, and it gets radiation poisoning and dies, sparing the healthy tissue around it.

All good so far. But how the hell do you build a radiation gun? Most modern clinics use x-ray beams. A lot are starting to adopt proton beams, which don’t do as much collateral damage, if you plan things right. A few specialist clinics use beams of neutrons or carbon ions. And some clinics use gamma rays. Gamma rays aren’t exactly easy to make, but some radioactive isotopes produce them when they decay. Cobalt-60 is one of those isotopes. Stick a little slug of cobalt-60 in a tube inside a big lead block, at the far end of a narrow hole. The lead stops most of the gamma rays. The hole lets the rest out as a narrow beam. Done! Gamma-ray gun! Cool, eh?

Understandably, the security around these little cobalt death-pellets is pretty tight. But people make mistakes. Sometimes, radioactive sources get stolen. Or they go missing. Or a nation goes through a revolution or a civil war, and the authorities who’re supposed to keep track of the death-pellets get swallowed in a coup. Or the sources simply get left behind when their clinics close. That’s what happened in 1987 in Goiânia, Brazil: A scrapper broke into an abandoned radiotherapy clinic, stole a cesium-137 gamma-ray source without knowing what it was, and took it home. Eventually, somebody broke the source capsule open with a screwdriver and got lethal cesium-137 chloride powder everywhere. People handled it. People touched it and then ate. People slept in beds right next to the source capsule. Four people died, 249 people got exposed, and a whole fucking village had to be decontaminated. Gamma-therapy sources are not to be trifled with.

So, if for some reason you’re breaking into radiotherapy clinics (please don’t do that) and you come across an ominous steel capsule that says “Drop and Run” on it, then for the love of everything holy, drop it and run.

Drop and Run Cropped

(You thought I was kidding about the “Drop and Run” thing, didn’t you? I wasn’t. 3500 Curies of cobalt-60 is enough that, if you put that source capsule it in your pants pocket, you’d drop dead in fifteen minutes flat. We’re not even talking about a “slow, miserable, rot-from-the-inside death from radiation poisoning” kind of dead. We’re talking “dead this time tomorrow” dead. Source: this online calculator, assuming 3,500 Curies of Co-60 at an average distance of 1.5 meters, and a rapid-death dose of 30 Sieverts, which, for gamma rays, equals 30 Gray.)

physics, science

The Moment a Nuke Goes Off

Nuclear weapons give me mixed feelings. On the one hand, I really like explosions and physics and crazy shit. But on the other hand, I don’t like that somebody thought “You know what the world needs? A bomb capable of ruining the shit of everybody in an entire city. And you know what we need? Like fifty thousand of the bastards, all in the hands of angry buggers that all have beef with each other.”

That aside, though, the physics of a nuclear explosion is pretty amazing. Especially when you consider that nuclear bombs were developed at a time when: there was no vaccine for polio, commercial airliners hadn’t been invented, the big brains in Framingham hadn’t even started to work out just what causes heart disease, and a computer needed one room for all the vacuum tubes and another for its air conditioning system.

There’s an absolutely awesome 1977 paper by Glasstone & Dolan that describes, in great detail, and from beginning to end, the things that happen when a nuke goes off. The paper’s also surprisingly readable. Even if you’re a little rusty on your physics, you can still learn a hell of a lot just by skimming it. That’s the mark of a good paper.

To me, the most shocking thing in that paper is just how quickly the actual nuclear explosion happens. But first, a little background. This is what the inside of an implosion-type fission bomb looks like (This is the type that was dropped on Nagasaki, and seems to be the fission device used in modern arsenals. Correct me if I’m wrong.)

Fat_Man_Internal_Components (1)


It looks complicated, but it’s really not. The red thing at the center is the plutonium-239 that actually does the exploding. The dark-gray thing surrounding it is a hollow sphere of uranium-238 (I’ll explain what that’s for in a second). The light-gray thing is an aluminum pusher (I’ll explain that in a second, too). And the peach-colored stuff is the explosive that sets the whole thing off. The yellow things it’s studded with are the detonators.

When the bomb is triggered, the detonators go off. Spherical detonation waves spread through the dark-peach explosives on the outside. When they hit the light-peach cones, the shape of those cones forms the thirty-two separate waves into one smooth, contracting sphere. That spherical implosion wave then passes into the dark-peach charges surrounding the aluminum pusher. So far, the process has taken roughly 30 microseconds.

When the implosion wave hits the pusher, it crushes the aluminum inward, generating remarkable pressures. This takes something like 10 microseconds.  The pusher’s job is to evenly transfer the implosion force to the core.

The imploding pusher then crushes the uranium tamper in roughly 15 microseconds. The tamper serves two purposes: it helps reflect the neutrons generated by the plutonium-238, and, being such a dense, heavy metal, its inertia keeps the core from blowing itself apart too quickly, so more of it can fission.

Speaking of the core, a whole bunch of crazy shit is about to happen in there. Normally, I don’t think of metals as the sort of thing you can compress. But when you’ve got hundreds of kilos of high explosives all pointing inwards, you can compress anything. The core is a whopping 6.4 kilos of plutonium (14 pounds). That’s how much plutonium it takes to wreck an entire city. But just having 6.4 kilos of plutonium lying around isn’t that dangerous. (Relatively speaking.) 6.4 kilos is below plutonium’s critical mass. At least, it is at normal densities. That implosion wave, though, crushes the plutonium down much smaller, until it passes the critical limit by density alone. (There’s also a fancy polonium-210 initiator in the center, to make sure the core goes off when it’s supposed to, but this post is already getting too rambly…)

Once the plutonium passes its critical limit, things happen very quickly. Inevitably, a neutron will be emitted from an atom. That neutron will strike a Pu-238 nucleus and cause it to fission and release a couple more neutrons. Each of these neutrons sets off another Pu-238 nucleus, and bam! We’ve got the right conditions for an exponential chain reaction.

Still, from the outside, it doesn’t look like much has happened. It’s been approximately a hundred microseconds since the detonators detonated, but next to none of the plutonium’s fission energy has been released. Here’s a graph to explain why:

Nuclear Explosion

(Generated using the excellent

Here, the x-axis represents time in nanoseconds. The y-axis represents the number of neutrons, expressed as a percentage of the number needed to release 21 kilotons-TNT of energy (the amount of energy released by the Fat Man bomb that destroyed Nagasaki). At time-zero, the neutron that initiates the chain reaction is released. And by time 240, all of the energy has been released. But the thing to notice is that it takes all of 50 nanoseconds for the vast, vast majority of the fissions to happen. That is to say, the plutonium core does all the fissioning it’s going to do–releases all of its energy–within 50 nanoseconds.

21 kilotons-TNT released over 50 nanoseconds is equivalent to a power of 1.757e21 Watts. That’s ten thousand times more power than the Earth receives from the sun. That’s roughly 5 millionths of a solar luminosity, which sounds small, until you realize that, for those 50 nanoseconds, a 14-pound lump of gray metal is producing 0.0005% as much power as an entire star.

The nuclear explosion happens so fast, in fact, that by the time it’s finished, the x-ray light released just as the chain reaction took off has only traveled 15 meters (about 49 feet). Everything happens so rapidly that the bomb’s components might as well be stationary. The casing might be starting to bulge outward from the detonation of the implosion device, and the bomb, while still bomb-shaped, is rapidly evaporating into plasma as hot as the core of the fucking sun. But even at those temperatures, the atoms in the bomb haven’t had time to move more than a couple centimeters. So, by the time the nuclear detonation has finished, the bomb and the surrounding air look something like this:

Fat Man End of Detonation.png

But perhaps the wildest thing of all is that we’re not limited to hypothetical renderings here. We actually know, thanks to the incomparable Harold Edgerton, exactly what those first moments of a nuclear explosion look like. Doc Edgerton developed the rapatronic camera, whose clever magneto-optic shutter is capable of opening and closing with an exposure time of as little as 10 nanoseconds. The results of Mr. Edgerton’s work speak for themselves:

Glowing Shot Cab

The thing above is the “shot cab” for a nuclear test. It’s a little shack on top of a tower, with a nuclear bomb inside. In this picture, the bomb has already gone off. Those white rectangles are actually the cab’s wall panels, being made to glow brightly by the scream of X-rays bombarding them. And those ominous-looking mushroom-shaped puffs are where the X-rays have just started to escape into the air and make a nuclear fireball. A moment (probably measured in nanoseconds) later, the fireball looks like this:

Very Early Fireball

I take my hat off to Mr. Edgerton for having the guts to say “Oh? You need a photograph of the first microsecond of a nuclear explosion? Yeah. I can probably make that happen.” (Incidentally, both those photos are taken from the paper “Photography of Early Stages of Nuclear Explosions”, by Edgerton himself, which is, regrettably, behind a fucking paywall. Grumble grumble.)

And, thanks to, we can see the evolution of one of these nightmare fireballs:


Progressing from left to right and top to bottom, we can see the shot cab glowing a little. Then glowing a lot. Then erupting in x-ray hellfire. And after that, just sort of turning into plasma, which things that close to a nuclear explosion tend to do.

Soon enough, this baby fireball evolves into a nightmarish jellyfish from the deepest pit in Hell:



The horrifying spikes emerging from the bottom of the fireball are caused by the so-called “rope-trick effect”: they’re the guy wires supporting the shot tower vaporizing and exploding under the onslaught of radiation from the explosion.

And soon enough (after about 16 milliseconds), the fireball swells into a monster like this:


(Source. Note, this is the fireball from the Trinity test, humanity’s first-ever nuclear explosion.)

It’s worth noting that, at this point, 16 milliseconds after the bomb goes off, your retinas have barely had time to respond to the flash. In the roughly 75 to 100 milliseconds it takes the retinal signal to travel down the optic nerves and reach your brain, you are already being exposed to maximum thermal radiation. And after a typical human reaction time (something like 150 to 250 milliseconds), about the time it takes to consciously register something, you’re probably already on fire.

So nuclear explosions are cool, and they’re awe-inspiring, but I must pose the question once again: who the hell saw the plans for these hell-bombs and thought “Yeah. That’s a thing that needs to exist. We need to have that nightmare hanging over humanity’s head forever! Let’s build one!”

astronomy, physics, silly

The Neutronium Necklace

Neutronium Jewel

If you want exotic jewelry, you’ve come to the right place! The Neutronium Necklace has a classic thick-link sterling-silver chain with a striking pendant containing a 26,000,000,000,000-carat brilliant-cut crystal of virgin neutronium, imported directly from J0108.

Care instructions: The pendant’s gravity may attract small objects such as crumbs, grains of sand, and loose paperclips. As the jewel is harder than all known materials, it may be cleaned with a damp cloth, sandblaster, waterjet cutter, high-power laser, or with high explosives. Its setting, however, is sterling silver, and so it should be cleaned separately with a suitable silver polish.

Safety instructions: For your safety, we do not recommend you touch the jewel with bare hands, as tidal forces may cause discomfort, dislocation, or dismemberment. We also strongly recommend against wearing the neutronium necklace in Earth gravity, as its weight will exceed 500,000 tonnes, which may result in neck or back injury or decapitation. For your own safety, and the safety of others, please avoid dropping the necklace, as the jewel will rapidly penetrate the Earth’s crust and be lost. In this situation, the necklace’s warranty will not cover the cost of replacement.

Please note that neutronium is not stable at pressures below 100 megaelectronvolts per cubic femtometer. Exposing the jewel to ambient pressures below this level will void the necklace’s warranty, and may result in a Solar-system threatening explosion exceeding 10 trillion megatons.

Note: As a precaution against theft, black-market resale, and usage by supervillains, demons, or malevolent alien lifeforms, your neutronium jewel is inscribed with an inconspicuous barcode on its rear side. If you wish to have the jewel re-set, please only consult a licensed jeweler who has been certified Not an Evil Psychopath.

Fair Trade Certification: The rough neutronium crystal in your Neutronium Necklace was purchased at fair market value from the neutron-worms of J0108. Mining conditions are certified humane by the RL Forward observatory committee. Please direct all concerns to the RL Forward committee, as the neutron-worms are only capable of communicating via high-energy neutrino beams, which may present a health hazard to untrained civilians.

astronomy, physics, science, Space, thought experiment

If the Sun went Supernova

I have to preface this article by saying that yes, I know I’m hardly the first person to consider this question.

I also have to add that, according to current physics (as of this writing in December 2017), the Sun won’t ever go supernova. It’s not massive enough to produce supernova conditions. But hey, I’ll gladly take any excuse to talk about supernovae, because supernovae are the kind of brain-bending, scary-as-hell, can’t-wrap-your-feeble-meat-computer-around-it events that make astronomy so creepy and amazing.

So, for the purposes of this thought experiment, let’s say that, at time T + 0.000 seconds, all the ingredients of a core-collapse supernova magically appear at the center of the Sun. What would that look like, from our point of view here on Earth? Well, that’s what I’m here to find out!

From T + 0.000 seconds to 499.000 seconds

This is the boring period where nothing happens. Well, actually, this is the nice period where life on Earth can continue to exist, but astrophysically, that’s pretty boring. Here’s what the Sun looks like during this period:

Normal Sun.png

Pretty much normal. Then, around 8 minutes and 19 seconds (499 seconds) after the supernova, the Earth is hit by a blast of radiation unlike anything ever witnessed by humans.

Neutrinos are very weird, troublesome particles. As of this writing, their precise mass isn’t known, but it’s believed that they do have mass. And that mass is tiny. To get an idea of just how tiny: a bacterium is about 45 million times less massive than a grain of salt. A bacterium is 783 billion times as massive as a proton. Protons are pretty tiny, ghostly particles. Electrons are even ghostlier: 1836 times less massive than a proton. (In a five-gallon / 19 liter bucket of water, the total mass of all the electrons is about the mass of a smallish sugar cube; smaller than an average low-value coin.)

As of this writing (December 2017, once again), the upper bound on the mass of a neutrino is 4.26 million times smaller than the mass of an electron. On top of that, they have no electric charge, so the only way they can interact with ordinary matter is by the mysterious weak nuclear force. They interact so weakly that (very approximately), out of all the neutrinos that pass through the widest part of the Earth, only one in 6.393 billion will collide with an atom.

But, as XKCD eloquently pointed out, supernovae are so enormous and produce so many neutrinos that their ghostliness is canceled out. According to XKCD’s math, 8 minutes after the Sun went supernova, every living creature on Earth would absorb something like 21 Sieverts of neutrino radiation. Radiation doses that high have a 100% mortality rate. You know in Hollywood how they talk about the “walking ghost” phase of radiation poisoning? Where you get sick for a day or two, and then you’re apparently fine until the effects of the radiation catch up with you and you die horribly? At 21 Sieverts, that doesn’t happen. You get very sick within seconds, and you get increasingly sick for the next one to ten days or so, and then you die horribly. You suffer from severe vomiting, diarrhea, fatigue, confusion, fluid loss, fever, cardiac complications, neurological complications, and worsening infections as your immune system dies. (If you’re brave and have a strong stomach, you can read about what 15-20 Sieverts/Gray did to a poor fellow who was involved in a radiation accident in Japan. It’s NSFW. It’s pretty grisly.)

But the point is that we’d all die when the neutrinos hit. I’m no religious scholar, but I think it’d be appropriate to call the scene Biblical. It’d be no less scary than the scary-ass shit that happens in in Revelation 16. (In the King James Bible, angels pour out vials of death that poison the water, the earth, and the Sun, and people either drop dead or start swearing and screaming.) In our supernova Armageddon, the air flares an eerie electric blue from Cherenkov radiation, like this…



…and a few seconds later, every creature with a central nervous system starts convulsing. Every human being on the planet starts explosively evacuating out both ends. If you had a Jupiter-sized bunker made of lead, you’d die just as fast as someone on the surface. In the realm of materials humans can actually make, there’s no such thing as neutrino shielding.

But let’s pretend we can ignore the neutrinos. We can’t. They contain 99% of a supernova’s energy output (which is why they can kill planets despite barely interacting with matter). But let’s pretend we can, because otherwise, the only spectators will be red, swollen, feverish, and vomiting, and frankly, I don’t need any new nightmares.

T + 499.000 seconds to 568.570 seconds (8m13s to 9m28.570s)

If we could ignore the neutrino radiation (we really, really can’t), this would be another quiet period. That’s kinda weird, considering how much energy was just released. A typical supernova releases somewhere in the neighborhood of 1 × 10^44 Joules, give or take an order of magnitude. The task of conveying just how much energy that is might be beyond my skills, so I’m just going to throw a bunch of metaphors at you in a panic.

According to the infamous equation E = m c^2, 10^44 Joules would mass 190 times as much as Earth. The energy alone would have half the mass of Jupiter. 10^44 Joules is (roughly) ten times as much energy as the Sun will radiate in its remaining 5 billion years. If you represented the yield of the Tsar Bomba, the largest nuclear device ever set off, by the diameter of a human hair, then the dinosaur-killing (probably) Chicxulub impact would stretch halfway across a football field, Earth’s gravitational binding energy (which is more or less the energy needed to blow up the planet) would reach a third of the way to the Sun, and the energy of a supernova would reach well past the Andromeda galaxy. 1 Joule is about as much energy as it takes to pick up an egg, a golf ball, a small apple, or a tennis ball (assuming “pick up” means “raise to 150 cm against Earth gravity.”) A supernova releases 10^44 of those Joules. If you gathered together 10^44 water molecules, they’d form a cube 90 kilometers on an edge. It would reach almost to the edge of space. (And it would very rapidly stop being a cube and start being an apocalyptic flood.)

Screw it. I think XKCD put it best: however big you think a supernova is, it’s bigger than that. Probably by a factor of at least a million.

And yet, ignoring neutrino radiation (we still can’t do that), we wouldn’t know anything about the supernova until nine and a half minutes after it happened. Most of that is because it takes light almost eight and a quarter minutes to travel from Sun to Earth. But ionized gas is also remarkably opaque to radiation, so when a star goes supernova, the shockwave that carries the non-neutrino part of its energy to the surface only travels at about 10,000 kilometers per second. That’s slow by astronomical standards, but not by human ones. To get an idea of how fast 10,000 kilometers per second is, let’s run a marathon.

At the same moment, the following things leave the start line: Usain Bolt at full sprint (10 m/s), me in my car (magically accelerating from 0 MPH to 100 MPH in zero seconds), a rifle bullet traveling at 1 kilometer per second (a .50-caliber BMG, if you want to be specific), the New Horizons probe traveling at 14 km/s (about as fast as it was going when it passed Pluto), and a supernova shockwave traveling at 10,000 km/s.

Naturally enough, the shockwave wins. It finishes the marathon (which is roughly 42.195 kilometers) in 4.220 milliseconds. In that time, New Horizons makes it 60 meters. The bullet has traveled just under 14 feet (422 cm). My car and I have traveled just over six inches (19 cm). Poor Usain Bolt probably isn’t feeling as speedy as he used to, since he’s only traveled an inch and a half (4.22 cm). That’s okay, though: he’d probably die of exhaustion if he ran a full marathon at maximum sprint. And besides, he’s about to be killed by a supernova anyway.

T + 569 seconds

If you’re at a safe distance from a supernova (which is the preferred location), the neutrinos won’t kill you. If you don’t have a neutrino detector, when a supernova goes off, the first detectable sign is the shock breakout: when the shockwave reaches the star’s surface. Normally, it takes in the neighborhood of 20 hours before the shock reaches the surface of its parent star. That’s because supernovas (at least the core-collapse type we’re talking about) usually happen inside enormous, bloated supergiants. If you put a red supergiant where the Sun is, then Jupiter would be hovering just above its surface. They’re that big.

The Sun is much smaller, and so it only takes a couple minutes for the shock to reach the surface. And when it does, Hell breaks loose. There’s a horrific wave of radiation trapped behind the opaque shock. When it breaks out, it heats it to somewhere between 100,000 and 1,000,000 Kelvin. Let’s split the difference and say 500,000 Kelvin. A star’s luminosity is determined by two things: its temperature and its surface area. At the moment of shock breakout, the Sun has yet to actually start expanding, so its surface area remains the same. Its temperature, though, increases by a factor of almost 100. Brightness scales in proportion to the fourth power of temperature, so when the shock breaks out, the Sun is going to shine something like 56 million times brighter. Shock breakout looks something like this:

Sun Shock Breakout.png

But pretty soon, it looks like this:

Sun Supernova.blend

Unsurprisingly, this ends very badly for everybody on the day side. Pre-supernova, the Earth receives about 1,300 watts per square meter. Post-supernova, that jumps up to 767 million watts per square meter. To give you some perspective: that’s roughly 700 times more light than you’d be getting if you were currently being hit in the face by a one-megaton nuclear fireball. Once again: However big you think a supernova is, it’s bigger than that.

All the solids, liquids, and gases on the day side very rapidly start turning into plasma and shock waves. But things go no better for people on the night side. Let’s say the atmosphere scatters or absorbs 10% of light after passing through its 100 km depth. That means that, after passing through one atmosphere-depth, 90% of the light remains. Since the distance, across the Earth’s surface, to the point opposite the sun is about 200 atmosphere-depths, that gives us an easy equation for the light on the night side: [light on the day side] * (0.9)^200. (10% is approximate. After searching for over an hour, I couldn’t find out exactly how much light the air scatters, and although there are equations for it, I was getting a headache. Rayleigh scattering is the relevant phenomenon, if you’re looking for the equations to do the math yourself).

On the night side, even after all that atmospheric scattering, you’re still going to burn to death. You’ll burn to death even faster if the moon’s up that night, but even if it’s not, enough light will reach you through the atmosphere alone that you’ll burn either way. If you’re only getting light via Rayleigh scattering, you’re going to get something like 540,000 watts per square meter. That’s enough to set absolutely everything on fire. It’s enough to heat everything around you to blowtorch temperatures. According to this jolly document, that’s enough radiant flux to give you a second-degree burn in a tenth of a second.

T + 5 minutes to 20 minutes

We live in a pretty cool time, space-wise. We know what the surfaces of Pluto, Vesta, and Ceres look like. We’ve landed a probe on a comet. Those glorious lunatics at SpaceX just landed a booster that had already been launched, landed, and refurbished once. And we’ve caught supernovae in the act of erupting from their parent stars. Here’s a graph, for proof:


(Source. Funnily enough, the data comes from the awesome Kepler planet-hunting telescope.)

The shock-breakout flash doesn’t last very long. That’s because radiant flux scales with the fourth power of temperature, so if something gets ten times hotter, it’s going to radiate ten thousand times as fast, which means, in a vacuum, it’s going to cool ten thousand times faster (without an energy source). So, that first bright pulse is probably going to last less than an hour. But during that hour, the Earth’s going to absorb somewhere in the neighborhood of 3×10^28 Joules of energy, which is enough to accelerate a mass of 4.959×10^20 kg. to escape velocity. In other words: that sixty-minute flash is going to blow off the atmosphere and peel off the first 300 meters of the Earth’s crust. Still better than a grisly death by neutrino poisoning.

T + 20 minutes to 4 hours

This is another period during which things get better for a little while. Except for the fact that pretty much everything on the Earth’s surface is either red-hot or is now part of Earth’s incandescent comet’s-tail atmosphere, which contains, the plants, the animals, most of the surface, and you and me. “Better” is relative.

It doesn’t take long for the shock-heated sun to cool down. The physics behind this is complicated, and I don’t entirely understand it, if I’m honest. But after it cools, we’re faced with a brand-new problem: the entire mass of the sun is now expanding at between 5,000 and 10,000 kilometers per second. And its temperature only cools to something like 6,000 Kelvin. So now, the sun is growing larger and larger and larger, and it’s not getting any cooler. We’re in deep dookie.

Assuming the exploding sun is expanding at 5,000 km/s, it only takes two and a quarter minutes to double in size. If it’s fallen back to its pre-supernova temperature (which, according to my research, is roughly accurate), that means it’s now four times brighter. Or, if you like, it’s as though Earth were twice as close. Earth is experiencing the same kind of irradiance that Mercury once saw. (Mercury is thoroughly vaporized by now.)

In 6 minutes, the Sun has expanded to four times its original size. It’s now 16 times brighter. Earth is receiving 21.8 kilowatts per square meter, which is enough to set wood on fire. Except that there’s no such thing as wood anymore, because all of it just evaporated in the shock-breakout flash.

At sixteen and a quarter minutes, the sun has grown so large that, even if you ignored the earlier disasters, the Earth’s surface is hot enough to melt aluminum.

The sun swells and swells in the sky. Creepy mushroom-shaped plumes of radioactive nickel plasma erupt from the surface. The Earth’s crust, already baked to blackened glass, glows red, then orange, then yellow. The scorched rocks melt and drip downslope like candle wax. And then, at four hours, the blast wave hits. If you thought things couldn’t get any worse, you haven’t been paying attention.

T + 4 hours

At four hours, the rapidly-expanding Sun hits the Earth. After so much expansion, its density has decreased by a factor of a thousand, or thereabouts. Its density corresponds to about the mass of a grain of sand spread over a cubic meter. By comparison, a cubic meter of sea-level air contains about one and a quarter kilograms.

But that whisper of hydrogen and heavy elements is traveling at 5,000 kilometers per second, and so the pressure it exerts on the Earth is shocking: 257,000 PSI, which is five times the pressure it takes to make a jet of abrasive-laden water cut through pretty much anything (there’s a YouTube channel for that). The Earth’s surface is blasted by winds at Mach 600 (and that’s relative to the speed of sound in hot, thin hydrogen; relative to the speed of sound in ordinary air, it’s Mach 14,700). One-meter boulders are accelerated as fast as a bullet in the barrel of a gun (according to the formulae, at least; what probably happens is that they shatter into tiny shrapnel like they’ve been hit by a gigantic sledgehammer). Whole hills are blown off the surface. The Earth turns into a splintering comet. The hydrogen atoms penetrate a full micron into the surface and heat the rock well past its boiling point. The kinetic energy of all that fast-moving gas delivers 10^30 watts, which is enough to sand-blast the Earth to nothing in about three minutes, give or take.

T + 4 hours to 13h51m

And the supernova has one last really mean trick up its sleeve. If a portion of the Earth survives the blast (I’m not optimistic), then suddenly, that fragment’s going to find itself surrounded on all sides by hot supernova plasma. That’s bad news. There’s worse news, though: that plasma is shockingly radioactive. It’s absolutely loaded with nickel-56, which is produced in huge quantities in supernovae (we’re talking up to 5% of the Sun’s mass, for core-collapse supernovae). Nickel-56 is unstable. It decays first to radioactive cobalt-56 and then to stable iron-56. The radioactivity alone is enough to keep the supernova glowing well over a million times as bright as the sun for six months, and over a thousand times as bright as the sun for over two years.

A radiation dose of 50 Gray will kill a human being. The mortality rate is 100% with top-grade medical care. The body just disintegrates. The bone marrow, which produces the cells we need to clot our blood and fight infections, turns to blood soup. 50 Gray is equivalent to the deposition of 50 joules of radiation energy per kilogram. That’s enough to raise the temperature of a kilo of flesh by 0.01 Kelvin, which you’d need an expensive thermometer to measure. Meanwhile, everything caught in the supernova fallout is absorbing enough radiation to heat it to its melting point, to its boiling point, and then to ionize it to plasma. A supernova remnant is insanely hostile to ordinary matter, and doubly so to biology. If the Earth hadn’t been vaporized by the blast-wave, it would be vaporized by the gamma rays.

And that’s the end of the line. There’s a reason astronomers were so shocked to discover planets orbiting pulsars: pulsars are born in supernovae, and how the hell can a planet survive one of those?

art, silly

Morbid Curiosity: “The Garden of Earthly Delights” (probably NSFW)

This blog’s gettin’ fancy now! Because today, my curiosity isn’t focusing on fever-dream hypotheticals. Today, I’m expanding my curiosity into classic Medieval art!

Unfortunately, that art is Hieronymous Bosch’s The Garden of Earthly Delights, which is an even worse fever-dream. I should warn you, this post is probably not safe for work, for children, or for those who dislike nudity and (very mild) gore. It’s also not suitable for anyone who can’t pass a DC 25 sanity check. Just so you know.

Here’s the painting in its entirety. It’s a classic, probably painted sometime around 1500:


It’s pretty typical of the symbolic religious art of the time. It’s also stuffed full of fucking nightmare fuel. I know it’s kinda hard to see from that image above, but fret not! I found a high-resolution scan of the painting so that I could carve up the nightmare fuel into little morsels and present them to you, the dear reader, one-by-one.

I’m not exactly a talented art-appreciator. I’m the kinda guy who looks at a Jackson Pollock painting and thinks “Nope. Don’t get it. Looks like an accident. Maybe spaghetti.” So I haven’t divided the little fragments of The Garden by theme or symbolism. I’ve divided them into four broad categories: The Bestiary, for horrible creatures; Architecture, for horrible buildings; People Doing Weird Things, which explains itself; and Nightmare Fuel, for horrible things which defy categorization. Let’s get started! But before we do, let me show you what Jesus Christ thinks about this whole situation.

Christ is Worried.png

It’s okay, Jesus. I’m worried, too…

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