Just Saw Bindi Irwin Got Engaged And Apparently Her Fiance Is American. She’s 21 And They’ve Been

Belarusian Greek Catholics celebrate the Divine Liturgy in a forest. 1930s. 

engage your neighbour across the lane in a shouting match about whether you observed a comet or an unnatural phenomenon, convinced you are in the right as you know very well he has no telescope

Pale Blue Dot

Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there–on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.

– Carl Sagan

Galilean moons Europa, Callisto, and Io pass in front of Jupiter. Photo of this rare triple-moon conjunction taken by the Hubble Space Telescope

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Tickling the Dragon’s Trail with the Demon Core

“Gentleman, what we have here is the most powerful force ever created by mankind. Lets poke at it with a screwdriver.”

—Louis Slotin, Los Alamos laboratory

After World War II the scientists at Los Alamos laboratory found themselves in possession of a spare core originally intended for a nuclear bomb. Nicknamed ‘“Rufus” the core would have been detonated as part of a third nuclear bomb dropped on Japan, however the Japanese surrendered before the bomb could be assembled. Instead the 89mm (3.5 inch) diameter sphere of plutonium-gallium was reserved for scientific testing, in particular criticality experiments.

Critical mass is the minimum amount of mass needed for a fissile material to sustain a nuclear chain reaction. When a fissile material reaches critical mass, it becomes “supercritical”, where it releases a large amount of energy.  Rufus was 5% subcritical, thus scientists thought it was ideal for use in criticality experiments. The experiment was designed to simulate critical mass by surrounding the core with neutron reflectors, in this case tungsten carbide bricks. The bricks would deflect released neutrons back into the core, increasing it’s reactivity. Completely surrounding the core would cause it to go supercritical, an event which was to be avoided because it would release a burst of neutron radiation that could kill everyone in the room. Essentially the purpose of the experiment was to see how much nuclear material could be added to the core before it would go supercritical, and measure how much energy is released in the process.

On August 21st, 1945 physicist  Harry K. Daghlian Jr. (pictured above left)was conducting a criticality experiment with Rufus when he accidentally dropped a tungsten carbide brick on the core. The core went supercritical, releasing a burst of neutron and gamma radiation while bathing the room in a bright blue light. Daghlian promptly responded by removing the brick from core, causing his hand to instantly blister from the radiation.

Daghlian had received a deadly dose of radiation, resulting in his death 25 days later. An accompanying guard,  Army Private Robert J. Hemmerly, was sitting at a desk 12 feet away but seemed unharmed by the accident, although he would die 33 years later from leukemia.

After the accident, Rufus was renamed, “The Demon Core”. A new procedure was designed to make the experiment “safer”, which was designed by physicist Louis Slotin (pictured above, right). The new procedure involved the core sitting between two beryllium half spheres. A screwdriver was jammed in between the two half spheres, creating a gap through which neutrons could escape. The screwdriver was used to manipulate the half spheres, raising or lowering them to increase or decrease the size of the gap, thus increasing or decreasing the reactivity of the core. If the two half spheres completely enclosed the core, it would go supercritical. 

If this sounds completely bonkers, you probably have more common sense than the brilliant physicists who conducted these experiments. In fact the experiment was named “Tickling the Dragon’s Tail”, based on a remark by physicist Richard Feynman who compared the experiment to “tickling a sleeping dragon”. Slotin was certainly aware of the dangerous nature of the experiment, he had been at Daghlian’s bedside when he had died. The famed physicist Enrico Fermi had warned Slotin that if he continued these criticality experiments, he would be dead within a year.

On May 26th, 1946 Slotin was conducting a criticality experiment with the demon core when he lost control of his screwdriver, causing the beryllium sphere to close. The incident is almost perfectly re-enacted in the 1989 film “Fat Man and Little Boy”,

Louis Slotin died of acute radiation poisoning nine days later. Of the other seven people in the room, two would die of cancer years later, although it is unknown whether the accident contributed to their deaths. 

After these two criticality accidents new experiments were designed which used remote controlled machines and cameras. The Demon Core was melted down and recycled into other cores.

You know when a black hole just goes yeet

Exaltation of the Holy Cross (c.1680)