Mariaagnesi-fangirl-blog - The Farmer's Daughter

“People can’t anticipate how much they’ll miss the natural world until they are deprived of it. I have read about submarine crewmen who haunt the sonar room, listening to whale songs and colonies of snapping shrimp. Submarine captains dispense “periscope liberty” - a chance to gaze at clouds and birds and coastlines - and remind themselves that the natural world still exists. I once met a man who told me that after landing in Christchurch, New Zealand, after a winter at the South Pole research station, he and his companions spent a couple of days just wandering around staring in awe at flowers and trees. At one point, one of them spotted a woman pushing a stroller. “A baby!” he shouted, and they all rushed across the street to see. The woman turned the stroller and ran. Nothing tops space as a barren, unnatural environment. Astronauts who had no prior interest in gardening spend hours tending experimental greenhouses. “They are our love,” said cosmonaut Vladislav Volkov of the tiny flax plants - with which they shared the confines of Salyut 1, the first Soviet space station. At least in orbit, you can look out the window and see the natural world below. On a Mars mission, once astronauts lose sight of Earth, they’ll be nothing to see outside the window. “You’ll be bathed in permanent sunlight, so you won’t eve see any stars,” astronaut Andy Thomas explained to me. “All you’ll see is black.””

— Mary Roach. Packing for Mars: The Curious Science of Life in the Void.  (via hummeline)

NASA has released new images of Jupiter, taken by the Juno Spacecraft.

You know when a black hole just goes yeet

I thought this was really interesting.. the subtle shift weak gravitational lensing has on the path of light!

As Christians it is actually our duty to be joyful. We have been commanded unto joy. This is not an impossible ask, for no cross can crush the joy of Christ, not even depression, grief, or sorrow. The joy of the Lord flourishes mysteriously, simultaneously, in the midst of such joy-blackholes; for when our own joy has disippated, God's Joy finally has full room to settle. God does not command the impossible, and so it is only fair that we ask not for Joy like timid slaves, but command it as a right as sons, as daughters of God. Yes, in Christ we possess this right, but only by faith can we claim it, and by the cross can we live it. Let the world have its joy, and we will have ours. Maybe out of envy they will seek out this Christ, this Joy of ours.

womb and the cloud

Winter in den Bergen

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.

a pair of chapel ceilings - both in wroclaw, poland

1700's medical illustrators be like "hey boss can I put a rhinoceros behind this anotomically correct sketch of the human skeleton" and the boss be like "only for the books being published in these specific european countries" and then they high-five and go out for drinks

Differentiation and Development

In this class, we observed (in the microscope) the main stages of the chicken embryonic development: 24h, 33h, 56h, 72h and 96h respectively.