A man is shown behind a table, on which a glass apparatus like a distillation apparatus is set, with outlets leading into a large container in the center of the table, and from there to a pump.

Pulling A High Vacuum With Boiling Mercury

October 3, 2025 by Aaron Beckendorf 20 Comments

If you need to create a high vacuum, there are basically two options: turbomolecular pumps and diffusion pumps. Turbomolecular pumps require rotors spinning at many thousands of rotations per minute and must be carefully balanced to avoid a violent self-disassembly, but diffusion pumps aren’t without danger either, particularly if, like [Advanced Tinkering], you use mercury as your working fluid. Between the high vacuum, boiling mercury, and the previous two being contained in fragile glassware, this is a project that takes steady nerves to attempt – and could considerably unsteady those nerves if something were to go wrong.

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The 19th Century Quantum Mechanics

September 26, 2025 by Al Williams 18 Comments

While William Rowan Hamilton isn’t a household name like, say, Einstein or Hawking, he might have been. It turns out the Irish mathematician almost stumbled on quantum theory in the or around 1827. [Robyn Arianrhod] has the story in a post on The Conversation.

Famously, Newton worked out the rules for the motion of ordinary objects back in 1687. People like Euler and Lagrange kept improving on the ideas of what we call Newtonian physics. Hamilton produced an especially useful improvement by treating light rays and moving particles the same.

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Set Phone To… Hyperspectral

September 26, 2025 by Al Williams 24 Comments

While our eyes are miraculous little devices, they aren’t very sensitive outside of the normal old red, green, and blue spectra. The camera in your phone is far more sensitive, and scientists want to use those sensors in place of expensive hyperspectral ones. Researchers at Purdue have a cunning plan: use a calibration card.

The idea is to take a snap of the special card and use it to understand the camera’s exact response to different colors in the current lighting conditions. Once calibrated to the card, they can detect differences as small as 1.6 nanometers in light wavelengths. That’s on par with commercial hyperspectral sensors, according to the post.

You may wonder why you would care. Sensors like this are useful for medical diagnostic equipment, analysis of artwork, monitoring air quality, and more. Apparently, high-end whisky has a distinctive color profile, so you can now use your phone to tell if you are getting the cheap stuff or not.

We also imagine you might find a use for this in phone-based spectrometers. There is plenty to see in the hyperspectral world.

Naturally Radioactive Food And Safe Food Radiation Levels

September 17, 2025 by Maya Posch 25 Comments

There was a recent recall of so-called ‘radioactive shrimp’ that were potentially contaminated with cesium-137 (Cs-137). But contamination isn’t an all-or-nothing affair, so you might wonder exactly how hot the shrimp were. As it turns out, the FDA’s report makes clear that the contamination was far below the legal threshold for Cs-137. In addition, not all of the recalled shrimp was definitely contaminated, as disappointing as all of this must be to those who had hoped to gain radioactive Super Shrimp powers.

After US customs detected elevated radiation levels in the shrimp that was imported from Indonesia, entry for it was denied, yet even for these known to be contaminated batches the measured level was below 68 Bq/kg. The FDA limit here is 1,200 Bq/kg, and the radiation level from the potassium-40 in bananas is around the same level as these ‘radioactive shrimp’, which explains why bananas can trigger radiation detectors when they pass through customs.

But this event raised many questions about how sensible these radiation checks are when even similar or higher levels of all-natural radioactive isotopes in foods pass without issues. Are we overreacting? How hot is too hot?

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Perovskite Solar Cell Crystals See The Invisible

September 16, 2025 by Heidi Ulrich 14 Comments

A new kind of ‘camera’ is poking at the invisible world of the human body – and it’s made from the same weird crystals that once shook up solar energy. Researchers at Northwestern University and Soochow University have built the first perovskite-based gamma-ray detector that actually works for nuclear medicine imaging, like SPECT scans. This hack is unusual because it takes a once-experimental lab material and shows it can replace multimillion-dollar detectors in real-world hospitals.

Current medical scanners rely on CZT or NaI detectors. CZT is pricey and cracks like ice on a frozen lake. NaI is cheaper, but fuzzy – like photographing a cat through steamed-up glass. Perovskites, however, are easier to grow, cheaper to process, and now proven to detect single photons with record-breaking precision. The team pixelated their crystal like a smartphone camera sensor and pulled crisp 3D images out of faint radiation traces. The payoff: sharper scans, lower radiation doses, and tech that could spread beyond rich clinics.

Perovskite was once typecast as a ‘solar cell wonder,’ but now it’s mutating into a disruptive medical eye. A hack in the truest sense: re-purposing physics for life-saving clarity.

Everything You Ever Wanted To Know About The Manhattan Project (But Were Afraid To Ask)

September 12, 2025 by Al Williams 34 Comments

There have been plenty of books and movies about how the Manhattan Project brought together scientists and engineers to create the nuclear bomb. Most of them don’t have a lot of technical substance, though. You know — military finds genius, genius recruits other geniuses, bomb! But if you want to hear the story of the engineering, [Brian Potter] tells it all. We mean, like, all of it.

If you’re looking for a quick three-minute read, you’ll want to give this a pass. Save it for a rainy afternoon when you can settle in. Even then, he skips past a lot of what is well known. Instead, he spends quite a bit of time discussing how the project addressed the technical challenges, like separating out U235.

Four methods were considered for that task. Creating sufficient amounts of plutonium was also a problem. Producing a pound of plutonium took 4,000 pounds of uranium. When you had enough material, there was the added problem of getting it together fast enough to explode instead of just having a radioactive fizzle.

There are some fascinating tidbits in the write-up. For example, building what would become the Oak Ridge facility required conductors for electromagnets. Copper, however, was in short supply. It was wartime, after all. So the program borrowed another good conductor, silver, from the Treasury Department. Presumably, they eventually returned it, but [Brian] doesn’t say.

There’s the old story that they weren’t entirely sure they wouldn’t ignite the entire atmosphere but, of course, they didn’t. Not that the nuclear program didn’t have its share of bad luck.

Ore Formation Processes, Part Two: Hydrothermal Boogaloo

September 8, 2025 by Tyler August 2 Comments

There’s a saying in mine country, the kind that sometimes shows up on bumper stickers: “If it can’t be grown, it has to be mined.” Before mining can ever start, though, there has to be ore in the ground. In the last edition of this series, we learned what counts as ore (anything that can be economically mined) and talked about the ways magma can form ore bodies. The so-called magmatic processes are responsible for only a minority of the mines working today. Much more important, from an economic point of view, are the so-called “hydrothermal” processes.

Come back in a few million years, and Yellowstone will be a great mining province.
Image: “Gyser Yellowstone” by amanderson2, CC BY 2.0

When you hear the word “hydrothermal” you probably think of hot water; in the context of geology, that might conjure images of Yellowstone and regions like it : Old Faithful geysers and steaming hot springs. Those hot springs might have a role to play in certain processes, but most of the time when a geologist talks about a “hydrothermal fluid” it’s a lot hotter than that.

Is there a point on the phase diagram that we stop calling it water? We’re edging into supercritical fluid territory, here. The fluids in question can be hundreds of degrees centigrade, and can carry things like silica (SiO2) and a metal more famous for not dissolving: gold. Perhaps that’s why we prefer to talk about a “fluid” instead of “water”. It certainly would not behave like water on surface; on the surface it would be superheated steam. Pressure is a wonderful thing.

Let’s return to where we left off last time, into a magma chamber deep underground. Magma isn’t just molten rock– it also contains small amounts of dissolved gasses, like CO2 and H2O. If magma cools quickly, the water gets trapped inside the matrix of the new rock, or even inside the crystal structure of certain minerals. If it cools slowly, however? You can get a hydrothermal fluid within the magma chamber.

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