AMOC And The Planet-Wide Impact Of Ocean Currents

May 27, 2026 by Maya Posch 14 Comments

Although it can be hard to tell from looking at the often placid waters of the Earth’s oceans, their currents carry immense amounts of water around the globe on a daily basis, underlying a dynamic system that – much like the Earth’s atmosphere – plays a major role in everything from weather systems to local climates and ecosystems.

Of all these ocean currents the Atlantic meridional overturning circulation (AMOC) is perhaps the most famous, as it is basically the sole reason why Europe has the mild climate that it does today, courtesy of it carrying thermal energy from the equator all the way to the coast off Scandinavia.

Although collapsing an ocean current seems as improbable as stopping the jet streams in the upper atmosphere, it’s actually significantly easier due to how much ocean currents rely on factors that we can fairly easily influence. Over the past decades we have seen worrying signs that the AMOC is indeed weakening, with the million-dollar question being what scenario we’ll be looking at.

While collapsing the AMOC within a decade may be theoretically possible, current models seem to point towards a weakening by about half by the end of this century, with a recent research article by Valentin Portmann et al. in Science Advances going over the various statistical models to come to this conclusion.

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Hunting Submarines Via Gravity Is A Tough Errand

May 27, 2026 by Zoe Skyforest 51 Comments

Among so many other technological advances, the Cold War saw the advent of the ballistic missile submarine. The concept was simple—pack enough nuclear warheads to destroy a small civilization into a compact metal tube, and then hide it underwater. The oceans would act as a cloak for your fleet of world-enders, and keep your enemies forever on their toes. A terrifying machine that could both start and end a war with the push of a button.

Most nation states are populated by humans with the will to live. Thus, there has been a great incentive to find ways to keep tabs on these sunken doombringers. Great efforts have gone into improving sonar and magnetic detection methods over the decades, which are the bread and butter of sub hunting to this day. However, military researchers have also explored the prospect of whether submarines could be detected via their effect on the gravitational field alone.

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Figuring Out What James Webb’s Mysterious Little Red Dots Are

May 26, 2026 by Maya Posch 16 Comments

After the James Webb Space Telescope (JWST) began operations in 2022, it soon made a tantalizing discovery in the form of mysterious red dots: small, red-tinted astronomical objects of unknown origin and composition. So far well over 300 of such little red dots (LRDs) have been identified, with many theories on what they are. Fortunately the Chandra X-ray Observatory recently added some more clues as detailed in an accompanying paper.

Current theories include them being a form of primordial galaxy, or a supermassive black holes embedded in a dense gas cloud. The LRD discussed in the paper with the designation 3DHST-AEGIS-12014 was found to emit X-rays unlike other LRDs. By comparing the data between JWST and Chandra for this LRD it lends credence to the theory that these LRDs are a transitional phase as a supermassive black hole ingests the material of said gas cloud.

X-rays produced during this can sometimes make it out of the gas cloud, after which we can observe it. If that’s the case, these LRDs should cease to exist the moment the black hole has consumed enough of the cloud, which is something that we may be able to find evidence for if we’re lucky.

This adds just another reason why keeping the Chandra X-ray Observatory mission funded, after it narrowly got saved in 2024.

Through-Glass Vias And The Long Road To Glass Substrates

May 25, 2026 by Maya Posch 16 Comments

Glass-based substrates are slowly beginning to push out organic substrates – as also commonly used in PCBs – due to often superior material properties for packaging. One area where glass substrates have however struggled is with through-hole vias and providing the conductive copper path through them. A 2024 article by [Keith Best] gives a good overview of the topic, with recent news showing how much companies like Intel are pushing for glass substrates, specifically for the packaging of dies.

One major advantage with vias in glass substrates is that they can be much smaller, enabling smaller than 0.1 mm diameter holes with far finer pitch. The challenge here is to make perfect holes with a laser that are defect-free, as well as have the intended diameter.

After that this through-glass via (TGV) has to be coated or filled with copper, much like their organic equivalent. Said TGV can be fully filled with copper, or use plating and add dielectric filler. Detecting flaws in such a finished TGV is important.

In a 2025 review article of glass substrate technologies by [Pratik Nimbalkar] et al. published in Chips the state of the art at the time was covered. The need for ever higher-density integration options with ASICs is highlight here, especially now that many chips today consist of multiple interconnected dies inside a single package.

The complications of creating TGVs with femtosecond laser pulses in Borofloat 33 glass are highlighted by [Daniel Franz] et al. in a 2025 research article, with microcracks and backside ablation observed without proper precautions, something which previously was often resolved by an etching step following said laser drilling. The main issue here is the post-drilling residual stress from the thermal shock, which the authors demonstrate can be largely prevented with careful tweaking of the laser drilling parameters.

As pointed out in a 2024 review article by [Chen Yu] et al. glass substrates are useful for far more than just high-density chip packaging. Glass substrates are also chemically resistant, have a higher heat resistance, are largely transparent to RF and can be hermetically sealed against outside influences. This makes them great for various advanced sensors and communication devices.

Meanwhile, if you wanted to do some metal-depositing on glass at home, we covered this recently.

A diagram of a neutron generator is shown in the top portion of the image, with the physical version below.

A Benchtop Neutron Generator For The Home Reactor

May 25, 2026 by Aaron Beckendorf 18 Comments

There are a surprising number of experiments an amateur nuclear physicist can perform, from making a Geiger counter to fusing hydrogen atoms in a fusor. One project which we haven’t seen before is a neutron generator, such as the benchtop neutron generator made by [Rapp Instruments] (translated).

This particular generator takes a feedstock of pure deuterium, which it ionizes and accelerates into a titanium target. The first deuterium nuclei to hit the target react with it to form titanium deuteride, immobilizing them until more ions strike them and they undergo nuclear fusion. The fusion reaction mostly forms helium-4, but sometimes forms helium-3 and a free neutron, which is radiated away. The radiated neutrons are slowed down by a block of high-density polyethylene, and a portion of them strike a silver or indium foil wrapped around a Geiger counter tube. The neutrons activate the silver or indium, and the Geiger counter detects the resultant increase in radioactivity.

The design is a linear particle accelerator built inside an evacuated glass tube. It uses two high-voltage power supplies: a 20 kV supply which ionizes the deuterium gas fed into the tube, and a 100 kV supply which accelerates ions emitted from the source into the target. The target itself is surrounded by a cup-shaped electrode to capture secondary electrons emitted during impact. To prevent arcing, the tube needs to be at a very low pressure, reached by extensive use of an oil diffusion pump.

Radioactivity measurements of the silver and indium foils showed that the generator did work; when irradiating the silver foil for five minutes, it generated 175 counts per second after the neutron source was turned off. Plotting the count rate versus time suggested that a mixture of two silver isotopes was being generated, Ag-110 and Ag-108, based on their half-lives. Irradiation of indium produced a similar exponential decay in radiation.

We recommend checking out the rest of the site; it’s a gold mine of projects, such as this mass spectrometer. For more background on neutron generators, we’ve covered their theory and some of the more common varieties.

Measure The Earth’s Rotation Victorian Style

May 13, 2026 by Al Williams 8 Comments

You’ve probably seen a Foucault pendulum in a museum. This Victorian-era science demonstration is named after physicist Léon Foucault and shows how the Earth rotates compared to a pendulum moving in a fixed plane. [RyanCreates] shows you how you can make your own, and it is surprisingly simple.

All you need is a heavy weight like a small mushroom anchor, fishing line, and a swivel — all things you can pick up at any sporting goods store. You’ll need a way to suspend it all, such as an eye hook in the ceiling.

In addition to the mechanical parts, the build calls for a camera to record the results and a lighter or other source of flame. The reason? To release the pendulum, you burn a thread that prevents it from swinging. This allows for a clean release with no sideways force.

The amount of your rotation depends on your latitude. At 33 degrees north, for example, you can expect 360*sin(33)/24 or 8.17 degrees per hour of rotation. [Ryan] measured a somewhat larger number, which was probably due to an error source, especially since he is measuring the angle using captured camera frames in Photoshop. That has to introduce some error, and small pendulums like this are incredibly sensitive to errors.

If you try it and find the source of the error, we’re sure [Ryan] would love to hear from you. Museum pieces are typically much larger, have ultra-low-friction pivots, and use electromagnets to keep the pendulum moving since, after all, even a Foucault pendulum can’t run forever.

The Walls Don’t Have Ears, But Fiber Optic Does

May 11, 2026 by Al Williams 12 Comments

You normally think of fiber optic as something used in network cables. However, scientists employ dedicated fibers to detect earthquakes. In simple terms, they fire a laser down the fiber and watch reflections caused by imperfections. When vibrations hit the cable, it changes the defects, which show up in the return pattern. However, with the right techniques, those vibrations could just as easily be from people speaking near the cable.

If you are alarmed, there’s good news and bad news. The good news is that the technique seems to be limited to coils of fiber that are not buried, and you have to be within about 5 meters of the fiber. The bad news is that there is plenty of dark cable all over the place. Besides, if researchers can do this successfully, you would imagine three-letter agencies around the world could do it even better.

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