The Physics Of Keeping Thermal Power Stations Cool

August 10, 2026 by Maya Posch 14 Comments

Recently thermal power stations have been in the news quite a bit, mostly in the context of them being throttled back or shut down due to the river water used to cool them either getting too warm or said river having dropped to a level where it can no longer provide cooling water. Obviously this is a problem, but it helps to understand how we got to this point and what can be done to fix it.

Thermal power stations – also called power plants – come in a wide variety of shapes and sizes, ranging from old-school coal- and gas-fueled power stations to modern nuclear power plants. Something like a concentrated solar power (CSP) station is also a thermal power station, as all of them have a heat source that’s used to generate electricity from, whether that’s a boiler, nuclear reactor core or a big vat of sodium heated up by the Sun via massive mirrors or oil-filled tubes in parabolic throughs.

Except for open-cycle gas turbines (OCGTs) – which are basically jet engines connected to a generator – this thermal energy is then used to generate steam that drives a steam turbine. Once most energy in the steam has been depleted, it has to be condensed back into e.g. water, so that it can be led back to the steam generator. How this condensing step is performed is the question here, with a number of methods available.

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A lightning strike is shown striking the ground at close range (fewer than thirty feet away).

Triggering Lightning With A Rocket

August 10, 2026 by Aaron Beckendorf 25 Comments

Lightning, despite being a common and readily-detected phenomenon, is nevertheless difficult to study. One reason is the difficulty of predicting when and where lightning will strike; tall structures do attract more lightning strikes, but it’s hard to move them into a storm’s path. Instead, researchers often use small rockets carrying a fine wire to trigger strikes, an approach [Electron Impressions] recently replicated (more details).

The science of this is less than straightforward: even in calm weather, there’s a surprisingly strong atmospheric electric field, about 100 volts per meter off the ground. During a thunderstorm, though, this can build up to kilovolts per meter, and may reverse polarity. When an updraft carries supercooled water, ice crystals, and graupel (ice particles formed by supercooled water freezing on a snowflake) upwards, the heavier graupel falls relative to the other components. As it collides with ice crystals, it builds up a negative charge and the crystals accumulate a positive charge; across a storm, this leads to positive charge building up near the top of clouds and negative charge near the bottom. Lightning equalizes this imbalance. In the relatively few cloud-to-ground strikes, a dielectric breakdown begins from both sides of the stroke, with leaders rising from the ground and descending from the cloud. The wire trailed by a rocket creates an artificial leader, ideally triggering a controlled strike.

To consistently get a strike, the rocket needs to be launched under a strongly-negatively-charged region of the cloud. An electric field mill measures the local field strength; these are usually quite expensive, but [Electron Impressions] managed to build his own. The rocket itself was 3D printed and designed to fly well under stormy conditions. It carried a strand of thin copper wire wound onto a plastic spool meant to minimize friction and prevent broken wires. The rocket’s igniter was waterproofed for storm conditions and remotely triggered using a walkie-talkie for safety.

After many attempts, [Electron Impressions] finally managed to trigger a strike and video the results. The first stroke created a plasma channel, along which several more strokes followed. This indicated that the cloud had probably been negatively charged, which was in agreement with the field mill’s measurements. The wind blew the plasma channel slightly to the side, where it caused a second rocket to explode on the ground. Both ignition systems were destroyed, and the remains of the rocket were never found. Sadly, the strike doesn’t seem to have formed a fulgurite, but it did fracture the ground as water flash-boiled.

For a more reusable solution, some researchers have also experimented with using drones to trigger lightning. There’s good reason for more study; the theory of lightning formation still has some major open questions.

Even On The Red Planet, Hexagons Are The Bestagons

August 10, 2026 by Tyler August 19 Comments

Though their pure Platonic Forms may only exist in the world of ideas, certain regular shapes can’t help but keep falling out of natural processes– case in point, the six-sided solid we call a hexagon, which is indisputably the bestagon. Don’t take it up with us– start an argument with the God of War, because its his planet that’s showing off six sided features, dubbed “polygonal fractures” which NASA’s Curiosity rover is currently crushing under tread in Valle Grande. Now, you might look at the photos and say– well, that’s clearly a dried mudflat. Evidence of water! No brainier, let’s all get Nobel Prizes. Not so fast.

Nothing in nature is ever single-sourced or that simple; if you live somewhere you get dried mud, you may have seen such hexagonal features, but ask anyone from the land of the ice and snow and they’ll tell you that freeze-thaw or frost heave can bring a field of rigolith’s inner Catan board out as well. Sure, we usually call it “dirt” here on Earth, but it’s rigolith by any other name. So NASA isn’t jumping the gun, and their announcement conservatively says that they aren’t sure how the polygonal features formed. Which is both fair enough and very interesting, as figuring it out is going to give some clues into what was going on in this part of Mars in the geologically recent past, especially since this vast field of grid tiles stretches as far as the camera can see. The consensus is that Mars was once “warm and wet” but that’s a relative term– how warm, and how wet, are very much up for debate.

Speaking of crushing hexagons under Curiosity’s wheels– did anyone think said wheels would last this long? They were already tweaking the traction control to extend their life nine years ago. Between it’s plutonium power and ongoing software updates, its a fair bet that Curiosity will outlast the late, lamented Opportunity who currently holds the endurance record at 15 Earth-years.

High-Density Parchment Paper Papertronics With Laser-Carved Hydrophilic Channels

August 8, 2026 by Maya Posch 6 Comments

Paper as a substrate for electronic circuits is not very common, but promising for flexible circuits with low cost and easy recyclability. That said, paper is not an easy material to work with when printing traces, as the cellulose material is both absorbent and irregular, limiting the resolution and accuracy of so-called papertronics. Even when using higher-quality paper with wax-based masks this resulted in poor resolution issues, so [Zahra Rafiee] et al. opted to approach the problem from the other direction, by using hydrophobic parchment paper as the base combined with a laser.

The nice thing about the inks used with papertronics that they aren’t just traces, but can also be functional elements like resistors, which is also demonstrated in the paper. The channels for the inks are created using a 50 Watt CO₂ laser, which etches away the silicone coating on the parchment paper. The achieved resolution in the article is around 250 µm for line widths and 300 µm line spacing, which is much better than that for wax-based alternatives.

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Rubidium Frequency Standard Explained

August 6, 2026 by Al Williams No comments

You’ve probably heard of rubidium frequency standards, which are used where you need an extremely accurate time or frequency reference. [IMSAI] guy has a good explainer video about what’s actually going on inside one of these standards. Much of the basic idea also applies to cesium standards.

The explainer starts with the periodic table. Rubidium and cesium are both alkali metals, with a single electron in their outermost electron shell. Rubidium has 37 electrons, with the outermost one relatively loosely bound. Naturally occurring rubidium consists mainly of two isotopes, rubidium-85 and rubidium-87, which have the same number of protons and electrons but different numbers of neutrons.

A rubidium standard typically has three gas cells that have a bit of rubidium in them. An RF-excited rubidium-87 discharge lamp produces light at very specific wavelengths. The RF energy excites rubidium atoms into higher electronic states, and when their electrons fall back to lower-energy states, the atoms emit photons.

That light passes through a filter cell containing rubidium-85. The filter preferentially absorbs part of the lamp’s spectrum, leaving light that optically pumps the rubidium-87 atoms in the second resonance cell into one of two closely spaced hyperfine states of the atom’s ground state.

Those two states differ because of the interaction between the magnetic moment of the outer electron and that of the rubidium-87 nucleus. Their energy separation corresponds to a microwave frequency of about 6.835 GHz.

The resonance cell is illuminated by the filtered light while also being exposed to microwave energy from a local oscillator. When the microwave frequency is exactly equal to the rubidium-87 hyperfine transition frequency, it transfers atoms between the two ground-state hyperfine levels. That changes how strongly the cell absorbs the optical pumping light, producing a detectable dip in the light reaching a photodetector.

Electronics then servo the microwave oscillator onto the center of that absorption dip, using a feedback technique somewhat analogous to a phase-locked loop. Once locked, the oscillator is effectively referenced to an atomic transition rather than to the dimensions or mechanical properties of a crystal, giving you an extremely stable frequency standard.

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Sketching Temporary Circuits With A Light-Triggered Floquet Topological Insulator

August 3, 2026 by Maya Posch 7 Comments

In semiconductor technology, a base material like silicon is permanently modified to induce certain electrical behavior. In comparison a topological insulator material could be used to create temporary circuits using something like light exposure. An example of this is the Floquet topological state, which has long been theorized, but is now claimed to have been demonstrated in SnTe semiconductor material, per a paper by [F. Chassot] et al. in Nature Physics.

The concept of topological insulators was first proposed in 1985, but proving their existence was hard. Recently photonic Floquet topological insulators (PFTIs) have gained interest, with experiments by [Qian Ma] et al. in 2025 as well as other teams confirming aspects of the theory.

This recent publication by [Chassot] et al. would thus confirm that optical control of topological insulators is thus possible. At the core of this effect is the band inversion that results from the light pulses, with the change in conduction being very brief, essentially for as long as the femtosecond pulses were maintained.

Although still very much in the fundamental research phase, the research on these electronic topological insulators offers an interesting look at potential new technologies, much like the field of photonic topological insulators does for photonics.

How The Vagus Nerve Promotes Healthy Cognition Via Acetylcholine Signaling

July 28, 2026 by Maya Posch 11 Comments

It’s been said for centuries that you cannot think on an empty stomach, and that love goes through the stomach. Although these may seem like merely cute jabs at the simplicity of human nature, recent research in rat models by [Logan Tierno Lauer] et al. indicates that the gut may be more influential in something as fundamental as memory formation and cognitive function than previously assumed.

Key to the gut-brain connection is the vagus nerve, an essential part of the autonomic nervous system that wires the brain into the body’s organs, including the gastrointestinal (GI) tract. It provides both sensory and motor fibers, so that the brain can literally sense the state of said GI tract, with various triggers as result. One of these is – as demonstrated in the paper – the release of acetylcholine (aCh) an important neurotransmitters in the CNS for cognitive functions including attention, memory and motivation.

Using in vivo fiber photometry it was found that during eating medial septum neurons released aCh, with various ways to impair this mechanism along the vagus nerve leading to this response disappearing. This also confirms earlier research that points the finger at a so-called early life Western Diet (WD) causing impaired memory and overall cognitive function, likely due this high fat and high sugar diet causing dysfunction in this aCh regulation mechanism.

Beyond once again reinforcing the need to eat healthily, this research also provides further insights in condition with declining cognitive function, such as Alzheimer’s and dementia.