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- Thorium Breeding, AI Biosecurity, a Nighttime Engine, and the Fermi Paradox
Thorium Breeding, AI Biosecurity, a Nighttime Engine, and the Fermi Paradox
This week’s science bits from SWTG
Marcus Gee-Lim
November 26, 2025
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China Achieves World-First Thorium-to-Uranium Conversion in Molten Salt Reactor
Researchers take fuel samples from the molten salt reactor Oct. Credits: Xinhua/Zhang Jiansong
Researchers at the Shanghai Institute of Applied Physics announced on November 1st that their molten salt reactor is now successfully producing energy from thorium. The small experimental reactor is designed to produce 2 MW of power and is currently the world’s only operating reactor of its type. Thorium is much more abundant on earth than uranium, which is why it’s widely considered the nuclear fuel of the future. Alas, Thorium itself is not fissile. One first needs to convert thorium-232 to fissile uranium-233, which then provides the neutrons to breed more thorium. The Chinese team just demonstrated that – after an initial startup phase using low enriched uranium – the reactor is now producing energy from the thorium cycle, though for now most of the energy still comes from the original low-enriched uranium-235. Press release here.
This week’s episode of Science News is about the Fermi Paradox. Why haven’t we heard from aliens? That’s a question that sounds simple but turns into a mess the moment you try to answer it. Recently, a mathematician tried to simplify the equation by trying to calculate the odds that we’re the only intelligent life in the universe – according to his math, we shouldn’t be. Let’s take a look.
OpenAI Invests In AI Biosecurity Startup
The US-Based startup Red Queen Bio launched with $15 million seed funding from OpenAI. Their mission is to prepare for biorisks created by AI, with more AI. According to their website “Red Queen Bio works with frontier labs to map AI-enabled biothreats and pre-build medical countermeasures against them.” It is likely that any laboratory capable of countering biothreats is also able to create them in the first place. While some rumours on X-Twitter have said that the company would be creating viruses, the CEO has denied it.
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New Nighttime Engine Runs Without Fuel or Electricity
Illustration of the engine driven by radiative cooling. Credits: Deppe et al, Science Advances 11, 46 (2025).
Engineers at the University of California, Davis have built a little motor that runs on energy generated by passive cooling. During the day, the device stores heat in a plate in the ground, and emits it at night as infrared radiation. The energy comes basically from the temperature difference between the plate and the night sky. They have experimentally demonstrated that (in California) during most of the year the temperature difference is large enough to produce roughly 0.4 Watts per square meter at night. They say that further upgrades of the system could improve the efficiency to several Watts. The application they envision is for example air circulation by small ventilators. Paper here.
