hakonjdjohnsen

Agreed, that was a really good talk! It is kind of scary how simple some of these exploits that find their way into smartwatched for children are

This video by AlphaPhoenix is absolutely incredible! I do research in (nonimaging) optics and I am used to thinking about the propagation of light. Still, there is something amazing about seeing a real recording of the propagation of a real beam of light. I also love the fact that you see artefacts due to how long light from different parts of the scene takes to reach the camera

Thermophotovoltaics is really cool. It is an old idea but recently several groups (including the group behind fourth power) have shown much better experimental performance than before, towards the level where this is starting to look like a real solid-state heat engine.

The idea is to use a photovoltaic cell (“solar cell”) to convert thermal radiation to electricity. A regular solar cell has limited efficiency because the sun has a wide spectrum and a single material is not efficient across the whole spectrum. With thermophotovoltaics, the hot surface is so close to the cell that you just reflect the “bad” photons back to the hot surface to recycle them instead of losing their energy.

In theory, a more efficient alternative to a traditional solar cell is to use the sunlight to heat a surface to ultra-high temperatures and then run a thermophotovoltaic cell on that hot surface, but this is easier said than done.

As an outsider I do think it looks like the competitor Antora Energy has a simpler approach: instead of pumping the heat using high-temperature liquid (with lots of moving parts), they just use thermal radiation to transfer the heat inside their battery.

I think there is at least some plausible interpretation of this that points to more than marketing fluff.

You want to count particles per volume of air, so conventional sensors use a fan to have a constant volumetric flow and then count particles per second to infer particles per volume.

The way I interpret the above marketing language is that they use the optical sensor not only to count particles but also to measure the particle movement and infer airflow. So as long as there is some natural movement in the air, they can measure both particle count and volumetric flow, and thus infer particles per volume.

Yeah good point!

When I came across this amazing project and wanted to share it to HN, I was debating whether to post the youtube link or the project page. I decided to post the project page and mention the youtube link in the description for those who prefer video, but somehow that description got posted as a comment instead (not sure how that happened?). Anyway as you said the video is embedded in the project page so it wasn't really necessary