Airplane contrails are real, but we know what they are: water vapor  and small amounts of other combustion products created by jet engines.   The other pollutants may be somewhat harmful, but they are basically the  same thing as produced by any other form of combustion.  So what are  chemtrails?  Wikipedia

High in the trees on the Fiji islands, ants in the species Philidris  nagasau are doing something extraordinary. They've brought in seeds from  several species of a large, lumpy fruit from a plant known as  Squamellaria and carefully planted them in the nooks and crannies of the  tree

Suppose there is an incline such as that shown below. When a ball rolls from A to B, which curve yields the shortest duration? Let’s assume that we have three hypotheses: a straight line, a quadratic, and a cycloid. The shortest path from A to B is the straight

In microgravity, flames given so little oxygen that on Earth they  would extinguish, do not go out but break up into tiny, two-dimensional  caps called flamelets. Much like smoldering coals in a banked hearth,  these flamelets can persist for long periods under near-limit conditions  and, if oxygen is reintroduced, ignite

Nocera’s artificial leaf, developed while he was at MIT, made a splash five years ago because the wafer of silicon and other elements can be dropped in water, exposed to sunlight, and it will continuously split the water into hydrogen and oxygen. Hydrogen, a clean burning fuel, is typically

Most of the caffeine you ingest is metabolized by a CYP450 liver enzyme called “CYP1A2.” This means that the body uses CYP1A2 to “demethylate” caffeine molecules, transforming them into other substances, chiefly paraxanthine, which are ultimately excreted in the urine.  CYP1A2 is one of the most abundant CYP liver enzymes

In the south-east of Romania, in Constanța county close to the Black Sea and the Bulgarian border, there lies a barren featureless plain. The desolate field is completely unremarkable, except for one thing. Below it lies a cave that has remained isolated for 5.5 million years. While our ape-like

The Wendelstein 7-X fusion device at Max Planck Institute for Plasma Physics (IPP) in Greifswald produced its first hydrogen plasma on 3 February 2016. This marks the start of scientific operation. Wendelstein 7-X, the world’s largest fusion device of the stellarator type, is to investigate this configuration’s suitability

Not quite, said Kenneth G. Libbrecht, a physicist at the California Institute of Technology, who found a way to create what he calls “identical twin” snowflakes in his lab. Since each snowflake faces a different turbulent path through the atmosphere, each twist, turn and fall grants it a unique symmetry.

In August, we posted a photograph of some odd, rare clouds known as Morning Glory clouds without providing an explanation for how they form. In response to reader interest, we followed up with meteorologist Roger Smith of the University of Munich, who has studied their formation. “Over the years we’

Why don’t your Christmas lights work? Sadly, in the event of a string of lights going out on your tree, replacing the strand is usually the best option. It’s pretty difficult to find that one bulb that’s causing the problem. However, this is a great time to

Picture when smoking was still allowed in the stadiums (taken with a Hasselblad): Recent picture, with clean air: https://petapixel.com/2015/10/15/why-old-sports-photos-often-have-a-blue-haze/ HN discussion https://news.ycombinator.com/item?id=10683217 Tyndall effect (similar to Rayleigh scattering) The Tyndall effect, also known as Tyndall scattering, is light

Do you buy orange juice at the store? If you do, I’m sure you’re careful to buy the kind that’s 100% juice and not made from concentrate. After all, that’s the healthier kind, right? The more natural kind? The kind without any additives? The kind that’

Nuclear scientists at the Pierrelatte uranium enrichment plant in south-east France noticed a strange deficit in the amount of uranium-235 they were processing in June 1972. That’s a serious problem in a uranium enrichment plant where every gram of fissionable material has to be carefully accounted for. (...) Physicists soon

Grab a cup of coffee, put on your thinking cap, and start working through this newly-released video from Minute Physics, which explains why guitars, violins and other instruments can be tuned  to a tee. But when it comes to pianos, it's an entirely differently  story, a mathematical impossibility.

Unlike any other life on Earth, these extraordinary bacteria use energy in its purest form – they eat and breathe electrons – and they are everywhere. https://www.newscientist.com/article/dn25894-meet-the-electric-life-forms-that-live-on-pure-energy/

Ever fancied having a superpower? Something you can call upon when  you need it, to hand you extra information about the world? OK, it’s not  X-ray vision, but your eyes do have abilities that you might not be  aware of. We are all familiar with color and brightness, but