magnetism

According to UN Water, "Each of us needs to drink 2 to 4 litres of water every day. But it takes 2000 to 5000 litres of water to produce one person's daily food." If that seems like a lot, it is. But it's funny how much depends on your perspective. A graphic from the USGS shows what it would look like if all the water on Earth were gathered into one drop. On A Few Things Ill-Considered, Coby Beck discusses the even smaller drop that represents all fresh water. Coby writes, "A full 74.5% of that much smaller ball is locked away in ice caps and glaciers and 24.7% is groundwater (much of that…
Farmers and herders have known for centuries that herds of cattle have an uncanny ability to all point in the same direction. Last year, a group of German and Czech scientists discovered the reason behind this alignment - unbeknownst to humans for thousands of years of domestication, these animals have a magnetic sense. The team used Google Earth satellite images to rule out alternative explanations like the wind and the sun, and show that cow and deer herds tend to point towards magnetic north like a living, hoofed compass needle. Now, the same team have found that high-voltage power lines…