We remember all sorts of things. We remember birthdays, anniversaries, and other celebratory dates (at least many of us do). We remember past events, sports triumphs and failures, life triumphs and failures. We remember kind words. We remember harsh treatment. We remember significant news stories, natural catastrophes, human-caused catastrophes. We remember times of peace. We…

According to the internet (which is never wrong, of course), the sharpest edges in the world are made from obsidian. Obsidian is not a type of metal. Rather, it is a substance formed from molten volcanic magma. Here is how it works: when molten magma cools very quickly, instead of crystallizing, it turns into obsidian.…