The Four Scientific Meanings Of 'Nothing'

When we look around at our world and Universe today, we talk and think about all the things that are in it. These range from particles, atoms, and human beings to planets, stars, galaxies, and the largest structures of all. Depending on what we're interested in, we might discuss gas, dust, radiation, black holes, or even dark matter. But all the things we see, observe, or infer the existence of today might not have been there forever. Some of these arose from some pre-existing matter that was around previously, but others seemingly came from nothing. Unsurprisingly, not everyone agrees about what we mean, scientifically, when we talk about what "nothing" actually is. Depending on who you ask (or when you ask them), you might get one of four separate meanings. Here's why they're all relevant.