Today is Edwin Hubble’s birthday. You’ve probably heard of him, or at least the space telescope named after him. Astronomer? Yep but it goes way beyond that. Waaaaay beyond.
What Hubble did was take us from a universe that looked like this:
…and put us in one that looks more like this:
See, up until about 1920, the universe was assumed to be the size of the Milky Way galaxy. But Hubble was studying a type of star called a Cepheid variable and noticed that some of them were a lot farther away than the edge of the galaxy. So far, in fact, that the nebulae they were in could only be other galaxies. Not surprisingly, this idea was met with some resistance from other astronomers. And that’s as it should be. I mean, it was a pretty crazy idea at the time. But Hubble had tons of observations to back up his claim and convinced the astronomy community. Say it with me kids: “Extraordinary claims require extraordinary evidence.” And he definitely had the evidence.
So, great! Woo! Hubble demonstrated that the universe is a lot bigger than we ever imagined. Time to sit back and relax, right? Yeah, not so much.
For an encore, he observed that red shift (the shift in EM frequency by an object moving away from you) increases with distance. In short, not only is the universe really, really big but it’s also expanding.