When you get a result you expect, you’re less likely to examine that result closely. This confirmation bias happens to the best of us, so how do we know that our scientific results are valid? How do we know we aren’t just fooling ourselves?
The Gripping Hand
The image above shows a pair of colliding spiral galaxies known as Arp 274. What’s interesting is not that they happen to be colliding, but that the two galaxies are spiraling in opposite directions. The one on the left spirals in a clockwise direction, while the one on the right spins in a counterclockwise direction. Sometimes we’ll refer to the left galaxy as left-handed, while the right one is right-handed. The reason is that if you hold hands up with your thumbs pointing at yourself, you’ll see the fingers on your left hand curve clockwise, and the fingers on your right hand curve counterclockwise.
A Biased View
The figure below shows the positions of more than a thousand galaxies in the universe. You might think that tells us things about the history and evolution of the universe, and you’d be right. But it also tells us something about how we observe the universe. Knowing the latter is important, because all measurements have biases. If you don’t account for observation biases, you might mis-interpret your data.