The grand spiral galaxy Messier 51, also known as the Whirlpool galaxy, has sweeping, extended spiral arms, most probably owing to its gravitational interactions with the nearby neighboring galaxy shown tugging on it. Although it’s now common knowledge that these cosmic spirals are galaxies all unto themselves, the evidence necessary to draw such a conclusion didn’t arrive until 1923: a full 100 years ago. (Credits: X-ray: NASA/CXC/SAO/R. DiStefano, et al.; Optical: NASA/ESA/STScI/Grendler)

The key lesson to learn from science’s greatest debate

In 1920, astronomers debated the nature of the Universe. The results were meaningless until years later, when the key evidence arrived.

So, you’ve arrived at a crossroads: you think the world works in a certain way, and someone else disagrees with you and thinks the world works in a different way. You’ve both got your reasons as to why you’re convinced that your way is right and the other person is wrong, but for some reason, you cannot come to an agreement with one another. Despite agreeing on the facts and the evidence, you don’t agree on how to interpret them, and you’re both unable to convince the other of their folly.

In most arenas of life, you’d rightfully chalk this up to a difference of opinion. But in science, opinions don’t really matter: the world and Universe really do behave in a particular fashion. Either your conception of how the world works agrees with reality, in which case it’s valid, or it doesn’t, in which case it isn’t. Yet scientific arguments and debates happen all the time, even though they never settle anything. The only solution that’s scientifically valid is to obtain the critical evidence: a lesson we all need to be reminded of.