Ask HN: What scientific phenomenon do you wish someone would explain better?
1. Carbon dating. Sure, I get that carbon decays over time and this changes the proportion of isotopes. But why does this give you any information? That carbon didn’t come into existence just to be in that bone, it was made in the sun billions of years before that, so why does the age of the carbon tell us anything about organic matter? The key fact, which I think is not emphasized enough, is that the ratio of isotopes in atmospheric carbon is kept at a constant equilibrium by cosmic rays. So you can use carbon dating to tell roughly when the carbon was pulled out of the atmosphere. Without this additional fact, the concept of carbon dating makes absolutely no sense.<p>2. The tides. The explanation I was given is roughly something like “the tides happen because the moon’s gravity pulls the water toward it, so you have high tide facing the moon. There’s also a high tide on the opposite side of the earth, for subtle reasons that are too complicated for you to understand right now and I don’t have time to get into that.”<p>The first problem with this explanation is this: gravitational acceleration affects everything equally right? So it’s not just pulling on the water, it’s also pulling on the earth. So why does the water pull away from the earth? Shouldn’t everything be accelerating at the same rate and staying in the same relative positions?<p>The second problem is that, when viewed correctly, the explanation for why there is a high tide on the opposite side of the earth as the moon is equally simple to why there is a high tide on the same side as the moon.<p>The resolution to both these problem is this: tides aren’t actually caused by the pull of the moon’s gravity per se, but are actually caused by the difference in the strength of the pull of the moon’s gravity between near and far sides of the earth, since the strength of the moon’s gravitational pull decreases with distance from the moon. The pull on the near water is stronger than the average pull on the earth, which again is stronger than the pull on the far water. So everything becomes stretched out along the earth-moon axis.<p>3. This one isn’t so much a problem with the explanation itself, more about how it’s framed. I remember hearing about why the sky is blue, and wondering, “ok, more blue light bounces off it than other colours. But isn’t that essentially the same reason why any other blue thing is blue? Why are we making such a big fuss about the sky in particular? ” A much superior motivating question is “why is the sky blue during midday, but red at sunrise &#x2F; sunset”? I was relieved when I saw this XKCD that I’m not the only one who felt this way:<p><a href="https:&#x2F;&#x2F;xkcd.com&#x2F;1818&#x2F;" rel="nofollow">https:&#x2F;&#x2F;xkcd.com&#x2F;1818&#x2F;</a>