Our brains are pretty good at physics. For example, you can see someone kick a soccer ball in front of you, and you can run to the point where you and that soccer ball will cross paths, considering the speed of you and the ball, how clever! Not only that, we can look at one object balanced on another and tell how sturdy it is without even touching it.
But sometimes our brains make uneducated mathematical guesses, and one of them is Kummakivi, the balanced rock in Ruokolahti, Finland. If it were up to your brain, Kummakivi, which means “strange rock” in Finnish, wouldn’t exist. It’s a rock resting on a chunk of rock in a position that, to our engineering monkey brains, seems impossible, or at least risky. Extremely improvised and temporary work, in the best of cases. And yet Kummakivi sits quietly in the Scandinavian forest of him, accumulating centuries. Millennials, even.
Kummakivi is huge, about 7 meters (23 feet) long. it’s rest in the tiny, steep footprint of a smaller rock mound that rises from the forest floor. The rocking rock looks like it’s about to slide off its perch, but it can’t move, at least not with human muscles. The reason for this isn’t as mysterious as it might seem: Kummakivi is big, but big things aren’t necessarily more affected by gravity than small things. Kummakivi is very rough, which helps it stay in place, and it doesn’t have the same density everywhere. The center of gravity looks the other way when you inspect the rocking rock with your eyes, but it’s actually doing exactly what physics wants it to do.
But the real question is How do I get there?
People have probably always wondered that, but we’ll never know because it’s been there about 12,000 years — long before we started recording anything. However, Finnish folklore says that giants or trolls carried the rock into the forest and balanced it on its pedestal. These days, geologists say it was deposited by a retreating glacier at the end of the last ice age, and as we know, a glacier is basically the only thing as strong as a giant or a troll.