Centrifuges spin really fast, so you need to balance out the things they’re spinning, otherwise it can fall catastrophically.

Stick everything on one side and it will effectively explode.

Think of it like a tilt-a-whirl. When you don’t distribute the load as best as possible and it starts spinning at an angle, someone (a test tube) will puke.

That thing spins really really fast.

If you put too many of those things in it in a not balanced way (like all at one side), it’s dangerous.

The picture is balanced, but it doesn’t look like it is at first glance.