Reminds me of this:
It's just that it's an entirely inappropriate metaphor. Exciting, but completely and utterly wrong and the absolute most backwards way of looking at it. The way evolution is usually talked about is along the lines of "they developed these adaptations, so they survived", but the correct way of viewing it is "the survivors all had these mutations, and that's how they adapted". This might sound really nitpicky, but the backward view really screws things up when you start talking about sexual reproduction and the adaptations that optimize fetal development in humans. They are written about as if there's an "arms race" (this exact term has been used over and over again) between male and female to maximize their own interests. This is not only not true, but it literally CANNOT BE TRUE unless we scrap everything we know about evolution and start from scratch with a completely different set of assumptions about what drives it. The "Arms race" perspective necessitates the assumption of intelligent design. The reality of fetal development is that the fetus which has the best checks and balances system is the one which is most likely to survive; it's not an arms race, but a finely-honed cooperative balance in which the system which produces a placenta that is maximized to absorb nutrients from the mother while restrained from taking too many nutrients is the system that will produce the most surviving offspring. Since "too much" varies from woman to woman, the optimal system is one in which the placenta grows as much as it can until the woman's body tells it to stop.
But that's not as exciting as depicting it as a DNA-level war of the sexes, and this is pervasive throughout the scientific literature.
No, we already had this conversation. The illustration of how gravity curves space-time, using the effect of gravity on a ball rolling into an invaginated plane, simply, will not do the trick. It's like a circular argument that presupposes it's conclusion. Teachers of physics, beware.