Hacker News Reader

Comment by mquander | Hacker News Reader

I remember clearly in elementary school when I suddenly understood that gravity is just a constant acceleration; if I were in a box in space accelerating at 9.8 m/s^2, it would feel exactly the same. For some reason, I found that absolutely mindblowing at the time. I spent all day trying to explain it to everyone else, and I don't think I've ever been so excited about knowing something again.

View on HN

Do you also find it weird to think about how without gravity we couldn't walk? That one gets me especially hard because it's a such a tangible example of how we've evolved to take advantage of laws of the laws of physics, and how if these laws were even slightly different then we wouldn't be here, or at least not the same as we're here now.

The first day of a robotics class, my teacher explained that we don't really walk. Each step is graceful falling. Place one foot forward, tilt and fall till the foot hits and repeat.

I hate to be the one to break to this to you, but your robotics teacher was off his or her rocker or was trying to make a much larger point with a bad example.

If walking was simply graceful falling, it would imply that once we begin the process of "falling" onto the next foot, we couldn't significantly affect the outcome. However, because I can start walking and then stop with a single leg half way between it's highest point and the ground, this explanation of walking as falling becomes very problematic.

Reply on news.ycombinator.com