How Are These Physically Possible

The more I look at whipbacks, the more I am convinced that they are like the bumblebee flying - there is NO way they should be possible. When I first heard them described as a back handspring with no hands, I thought "Oh, so a flip." But they actually look like a gymnast is pushing off the air, which is not a possibility. How can they even be done? And I recall someone (Natasha Kelley?) even doing them looking like they are one armed, which is even more bizarre.

Also, the Arabian doubles that go around the side, like Ragan or what I read once with Jamie Dantzscher. How do they work? I've seen Ragan do it and she does look sideways, but again, I can't understand HOW that can happen.

Thanks in advance. And yes, I barely passed physics in school LOL

How Are These Physically Possible