Physics of Rock Climbing: Part V

This is our fifth and final installation of Physics of Rock Climbing (for now). Of course, I saved the most exciting stuff for last: BLACK HOLES! Feel free to skim over my general relativity (GR) piece from last time for some extra review of gravity.

We won’t be discussing Kerr black holes specifically, but nevertheless our hypothetical climber’s name today is Roy. Roy is a bit of an adrenaline junkie, and so he’s climbing right next to a black hole on a route called Robert’s Walk. The route extends away from the black hole in a straight line such that the start is nearest the black hole and the finish is farthest from the black hole. Our previous facts from GR still hold, of course. Roy experiences what Karl did, except much more noticeably since the black hole is magnitudes heavier and more dense than the earth. If you remember, we compared the earth to a bowling ball on a trampoline. A black hole on that trampoline would be something like the mass of a skyscraper in the volume of a grain of rice. You can imagine the difference our marble would feel on the trampoline if it had a bowling ball versus the really heavy grain of rice in the middle. If the trampoline were super tall. And super stretchy.

One interpretation is that space and time somehow switch meanings. In other words, Roy could experience space as we experience time (a flow where we can never see forward) and experience time as we experience space (we can’t really imagine what this would be like). Another possibility is that Roy emerges from the other end of the hole at a white hole. This white hole could be on the other side of spacetime (he would have traveled through a wormhole!). One thing we do know is that if Roy actually tried to do this, he would be dead long before he reaches the Schwarzschild radius. The force at his feet would be much greater than the force at his head, and he would snap/get squished. It would be like hanging a couple tons on Roy’s feet while he is hanging from a pull-up bar. Yikes.

The moral of the story is do not try this at home or at your nearest black hole.

Thank you for exploring the interface of physics and rock climbing with me! It has been an absolute pleasure, and if there’s anything else I can expand on, please let us know!

5 Replies to “Physics of Rock Climbing: Part V”

1. I loved this! My dad was a mathematician/physicist and two of his favorite ways to entertain the little girl who was bugging him were 1) having her divide 22/7 and 2) imagining time as an attribute of space or vice-versa. As far as I could get was it takes time to travel through space, but it doesn’t require space to travel through time. It kept me quiet. 😉

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1. The time/space thing was fun. The thing we humans are trapped in is duration and sometimes that seemed eternal while I puzzled this stuff out… His other thing was having me work on the volume of a torus. I succeeded there, but it took a year…

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2. But think of the possibilities! If Roy could arrange to use their hangboard with their feet pointing toward a black hole, they’d be totally ripped, with 12-pack abs, bulging muscles, and capable of redpointing any 5.15 on this planet! Assuming, of course, they could come up with a work-around for the snapped / squished part. 😉

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