# Physics of Rock Climbing: Part II

Welcome back to our Physics of Climbing series! Last time we talked about classical mechanics, which we can use to describe nearly anything we experience while climbing. Today, we get to talk about climbing in the quantum realm.

Quantum mechanics has been developed over decades by numerous scientists, and we don’t usually associate it with a specific scientist in particular, but today we’ll call our hypothetical climber Erwin. Perhaps you have heard of his cat…

Erwin is on his 5.8 warm-up, Probability Wave Zero, at his favorite crag. Let’s see how far we can zoom in.

Where is Erwin? Well, he’s between second and third clip.

Where is Erwin’s hand? It’s on a pinch right below third draw.

Where is Erwin’s thumb? Clearly his pinch is bomber; he definitely caught the thumb catch.

Where exactly in the thumb catch is his thumb? Hmm…the ruler says about 2 millimeters from a chalk mark. With a microscope, we can see where the first skin cell is. With more high-end equipment, we see the first molecule on the skin cell, then the first atom in the molecule, then…well, it’s tricky.

There are different schools of thought in this realm. First, we really need to figure out what we mean by “where?”. What Erwin feels as grippy sandstone is electromagnetic forces from the rock opposing the charged particles (i.e. electrons and protons) in the atoms in his hand. So, some people would argue that you don’t get to ask, “where?”. It doesn’t make sense or hold meaning in this realm. Still, maybe you are determined to find Erwin’s first electron in the thumbcatch. Then, some people might turn the question around and ask you what you mean by electron. This is where our intuition starts to break down; the best we can do is say that it’s a negative charge in a very small region of space. Some would advise that you toss away the notion of a little negative ball and consider it just a bundle of waves, each describing some property. Some might point out that since you can’t resolve past particles, maybe our reality isn’t actually continuous, but rather tiny discrete pieces that look continuous from far away.

There is a lot to consider here, and I could go on forever, but the message from quantum mechanics is essentially this: “Listen, there’s a limit to how precise we can be. There will always be an error tolerance when we measure something. At best, we can give you some probabilities of where Erwin could be, but you cannot escape uncertainty.”

Zooming back out, we can look at Erwin himself as a big bundle of waves. We can see Erwin’s probability of being in a particular location, and because Erwin is made up of so many particles, we feel pretty certain about where he is on the rock. Perhaps Erwin doesn’t actually exist in an exact location until we measure it. Perhaps Erwin has climbed Probability Wave Zero in every possible way in different universes inside the multiverse. Perhaps Erwin does actually have an exact position on the wall, and if we knew everything about each of his constituent particles since the beginning of time, we could determine with absolute certainty how he would climb this route. Perhaps Erwin is just a holographic projection of information on the surface of a black hole and his send indicates more than Erwin’s grip strength.

I have my favorite interpretations of quantum mechanics, but I would argue (right on the border between philosophy and physics) that we’ll probably never really know for sure which interpretations are correct, or if there even is a correct interpretation. I hope you have enjoyed our journey into the quantum realm with Erwin. I am happy to answer any quantum questions you may have…be sure to share your favorite interpretations if you’d like as well!

## 10 Replies to “Physics of Rock Climbing: Part II”

1. Exactly! Now I ask…did Erwin already have a location for me to change before observing him, or did I just force him to have a location?

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1. I suppose in this context “…collapsing the wave function…” means that Erwin’s belay failed? Thus making him a particle at the base of the climb? Or did Erwin just take his cat and go home?

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1. An interpretation is that the observation collapses Erwin’s probability waves, forcing him to “choose” a location instead of being everywhere with some probability 😎

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