Do We Need Quantum Mechanics?

Faith & Science Conversation
1

If spectroscopy can tell us which element is which in the periodic table at various temperatures why do we need Quantum Mechanics?

2

We need QM to describe and predict a huge range of physical phenomena.

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3

I take it you mean chemical bonds. Why QM is needed if chemical bonds are explained by chemistry?

4

Spectroscopy works because of quantum mechanics.

5

They aren’t explained by chemistry, just described.

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6

That’s like asking why we need nouns when we already have the English language. When chemistry explains (rather than simply describing) chemical bonds, it uses QM. It’s also used in great swathes of physics.

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7

Reminds me of the old saying:
Life is Biology.
Biology is chemistry.
Chemistry is physics.
Physics is math.
Therefore, life is math.

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8

I’m pretty sure some of my students are feeling that way right now.

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9

What do you think quantum mechanics is?

Vinnie

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10

I couldn’t agree more but that is probably deeper than the OP was looking for…

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11

Does QM “explain” Chemistry while Chemistry “describes” Chemistry?

12

Where does mechanics figure in the old saying?

13
  • Chemistry/QM maps behavior, it doesn’t bestow existence. You don’t point to the rules of chess to explain the existence of a chessboard.
  • The “Laws” of Chemistry/QM are descriptive, not prescriptive. It is logically backwards to imagine invisible forces making atoms do things. Instead we have human descriptions of the inherent nature of the atoms.
  • Chemistry/QM is blind to teleology and final causality. It certainly can’t solve the problem of induction or justify the regularity in nature it depends upon.
  • The map is not the territory. Models are mathematical abstractions, not ontological explanations of reality.

Chemistry and quantum mechanics are both wonderful methods of learning about our world. We just need to avoid the category error of expecting them to answer the metaphysical questions they weren’t designed for.

Vinnie

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14

I think it’s a description of substances at various temperatures.

15

I think you are a few hobbits short a Shire.

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16

There is no shortage of ChatGPT in the Shire as well. But what good is Quantum Mechanics when Chemistry already explained chemical bonds?

Especially when spectroscopy explains everything there is to know about the elements in the periodic table at various temperatures — is QM really warranted? Isn’t Chemistry and Spectroscopy enough?

Hobbits are dime a dozen. This is Gandalf the gray addressing you.

17

Pretty much, yes. Chemistry describes chemical interactions, but it takes QM to explain them.

18

Crap, my first two chem professors flat out said that it takes QM to explain chemical bonds – chemistry just describes the working, how the pieces go together, it doesn’t tell us why they work the way they do.

19

sp3 orbitals and all that …

20

Let’s take water for example. It’s a polar bond. This bond was invented and explained by Chemistry (Gilbert Lewis) long before QM was invented. How is QM adding value or utility to a polar bond that Chemistry hasn’t already?

PS: Protons, electrons, Coulomb’s law which chemistry uses — and spectroscopy pretty much explain and identify everything in the universe. This was pre QM science.