*This is about Planck's Constant, which is the constant in the Uncertainty Principle. I've edited it down to the relevant bits, so that it makes more sense for other students. Jason*

I want to ask about why would such limitation in observation has that particular scale, and would it be related to the behaviour of nature or would it be more like a limitation arise in theory of quantum mechanics.

Chul

Is this a question about whether Planck's Constant is something limited to quantum mechanics, or whether it will be important in whatever theories we come up with next? That's a good question. I wish I knew the answer. I suspect that the answer is yes: Planck's Constant will continue to be important. It's certainly mentioned in the theories that extend quantum mechanics.

Jason

Hello, thank you for fast reply!

Yes I am aware of the point you made in recent lecture and I was actually shocked when I first heard about this because I never thought about this different interpretations of the principle from different versions of theory.

The question I made was about the scale of Planck's constant, because it seemed to appear in many place in quantum mechanics and it seemed to be a scale that lots of interesting things are related to (like least action principle etc). So thank you for sharing your opinion. The more I read about quantum mechanics I feel more confused. I'll revise again. Thanks again for your kind replies.

Chul

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Oh, great. Thanks, Chul. Sorry that I misunderstood your question. It makes a lot of sense now. Yes, Planck's Constant appears all over the place, not just in quantum mechanics but in more recent theories too.

The idea of having a fixed constant comes directly from the original idea of quantum mechanics, that energy can only come in certain sizes. But why Planck's Constant has the value it has is a big mystery. It's one of the mysteries Dayal's going to talk about in the very final lecture, next week, on anthropic principles.

Jason