Why do we need Quantum Mechanics so much?

[fxdung]

Almost phenomena at macro level are classical phenomena,why physics needs QM very much?Is it rational need or practical need?

 

[fresh_42]

It's a rational need. Humans are built this way: they want to know!

 

[bhobba]

Is it rational need or practical need?

Both.

The truth will set you free.

Thanks
Bill

 

[fxdung]

I think Chemistry,Nuclear Physics have practical needs,but how about other branch?

 

[bhobba]

I think Chemistry,Nuclear Physics have practical needs,but how about other branch?

Integrated circuits and the whole digital revolution. Transistors work on a purely quantum effect - absence of electrons, called holes, actually act like particles.

Thanks
Bill

 

[rootone]

Quantum mechanics is a name for observable phenomena, and quantum field theory is currently the best explanation for it.

 

[e.bar.goum]

The fact that this post exists at all is because of a computer which relies on quantum mechanics. Every piece of consumer electronics contains transistors, whose functioning requires quantum mechanics. Further, to communicate to someone on the other side of the world, you have used the internet which is transmitted over fiber optic cables using lasers. Those lasers exist as a result of our understanding of quantum mechanics. So, yeah, I'd say it's a practical need.

ETA: And these are just two examples. There are hundreds more.