Feynman’s Derivation of the Schrödinger Equation • Hacker News Board

Re: Feynman’s Derivation of the Schrödinger Equation

#11

Post by foob » Tue, Jan 26, 2016, 10:02 PM UTC

77pt77 wrote: post #9

wyager wrote: post #5

Where did we get that [Schrödinger's equation] from? It's not possible to derive it from anything you know. It came out of the mind of Schrödinger. -The Feynman Lectures on Physics For anyone who wants to study quantum mechanics and has a math background, I strongly recommend Shankar's quantum textbook. It has the most rigorous, clear, and correct derivations I have seen thus far, starting with vector spaces and movi…

For the love of God, do not use Shankar! The book is just down right atrocious. The fact that it became almost standard in American universities speaks more of the power of networking than anything else. Shankar's book is anything but rigorous, quite on the contrary. There are so many good QM books: For an absolute beginner I'd recommend David Griffiths Dirac's is very readable Sakurai's is very good though a bit adv…

I personally think that Shankar makes a great companion to Sakurai. Shankar is less rigorous but it explains things in a more accessible way which can be extremely helpful if you find Sakurai too terse on some topics.

Re: Feynman’s Derivation of the Schrödinger Equation

#12

Post by thinkpad20 » Tue, Jan 26, 2016, 10:22 PM UTC

spikels wrote: post #4

This was written by a high school physics teacher. Very cool.

He was actually my high school physics teacher! And very good. A really cool guy and super smart.

Re: Feynman’s Derivation of the Schrödinger Equation

#13

Post by mrcactu5 » Tue, Jan 26, 2016, 10:35 PM UTC

Feynman's "Quantum Mechanics and Path Integrals" is about $18 on Amazon

http://www.amazon.com/Quantum-Mechanics-Path-Integrals-Emend...

That is a serious graduate level book - written in his own style.

Re: Feynman’s Derivation of the Schrödinger Equation

#14

Post by acqq » Tue, Jan 26, 2016, 11:10 PM UTC

giardini wrote: post #3

Apparently Schrodinger _guessed_ his equation. Not that it was an easy guess - a woman was involved. See p. 547 of "Quantum Foundations and Open Quantum Systems:Lecture Notes of the Advanced School" https://books.google.com/books?id=LVICCwAAQBAJ&pg=PA547&lpg=...

Can you please write which woman and how she was involved? I failed to find that in the linked material.

Re: Feynman’s Derivation of the Schrödinger Equation

#15

Post by theoh » Tue, Jan 26, 2016, 11:22 PM UTC

acqq wrote: post #14

giardini wrote: post #3

Apparently Schrodinger _guessed_ his equation. Not that it was an easy guess - a woman was involved. See p. 547 of "Quantum Foundations and Open Quantum Systems:Lecture Notes of the Advanced School" https://books.google.com/books?id=LVICCwAAQBAJ&pg=PA547&lpg=...

Can you please write which woman and how she was involved? I failed to find that in the linked material.

"A few days before Christmas, 1925, Schrodinger, a Viennese-born professor of physics at the University of Zurich, took off for a two-and-a-half-week vacation at a villa in the Swiss Alpine town of Arosa. Leaving his wife in Zurich, he took along de Broglie's thesis, an old Viennese girlfriend (whose identity remains a mystery) and two pearls. Placing a pearl in each ear to screen out any distracting noise, and the woman in bed for inspiration, Schrodinger set to work on wave mechanics. When he and the mystery lady emerged from the rigors of their holiday on Jan. 9, 1926, the great discovery was firmly in hand."

http://www.nytimes.com/1990/01/07/books/the-lone-ranger-of-q...

Re: Feynman’s Derivation of the Schrödinger Equation

#16

Post by cyphar » Tue, Jan 26, 2016, 11:42 PM UTC

The Schrödinger equation was not derived, a more accurate word would be guessed. It's a fundamental law, like F = ma (although that is actually more of a definition than a law). There is no fundamental explanation why electrons obey the Schrödinger equation, just like there's no fundamental explanation why macroscopic objects obey F = ma.

Re: Feynman’s Derivation of the Schrödinger Equation

#17

Post by randlet » Wed, Jan 27, 2016, 1:07 AM UTC

77pt77 wrote: post #9

wyager wrote: post #5

Where did we get that [Schrödinger's equation] from? It's not possible to derive it from anything you know. It came out of the mind of Schrödinger. -The Feynman Lectures on Physics For anyone who wants to study quantum mechanics and has a math background, I strongly recommend Shankar's quantum textbook. It has the most rigorous, clear, and correct derivations I have seen thus far, starting with vector spaces and movi…

For the love of God, do not use Shankar! The book is just down right atrocious. The fact that it became almost standard in American universities speaks more of the power of networking than anything else. Shankar's book is anything but rigorous, quite on the contrary. There are so many good QM books: For an absolute beginner I'd recommend David Griffiths Dirac's is very readable Sakurai's is very good though a bit adv…

It's been a long time now, but I pretty much agree with you. I really enjoyed Griffiths as an introduction but for reasons that escape me now I remember having a bad time with Shankar.

Re: Feynman’s Derivation of the Schrödinger Equation

#18

Post by qrendel » Wed, Jan 27, 2016, 1:20 AM UTC

77pt77 wrote: post #9

wyager wrote: post #5

Where did we get that [Schrödinger's equation] from? It's not possible to derive it from anything you know. It came out of the mind of Schrödinger. -The Feynman Lectures on Physics For anyone who wants to study quantum mechanics and has a math background, I strongly recommend Shankar's quantum textbook. It has the most rigorous, clear, and correct derivations I have seen thus far, starting with vector spaces and movi…

For the love of God, do not use Shankar! The book is just down right atrocious. The fact that it became almost standard in American universities speaks more of the power of networking than anything else. Shankar's book is anything but rigorous, quite on the contrary. There are so many good QM books: For an absolute beginner I'd recommend David Griffiths Dirac's is very readable Sakurai's is very good though a bit adv…

The QM class I originally took used Liboff. I could barely understand a word of it and ended up dropping the class. Later I found the Shankar book and was thrilled with it by comparison. I'm not a math whiz though, so lack of "rigor" on a first pass is just fine by me. For an intro level text for the average person, I found Shankar was one of the few accessible ones.

Haven't read Griffiths yet so I can't comment on it.

Re: Feynman’s Derivation of the Schrödinger Equation

#19

Post by subnaught » Wed, Jan 27, 2016, 1:44 AM UTC

77pt77 wrote: post #9

wyager wrote: post #5

Where did we get that [Schrödinger's equation] from? It's not possible to derive it from anything you know. It came out of the mind of Schrödinger. -The Feynman Lectures on Physics For anyone who wants to study quantum mechanics and has a math background, I strongly recommend Shankar's quantum textbook. It has the most rigorous, clear, and correct derivations I have seen thus far, starting with vector spaces and movi…

For the love of God, do not use Shankar! The book is just down right atrocious. The fact that it became almost standard in American universities speaks more of the power of networking than anything else. Shankar's book is anything but rigorous, quite on the contrary. There are so many good QM books: For an absolute beginner I'd recommend David Griffiths Dirac's is very readable Sakurai's is very good though a bit adv…

Griffiths is really great.

Re: Feynman’s Derivation of the Schrödinger Equation

#20

Post by [deleted] » Wed, Jan 27, 2016, 2:10 AM UTC

giardini wrote: post #3

Apparently Schrodinger _guessed_ his equation. Not that it was an easy guess - a woman was involved. See p. 547 of "Quantum Foundations and Open Quantum Systems:Lecture Notes of the Advanced School" https://books.google.com/books?id=LVICCwAAQBAJ&pg=PA547&lpg=...

[deleted]