Monday, 13 May 2013

Coursera - Quantum Mechanics

A course on quantum mechanics! What am I thinking?

So I signed up for a course on quantum mechanics. I mean, how hard can it be?
Answer - *!?**!!* hard!

I brushed off my knowledge of imaginary numbers, I went through the introductory maths materials - they didn't seem too hard. OK - I struggled to remember complex conjugates, and one or two other things.

I thought there might be a reasonable introduction, and an explanation about things - which there was. However the learning curve was incredibly steep, and was sort of emphasised by the first homework.

Q1 For what was Albert Einstein awarded the Nobel prize?

  • General Relativity
  • The expansion of the universe
  • The photo-electric effect
  • Electron diffraction
OK - I actually knew that one - although it was in the course materials too.

Q2 Recall how the Schrödinger equation was motivated by the non-relativistic dispersion relation 
E=p22m. If we follow the same procedure for the case of a relativistic dispersion relation (E2=p2c2+m2c4), what equation do we arrive at? (For simplicity consider the one-dimensional case)

Ouch! The gloves are off! The lectures also had a grading system. No stars was for everyone, 1 star had some maths in it, two stars extensive maths, and three stars - mega maths. Most of the videos were in the 2/3 star range.

I actually enjoyed doing some of the integration - but realised I was gradually losing the plot as the course went on. I never really got a good handle on the bra-ket notation - I still don't really get it's power - I'm missing something I'm sure, but they didn't spend very long on it, and the books I got didn't help. Then it was onto Dirac deltas, Levi-civita notation and stuff about spin. By now I was really struggling with the weekly homeworks, and guessing as many as I was solving - I was no longer learning and close to drowning. I did think about giving up on the course, but I stayed the distance, and finished all the videos, all the homeworks.

This course had an exam - 1 chance at answer each question - 6 hour time limit. A couple of questions I could answer, the rest I guessed at, except those that required a numeric answer - which I couldn't do. I got 42% which I consider more than fair.

This gave me a total course mark of 72% - again more than I deserve.

So I probably got half way before I couldn't keep up, and for me it was hard to turn all that maths back into what it meant in the real world - even in the abstract. I guess that's not unusual in quantum mechanics!


Sayan Datta said...

Hello Julian,

Thanks for this post.
I am doing this course at its present iteration. Can you give me a rough idea about what percentage of homework and exam questions require entering numeric answers? I have trouble entering numeric answers...that's why I am asking the question.

Julian Onions said...

Quite a number of the homeworks require you to either work out maths expressions, or solve for numbers. Good luck!

Sayan Datta said...

Thanks for the reply...