Friday, 31 May 2013

Udemy - Astronomy - state of the art.

Astronomy - State of the art

I spotted this course just moments before it actually started - well a day or two. I hadn't heard of Udemy before - so this was new.

It looked really good - it promised to cover a lot of areas - and I'm often concious that I only get to see stuff on galactic scales, and mostly theoretical - so this looked like it would be good for balance.

I have to say it was fantastic. You can take the course at your own speed. There was some initial attempts to have quizes as part of them - they had issues getting the system to work so they were shelved.

It really did cover pretty much the whole of astronomy, from telescopes, to planets, to stars, black holes, and galaxies to cosmology - and all stops in between in 77 chunks. It breaks down in the following topics.

      • Course Overview,
      •  Description,
      •  Introduction
      • State of the Art Observing, 
      • Telescopes, 
      • Observing Limitations, 
      • Observing Solutions, 
      • Adaptive Optics, 
      • Space Astronomy, 
      • Big Glass, 
      • Gravity Waves
      • Overview - Planetary Exploration
      • Mars
      • Mars and Water
      • Mars Up Close
      • Jovian Planets
      • Solar System Satellites
      • Titan
      • Water Worlds
      • Overview - Extra Solar Planets
      • Exoplanets
      • Detection and Imaging
      • Characterizing Exoplanets
      • Kepler
      • Habitable Zones
      • Overview - Stars
      • Stars and Life
      • Supernovas
      • Pulsars
      • Black Holes
      • Testing Gravity
      • Overview - Structure & Evolution of Galaxies
      • Milky Way
      • Dark Matter
      • Galactic Center
      • Active Galaxies
      • Structure Formation
      • Dark Energy
      • Overview - Cosmology
      • Cosmology
      • Microwave Background
      • Big Bang
      • Early Universe
      • The Multiverse
      • Overview - Life and Astrobiology
      • The Unity of Life
      • Extremophiles
      • Exobiology
      • Weird Life
      • Drake Equation
      • Communication
    As well as videos, there were PDF's to read and slides available. Also supplemental audio recordings of the tutor, Professor Chris Imprey, interviewing other astronomers.

    Towards the end of the course he also conducted some live sessions where we could send in questions either live or by email/twitter and he'd answer them live on video conference. They ranged from "Is there life on Mars?" to "What happens in a black hole?" and many others. Nothing seemed to phase him, and each question got a good 5 or 10 minute answer.

    The course is still going - and anyone can watch the videos, read the material and take part in the interactive sessions. It's well worth it if you are at all interested.

    Even better - after the quantum mechanics course I'd just taken, it was a complete relief to feel on top of a subject!

    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!