Wednesday, 30 January 2013

G+C: Module 5 & 6

So week 3, and this week there are some more topics introduced.

First it starts with one on Cosmological tests, how you can check what we work out. Then some tests in detail, such as the Hubble diagram, the Cosmic Microwave background (of course) and then source counts.
It wraps up nicely by look at the concordance model, where all tests are brought together to constrain various values. 54 minutes of video split across 5 topics.

The next module starts with the very early universe, talking fractions of a second after the big bang. Then some stuff of big bang nucelosynthesis, and a bit about inflation. Then more about the early universe, including recombination and reionisation.
Just 4 videos in this bit,  42 minutes, so just over an hour and a half total of videos.

The quiz was a bit harder, and I only managed 7/10 this time. One I think the question was a bit iffy, and a couple were just answers I couldn't find easily.

Sunday, 20 January 2013

G+C: Module 3 & 4

Modules 3 & 4.

This weeks work is module 3, which is on cosmological models.

It starts by introducing the cosmological parameters, then takes us briefly through solving the various Friedman equations for different models. It then looks at the different cosmological models that arise from these, what sort of universe they predict, and what they would look like. Finally a quick introduction to distances in cosmology.

4 videos comprising 37 minutes

Module 4  is on distance scale, age of the universe and expansion
So it starts by looking at the scale of the universe, then starts with the cosmic ladder of distances, from parallax and upwards. This is followed by distance indicator relationships, and then a look at supernova standard candles. Then 3 more videos, on the HST distance project, estimating the age of the universe, and finally tests that can tell us if the universe is expanding, or light is just "tired".

So 7 videos in this section. 75 minutes in total.

This together with the module 3 videos I found quite a lot to squeeze into a week. It takes a while to get through all these and there is only so much you can take in in one go.

The quiz was a bit harder than last weeks, I had to go searching for some of the answers, another 10 questions, but I managed to get through them all eventually. Some I thought slightly imprecise, but anyway - all ok.

So onwards and upwards - next section is early universe stuff like the big bag, inflation and nucleosynthesis.

Thursday, 10 January 2013

G+C: Module 2

The second module is all about basic cosmological stuff. There are another 4 lectures with embedded questions running to about 25 minutes in total.

It starts with some basic definitions, then discusses homogeneity and isotropy. Then some time spent on the expanding universe, and finally a quick derivation of the Friedman equations.
The questions I'm getting more use to and managing to cover OK. A few of them I have to think a little, but so far not needed pencil and paper, but that will probably change with the questions that are up coming.

So nothing I haven't seen before, but I struggled to follow the mathematical derivation - I have done it before so if necessary I think I could follow it.

So after thinking about it, I decided to tackle the questions. There were 10 multiple choice questions based on the text, and most of them were reasonably easy to answer. A few were more tricky, and I had to review material, but actually still nothing requiring pen and paper as yet.

Tuesday, 8 January 2013

G+C: Module 1

So - the course starts! First thing is it seems to go at quite a rate. We're expected to go through two chapters a week, and then answer a quiz on the topic. You need 60% to pass for each quiz. You get two deadlines to complete the quiz by, with only half marks available if you slip the first dead line. So the pressure is on!

The first lecture is a 15 minute video on the history of cosmology and some background material. The video is powerpoint like slides mostly with narration over it, and occasional inset video of the speaker.

I noticed some yellow marks on the slider at the bottom of the video, and found when it got to that point the video paused and you got asked some questions. You get instant feedback on these so it's quite interactive.
However some of the questions were suddenly a little heavy for late night consumption!
Quick, integrate between limits 0 to 1 ex dx. What quantum jump gives the H-alpha line. I admit to having to google that one - I thought it was probably 3-2 but wasn't confident when it came to it.

A couple of things I did learn from this though, which I presumed I'd learn some new things.

  • Bolometric output is the whole output of something. I sort of knew that, but it's not something that concerns me normally, but something clicked here.
  • He went over Olber's paradox, and said not only did it apply to light, but also to gravity. You can recast the paradox into "why aren't we ripped apart by the total tidal force of the gravitational interactions?"
So most of it was a general introduction. The spontaneous calculus was a bit of a shock - but apart from that it was ok.

The next two videos were on more general history leading up to CMB and Dark matter and things like that, taking us up to the present day. These also had quizes in them, but I found them much easier to answer!

So that's module 1 done - about 45 minutes of video in all, with some questions thrown in. Not bad for the first day :) I need to do module 2 though before attempting the assessed quiz.

Monday, 7 January 2013

Change of direction

So I finished my OU degree, and I've gone into postgraduate studies in astronomy now. I did do one last OU course, SXP288, but really only for the residential component. The way education is funded has also changed, and this means the course fees have quadrupled. I can get some transitional arrangements if I was studying for another degree, but I think I don't really have time for that, and really I would only want to pick and choose which courses I would do.

So reluctantly, I've probably come to the end of my time with the OU, through pressure of time, finance and the changing face of education.

I'm learning a lot of new stuff in my postgraduate studies, and did 6 course last year local to the university, which I'll skip over. However chatting to a friend, she mentioned the new set of courses which are free through - and I thought, why not give them a try, So here I am, signed up for something reasonably relevant - a course on Galaxies and Cosmology. Yes - I'm staying somewhat in my comfort zone, and partly worried I won't be able to manage it which would be embarrassing. I'm also just interested in what the format will be (this one comes from CalTech!) and how it will all work.

So slightly scary, but well worth the price!