wendy’s wordpress


So you want to teach yourself physics?

So, firstly, I’d start with these three:

1.1 Udacity “Intro to Physics – Landmarks in Physics”

” Learn the basics of physics on location in Italy, the Netherlands and the UK, by answering some of the discipline’s major questions from over the last 2000 years.
This unique class gives you the chance to see the sites where physics history was made and learn some of the subject’s most captivating concepts. ”

https://www.udacity.com/course/ph100
Prereqs “This course is suitable for anyone; a basic understanding of algebra is suggested.”

Work through this course at your own pace – If you find yourself enjoying it, you’ll then know that this path is one worth following for you!

The suggested length of the course is 2 months with 6 hours work per week, but of course longer if you have less time per week available than that.

These next two are two more courses from MIT’s OCW range. I haven’t been through them myself, but they look like they could be very good, and at the right level for you currently. They are called “Highlights for Highschool”, and were designed as weekend enrichment classes for students in the 7th to 12th grades.

1.2 “The Big Questions”

“With recent advances in physics (and philosophy), we are finally able to make some headway into some of the most pressing questions of the universe. We will explore such topics as the big bang theory, time travel, relativity, extraterrestrial life, and string theory. We will attempt to answer some big questions such as: Was there a beginning of time? Will there be an end? Is time travel possible?”

http://ocw.mit.edu/high-school/physics/the-big-questions/

1.3 “Excitatory Topics in Physics”

“What sorts of things get physicists (or wannabe physicists, like the teacher of this class) excited? Is it the dream of building grand intellectual edifices capable of describing the Universe with amazing accuracy and elegance? Or, perhaps, discovering something so unexpected that it totally blows your mind? Maybe it’s simply the act of doing physics! Whatever the case, there are certainly many things in physics to get excited about, and we’ll explore some of them in this class.”

http://ocw.mit.edu/high-school/physics/excitatory-topics-in-physics/

These two courses are also listed as 2 months long, although they give no indication of how many hours per week.

Once you’ve been through the above three, if you’ve enjoyed them, you’ll have a great feel for what physics is all about and for the way experiment and theory interconnect from the Udacity course. You’ll also have been introduced to some of the ‘big themes’ of physics in a general, non-rigourous way fro the other two MIT enrichment courses.

After that, you may be relatively satisfied, or you may … want … more. If you want more, fear not, your journey is still only just beginning!

—-
At this stage I would recommend Walter Lewin’s 1st year university classes on Classical Mechanics and on Electricity and Magnetism.

Lewin’s lecture courses are absolutely extraordinary, in all senses of the word, and very famous. They are a lot of fun but also rigourous – they are aimed at MIT first year students, who are basically the ‘best of the best’ of American science students,

Here is a short (1.5 minute) promo video someone has made showing Lewin at his best:

https://www.youtube.com/watch?v=7Zc9Nuoe2Ow

It is at this point (during Lewin’s lectures) you may begin to really feel you need some more math, if you did not complete advanced high-school math.

But it’s probably worth watching some of the lectures and _then_ going back and finding the math you need, on the Khan academy website or elsewhere, as this way you will be more able to hone in on the math you actually need, and also it will seem more exciting and worthwhile if you have seen what it will be used for (mathematicians in the audience feel free to look at me in horror now!).

In particular, at this stage you will need to get at some point a very good understanding of elementary vector mathematics in 2 and 3 dimensions, some understanding of complex numbers and how they relate to trigonometry and to harmonic waves ( for the electromagnetism). And a very very strong grasp high-school grasp of high-school algebra in general.

Here are the three actual courses:

2.1 Here is Walter Lewin’s Physics I: Classical mechanics:
http://ocw.mit.edu/courses/physics/8-01sc-physics-i-classical-mechanics-fall-2010/

2.2 Here is Walter Lewin’s Physics II: Electricity and Magnetism:
http://ocw.mit.edu/courses/physics/8-02sc-physics-ii-electricity-and-magnetism-fall-2010/

Here is Walter Lewin’s Physics III: Vibrations and Waves
2.3 http://ocw.mit.edu/courses/physics/8-03sc-physics-iii-vibrations-and-waves-fall-2012/
(You really need to know about waves if you are going to understand quantum mechanics.)

I think these courses are meant to be one semester each. I’d say that you will need at least 6 months to complete each one, but probably longer as you will be doing this ‘on the side”, and also you may need to go and ‘catch up’ on certain mathematics along the way.

After these three courses, you’ll find the world of physics really begins to open up for you.

Onwards and Upwards….

At this stage, you will still need a good course on quantum mechanics – there are a few out there, various online MOOCs etc.

I won’t list them now as it will be a year or two before you are going to be seriously looking for one, and anyway, there could be all sorts of other things available by then. My main advice would be

1) You want a really good understanding of wave mechanics first, and

2) You will need more math, again. In particalar, you will need now an advanced course on vector spaces and linear algebra – this is related to, but far more abstract than, the vector math you will have learned initially at high school/or onn your own. You will also need a reasonable grasp of differential equations – you don’t need to be an absolute expert in them, but you need to know what they are, and what their solutions represent. ( In fact learning about wave mechanics can help a lot with this, as wave mechanics provides many practical illustrations of differential equations.)

Anyway, hope that all helps!

Wendy Langer ūüôā

Some other resources you may find useful on the way:

A fantastic general resource is the online physics forums website at

http://www.physicsforums.com/index.php

Here you can discuss physics questions with a range of others including fellow beginners, advanced students, post-graduate students, and lecturers. Have a browse to see the range of topics and levels covered.

They also have a guide to many physics learning materials here:
http://www.physicsforums.com/forumdisplay.php?f=160
And one of these is a link to specifically to beginner learning materials here:

http://www.physicsforums.com/showthread.php?t=95523

Stanford’s OCW (Online Courseware) materials:

Here is an index to all of Stanford’s OCW p[ysics courses and other materials:
http://ocw.mit.edu/high-school/physics/

This one has some great high-school level resources, but I’m not sure if it has the format of an actual ‘course’ that youwork through in sequence.

http://www.physicsclassroom.com/

Finally, physics.org has a page called “teach yourself physics”, with links to some great resources:

http://www.physics.org/toplistdetail.asp?id=26


William Morris – A Dream of John Ball

[object HTMLTextAreaElement]

via William Morris – A Dream of John Ball.


Not a Tomato!

Here is my creation for the Not-A-Tomato … initiative? game? puzzle? – well, for the¬† Not-A-Tomato-whatever-it-is, anyway !

It is a photograph of Einstein playing the violin which I gimp-shopped a little. I found the image using the Creative Commons search tool plugin for firefox. The original photo is hosted at the wikimedia commons at http://search.creativecommons.org/?q=einstein+violin&sourceid=Mozilla-search

Einstein playing the tomato!

Einstein playing the tomato!

For more about Not-a-Tomato, see notatomato.com


Emmy Noether – Ada Lovelace Day!

This is began just a really quick posting, as I had hoped to be the first to post about Emmy Noether as part of Ada Lovelace day, but I didn’t have time to properly fill this out until I got home!

However, as it turns out, another blogger had already created a great post about Noether, which you can read here.

In it the author discusses a little about Noether’s background, and has a link to the wikipedia article about her, which is a great place to start if you want to know more.

Since the other blogger has already introduced Emmy Noether much better than I could have, I have decided to discuss her life only very briefly, and  focus more on her work.

In particular, I’m going to talk about a theorem she proved which links the worlds of physics and abstract mathematics in a very deep way. This ¬† theorem is called, naturally enough, “Noether’s Theorem” (*) , and to this day it remains one of my favouritest theorems of all time ūüôā It is definitely one of the most important and beautiful theorems in mathematics.

Noether was a mathematician early last century. Her work ocurred around the time that quantum mechanics and the theory of relativity  were shaking the foundations of our understanding of the physical world. She was a contemporary,  peer, and friend of men such as Einstein, Hilbert, and Klein amongst others.

Mathematicians often know her best for her main body of work, which was in the area of modern abstract algebra. Physicists, on the other hand, are more likely to come across her work by way of the theorem I am about to describe.

When I first read about this theorem,¬† during my university traning in physics, I thought it was one of the most wonderful things I had ever learnt. It was at one and the same time¬† singularly beautiful and yet extremely useful. You can imagine how excited I was when I found out the the Noether of¬† ‘Noether’s Theorem’ was a woman!

Most people will have heard of things like ‘the conservation of energy’, and those who studied high school or college physics will have also heard of the ‘conservation of momentum’, and even the ‘conservation of angular momentum’.

We all have an intuitive notion that, during physical interactions,¬† there is a certain amount of book-keeping going on.¬† If something is moving very fast and is suddenly stopped, it tends to make a lot of noise and generate heat. So we might say that the ‘movement energy’ has been transformed into heat and sound energy. Or we could say that there is a balance of energy which needs to be restored. Whatever is lost from one column of the accountant’s ledger needs to be regained in another. The trick is discovering what all the columns are!

If an ice-skater is spinning slowly with their arms spread out, and then they pull¬† their arms in towards them, they will begin to spin much faster… this time, informally, we could say that slower ‘wide spinning’ has been transformed into faster ‘narrow spinning’.¬† Again, there appears to be some kind of balance, a set of quantities which can be traded for one another.

In all these cases, a physicist would say that there exists a ‘conserved quantity’. In the first case above, the conserved quantity is energy. In the case of the ice-skater, the conserved quantity is something called ‘angular momentum’.

Finding out ways to describe and to quantify which physical attributes of bodies in interaction can be ‘swapped’ with which others has been a main-stay of physics for a long time.¬† Ever since the incredibly fertile linking of empirical methods with abstract mathematical analysis around the time of Kepler, you could probably say that once you have found out exactly what is conserved, under which conditions, you know everything that can be known about a physical¬† system!

So on the one¬† hand we have the bread-and-butter work of physicists – measuring quantities before and after interaction. Drawing up equations to see how these quantities change, relating these equations to one another and to theories about ‘how the world works’.¬† [ Of course, there’s actually a lot more to it than this, but I am trying to give the simplest description I can! ]

This is all wonderful stuff, and we could say a lot about physical systems using the techniques, but we wouldn’t expect to say much of interest about topics such as one-dimensional Lie groups of transformations.

On the other hand, we have a purely mathematical world,¬† the¬† abstract theory of symmetries and group theory.¬† In this world we can describe the ‘symmetries’ of¬† ‘sets of permutations’, we can wonder about the possible roots of polynomials, and much more. But we wouldn’t particularly expect to have anything very interesting to say about, say, a spinning ice-skater.

Noether’s theorem bridged these two worlds, producing an understanding in which statements made in seemingly seperate fields¬† could be related. Naturally, this new way of understanding things had a profound influence on the development of physics throughout the rest of the century and beyond.

The theorem states, roughly, that conserved quantities in physical systems (energy, angular momentum and so on) are in reality the reflections of symmetries in certain deeper mathematical structures underlying them (**).

Thus, the theorem makes a connection between these two apparently disparate areas, and shows that not only that they are connected, but also describes in precisely what way they are connected.

The lovely thing is that we discover that talking about the symmetries of a physical system and talking about what kind of ‘book-keeping’ that system uses are in¬† an important sense both just different ways of saying the same thing.

That’s all for now, I hope to refine this post a little more and perhaps add a couuple of images at a later date ūüôā

(*) Also sometimes¬† known as “Noether’s First Theorem”.

(**) A reasonably¬† exact wording,¬† as I recall it from my physics training,¬† is something like this:¬† “To every continuous symmetry in the Hamiltonian of a Dynamical System there corresponds a conserved quantity”.¬† Wikipedia gives the following informal wording: “To every differentiable symmetry generated by local actions, there corresponds a conserved current.”


krugle code search

Krugle – Wikipedia, the free encyclopedia

A wikipedia article about krugle – a search engine specifically for searching for code. Also mentions other options such as google code and Koders.

Powered by ScribeFire.


open-office’s .odt format

Chapter 1. The Open Document Format


3D Xgl Compiz Eye Candy for Ubuntu/Kubuntu Dapper and NVidia | Linux Journal

3D Xgl Compiz Eye Candy for Ubuntu/Kubuntu Dapper and NVidia | Linux Journal


openoffice word-processor (ie oowriter) FAQ

documentation: Writer FAQs


Bruce Byfield’s openoffice articles

documentation:


nixCraft – soft and hard links :)

nixCraft: Understanding UNIX/Linux symbolic (soft) and hard links