Monday, November 30, 2009

Poem mystery author

Although I can't say I'm a big fan of poetry, I do like a very few which deal with the stars, our Universe and (big surprise here) Man's quest to venture to the stars. When I was a small boy and pointed my telescope to Saturn for the first time, this was one of those moments you never forget for the rest of your life. After countless nights behind the eyepiece (it's quite addictive!), one eventually starts to ponder on thoughts on interstellar travel and watching StarTrek makes it worse ;-) There is one poem which I can't seem to find out who wrote it. I've posted the question to poem newsgroups and contacted various knowledgeable people but to no avail. It's engraved on the back on one of my brass compasses (Dollond London) which I got from a flea market a while ago next the Maritime Museum. Do you know who wrote this poem so I can give this mystery author proper credit?

One of the reasons why I bought this compass was because I liked this poem very much, if I didn't know better my first thoughts were either a Physicist wrote it or an author with deep thoughts on Nature. It talks about time, "a continuum moves and swirls..." (the vacuum?), the celestial sphere and life. Talk about big topics! The vacuum is central to Physics and today is still "beyond my inner sight and imagination" ie Physicists still don't understand it at the quantum level although they are getting better. Actually understanding the vacuum has been central to Physics most of our history, see this very interesting painting.

Some of you who work on Sydney Harbour may have noticed that Thor Gitta was docked in White Bay for quite a while (over a month), the mystery why she was there for all this time has been solved: she was waiting for this barge to unload her big load of cable:

Tuesday, November 17, 2009

Cosmology, The Big Bang and Entropy

I went to Sean Carroll's talk yesterday at Sydney University. As many of you are aware, Sean is one of the bloggers on Cosmic Variance and is touring Australia for his talks. He also has an upcoming book titled From Here to Eternity: The Quest for the Ultimate Theory of Time.

Sean talked about all the big ideas that face Cosmologists these days and in particular Entropy and its relation to the evolution of our Universe starting from a state of low entropy / high order progressing towards a state of high entropy / low order. I didn't like his interpretation of time (particularly the "arrow of time") as mentioned in my previous post and as for the state of the Universe, this is ambiguous because we cannot observe the Universe from the outside hence there is no entropy for the Universe either.

Cosmologists have a fairly good idea what the state of the Universe was 1 second after the Big Bang however at "t = 0" (time cannot be defined here as there is no matter at this stage hence no clocks), no one knows as General Relativity breaks down however before the Big Bang? Sean speculated on an idea that our Universe may have begun from a single quantum fluctuation from the inherent energy of the vacuum, ie we live in a baby Universe an offshoot from another Universe. There was quite a good turnup and the lecture theatre was pretty full, all in all enjoyed the talk.

Still experimenting with $\LaTeX$ in Blogger using this script. Testing...

\[\tan(2\theta) = {2\tan\theta \over 1-\tan^2\theta}\]

\[\int \csc^2x\, dx = -\cot x+ C.\]

\[\ P_{r-j}=\begin{cases} 0& \text{if $r-j$ is odd},\\ r!\,(-1)^{(r-j)/2}& \text{if $r-j$ is even}. \end{cases}\]

\[\qquad \lim_{\alpha\to \infty} {\sin\alpha \over \alpha} = 0\]

\[\root n \of {\prod_{i=1}^n X_i} \leq {1 \over n} \sum_{i=1}^n\]

\[\ \cfrac{1}{\sqrt{2}+\cfrac{1}{\sqrt{2}+\cfrac{1}{\sqrt{2}+\dotsb }}}\]

\[\ \nabla \cdot \mathbf{D} = \rho_f \]
\[\ \nabla \cdot \mathbf{B} = 0 \]
\[\ \nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}} {\partial t} \]
\[\ \nabla \times \mathbf{H} = \mathbf{J}_f + \frac{\partial \mathbf{D}} {\partial t } \]

\[\ \boxed{m &= \frac{m_0}{\sqrt{1-\frac{v^2}{c^2}}}}\]

Sunday, November 15, 2009

Review: LyX and viXra

Been busy the last few days between work learning about LaTeX. Widely used by the academic and research community to write up high quality documents, scientific papers, books etc and especially useful for writting out mathematical formulae with their many special formatting requirements. The text it produces is beautiful.

I tested out LyX, which is a free Windows based Graphical User Interface (GUI) document processor for LaTeX and automatically will download MiKTeX during installation which is also required for your computer. Seems to work very well on my small laptop. Once you write up your document, you can preview it with Lyx's DVI previewer. Once you're happy with it, export the document in Adobe PDF format and you're done. LaTeX has many formatting tags if you look at the source code and although Lyx has also many GUI buttons, it's useful to sometimes type in the code by hand. There's also an excellent beginer's guide to LaTeX which I found handy called A Gentle Introduction to TEX. Great thing is, MiKTeX and LyX are both free for download! Google Documents also have the ability to insert equations and their online chart rendering feature has LaTeX command options (see links for the following):

 A few days ago I also found out about the new e-print archive. Unlike, this is open to anyone who wants to publish a paper and you don't need a "sponsor" (which is required by arXiv). This is great for people who aren't affililated with a research institution, university etc or can't find someone to endorse their paper. There are many Physics papers out there that are highly speculative and many academics aren't willing to be affiliated with a paper that at first appearances could be junk. The only problem is this doesn't help scientific progress. Their Why page explains all this in more detail. Because this is open to anyone, many junk papers will be found there however there are some interesting ones as well worth a read, all in all think viXra is a great idea. Worth keeping an eye on.

Attached photos: Students practicing survival at sea skills, liferaft deployment etc at the Qantas training pool, Sydney Airport.

Wednesday, November 4, 2009

What exactly is time?

I came across today the following paper reviewed on the arXiv Blog and also on arXiv: Can the Arrow of Time be understood from Quantum Cosmology?

The question itself used as the title is flawed. There is no such thing as the "Arrow of Time" in Nature and after reading the paper suspect this will lead to another Not Even Wrong theory. This is a common misunderstanding in Physics so what exactly is time? It's about time we have a look. There's a wiki article however I prefer the explanation on p40 of the first volume of Motion Mountain:
"Time is what we read from a clock."
That's it! Your first intuition is correct ie you check your clock to find out what time it is. Note that clocks can be the Moon, the Sun, sundials, atomic clocks, Harrison's H1 clock etc.

Schiller goes on:

"Time is a concept introduced specially to describe the flow of events around us; it does not itself flow, it describes flow. Time does not advance. Time is neither linear nor cyclic. The idea that time flows is as hindering to understanding nature as is the idea that mirrors Page 71 exchange right and left. The misleading use of the expression ‘flow of time’, propagated first by some flawed Ref. 36 Greek thinkers and then again by Newton, continues. Aristotle (384/3–322 bce), careful to think logically, pointed out its misconception, and many did so after him. Nevertheless, expressions such as ‘time reversal’, the ‘irreversibility of time’, and the much-abused ‘time’s arrow’ are still common. Just read a popular science magazine chosen at random.

The fact is: time cannot be reversed, only motion can, or more precisely, only velocities of objects; time has no arrow, only motion has; it is not the flow of time that humans are unable to stop, but the motion of all the objects in nature. Incredibly, there are even books written by respected physicists that study different types of ‘time’s arrows’ and compare them with each other. Predictably, no tangible or new result is extracted. Time does not flow."

There you have it, if you were thinking of becoming a time traveller with exotic machinery don't waste your time. However time machines are available for purchase if you want one ;-), they only allow you to see back in time though and we are constrained to seeing the observable Universe.
Because light from the Sun for eg takes just over 8 minutes to reach us here on Earth, astronomical objects you see in the sky are essentially as they were when the light left them and because of the vastness of space and the speed of light, it takes time for the light from these objects to reach us. For eg light from our neighbour the Andromeda Galaxy takes 2.5 million years to reach us so if you look at it with a telescope (or with binoculars), you are seeing the galaxy as it was 2.5 million years ago. The bigger the telescope, the further you can see back:

At time t = 0, current Physics cannot explain what happened as the Physics cube mentioned in the previous post isn't complete. And before that? Roger Penrose gave a good talk in 2007 at Darling Harbour titled: What happened before the Big Bang?

Photos: Claudia I coming into Blackwattle Bay the other day delivering more concrete supplies.