Showing posts from October, 2011

How was the Universe born?

Just a quick note to say that I had an article published in  Australasian Science  on the birth of the Universe. As you can see, I also got the cover. Unfortunately, you have to pay to subscribe, but I think this appears in many Australian schools. Anyway, here's the abstract Modern cosmology tells us that the universe as we know it arose 13.7 billion years ago in the fiery birth of the Big Bang, but our understanding of the laws of physics is incomplete and we are currently unable to answer the questions of where the universe actually came from. Cosmologists have many ideas, ranging from the reasonably strange to the extremely outlandish.

Gravitational Lensing with Three-Dimensional Ray Tracing

One of the cool things about the universe is that light rays don't travel in straight lines. As they pass through the cosmos, lumps of mass (stars, galaxies, clusters, black holes etc) tug on the path of light rays and so they follow a wiggly path. It looks something like this The colours here represent density in the universe, where yellow is high density, purple middling and black low density, and you can see the cosmic web of mass which has come from a computer simulation of structure formation. The green line is a light path travelling through the universe, and as you can see, it wiggles. Here's another version of the picture The result is that view of the distant universe is distorted, and a considerable focus of future telescopes is to measure the amount of distortion that we see. This will allow us to measure a couple of key things, namely the distribution of matter (which is good, because a lot of it is that pesky dark matter that we can't see), and als

A sad C day

I understand a lot of people were moved by the death of Steve Jobs , but IMHO a gianter (if that's a word) person of the computer world also died last week. Sadly, Dennis Ritchie died on the 12th October. While Steve gave us shiny toys (and yes, I am typing this on a MacBook, and I have an iPad), Ritchie gave us (well, me) some of the vital tools of the trade. With Ken Thompson , he developed the best operating system in the world, namely Yes, UNIX . When I started my PhD, we used VMS on VAXes, but these were superseded by these beauties - Sun machines running SunOS , my first experience of UNIX. Soon after, we had the birth of penguin, and we could have real computing in the home with Linux. In the old days, we were spending a fortune on maintenance contracts for Vaxes and Sun machines, so the prospect of running a free proper operating system on cheap hardware was very appealing (and no, windows of any variety is not a proper operating system - good for games, but n

Faster than the speed of light

After a weekend of great rugby (from the Welsh, the English and Australians were rather blah), I have responded to a good question posted over at The Conversation on distances in the Universe. It's a question that gets raised quite a bit and basically put it goes something like If the Universe began 13.7 billion years ago, when the distance between any pair of points was zero, how can anything be more than 13.7 billion light years away? The answer is the difference between local motions and global motions. Here's the response I posted An excellent question, and one which may not make sense to start with. We know from special relativity, nothing can travel faster than light (recent neutrino claims excepted). But in reality, special relativity says that nothing can go faster than the speed of light **locally**, so in a small box, if I try and race an electron and a photon across the box, the photon will win. With the expanding universe, the question we are a

Accelerated Expansion

The Science Blogosphere is going to be full of comments on the winning of the 2011 Nobel Prize by Perlmutter, Riess and Schmidt, and so I am not going write a lot on this topic, other than to say that I know Brian well and I am very happy for him. The fact Riess is younger than me suggests that I may not be personally on the Nobel Prize trajectory :) Anyway, I quite like the Nobels. Not the prize itself, as it rewards individuals from what are typically large groups, but guessing who the next winner will be is fun. This year I was correct, and I have evidence over at Uncertainty Principles , and it looks like I win a prize myself :)