Cosmic Horizons

It is now the twilight zone between Christmas and New Year. 2016 has been a difficult and busy year, and my recreational physics and blogging has suffered. But it is time for a rebirth and I plan to get back to the writing about science and space here. But here's some things from 2016. A Fortunate Universe: Life in a finely tuned cosmos  was published. This has sucked up a huge amount of time and mental activity, and that continues. I will blog about the entire writing and publishing process at some point in the future, but it really is quite a complex process with many mine-fields to navigate. But it is done, and am planning to write more in the future. We also made a video to advertise the book! I've done a lot of writing in other places, including  Cosmos magazine on "A universe made for me? Physics, fine-tuning and life" , and commentary in  New Scientist  and several articles in  The Conversation  including Peering into the future: does science requir

I hate starting every blog post with an apology as I have been busy, but I have. But I have. Teaching  Electromagnetism  to our first year class, computational physics using  MatLab , and six smart  talented students  to wrangle, takes up a lot of time. But I continue to try and learn a new thing every day! And so here's a short summary of what I've been doing recently. There's no secret I love maths. I'm not skilled enough to be a mathematician, but I am an avid user. One of the things I love about maths is its shock value. What, I hear you say, shock? Yes, shock. I remember when I discovered that  trigonometric functions  can be written as infinite series, and finding you can calculate these series numerically on a computer by adding the terms together, getting more and more accurate as we add higher terms. And then there is  Fourier Series ! The fact that you can add these trigonometric functions together, appropriately weighted, to make other functions, fun

After an almost endless Sunday, winter has arrived with a thump in Sydney and it is wet, very, very wet. So, time for a quick post. Last week, I spoke at an  Early Career Event  in the Yarra Valley, with myself and  Rachel Webster  from the University of Melbourne talking about the process of applying for jobs in academia. I felt it was a very productive couple of days, discussing a whole range of topics, from transition into industry and the two-body problem , and I received some very positive feedback on the material I presented. I even recruited a new mentee to work with.  What I found interesting was the number of people who said they had decided to be a scientist or astronomer when they were a child, and were essentially following their dream to become a professor at a university one day. While I didn't really discuss this at the meeting, I have a confession, namely that I never wanted to be an astronomer.   This will possibly come as a surprise to some. What I a

I've written an article 'On the Relativity of Redshifts: Does Space Really "Expand"?' which has appeared in Australian Physics (2016, 53(3), 95-100). For some reason, the arXiv has put the article on hold, so you can download it here . I like it :)

Obligatory "sorry it's been a long time since I posted" comment. Life, grants, student, etc All of the usual excuses! But I plan (i.e. hope) to do more writing here in the future. But what's the reason for today's post? Namely this video posted on your tube. The conclusion is that humans are destined to explore the Local Group of galaxies, and that is it. And this video has received a bit of circulation on the inter-webs, promoted by a few sciency people. The problem, however, is that it is wrong. The basic idea is that accelerating expansion due to the presence of  dark energy  means that the separation of objects will get faster and fast, and so it will be a little like chasing after a bus; the distance between the two of you will continue to get bigger and bigger. This part is correct, and in the very distant universe, there will be extremely isolated bunches of galaxies whose own gravitational pull overcomes the cosmic expansion. But the rest, just ho

There was a movie, in the old days, Journey to the Far-Side of the Sun  (also known as Doppleganger) which (spoiler alert) posits that there is a mirror version of the Earth hidden on the other side of the Sun, sharing the orbit with our Earth. The idea is that this planet would always be hidden behind the Sun, and so we would not know it there there. This idea comes up a lot, over and over again. In fact, it came up again last week on twitter. But there's a problem. It assumes the Earth is on a circular orbit. I won't go into the details here, but one of the greatest insights in astronomy was the discovery of Kepler's laws of planetary motion , telling us that planets move on elliptical orbits. With this, there was the realisation that planets can't move at uniform speeds, but travel quickly when closer to the Sun, while slowing down as their orbits carry them to larger distance.  There has been a lot of work examining orbits in the Solar System, and you can  s

A long time ago, I wrote a post about the  Physics of Rendezvous with Rama , a science fiction story by  Arthur C. Clarke  set on an immense alien spaceship. The spaceship rotates, providing the occupants with  artificial gravity , a staple of science fiction. I mentioned in the article that I am not an immense fan of a lot of science fiction, as much of it relies on simple "magic", but Clarke knew his physics and so he knew that the "gravity" experienced in the rotating ship will differ to that on Earth, and previously I wrote about what happens if you jump off a cliff. In the last week, there was a question on twitter (it's an internet thing) about the movie  Elysium  which has a spectacular rotating spacecraft with the Earth's rich abroad. While it's a shame that the plot was not as spectacular, the question was how can such a station keep it's atmosphere. This is an interesting question, as you might think that it would all simply zip off