Archive for the 'review' Category

[Book Review] The Demon-Haunted World, by Carl Sagan

Demon-Haunted_WorldSummary: If everyone read and understood this book, the world would be a much more sensible place. It should be required reading for everyone, whether they’re interested in science or not.

Review: The Demon-Haunted World: Science as a candle in the dark is in my opinon one of the Carl Sagan’s most important works. In it, Dr Sagan does nothing less than explain how science works, and provides a clear framework for readers to understand how to view the world rationally and skeptically.

While the internet is potentially a veritable goldmine of information, nowadays it is a double-edged sword. On the one hand, it’s a great resource for research and learning about the world if you know how to look for relevant material and how to assess it and filter out what you don’t want or need. On the other hand, there’s a lot of noise to wade through, consisting of wacko pseudo-science, crazy conspiracies and New Age ideas like the end of the world in 2012, Nibiru, faked moon landings, “Intelligent Design”, religious raptures, magic healing rocks, crop circles, “energy healing” and other such nonsense. Much of this is presented “authoratively” and if a reader doesn’t know better – or doesn’t know how to question these ideas – then it’s not surprising that people can be taken in by them.

While many of these ideas gained popularity after the book was first published in 1996, The Demon-Haunted World is aimed at addressing this problem. Thematically, the book is divided into three parts – the first few chapters present some of the pseudoscience ideas (those prevalent during the 1990s, at least) and debunks them by discussing them skeptically and presenting reasoned scientific arguments against them. The second part – the meat of the book – presents the “Baloney Detection Kit”, which describes how science works and how to think logically and skeptically about what you’re presented with in order to determine an idea’s validity. Can the idea be tested? Can the facts be confirmed independently? What happens if the idea is extrapolated beyond its initial statement, etc? This is an invaluable manual for honing one’s critical thinking skills – something that sadly doesn’t seem to be taught much as a specific subject at schools and universities, and seems to be very much lacking in the world today. The final part of the book is more a collection of essays related to the theme of science communication, the standard of science education in the US, and freedom of expression (with a bit of politics thrown in) – not directly relevant to the rest of the book perhaps, but still an interesting read.

Science is presented as a “light” that shines against this oncoming “darkness” – dramatically put perhaps, but I do genuinely think that there is a real danger that scientific ideas are slowly being cast aside in favour of superstitious nonsense. Already we have had politicians with “faith-based policies”, “alternative medicine” touted as being superior to real medicine without clinical trials or peer-reviewed studies, and pseudoscientific garbage against evolution presented as a valid alternative in school science classes. Is this really where we want to be in the 21st Century? I don’t think so, and I fully believe that these ideas should be actively fought against wherever they may arise.

The Demon-Haunted World most likely won’t convince people who are already hardcore believers in pseudoscience of the fallacy of their ideas – they’re probably too far gone for that – but it can at least be used to immunise others against their ideas. It provides a very useful mental toolkit, not only when it comes to understanding science but also for constructing a rational view of the world in general. As such, I think everyone needs to read this book!

[Book Review] How I Killed Pluto and Why It Had It Coming, by Mike Brown

Summary: A tale of discovery, long hours, family and scientific skullduggery! Very enjoyable and easy to read, and well worth picking up!

Review: Readers who are familiar with this blog may have already gathered that I have a strong interest in the question of “What is a planet” and the events and discoveries surrounding that debate. So when Prof. Mike Brown (the discoverer of Eris, the object that ultimately toppled Pluto from its perch as the ninth planet) published a book describing his side of the story I was naturally keen to read what he had to say about the affair.

Continue reading ‘[Book Review] How I Killed Pluto and Why It Had It Coming, by Mike Brown’

[Review] Fun with Gravity Simulator

Lately I’ve been playing around (again) with a very interesting program called Gravity Simulator. I’ve been using it on and off for the past four years or so, and it’s proved to be a very useful tool for worldbuilding.

Gravity Simulator is a Windows-based program that allows you to create celestial objects orbiting eachother and see what happens to their orbits under the influence of gravity. You can create planets orbiting stars, satellites orbiting planets, and even asteroid belts – if it can orbit something, it can be made to work here. The algorithms used in the program don’t quite account for everything (for example, the change in orbit caused the transfer of angular momentum between two bodies by tidal forces is not calculated), but the results are still very accurate.

Planetary orbits evolving (spiralling outwards) while a star loses mass

The good points are that it’s a very powerful orbital modelling tool, and known phenomena such as orbital resonances and the Kozai mechanism (where a planet’s eccentricity can be increased by interactions with a nearby massive object in an inclined orbit) have been known to naturally come out of the simulations. It can also output to a data file that you can then use to plot graphs of parameters using Excel (e.g. semimajor axis vs time), and can output screenshots too so that you can make animations if you have movie-making software.

To create a system, you just enter the mass and orbital parameters for all the objects and then set it going – you can even create entire asteroid belts by getting it to create many objects with a range of parameters that you specify (though the more objects you have, the more processing is required which obviously slows things down). The program uses a ‘timestep’ system, in which it recalculates everything once per timestep – a smaller timestep means that the resolution of the interactions is higher and they are more accurate as a result, but the downside is that it takes longer to do the calculations. If the timestep is set too large however then the accuracy can be compromised – so the trick is to find a value that is a balance between processing speed and accuracy, which varies depending on what you’re looking at. If you do it right though, you can run a simulation for hundreds of thousands (or millions) of years of simulated time if your system is left running for long enough. This literally brings stuff that formerly was done on supercomputers into the hands of desktop users!

To show off a bit, here’s a relatively basic example of a sim I made – 10 closely spaced planets the same size and mass as Earth, separated by 0.1 AU between 1 and 2 AU from the sun. This is what happens when the system is left to run for 175000 years (every second of video corresponds to the passage of 747 years of simulated time) – all of the action is in the first 2:50 mins of the video, after that nothing much happens other than a bit of precession of the remaining orbits. The planets start off in circular orbits but then they start to get unstable and individual worlds eventually start making close approaches to eachother, which really disrupts their orbits. This one has it all – orbital precession, collisions, and planets thrown into very eccentric orbits! At the end of the run, only four planets are left, and I suspect that if I’d left it running for longer one or two of those might eventually be lost too.

Orbital Evolution of 10 close planets, simulated over 175,000 years

There’s a good discussion forum for it too, and the author of the program is there quite often and is very helpful. Being a rather specialised program, only a handful of people post to the forums on a regular basis (I am one of them – I post there as “EDG”) but there’s a lot of interesting material posted there (especially by frankuitaalst, who posts a lot of very interesting animations and graphs of resonances). I’ve done some investigations myself of the Kozai mechanism, and used the program to track the evolution of asteroid orbits while a star loses mass as it changes from red giant to white dwarf.

This is why I think Gravity Simulator is so great – it’s an excellent tool for curiosity-driven science (the best kind of science, I think!). I know that more often than not I didn’t have a clue what the result would be when I started running my simulations, and it’s really fun to see how a complex system turns out. As a result, it’s fantastically educational too.

The downside is that the program is a little fiddly to use, and it’s probably going to be a bit scary at first if you haven’t had any previous experience with orbital dynamics. There are example simulations that you can download from the gravity simulator website though, and you can find the Tutorial/Help File there too which explains how everything works (you can also access this page through the Help menu in the program). Plus you can always ask for help on the forums if you’re stuck!

Another thing to be aware of is that the version of the program that you can download from the website via the download page there is somewhat old – once you’ve installed it from there, you should grab the latest beta of the executable from the forums, copy that into the folder you installed it to, and use that as the executable instead. This adds some very handy functionality, including the ability to create new objects with a range of values (handy for asteroid belts) and to dynamically vary the timestep so that it slows down when objects get close enough to gravitationally interact.

Overall, Gravity Simulator is a great educational tool and produces some fascinating results. It’s pretty much unsurpassed as an general orbital modelling tool (I’m sure orbital dynamicists use their own custom programs that are way more technical, but this is great for us non-professionals!), and there’s a lot of support for it (many sample simulations can be found on the rest of website as well as on the forums). It’s well worth checking out and playing around with anyway, and if you have any interest in orbital dynamics then it’s a must-have!

[Book Review] Voyager, by Stephen J Pyne

Summary: If you want to learn about the Voyager mission, then this is not the book for you.

Review: Being a Voyager fan, I really had high hopes for this book. Unfortunately, it isn’t the book I thought it would be.

I was hoping that this would be a definitive book describing the Voyager mission in detail and talking about its goals, the troubles and triumphs it encountered as it travelled through the solar system, the new discoveries it made and how they revolutionised planetary science (and how it captured the imagination), as well the people involved in the Voyager project.

What I got instead was a lot of meandering, historical waffle comparing Voyager’s exploration of the solar system to past historical ages of discovery, with a few little nuggets of actually Voyager-relevant detail thrown in. I’d say that about 80% of the book is historical waffle, and 20% of it is actually about Voyager. After a while I was actively skipping pages of the historical stuff (which I really wasn’t interested in) to get to the Voyager “meat”, but in the end even that couldn’t hold my attention because there just wasn’t enough of it. The descriptions of the planetary encounters contain very little actual information and a lot of the really cool stuff is glossed over as if it was a distraction to the real purpose of the book. This is surprising given that the book is divided quite methodically into the various phases of the mission (e.g. Cruise, Asteroid Belt, Cruise, Jupiter flyby, Cruise, Saturn flyby, etc) – it’s not as if there isn’t enough science or stuff happening involving Voyager itself fill up those chapters! I got through about half of the book before giving up, because it turned into a very frustrating read – had I continued I think I would have thrown it against the wall in anger! And skipping through the rest of the book, I didn’t really see any change for the better later on either.

To be fair, its subtitle is “Seeking Newer Worlds in the Third Great Age of Discovery”. That being the case, I was expecting a little bit of historical comparison, maybe a chapter at most at the start… but the author scatters this throughout the whole book, breaking off a perfectly good narrative about Voyager itself and veering off on vaguely related tangents about Vasco Da Gama, Magellan, Cook, and Darwin’s expeditions. Even when it’s on topic, it hops randomly back and forth between Voyager itself and the politics and history of what was going on at JPL on Earth, which is somewhat jarring and more annoying if you just want it to focus on Voyager. The reviews on Amazon raise the same issues as I’m describing here, and in retrospect I really should have read them before picking this up. Oh well.

I suppose that if you were actually looking for a book that was low on actual science and high on the author’s opinion about comparisons between planetary discovery and exploration and the historical exploration of new lands on Earth then this book probably has a lot going for it in that regard. Even then though, the author wanders around all over the place with his discussion, and expounds and opines and waffles on with annoyingly flowery language that rapidly grated on me. In the end, I don’t really think it rightfully belongs in the Science section of a bookstore, but rather in the History section instead.

Maybe I’m being overly harsh, and I’ll admit that my negative review is in part because I was expecting the book to be something different to what it actually was. But even then, I think it still lacks focus and that it isn’t actually very well written either.

In short – if you want to learn more about the Voyager mission itself (rather than its historical context), I can’t recommend this book at all. I am searching for a better book on the subject, and I have it on good authority (from the Voyager2 twitter feed itself!) that “Voyager Tales” by David W. Swift or “NASA’s Voyager Missions” by Ben Evans are much more like what I hoped this book would be (the latter looks particularly promising).