Saturday, December 15, 2012

Review: Blue Silence by Michelle Marquardt

This  review is posted as part of my Australian Women Writers Challenge. I have cross-posted it from my review blog. I have now completed the Australian Women Writers Challenge for 2012, and you can read my de-brief here.

Blue Silence by Michelle Marquardt was originally published in 2002 and is sadly now out of print. Although I see it's in stock at Infinitas as of this writing. It was a winner of the George Turner Prize (as my edition proclaims on the cover).

The story opens when a mysterious ship docks with one of the space stations in orbit around Earth. The ship is, on the outside, an exact replica of one that was sent out into deep space 180 years ago, and then never heard from again. The difference? This ship has new drive technology which was only invented a couple of years ago. And instead of the seven original crew members, it's full of stasis pods and five hundred creatures, half of whom look human, half of whom look almost human.

None of the aliens know where they came from or why — they have no memories before waking up docked with the space station — and the authorities on the space station don't really know what to do with them either.

Senator Maya Russini is the leader of the group of people who first board the ship. A mission which one of the group does not return from alive. Are the aliens dangerous? What do they mean for the various political machinations happening within the space station's government and between them and other governments?

I liked Maya. She was an excellent example of a female character that doesn't need to run around kicking people in the head to gain power. She's also secretly a telepath (secret because she didn't register when she turned 21), but in a nice twist, she's the weakest kind of telepath, only able to read emotions, not thoughts. I think Marquardt has done a good job of portraying a society in which women are equal without making a big deal of it. (There are, in the end, more male characters, but that's mostly because the two main aliens are male.)

Her friend Ienne, the Minister for Foreign Affairs, also gets involved with the aliens. Unlike Maya who mostly regards them as suspicious and dangerous, Ienne is always looking for a way to use them to his advantage (there's a treaty they and another space station are wrestling over). He also goes out of his way to be rude to everyone with the occasional exception of Maya.

As I noticed when I was past half-way, Blue Silence is a very character driven story, unusually so for science fiction. The world does not need saving, nor does any war break out. Instead the action comes directly from the interactions between the characters, including two of the aliens who I don't think I can say much about without spoiling key elements. There is excitement and there's no missing the climax, but it's not like a plot driven story where all the action was building up to an inevitable climax and world-saving event. In the end, we know more about the aliens, but we don't know everything. Some answers are only hinted at or presented as speculation. In a way, this was slightly annoying because I like to know all the answers (arguably why I'm a scientist in real life), but it worked for the book. The story wasn't about the people trying to study the aliens, it was about people whose paths happened to cross theirs.

Also, the science, which I feel obliged to comment on, was well done. It wasn't a technology-oriented story, but having been published ten years ago, there was a risk the technology would feel a bit dated now. It didn't. They didn't have smart phones, but they did have pagers which were functionally mobile phones and received the equivalent of email on ubiquitous computers. There was also a discussion on the merits of different kinds of space stations (mimicking Earth versus giant building floating in space) which was interesting.

I highly recommend Blue Silence to anyone looking for something a bit different in their science fiction. It also emphasises the variety we have in the Australian science fiction field, something you might miss if you only looked at the most recent few releases.

4.5 / 5 stars

Friday, December 7, 2012

Year-long days and living in them

This blog post was inspired by an email conversation with someone regarding the possibility of a planet having year-long (or half-year long) day/night cycles. The original question was whether this is even possible and whether such a planet would be habitable.

From a purely astronomical point of view, this is definitely possible. There's no reason why you couldn't have a slowly rotating planet at around the same distance from it's sun as Earth is (well any reasons that do exist are fairly theoretical so we can ignore them). That said, if the planet is similar to Earth and its sun is similar to ours, then you kind of have to have the same length year because the length of the year (ie how long it takes to orbit the star) depends only on the mass of the star and the distance from it. This is due to Kepler's Laws, which I have previously discussed here. If you made no changes to star/planet distance, the year length would have to be the same.

Image nicked from Wiki here. The little red line
represents the same point on the surface of
Mercury. The numbers are the order in which
the positions happen: 6, 1, 2 are night for
the red line and 3, 4, 5 are day, roughly.

You could also have something similar to Mercury which has three rotations (called "sidereal days" which are measured relative to the stars, not the sun) to two years. Because it rotates so slowly, weird stuff happens with its solar days (the light/dark periods, completely ignoring the positions of stars) so that in one year it experiences half a solar day. Mercury is like this because it's so close to the sun. It could have been tidally locked (the same side always facing the sun – discussed further, including for Mercury in particular, here) but the gravitational effects of the other planets in the solar system caused this more unusual resonance.

However, if we're talking a planet as distant from the sun as Earth is, there's no danger of it becoming tidally locked in the sort of cosmological time frame we're currently living in. The time taken for the angular momentum between planet and star to be distributed into the tidally locked configuration takes longer the further apart they are (and the less massive when they're close enough). The Earth-moon system will eventually become more tidally locked: the moon already faces the same side towards us all the time, and eventually the same side of Earth will always point towards the moon.

But that's a bit of a tangent, back to planets with long days and nights. You could have a planet rotating as slowly/quickly as you like, but you should be mindful that the people living there would almost certainly have a way of distinguishing between sidereal and solar days. Ancient people on Earth already had this worked out (the difference between sidereal and solar days is why the stars move across the sky with the seasons).

Living there

Uranus: almost completely sideways.
If you did have a planet with a year-long day, the periods of day and night would be roughly equal in the same way they are on Earth, just scaled up. It could vary a bit depending on the planet's axial tilt (how much the line between the poles is tilted relative to the plane of it's orbit — Earth's is around 23º and changes slightly when earthquakes occur) so the more inclined the axis, the more extreme the seasons. If there was no or very little axial tilt, there wouldn't be seasons. The other variable in day/night lengths is the latitude. Further away from the equator sunrise and sunset would last longer and the shortness of winter days and length of summer days would be more extreme (as on Earth, but a different axial tilt could make this more so). If there was no axial tilt, the poles would be in a state of twilight permanently. The other extreme is something like Uranus which has a 90º-ish axial tilt so that during a southern summer the south pole points towards the sun and during a southern winter the south pole gets no sun at all. Spring and Autumn are the transition period. The equator is in twilight during summer and winter and has more "normal" days, like what we're used to, during spring and autumn.

Also, astronomical plausibility aside, I'm not convinced complicated life could naturally arise on a planet with a super-long day/night cycle, due to the long periods of boiling (day) and freezing (night). In terms of temperature-stability, probably only the twilight areas would be habitable. I suppose you could have migrating species (but that also has problems because in staying in permanent twilight they'd need sufficient landmasses connecting the two poles). Also, you'd probably get some sort of storms around the twilight zone, since the temperature would be in in a state of flux. I'm not an expert on atmospheres or meteorology, though, so that's a (-n educated) guess and I can't be too specific. But in short: our 24 hour days are what keeps Earth's temperature relatively temperate and suitable for life.

There's be fewer issues for microbial life to arise but I don't know that anything larger would be viable. Maybe at the poles: if the planet was slightly closer to its star than Earth is, there could be non-migratory life living near the poles and with a stable orbit and rotational period, it should survive. Since the non-polar regions wouldn't have naturally arising complex life, there could be with completely different ecosystems/forms of life at either pole with only something like microbial ancestors connecting them.

Sunday, October 21, 2012

Atmospherically Speaking

Today I have another Ask Tsana post.

Brookelin asked:
Hi again, Tsana.

I was wondering - in an alternate universe, what would it take for a species to survive on Mars?

I know that it has some atmosphere, but not a whole lot. With the pressure being below the Armstrong limit, could there feasibly be large creatures (between collie and bear size) that could survive would have higher thresholds and what would they need to do so?

If the water on a human's tongue boils in space, would an alien creature in these environments be able to have eyes and mouths?

What might these species' need to overcome the intense radiation caused by Mars' weak magnetosphere?

Could bio-genetically enhanced humans ever survive these conditions outside a space suit for periods of time upwards of an hour, but less than a day?

Are these too many questions? Do you know the answers to any of them, or is this more of a medical thing?
I don't have answers to all of these questions because, as Brookelin said, some are more medical/biological and that's not my area of expertise. I will say that what we generally know a lot about is life on Earth. There are some constraints that exist for life on other planets but there is nothing to say that it has to resemble Earth life. They could have eating and seeing organs completely different to what we're used to. Even on Earth there's a pretty wide variety. I'm not sure that merely genetically enhancing a human would be enough to let them walk around on Mars. Science fictions stories have gone there, but I'm not sure genetics is up to it. I could be wrong, I'm just guessing. Hopefully my comments below on atmospheres and life on smaller planets such as Mars will answer the rest of the questions, though.

Mars. Credit: NASA, ESA, and The Hubble Heritage Team
It's true that Mars has a very thin atmosphere; it's about 0.6% as dense as Earth's at their respective surfaces. Part of the reason for this is Mars's lower gravity. In general, gases will expand to evenly fill the container they're in. When the container is a planet's gravitational field, we get denser air closer to the ground and less dense air higher up. This is because the air higher up is pushing down on the lower air while having less air above it to push it down. More or less.

Air is made up of particles (atoms and molecules) which move around very quickly and bounce off each other. That's why a gas is a gas and not a liquid or solid: the particles in a liquid don't move quickly enough to completely overcome the forces attracting them to each other and the particles in a solid can't move more than vibrating on the spot because the forces holding them in place are so strong. The energy that makes the particles move, for all states of matter, depends on the temperature: the hotter, the faster. The other important consideration is particle mass. At the same temperature, oxygen and hydrogen molecules (O2 and H2) have the same energy. However, oxygen weighs sixteen times as much as hydrogen (because the atoms are larger and heavier) so it takes more energy to move oxygen molecules at the same speed as hydrogen molecules. The result is that at the same temperature, oxygen molecules move more slowly than hydrogen molecules. And it takes less energy for hydrogen molecules to reach escape velocity (the speed required to escape the gravitational pull of Earth/whatever planet) than oxygen. And that's why there is very little hydrogen in Earth's atmosphere despite it being the most abundant element on a cosmic scale — it escapes into space. It's also the reason only the gas giants, notably Jupiter and Saturn, have any significant about of hydrogen in their atmospheres — they have the strongest gravitational fields.

So, Mars. Mars is smaller than Earth, with about a third the acceleration due to gravity at its surface. Mars is made up of similar elements to Earth, most likely because they formed so closely together, so it's likely that the same sort of lighter elements could have made up Mars's atmosphere. However, due to the lower gravity, not only hydrogen but oxygen and nitrogen would also have escaped or never been captured by the planet. I would guess the main reason there's so much frozen carbon dioxide at the poles is because it has a relatively high melting point of -78ºC rather than the much colder melting points of oxygen (-219º C) and nitrogen (-210º C). For comparison, Mars's surface temperatures vary between -143º and +35º C. So basically, even if you imported or mined enough gas to raise the air pressure to human survivable levels, it would all be lost into space and would need constant replenishing which would get tedious and be difficult to sustain. You'd also, ideally, raise the surface temperature to more consistently human survivable levels — probably using some sort of greenhouse effect to trap more of the sun's energy — but that would just hasten the atmosphere's escape.

Titan's atmosphere as seen by Cassini. Credit: NASA
But all is not lost. Heavier molecules exist, particularly those made out of carbon. Titan, one of Saturn's moons, is smaller than Mars but has an atmospheric pressure greater than Earth's by about 45%. It's colder than Mars, which allows its atmosphere to condense a bit, but it's only got a surface gravity of around a seventh that of Earth's (less than half of Mars's). According to Wiki, its atmosphere is composed mainly of nitrogen (as is Earth's) and methane with some traces of heavier carbon molecules. It's a combination of the temperature, the distance from the sun, Saturn's magnetic field and some form of replenishing methane that keeps Titan's atmosphere thick and, well, full of methane. Distance from the sun is significant by itself because Titan is far enough that the ionising solar wind is weak enough to not completely ionise and destroy the top layers of its atmosphere. The same strategy probably wouldn't work on Mars to increase the atmospheric pressure permanently unless you could find some magically resistant to solar radiation molecule to populate the atmosphere with. There are two interesting theories for what keeps replenishing the methane on Titan (which should be destroyed even by the lowered energy it receives from the sun): cryovolcanoes — volcanoes shooting icy hydrocarbons instead of lava — or biological processes using/generating methane in place of water.

The high levels of ionising radiation on Mars are as much due to its lack of atmosphere as its lack of magnetic field. (Side note: there's evidence that there was a magnetic field on Mars in the past, though I don't think we know why it went away.) Earth's atmosphere absorbs a lot of the ionising and UV radiation the sun throws at us (part of the reason the ozone layer is important). Not all of it is deflected — and things like X-rays and gamma rays can't be deflected because they don't have an electric charge — especially near the magnetic poles where the aurorae are caused by charged particles, mostly from the sun, interacting with the atmosphere. However, giving Mars a magnetic field would definitely help. Earth's is generated by molten iron in its core so it's not outside the realm of over-dramatic science fiction to drill a hole into the centre and start the core spinning. Come to think of it, Hollywood's already done that, just with Earth not Mars. (For the record, the ridiculous issues with that movie include the structural integrity of the hole and the failure to correctly represent changes in gravity.) A more feasible way to avoid radiation on Mars would be to live underground so that the ground above you did the work of absorbing harmful radiation. The reason too much radiation is bad for all forms of life is that it destroys and changes molecules. In humans this is one of the causes of cancer. In microbial life, which might only have a few cells to begin with, it's more deadly. It's why sterilising things with UV light works.

So basically, the easiest way to get people living and wandering around on Mars is to have them live in airtight structures and give them suits for walking around outside it. The suits wouldn't have to be as extreme as space suits though, so that's something. I'm not saying it's completely impossible to walk around on the surface with less protection, just very difficult. And because someone will mention it in the comments if I don't, I've heard that Kim Stanley Robinson's Mars books, starting with Red Mars, do a good job of talking about the terraforming process, although I haven't read them. Ben Bova's Grand Tour of the solar system books (eg Mars or Saturn and Titan) explore alternative forms of life all over the solar system. If you can stomach a bit of sexism, some of them are worth a read.

Monday, October 1, 2012

Turning around in space

Another ask Tsana question today. (And a relatively shortish response, sort of. Gasp!) Keep 'em coming, guys :-)

Anon asked:

How hard would it be to turn around in space... Say for some reason, Curiosity needed to turn around midflight and return to earth. Would BURNING fuel on some sort of reverse thruster work or would it have to make the trip to Mars, orbit the planet and break orbit to return
This is for a picture book that I feel impelled to be at least somewhat based in reality... which may be dumb.

Hi Anon,

It's absolutely NOT dumb to try to make picture books or any sort of books for kids plausible or semi-plausible. Especially when it comes to these sorts of areas where they can't possibly have any hands-on experience. Hollywood bombards them (and all of us) with so much inaccuracy that any little bit of truth helps. If they remember your book when they come to learn about these things later on, it will help the science stick. If all they have to go on are poorly researched movies which have given them wrong "intuition" about these things, it makes it a lot harder for them since they have to unlearn the rubbish first.

On to the actual question part!

It's pretty tricky to turn around in space. Because there's no friction, you have to use the same amount of energy it took to speed up to slow down by the same amount (so to come to a stop, say). This is a huge waste of fuel. Changing course more subtly isn't as difficult, however.

Apollo 13 Movie poster. (Nabbed from Wiki)
For something specifically like Curiosity: an unmanned probe sent to another planet, I can't think of a reason they'd try to get it back to Earth (unless a sample return was specifically part of the mission plan, but I don't think that's what you're asking). If something went wrong, they'd be more likely to cut their losses and abandon it. Also, almost all of that kind of probe's fuel is used up during take off, leaving only enough for minor course corrections and landing. In that case, plausibility would dictate that attempting a gravitational slingshot around Mars would be the only way to maybe get it back. You'd also have the issue of how to collect it from Earth's orbit since a) Earth would have moved a lot while it was travelling and b) if you were lucky enough to get it to pass close to Earth, it would be travelling quite fast and probably wouldn't have enough fuel to go into orbit around Earth for collection. It would definitely be tricky.

A very good example of a scenario relating to your question is the movie Apollo 13. If you haven't seen it, I recommend that you do. As far as I can remember (and I freely admit it's been many years since I watched it, so don't hold me to this), the physics in it was pretty accurate. In that, things go wrong with the (real life) 70s moon mission and, among other fixes, the astronauts have to slingshot around the moon to get safely back to Earth.

In the end, I'd say it depends on the nature of your mission as to what would be done. If it was a manned mission to Mars, for example, they might try harder to bring them back early, but physics would not be on their side.

Hope that answers your question!

Friday, September 21, 2012

Gravity and atmospheric pressure

I have another response to an "Ask Tsana" question today.

Brookelin asked:
I was wondering... with planets like Europa and possibly Ganymede, who possible have oceans, if humans made future settlements under said oceans, would the pressure from the water above counteract the effects of reduced gravity on the human body?

Interesting question. A preliminary point: it's Jupiter's moons Europa and Callisto that probably have sub-surface oceans (especially Europa), not Ganymede which is a solid rocky moon.

Europa, one of Jupiter's moons, has a vast ocean beneath
its surface. Credit: Galileo Project, JPL, NASA;
reprocessed by Ted Stryk
So, how do pressure and gravity work? In this context, gravity is the force that holds a planet/moon/star together and which attracts other objects to it. So we're all being pressed into the surface of Earth due to Earth's gravity. Pressure is the force a surrounding fluid (air, water, etc) exerts on something. So the atmospheric pressure we feel on Earth is pushing at us from all sides (well, OK, not out from the ground) and is due to all the air in Earth's atmosphere.

When you go swimming, the further you dive down, the higher the water pressure around you gets. This is because the deeper you are, the more water is above you to press down on you and the more water is above the bits of water on either side of you, also pressing into you. If you've ever been snorkelling (or scuba diving, I suppose but I can't vouch for that due to lack of experience) you might have noticed that it gets harder to breath the deeper you go (assuming a long enough snorkel). This is due to the water pressing down on your chest. Air does the same thing, but we're used to it, so we don't notice. The other thing that happens under water is that the water underneath you pushes up on you: this is called the buoyancy force and it's why things (people, tennis balls, icebergs, etc) float.

The higher up you go from sea level on Earth, the thinner the atmosphere gets (basically, the less atmosphere left above you). To halve the atmospheric pressure you experience, you need to go 5 km above sea level. (On the other hand, to double the pressure, you only need to be about 10 metres under water.) At that height, gravity is still pretty much the same as at sea level (the difference is about an eighth of a percent) and your main problems are getting enough oxygen (not a huge problem if your lung capacity is OK) and possibly altitude sickness (potentially a problem).

We need some amount of air pressure around us to survive which is part of the reason astronauts wear space suits. However, there is a range at which we can still function and that range increases if we have extra oxygen (and don't get altitude sickness). People have climbed Mt Everest (8.8 km above sea level) which has an atmospheric pressure of about a third that at sea level at it's peak without oxygen, but even doing it with oxygen requires training and acclimatisation and isn't something anyone can just decide to do one morning (well, unless they also decide to put in all the training).

On the surface of Europa or Callisto, there is no atmosphere and hence no atmospheric pressure. The ground is frozen water (probably not pure water, if only due to meteorite bombardment, but that's beside the point), but let's suppose we somehow got under the surface and set up a habitat. Since we're human and breathe air (a particular mix of mostly nitrogen, with some oxygen, carbon dioxide and misc) we'd have to have some sort of bubble habitat under the sea. But it's not just the air part that we need, we also need it to be around one (Earth) atmosphere of pressure. So we build a habitat with solid walls and fill it with the right amount of air... and then we're inside an air bubble and the water outside the bubble is having no effect on our bodies directly. The only way it would is if we went out into the water without pressure suits. Which probably wouldn't be the best idea in the world for a variety of health and safety reasons that don't necessarily have to do with the water pressure.

Now let's talk about gravity. The main way we detect small changes in pressure is though our ears, for example when they pop on taking off and landing in aeroplanes. The main way we detect changes in apparent gravity (which is the same as changes in acceleration) is when we feel lighter or heavier. If you're standing, this might manifest as extra strain on your legs, if the apparent gravity has increased, or a feeling like your stomach is moving upwards (possibly accompanied by nausea), if the apparent gravity has decreased. You don't experience the same feeling underwater or up a tall mountain because the gravity doesn't change in those places although the pressure does.

So what I'm ultimately trying to say is that the effects of gravity and atmospheric pressure are different. You can't compensate for a decrease in gravity by increasing pressure. Pressure is a force applied from all directions simultaneously, while gravity acts in just one direction. We know about the effects of Earth gravity, high gravity (from fighter pilots for example) and zero/microgravity (like on the space station) on people but much less about the effects of gravitational fields less than Earth's and more than zero. Europa's and Callisto's accelerations due gravity at the surface are about 13% Earth's and for comparison, the moon's is about 17% Earth's) so while we have had some experience with the moon landings during the Apollo missions, we don't really know how serious the health problems associated with spending prolonged periods at such low accelerations would be. There almost certainly would be some, but they probably wouldn't be as severe as zero gees. So while we can't use water pressure to compensate for gravity, it's not impossible for people to live on one of the moon's of Jupiter. We just don't know enough about what long term problems might arise.

Wednesday, July 25, 2012

Quick note on terraforming Galilean moons

This post comes from an "Ask Tsana" comment.

Sam Keola asked:
Aloha from Hawai'i again Tsana! I have a hypothetical question. If in the very distant future we had the technology to terraform, would it be best to terraform Callisto and Ganymede or set up domed bases? Ganymede is suppose to have an ocean similar to Europa, but I'm not sure if that's "world wide". Your thoughts on terraforming!
The main problem with terraforming either of those moons is their gravity isn't large enough to keep any atmospheric gases for long after they're introduced. Ganymede, which is larger, has a surface gravity of close to a seventh of Earth's which is less than half of Mars's and Mars has difficulty keeping much of an atmosphere itself. Purely from that point of view, domes or something else sealed would be better.
Credit: Galileo Project, Voyager Project, JPL, NASA

Once you've decided to build something sealed, then it would be better for colonists to build on Ganymede, as opposed to the other Galilean moons, for a few reasons:
  • It has the highest surface gravity, not by much but every little bit would prevent colonist's bodies from degrading. Actually, because the Galilean moons are less dense than Earth's moon, they have a lower surface gravity, despite being larger in volume. You're going to have low gravity-related heath problems in any case, however.
  • It's not as close to Jupiter as Europa (and Io!) is. The phenomenon responsible for keeping Europa's interior liquid is tidal friction thanks to its proximity to Jupiter. It's the sort of thing that also makes the surface more unstable (prone to volcanoes -- not as much as Io, of course -- and quakes) and less hospitable to people. You can read more about it here.
On the other hand, if what you're doing is mining and the minerals etc you're interested in are found on both Ganymede and Callisto, then Callisto is the place to put your colony. It's gravity slightly lower and, more importantly, it's further from Jupiter, meaning that when you're exporting your rocks, there's less gravitational pull from Jupiter to overcome.

In terms of finding water to mine, all three moons in question (ie, not Io) have water on them, so that shouldn't be too much of a problem, especially if you're already planning to mine other things.

Of course, there are also reasons why Europa would be a desirable place for a colony, especially for scientific reasons, exploring it's subsurface ocean primary among them. There's a good chance there's microbial life there.

So there you have it, if you're going to colonise the larger Galilean moons, it's better to build a close structure on them rather than try to impart an atmosphere. It would be even harder than giving Earth's moon a permanent atmosphere.

Thursday, June 7, 2012

Review: Polymer by Sally Rogers-Davidson

This  review is posted as part of my Australian Women Writers Challenge. I have cross-posted it on my review blog.

Polymer by Sally Rogers-Davidson is a science fiction story which I would categorise as adventure. Apart from being in first person, it reminded me of pulpy SF adventure stories from way back when. Except with a female protagonist and, like, more female issues than would ever have come up in those books.

The main story takes place within the pages of a long-lost journal written by Polly Meridian (aka Polymer). On the night of her graduation ceremony, her space station home is invaded by aliens. (Aliens, in this book, pretty much means "people not from the same place as me who might be human or could be blue aliens".) She almost dies in the invasion but is "lucky" enough to be taken prisoner and enslaved instead.

Without spoiling any plot, a lot of things happen to her. Some of them are externally driven (like being taken prisoner) and some are on her own initiative. Either way, the book is full of action (although I thought there was a bit of a slump shortly after the invasion, it definitely picked up later on).

Unlike Spare Parts, the other Sally Rogers-Davidson book I've read, I wouldn't call this one YA. Sometimes the writing felt like it could be and the main character is horribly naïve as isn't uncommon in YA, but ultimately the book dealt with more grown-us issues. I wouldn't stop a teenager reading it — it's not very M rated (there's sex and a bit of rape but it's mostly off screen or not described in detail) — but I wouldn't call it YA. Also, I think the main character is right on the cusp of the YA protagonist age range.

There were some problematic elements in the book. I don't want to spoil anything, but I felt a bit uncomfortable by Polly's shifting attitudes towards one of her captors. Given earlier events, it just didn't sit well with me, even though I could understand it from her point of view.

I would recommend Polymer to anyone who enjoys a SF adventure story. I think Rogers-Davidson's writing style improved in Spare Parts, but that's understandable since Polymer was published four years earlier and I think it was her debut novel. If you enjoyed Spare Parts, give Polymer a go. It's a very different setting, but there are some similarities in outlook (relatively cheery). From a science point of view, it's fairly soft. There's hyperspace and FTL comms but it's not trying to be realistic, so the lack of rigour is in no way abrasive.

If you're wondering about the different covers, the top is the recently released ebook cover (which is the version I have), the middle is the original paperback cover, now out of print, and the bottom is the re-released paperback. I think the bottom is my favourite.

You can currently purchase Polymer from Lulu in paper or ebook formats. Hopefully the ebook will be coming to Smashwords and other retailers soon.

3.5 / 5 stars

Saturday, June 2, 2012

Other Foreign Skies

This post is a response to a question I got on my Ask Tsana page.

Sam Keola asked:
Love the views of Jupiter from Ganymede and Io. How large would it appear from Europa or Callisto? And how large exactly would the sun appear? (I know tiny as hell, but another lovely picture would be amazing.)
The mathematical answer to that is explained in this old post. And my first set of Jupiter images (Io and Ganymede's skies) can be found here.


This time around, I used a different image of Jupiter so if you're wondering why it's rotated relative to the old pictures, that's why. For the Jovian images, I've used the same starting image because in the year since I last did this, I haven't managed to take a more suitable photo. Such is life.

The original photo with a full moon in Earth's sky.
So. Europa is the second Galilean moon out from Jupiter. It's made mostly of ice, is the smallest of the Galilean moons and might harbour life in its subsurface liquid ocean. The diameter of Jupiter as it would appear in the Europan sky is almost 24 full moons across. Remember that Europa's sky wouldn't actually look blue either since it doesn't have an atmosphere but I don't have a decent night skyline to work with. I'll do a night version eventually.

The size Jupiter would appear in Europa's sky. Or in Earth's sky if you swapped it with Europa.

You might be wondering whether Jupiter would actually be oriented the way it appears in these images. Well it depends. The direction the bands run relative to the moon's horizon would depend on where on the moon you were. Close to the equator, the bands would be vertical (although if Jupiter was high in the sky, it would be pretty difficult to tell. Perhaps better to say east-west). If you were near a pole, they'd be horizontal as in these images. And remember, the Galilean moons are all tidally locked, so Jupiter would never move, just change how much of it was illuminated by the sun.

And Callisto, the most distant of the Galilean moons. Callisto's Jupiter would appear "only" about 8.5 full moons across.

The size Jupiter would appear from Callisto. If Callisto had an Earth-like atmosphere and gum trees.

The Sun
The second part of Sam's question was how large would the sun appear from Jupiter. Well, on Earth, the sun and the moon appear to be approximately the same size (there's a little bit of a difference when the sun is at its closest and the moon at its furthest and vice versa). So the sun from Earth is about one full moon in diameter.

From Jupiter (or its moons) the sun would appear about 0.4 full moons across which is a little bit less than a sixth of the area of the sun as seen from Earth (remember, the moon and sun seen from Earth are on average the same size).

I cheated a little bit with these next two sun photos. They're actually two separate photos and I made the sun smaller in one of them. The reason the rest of the photo looks darker for the Jovian sun is because I was fiddling with settings on my camera. And if you're wondering why I chose sunsets, it's because those (and sunrises) are pretty much the only kinds of photos where the disc of the sun is properly visible.

Ordinary sunset on Earth:
Sunset. A little bit more than half the sun is below the horizon.
Sunset if Earth was at the same distance as Jupiter (but yet still warm enough to have liquid water. And plants. By the way, with these two, it's probably clearer if you click on the images to enlarge and compare the sun side by side.
A more diminutive sun, less than a sixth of the area of Earth's.
And there you have it. Photoshopped images (well, actually, I used Pixelmator) depicting the sizes of Jupiter and the sun from the Galilean moons and the Jovian system, respectively.

Monday, May 21, 2012

Cool article

Browsing the internets, I came across this rather neat article about Earth's final solar eclipse (many, many years hence). Check it out here. It talks about the moon moving away from the Earth until one day it will be too small to completely cover the sun in our sky.

If that sounds familiar, it might be because of this post I wrote about the moon being closer to the Earth in the (now cancelled) TV show Terra Nova. (Hint: not for the reasons they said in the show.)

Monday, May 14, 2012

Review: When We Have Wings by Claire Corbett

This review is part of my Science Fiction Australian Women Writers Challenge. You can check my progress here and about the challenge in general here. Since starting the challenge, I have started a review-only blog and this review is cross-posted there.

When We Have Wings by Claire Corbett is set in a vaguely near future Sydney where the rich can fly thanks to having wings implanted on their backs.

Before I get into talking about the story, I want to point out that, from a physics point of view, Corbett has described a very plausible situation. The wings people get are quite large (the impression I got was comparable to the height of the person) and they also get treatments to change the physiology to make their bones lighter (carbon fibre was involved) and their muscles stronger. And, of course, to grow the new muscles needed to control their wings. (For the record, the fictional wings were larger and more interestingly-coloured than on the cover, although it’s a nice cover despite that.)

I have little idea of how plausible the biology was, but assuming those biological modifications were possible, the physics seemed to check out (y’know, without actually writing out equations or anything). The descriptions of flight and weather patterns were also quite rigorous and I commend Corbett on her dedicated research. Those details made the book all the more realistic and helped with the suspension of disbelief so we could focus on the social issues surrounding flight.

The story follows two characters: Zeke, a PI investigating a nanny kidnapping the child of a flyer couple, and Peri, the nanny on the run. The mystery of why and where the nanny took the baby is not the real mystery, however — especially since about half the story is told from her point of view. The real mysteries become apparent when Zeke digs a little deeper and when events get away from everyone.

The setting isn’t a dystopia. Similar to what I said about Spare Parts, just because there is a widening gap between haves and have nots, doesn’t make it a dystopia. Especially when, other than the size of the gap, there aren’t many social or political differences to our world. It’s a commentary on where our world could go, given enough scientific progress. And it doesn’t make the assumption that the medical developments are inherently a bad thing, either. Partly, this is explored through Zeke having to make a choice as to whether to give his toddler son wings from an early age (it’s easier when they’re children) or whether to deprive him of flight and bar entrance into the elite flyer society.

In many ways, flight is a metaphor in When We Have Wings. However, it’s not just a metaphor, as evidenced by the rigorous world building and the real exploration of social issues surrounding flight. What makes us human? How much of a disadvantage is not being able to afford wings? Is being an ordinary human (in their world), without modification, edging towards being a disability since they can’t fly? There was a lot of background political discussion about equality and quotas (of non-modified humans) and equal access. In a world where everyone is expected to choose the most favourable characteristics for their unborn children and concerns like baldness are trivial to “fix” where do you draw the line? If you want an unadulterated genome, where does that leave you (other than as a member of the conservative anti-modification cult)?

Progress marches on.

When We Have Wings was an excellent read. I highly recommend it to fans of science fiction, fantasy and anything in between. I suspect it’s being at least partially marketed as main stream, so hey, all readers of fiction, go out and buy it!

4.5 / 5 stars

Thursday, April 26, 2012

Review: Black Glass by Meg Mundell

This review is part of my Australian Women Writers Challenge (see banner at side). Since starting the challenge, I've started a dedicated review blog (with fantasy as well as SF books reviewed) here. This post is cross posted from said other blog.

Black Glass, debut novel by Meg Mundell, caught my eye because it was shortlisted for Aurealis Awards in both the SF and YA categories. (And being written by a woman, hence counting towards my SF Aussie Women Writers Challenge also helped.)

The narrative style and presentation of the story and characters is exactly the sort I usually dislike. The scenes, as well as presenting the two most central characters in a reasonably conventional narrative, alternate scenic mood scenes (sometimes with a temporary character as a focus), often (always?) in present tense, and dialogue without any framing.

I’ve stopped reading books written like this in the past because they annoyed me. But you know what? Mundell pulls it off really well. I was captivated from the start, never bored and the ending packed an unexpected punch.

The setting is Melbourne, a depressing near future. A dystopia but a plausible one, scarily close to our world now. Just a little bit more technology, regulation and surveillance than today. Unlike certain other YA dystopias I could mention like The Hunger Games, Uglies or Divergent, there is no bizarre disconnect between our world and the world of Black Glass. (Infinitely so when you compare with Divergent — good book, but I found the back story mind-bogglingly implausible. You’re unsatisfied with the world so you sort yourselves into factions resembling Hogwarts houses? REALLY?) Also, it’s set in Australia, so it gets bonus setting points for not being doomed-US.

The most science fictiony element, and my second favourite part of the world building (my favourite being that it was set in Melbourne and I enjoy visiting home vicariously), was the side story of Milk the mood engineer. He uses scents and subtle changes in lighting to evoke moods and emotions in whoever is in range of his devices. His mission is to artistically make the spaces he works with more harmonious and the people in them happier. I thought it was a fascinating concept and explored with surprising depth in the relatively short novel.

The central-most characters, Tally 13 and Grace 16, are sisters who, up until the first chapter or so, have spent their lives following their deadbeat father around small Australian towns, often leaving town at a moment’s notice. The story starts when an accident kills their father and separates the sisters. They had been planning to run away to the city (Melbourne) “soon” but now they are forced to make their way there separately.

We follow the girls, the city and a few miscellaneous characters, sometimes obliquely, as they make ends meet, get by and wonder where their lives are going. By the time I was reading the climax, I was sceptical of a satisfactory ending but by golly, I was not disappointed. On the other hand, without spoilers, I can understand other people not feeling the same way.

I’m not sure I’d call Black Glass YA. The other characters are mostly adults and a lot of the concepts explored are things you don’t necessarily want kids to have to worry about. Of course, the reality is that many kids today do worry about similar things to Tally and Grace. I wouldn’t stop a twelve year old from reading it, but I would also encourage them to wait a few years. I could see it as the sort of book that might be studied in year 11 or 12, though.

In any case, it’s an excellent piece of writing. I highly recommend Back Glass to not only science fiction fans but everyone. Even if you think you don’t like science fiction, science fictional element in Black Glass is so minor you’ll barely notice.

4.5 / 5 stars

Thursday, March 22, 2012

Destroying the Earth

This post is inspired by a question I got on my Ask Tsana page. Katrina asked:
I'm trying to come up with a simple (haha) and plausible way to destroy a planet to kick things off for a story but am having trouble getting the science right.

One of the first sites I visited to figure this out was this Geocide site:

Under the Geocide in fiction page (, the author says, "The Sun Crusher is a relatively small ship which carries a small number of missiles, each of which is tough enough to shoot into the centre of a star and cause it to go nova, which would certainly annihilate any nearby Earthlike planet."

My question is, don't stars that get massive enough to go nova have brief lives and thus not live long enough for a habitable planet to develop? I'm just basing that on Wikipedia (, though, so I was wondering if you could tell me more. Can the habitable zones of massive stars ever actually be inhabited (and then later die in a supernova)?
Excellent question!

The answer depends a bit on to what extent you want to destroy your planet. Geocide pretty much defines "destroy the Earth" as "annihilate in the particle physics sense, or dismantle/tear apart on either a macroscopic (large) or microscopic scale". He doesn't count Earth as destroyed if there's still a planet-like object there. However, for many narrative purposes, rendering the Earth entirely uninhabitable will do the trick.

So, leaving the dismantling and annihilation to Geocide (the website is amusing, although be warned that some of the details of physics are slightly off, but close enough), what are some ways of rendering Earth unfit for life?

Destroy all humans

So maybe what you want is not so much to destroy the planet as to destroy all the people on it. That's not really that hard. Or, at least, destroying most of the people isn't that hard. Some methods, which generally don't require elaboration:
  • Widespread nuclear holocaust
  • Some sort of plague
  • Climate change. No, really, melt the icecaps and raise the temperature enough so that it is too hot and humid to survive without air-conditioning and eventually you'll run out of people. Or throw in some crazy weather disasters too. The Rhesus Factor by Sonny Whitelaw touches on this a bit (see my review here), also on the plague scenario.
  • Very large volcano eruption. This is one of the things thought to have caused at least one of the prehistoric dinosaur(ish)-era extinctions. A less epically large volcano (actually, a few of them probably contributed) in 1816 caused the Northern Hemisphere (or Europe and America at least, not sure that Asia was affected as strongly, but google it if you're interested) to not thaw out in the summer. This was "the year without a summer". (And now I have that Rasputina song stuck in my head. Click the link and you will too.)
  • Asteroid -- this one's a toss up between destroying all (most) humans and destroying all life. Ultimately, I suppose it's a matter of scale. Let's say this asteroid kills human life but not necessarily all the microbes. It would be somewhat similar to the volcano in the throwing dust and rubbish into the atmosphere, blocking out light and generalised doom.
  • Magnetic field of the Earth turning off in the process of flipping. This is something that happens spontaneously every so often. It's bad because a whole bunch of ionising radiation (miscellaneous charged particles) from space is kept at bay thanks to our nifty magnetic field. Taking it away would give us a lot more cancer and sterility and could wipe out a large chunk of humanity. Microbes and probably a lot of (some?) sea life would be OK. Good luck artificially killing the magnetic field, though.
All of those methods probably won't wipe out all life and, frankly, it's possible/likely that some tenacious dregs of humanity will hold on. Generally, evacuation is the surest way to avoid these apocalypses. Or prevention, but that's only really applicable in two or three of those scenarios.

Destroy all life

Why aim low? Bugger humanity and everything else with one of these sterilising scenarios:
  • Self-replicating nanobots (von Neumann machines) which consume all the [insert important chemical here -- carbon is popular]. This is also know as the grey goo scenario. Depending on the nanobots, this is likely to render the Earth inhospitable to life while they're still doing their thing.
  • Large asteroid/comet or small moon colliding with Earth. Where a small impact would cause natural disasters (earthquakes, tsunamis) and potentially block out the sun with dust, a large impact could do many detrimental things. It could change the Earth's rotation, knock it into a slightly different orbit (or send it spiralling into the sun, but that would require a particularly large body), it could smash the Earth into chucks (which, thanks to gravity, would probably later re-collide to form Earth 2.0), render an appreciable fraction of the surface molten... Actually, I now have a brilliant mental picture of two or six asteroids hitting the Earth simultaneously from opposite sides and sort of turning it into molten goop... Not actually sure that would work with two, but six seems faintly plausible in a hand-waving way. Anyway, point is, hit Earth with something big enough and bye-bye life. Depending on conditions, it's possible life could spontaneously arise again, depending on how reliably life arises and how long it takes (before, for example, the sun goes red giant).
  • Supernova/nearby gamma ray burst. The main problem with this notion is the lack of suitable supernovaing stars nearby, as Geocide mentions. However, you mentioned destroying a planet, not specifically Earth. A planet orbiting a star when it went supernova would be toast. Probably, it would be fairly inhospitable before the actual explosion, if Eta Carinae is anything to go by. A planet orbiting a non-explosive star near another star that went supernova could well end up sterilised, which is what I talked about in my post about the galactic habitable zone (and near in the astronomical sense isn't that close by). And, actually, if we're talking about Type Ia (which is to say not core-collapse supernovae; not the death throes of a large star) supernovae, which involve white dwarfs and (probably) ordinary stars going through their red giant stage, we might not even see the supernova coming. That's a slightly unsettling thought.
  • Some sort of implausible doomsday device. Really, you can make up whatever rubbish you want for this one if you're so inclined. (But if you do, I don't promise not to tear your science apart if I read/see/whatever it.)

A few words on supernovae and novae

Supernovae are how stars bigger than about 8 solar masses end their lives. Novae are not small supernovae. I know, that's what I originally learnt as a child/teenager by osmosis from SF novels. I think the connection between the words nova and supernova are primarily historic; a star suddenly appeared or became much brighter and acquired the label (nova meaning new), but the different causes weren't understood until much more recently.

Stars smaller than around 8 solar masses don't explode. They expand relatively slowly (well, y'know, compared with a supernova explosion) when they run out of hydrogen to fuse in their cores, then contract then expand again when they run out of helium. At this point, a large star going through the stages much more rapidly would collapse again under its own gravity and then kaboom supernova. Smaller stars aren't massive enough to collapse again under their own gravity. Instead, after the helium is used up, leaving either carbon or oxygen (or a combination) in the star's core, what was once the stellar atmosphere will keep expanding indefinitely. Initially, it forms a planetary nebula (not actually anything to do with planets), but eventually it will all dissipate and be undetectable. What's left behind is a white dwarf; basically a small, hot star which was once the core of the red giant star.

Suppose there were two stars near each other, and one went through the red giant to white dwarf steps before the other. When the companion star undergoes its red giant phase, maybe it expands enough that some of it's outer atmosphere is close enough to the white dwarf to accrete onto it. The reason these stars didn't supernova is because they were too small. There is a very definite upper limit to how massive a white dwarf can be before it collapses in on itself and explodes. That limit is 1.4 solar masses (but remember, most of the original star's mass is lost when it's doing the expanding thing, which is why the original star can be up to 8 solar masses). If the companion star accretes too much matter onto the white dwarf, the white dwarf will go over the 1.4 solar mass limit and explode. This is a Type Ia supernova. For the record, the alternative explanation for Type Ia supernovae, which is presently gaining more traction, is two white dwarfs colliding.

Since white dwarfs are small (1.4 solar masses in a volume roughly the size of Earth), they're not very visible, especially once they start to cool down. See how we might not see that kind of supernova coming? It could potentially not be that difficult to artificially orchestrate, either, if you have enough spare matter to throw at a conveniently placed white dwarf. Well, y'know, sort of easier than some large-scale astro-engineering projects could be.

 Back to the point

 If you recall the original question, Katrina asked:
My question is, don't stars that get massive enough to go nova have brief lives and thus not live long enough for a habitable planet to develop? Can the habitable zones of massive stars ever actually be inhabited (and then later die in a supernova)?
In general, the bigger the star, the shorter its life. Our sun's total lifespan is something like 10 billion years, a blue giant could live only 10 million years, and a red dwarf's lifespan is in the trillions of years. The current theory is that it took a couple of billion years for (very basic) life to arise on Earth. It then took a long time to progress to where we are now (Earth's age is 4.6 billion years, from memory). If we see this as typical, it seems like there isn't enough time for life to arise around a much larger star. On the other hand, if there was a planet at a suitable distance from the star, it could be inhabited by sufficiently motivated humans with spaceships. They wouldn't be able to stay there indefinitely, but even a few million years is more than ages on human scales, so that's OK.

The other issue is metallicity. Planets like Earth have rocky cores, which means they have high metallicity. Remember, metallicity in an astronomical sense refers to the abundance of elements heavier than helium, not necessarily just the things chemists/sane people identify as metals. Very massive stars generally form in metal-poor environments and are metal-poor themselves. This makes the presence of heavier elements as requires for rocky planet building less likely. Not necessarily impossible, but much less likely.

So yes, you can potentially have planets around the sort of stars that go supernova and, while native life probably won't get very complex if it arises at all, said planets could be inhabited by plucky humans.

Thursday, March 15, 2012

Review: The Rhesus Factor by Sonny Whitelaw

The Rhesus Factor by Sonny Whitelaw has been sitting on my harddrive for a few years, waiting for me to finally get around to reading it. The Australian Women Writers Challenge gave me the push I needed to pick it up. The Rhesus Factor can be downloaded as a free pdf from Whitelaw's website (you have to click on the link in the left menu).

In essence, The Rhesus Factor is an eco-thriller. Set in the near future when the Gulf Stream has stopped, climate change is decidedly noticeable and drug-resistant epidemics are sweeping the Earth. Since it was written about ten years ago, some of the technology of our very near future isn't quite here (no space planes to hop across the pacific in a matter of hours, not even for the US Airforce) but some of her predictions are eerily true. There was a throwaway paragraph that included severe bushfires in southern Australia and Brisbane flooding, for example. Granted, those aren't exactly outlandish predictions, and the Gulf Stream is still with us, but still, some of the crazy weather Whitelaw describes doesn't feel like it's as outlandish as it would have been ten years ago.

There was also this great line about the US congress which predicts a situation that has become slightly old news now:

"So you voted in a Democratic President—but hedged your bets with a Republican Congress that will not entertain any motion to install a fair and equitable health care system."
Sound familiar?

Anyway, back to the story. The Rhesus Factor follows a handful of characters through dramatic* climate change, the discovery of a virus which is on track to sterilising 99% of humanity, terrorist attacks, and assorted other emergencies. Some of the characters are clearly there to demonstrate consequences to ordinary folk, but most of them play some sort of governmental role (including scientific research) in mitigating the damage. A nice touch, I thought, was that almost all of the characters were quite competent and none of the disasters were because of any one person stuffing up. They were all just sort of inevitable.

My favourite character, and the one I felt was the most developed, was Kristin: an Australian marine engineer, initially based in Vanuatu, who has the unfortunate luck to be present for almost all the on-page explosions. (There are a lot of explosions.) Her back story, complete with an ex-boyfriend who has the emotional intelligence of a wet rag, is well drawn and she's not one of the people who knows everything up front, so it was nice to discover some of what was going on as she did. She also had a strong "Australian, no-nonsense" pragmatism which helped keep up the pace of the book (not that it was ever in any danger of dragging).

Another enjoyable character to read was the Australian Prime Minister. I suspect half the reason I liked him is because the world would be a better place if we had more political leaders that cut through bullshit and did what needed to be done. The other half is that his scenes — particularly some of the comments he makes when not in front of the press — were some of the most amusing and did a good job of diffusing some of the inherent doom of the novel. The most unbelievable aspect of both his character and the US President is that, before becoming politicians, both were scientists with ecology-related (I forget the specifics) PhDs. I just don't really buy that they got elected, especially the President, but it's a good thing for their world that they did.

I also enjoyed Australia being so central to many of the events taking place. Other prominent settings were Vanuatu and the US, but while the US was obligatory (greatest impact of Gulf Stream failure, powerful government), the Australian scenes were more lovingly carved. From the outback, down to Kristin complaining about Canberran weather.

The Rhesus Factor is a fast-paced, thriller crammed with one disaster after another. Set in the near future in a world a little bit more disease-ridden, with a slightly more altered climate than ours, it will keep you flipping/tapping the pages to find out what happens next. I should warn you though, Whitelaw set out to present a realistic picture of the near future. The only fabricated factor is, as the title will tell you, the Rhesus factor which acts as a catalyst for some disasters and an also-ran for others. There is no quick-fix offered in the novel and the ending isn't exactly a happy one — though it is somewhat hopeful. Nevertheless, it's an entertaining and, if you're into getting science out of your fiction, an educational# one.

4.5 / 5 stars

* I say dramatic because the Gulf Stream failed. It's not quite Hollywood dramatic, if you're wondering.
# Actually, The Rhesus Factor is available as a free pdf because at one point it was cited by an Australian MP in Queensland parliament for its realistic and alarming predictions.

Saturday, March 10, 2012

Sciencefail rant: Across the Universe by Beth Revis

First things first: sorry it's been a while between posts. Life has been busier of late and I haven't quite had the brain space to devote to writing a serious sciencey blog post. Until now. I was reading Across the Universe by Beth Revis, a recent YA science fiction book set on a generation ship and just as I got up to the "ooh, things are getting interesting" plot-thickening part, I was smacked in the face by an epic science fail. This is what I am now going to rant about.

There will be spoilers. Many crucial spoilers. If you'd rather read a spoiler-free review and live in science fail ignorance, then you can read my ordinary review here.


I mentioned spoiler-warning, right?


Don't read on if you don't want to be spoiled.


The Fail of the Science

Some background

In Across the Universe we have two main characters: an American teenage girl and the future leader of the generation ship. The girl gets frozen and loaded onto the ship as cargo because her parents are part of the colonisation mission on the new planet they're going to. For reasons unimportant to science fail (and which I hence won't spoil), she is accidentally unfrozen early, supposedly 50 years before they're due to land. The entire journey was supposed to take 300 years.

When she wakes up, she finds herself in a very different world to the Earth she left behind. Blah, blah, dystopia -- if you're interested in that aspect, go read my proper review. In the course of events, the two main characters discover that among all the secrets and lies aboard ship is the secret of what's going on with the ship's engine.

The parts I don't have a problem with is that the engine nuclear and they have some sort of process which is supposed to recycle the uranium so that it keeps running long enough. I mean, I'm sceptical of the whole re-enriching uranium part -- entropy, conservation of energy, the lack of a particle accelerator on board, etc -- but I'm willing to buy future technology with fancy engines. If we didn't have future tech with better stuff than our present tech, then science fiction would be a little dull.

Unfortunately for the residents (and cryo-residents, I suppose) of the generation ship, there is something wrong with the engine. It is losing efficiency. Given the magic physics that was making it run in the first place, this isn't surprising either. Do you know what is surprising? The fact that the engine failing is somehow slowing the ship down.


I know, I know, I don't usually actually scream when I'm ranting, but this blatant disregard for one of the most basic and fundamental ideas in physics infuriated me. I shouted, in real life, and bashed the book on the couch in my frustration* at this neglect of research. Ask anyone who's taken a first year university physics subject, gosh, even anyone who passed high school physics, and they should be able to tell you what happens on a spaceship when the engines fail.

It keeps going in a straight line until it hits something.


Galileo, who lived way back in the 1500s–1600s, worked out that an object will continue to move in a straight line. Newton, in 1687, appropriated this concept and dubbed it his first law of motion:
A body in motion will continue moving with a constant velocity unless an external force is applied to it.
On Earth, friction is usually that external force. Your car's engine has to keep running while you drive because if it doesn't, you're car will eventually roll to a stop as the friction between the axle holding the wheel in and whatever's on the other end of the axle. A boat slows down because of the drag force of the water around it -- drag force being a type of friction. Your bike might roll down a hill, but if you don't pedal, friction in the axles will eventually bring you to a stop. An aeroplane needs to keep firing its engines because of the drag force of the air slowing it down (they can sometimes coast down to a landing if the engines fail, but they need to over come the drag to maintain a constant speed so that they can stay in the air because of other physics I'm not going to go into right now).

You get the idea.

The drag force happens because something -- air particles, water molecules, etc -- collide with the moving object and push it slightly in the opposite direction. If only one particle hit the much larger object, it wouldn't make a difference, but there are very many particles in the air around you right now. There are even more surrounding a boat (or person) in water. That's why it's harder to move underwater than in air. The fewer particles around to collide with an object down, the less it will be slowed down.

Space, unlike the surface and atmosphere of Earth, is characterised by its vacuum. It's lack of anything substantial. There is no air in space. Sure, there are a few stray molecules and atoms floating around but, except in the densest of nebulae/molecular clouds, they are far sparser than even the best industrial vacuum we can create on Earth.

In space, there is no drag force. There is nothing to slow you down. If your engine failed, you wouldn't slow down, you would just keep going, indefinitely, until you collided with something, or came close enough to a gravitational field (of a star, for example) to change direction. Then you would keep going in that direction unless you were particularly well aimed to go into orbit around that star.

So when the engine of the generation ship in Across the Universe starts to fail, their problem isn't that it will take them longer to reach their destination. If it fails completely, they will not be "dead in the water". There is no water. It might be called a spaceship, but that doesn't mean it shares the same watery drag force as an ocean liner.

Their problems are more likely to be related to not being able to land or go into orbit around their destination, or not being able to make course corrections, or not being able to slow down and zooming straight past their destination.

By a similar token, people or things ejected out of the airlock wouldn't get left behind. Again, space is not an ocean. Once the airlock is opened and the air rushes out (pushing any lose objects out with it, perhaps), the ejected objects would appear to float close to the ship, continuing to move in the same direction along with the ship. If someone was thrown out an airlock, their body would only stop shadowing the ship when the ship did one of: speed up, slow down or change direction.

I grant that if the ship has magic artificial gravity (which the generation ship in Across the Universe does), some strange things might happen to throw the body further away from the ship, or make it somehow react unusually with the artificial gravitational field, but there was absolutely no indication of that being the case in this book.
* Don't worry, the book was unharmed.


My first thought, in my brain's desperate attempt to fix the gaping science fail hole in Across the Universe, was that maybe the ship was accelerating and that's why they needed the engine to maintain efficiency and why things thrown out of the air lock got left behind.

Unfortunately, it can't have been.

According to the original mission plan (which the book gives us no reason to believe is a trick), the voyage is supposed to take 300 years. Also, their destination is called Centauri-Earth (and our world is referred to as Sol-Earth). This could refer to Alpha Centauri, the closest star, but given the fact that the planet they're headed for is supposed to be habitable, that doesn't seem likely (Alpha Centauri is a triple star system and the chances of conveniently habitable planet being there are slim). So it must be another star with Centauri in the name. There are lots. Here is Wiki's list of stars in the Centaurus constellation. If you sort that list by distance, you see that there aren't that many stars within 300 light years.

Since no relativistic effects are ever mentioned (see this blog about travelling close to the speed of light, and this one about accelerating up to fractions of the speed of light), it seems fair to assume that they never reach an appreciable fraction of the speed of light. Let's say that means less than around five percent time dilation goes on (see aforementioned links for previous posts if you're lost at this point). Well, travelling at a third of the speed of light gives us six percent time dilation, so close enough. So the maximum speed we're allowing is 0.33c. If we ignore acceleration, that limits us to stars within 100 light years. Habitability is probably limited to F, G, K and maybe M stars. Within 100 light years in the Centaurus constellation, that leaves us with... 14 viable stars (11 of which don't actually have Centauri in their name...). The furthest with Centauri in the name (not an unreasonable requirement, given the context of the book. If they were going to a star with a dull designation, surely they would have given it their own name?) is about 60 light years away.

If we assume they're accelerating until they get half way, then decelerating the rest of the way (the fastest way of getting there and also the main way to require the engine running the entire time), that requires a very low acceleration of 0.0013g or 1.3 cm/s2. Which at least explains why a uranium engine might be the fuel source of choice. (For the record, if their destination was Alpha Centauri, then this value wouldn't change appreciably - it would be about 0.05 cm/s2 less. Furthermore, for Alpha Centauri it would make much more sense to accelerate a bit and then spend most of the journey coasting until they needed to slow down at the other end.) The maximum velocity the ship would reach would be 0.37c, so that's not too far above my imposed limit of 0.33.

This low acceleration means that my point about bodies not being left behind when ejected from the airlock still stands. They still wouldn't appear to drift away that quickly.

The final piece of information we're given in the book is that the engine started failing when they were about halfway through their journey. What does this mean? It means that they wouldn't be able to decelerate, would reach their destination faster not slower and would zoom straight past it too quickly to go into orbit. Pretty much the exact opposite of the problems described in the book.


No. For two reasons. The first is just it's bad writing -- the science fail error jolted me completely out of the story and undermined my suspension of disbelief and plausibility of the whole setting. To achieve the same plot-mandated end, the author could have had the engine start to fail while accelerating or, without much consequence to the plot (as far as book 1 in the trilogy goes, at any rate) the ship could be unable to slow down, unable to correct its course or they could have found out that the planet wasn't as viable as they originally thought. Each of these things would have got the job done, but no, the author chose to not check physics.

The second reason is twofold. From a personal point of view, when learning physics for the first time, in high school or university, it's usual to relate everyday situations to the concepts you learn. In this way, you can intuitively predict basic mechanics based on experience. However, everyday situations tend to take place on the surface of Earth, so when trying to predict the mechanics of what happens in space (which, yes, does come up in physics classes -- take some if you don't believe me) the situations the student has to fall back on are what's portrayed in various media -- books, movies, perhaps computer games. However, thanks to the the generalised scientific illiteracy of most of society, half of these portrayals are plain wrong. They're why I have this blog, in fact. Honestly, having taught physics to new students, I have seen a lot of evidence for this sort of thing contributing to poor understanding and requiring a lot of unlearning.

Hollywood, poorly researched books, and other media undermine what little science education kids get. At least if the media surrounding us strived for some semblance of accuracy, perhaps people would pick up some science by osmosis. Then the climate debate wouldn't be so controversial, US presidential candidates wouldn't think a moon colony in 20 years was a viable idea, and we wouldn't have an anti-vaccination movement. Scientific literacy is important and, really, science fiction as a genre is uniquely positioned to encourage an interest in science. Sure, this wasn't a hard SF tech-centric book, but it was a giant spaceship. That's the sort of thing that can capture an imagination and ingraining wrong science while doing so is just irresponsible.

And it makes me angry.

(Other than the science fail aspect, this isn't a terrible book. I give it 3.5 / 5 stars -- half a star subtracted for the science fail. For a less science-oriented discussion of the book -- y'know, an actual review -- see my book reviews blog.)

Monday, February 13, 2012

Review: Wanted: One Scoundrel by Jenny Schwartz

I stumbled upon this book quite by accident after following a link that took me to the author's website. When I saw she had written a steampunk novella set in Australia, how could I possibly resist buying it? I didn't really need the added incentive of being able to count it towards the Australian Women Writers Challenge. And before you argue, steampunk counts as science fiction because of the technological and scientific sentiment inherent in (the characters) inventing new old tech.

Wanted: One Scoundrel by Jenny Schwartz is set in and around the Swan River colony -- mostly in Perth and Fremantle. The protagonist, Esme, is the daughter of a gold prospector and inventor who struck it rich relatively recently. She is also a suffragette spearheading a political party with the goal of giving women and non-Anglos rights and votes.

The story opens with her realisation that, since her main political opponent has somehow arranged for all political debates to take place at gentlemen's clubs, she needs a male spokesperson to be a figurehead leader. Unfortunately, all her present male supporters are too busy with their own affairs to devote sufficient time to actually leading a political party. So, with the aid of her captain uncle, she set about finding herself a newly arrived scoundrel ("fresh off the boat" -- would that there weren't other connotations to that phrase) whom she intends to pay to be her puppet.

Enter Jed. A conveniently unknown American recently arrived from England with her uncle's (steam-powered) ship. Jed quickly agrees to be the front-runner for her political party and a friendship/attraction blossoms between them (well, it is also a romance story).

Esme's main rival is an old-money easterner (insofar as there is any aristocracy in pre-federation Australia, he seems to be a prime example). Unlikeable to the bone, he doesn't seem to realise that Esme finds his desire to prevent anyone that isn't male, white or rich (or, really, anyone that isn't him or his friends) from voting abhorrent. He started off merely an arrogant prat, but this escalated for the climax in an exciting way, I thought. (No spoilers.)

The steampunk elements are scattered throughout the story. For example there are the steam powered boats that make it to Swan River from England in a matter of weeks, not months, miscellaneous minor steam-powered contraptions and even forays into electricity and magnetism (Tesla gets a very brief mention, too). From a scientific point of view, I found no obvious faults, although I'm a little sceptical of the kangaroo-inspired land vehicle mentioned at one point.

As I implied at the start, the thought of a steampunk story set in Australia made me very keen to read this and I was not disappointed. I hereby encourage more Australian authors to write Australian steampunk. Steam + gold rush allows for a wealth of material to draw from.

Speaking of the gold rush, being an easterner myself, I only really know a bit about Victoria's gold rush, and next to nothing about Western Australia's (arguably, I know more about Western Australia's current mining boom than any of the past). It was nice to read about a slightly different gold rush. I even learnt about the significant Indian population of the time (cf Chinese miners in Victoria).

The writing was ever so slightly clunky in places, mostly when there was an instance of head-hopping (between Esme and Jed) within the same scene. I also found the story got more amusing as it went along -- after a slightly uneventful beginning --  and I really enjoyed the climax and ending. It had my laughing out loud a few times in the second half. I loved Esme, who was strong, progressive (obviously) and kept her head in trying circumstances. Overall, I recommend this to anyone with a passing interest in steampunk or Australian history.

(Oh and if you're wondering, the Christmas element is extremely minor, limited to a single Christmas in July ball, so yeah, ignore that subtitle. Well, unless you like Christmas, in which case, read the book anyway.)

4 / 5 stars.


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