Category Archives: Science fact

How does Superman fly?

Osprey flyingI used to love Superman when I was a kid. I enjoyed the TV series, when Superman wore what looked like woolen undies over his tights and I quite enjoyed the movies. The special effects were much better, of course. Chris Reeves didn’t look like he was standing, one fist out, in a wind tunnel.

I’ve no particular interest in seeing Man of Steel, but the release of this new movie, in which several of the core assumptions percolating through from the comics have been ignored, has got me to thinking.

What is Supe’s most amazing power? I have to tell you, for me it’s his ability to cause selective myopia in all humans. You know what I mean. He puts on a pair of clear glass specs and nobody seems to be able to work out that Clark Kent (mild mannered reporter) is really Superman. As an aside, I recall reading a comic where Superman insisted that the photo of him the Burmese government used for a stamp had to be side on, not facing the camera. And why was this? Because the stamp might be post marked ‘Rangoon’ and the double O might have formed glasses over his eyes. Gosh.

Anyway, back to Superman’s powers. How does he fly?

Think about it. What flies – or floats in the air? Gas rises in air if it has a lower density than the air. So hot air, helium, hydrogen, smoke, water vapour etc. Birds fly by flapping their wings, creating an area of lower pressure above their wings That’s what aircraft do, too. I guess magnetism is a contender if you don’t want to fly too high. Rockets have explosive propulsion at their rear, using brute force to overcome gravity. Of these, rockets are the only ones able to pass beyond the planetary atmosphere. As the atmosphere thins and becomes colder balloons burst, water vapour condenses, jet engines have nothing to push against. Yet Superman can ‘fly’ in space – without a protective suit or breathing apparatus. Unlike Ironman, who has the suit and jets and things.

So okay, let’s accept Supe can levitate. That current magician, Dynamo, claims to be able to do that and some mystics have been reported to be able to achieve the feat. But getting up there is only part of the deal. Then you have to move. Birds and planes can glide and change direction by changing directions. They can go faster by applying more energy. But balloons are at the mercy of the wind. And while winds can be brutally fast, they’re not as fast as Superman. (faster than a speeding bullet, in fact and with more power than a locomotive). So now somebody will trot out the Alien card. Sorry, it doesn’t work for me. Kal El looks just like us. I’ve never seen any suggestion he’s a shape change, like the Thing. But hey! Maybe that’s the deal! He can be anything he wants to be, yet we’ll all see this well built hunk of a man with a rippling cloak, even when he’s emulating a speeding bullet. Cool. Somebody whould write a story.

It’s a bit of fun, folks. Tell me who has your favourite super power. Or explain to me how YOU think Superman flies?

Is telepathy science fiction – or should we shove it in the fantasy basket?

Picture of a neuronI’ve always had a thing about telepathy in a science fiction novel. To me, it smacks far too much of ouija boards, mind reading and charlatanism. So when I come across telepathy as a skill in an SF book, I roll my eyes, sigh – but if it’s somebody whose work I like, I’ll keep reading. One such is Linnea Sinclair. Her book Games of Command has two story arcs, one which is high tech SF, the other concerning telepathy. I really enjoyed the book, but I much preferred the high tech action half. Because of my preferences, it took me a long time to actually get around to reading An Accidental Goddess. And again, while I enjoyed the book, the whole mental powers higher human thing required me to not analyze too deeply.

Anne McCaffrey had her telepath type series, too. That was To Ride Pegasus and its sequels and it didn’t press buttons for me. In fact, it was a did-not-finish.

So this article in io9, entitled how much longer until humanity becomes a hive mind, left me somewhat bemused. Because a form of mental telepathy does seem to be… well… just around the corner. Granted, you need electronics to make it work, but even so. Lots of novels (including mine) foresee humans enhancing their mental capability with a neural chip. Not many novels consider the dangers, though. One of my regular readers mentioned the idea of Facebook playing in one’s head. And, of course, viruses, worms and the like. It’s a scenario I consider in The Iron Admiral: Deception. Then there’s who controls the systems? And what about privacy?

But as far as the nuts and bolts are concerned, the thing about this article which really had me thinking was the transmission of ideas. Let’s take something really simple, like colour. As it happens, my husband is colour blind. I’ve often wondered what he sees when he looks at (say) a red rose. I know the flower sort of disappears into the foliage for him, so I’m guessing that his brain sees that wave length the same as what I call green. But really, I don’t know, because his brain is interpreting the signals in a different way to my brain. The same thing takes place when we talk about objects such as trees, or mountains – or anything else you care to name. As the article points out, we use a thing called language to kind of code what we’re talking about. The fact that the tree you visualise in your brain isn’t the same as the tree I visualise in mine, doesn’t matter. So given all that, speech is much, much easier to transmit than a mental picture.

So has all of this changed my mind about telepathy in SF? Show me how its done – with some sort of neural net or nanotech or a chip or something, and yes, I’ll go along for the ride. Otherwise – it sits over in the corner marked ‘magic’, I’m afraid. Don’t worry, though. It’s in good company. The Force is lurking around over there, too.

Thoughts? Telepathy in SF – yes, no?

Moons and tides and stuff like that

Picture of low tide

Low tide at Hervey Bay

I think everybody knows that the moon has an awful lot to do with the height of the ocean’s tide, and so it’s self evident that the highest tides would coincide with the full moon. But hang on a minute. There are two tides each day. Why would that be?

It has to do with gravitational attraction. I wrote about that when I discussed how much you would weigh on an exoplanet. We have established that there is gravitational attraction between the Earth and the Moon. That’s why the Moon orbits Earth. Water, being a fluid, is able to respond to this attraction better than solids, such as mountains. Now while this neatly explains why we have a high tide when the Moon is visible, why would there be a second high tide twelve hours later? The Moon isn’t in the sky, it’s on the other side of the Earth. By rights there should be a low tide, as all the water is attracted to the Moon down there (author points down at her feet).

This does not happen because, as noted in the previous discussion, the power of gravity decreases over distance. The Moon is about 384,000km from the Earth. The opposite side of the Earth is 40,000km further away (the approximate diameter of the Earth) at 424,000km. The water on the opposite side of the Earth to the Moon is attracted less (due to the distance) than the water closest to the Moon, as shown in this simple diagram.Diagram of earth, moon and tidal forces

We have two high tides facing the Moon, and two low tides at the sides. Why Spring tides and Neap tides? For that, we have to consider the sun. The very fact that Earth orbits the Sun illustrates the power of gravitational attraction. When the Sun and the Moon are in the same side of the Earth, as at New Moon, the gravitational attraction of the Sun on the world’s oceans is added to that of the Moon, and we have unusually high tides and low tides. At Full Moon, the Sun is at the opposite side of the Earth from the Moon, so the two bodies might seem to be pulling against each other. Remember, though, the Moon and the Sun both produce two bulges, so the two forces still operate to increase the tide. It stands to reason that if the Sun was to the right of the Earth in the diagram, the forces of the Sun and Moon would tend to cancel each other out. But not completely. That’s because the Sun produces a lesser bulge on the far side of the Earth. It is larger than the Moon, has a far greater gravitational pull, but the relative difference in the distance between the Sun and one side of the Earth, as opposed to the other, is much smaller, so the lesser bulge is less pronounced.

And there you were, thinking this was simple. It is, really, I suppose. But I bet you needed to concentrate.

I love this stuff.

Now go away and work out what the tides would be like on a world with large oceans, and three moons of varying diameter, in three different orbits.

ET phone home? Really?

picture of a telephoneReal time conversations are a problem in space opera if you’re planet hopping. Why? Think about it. If light can take years to go from one star to us, how long would it take any other type of signal? (We’ll leave out sound waves, which don’t move through a vacuum.) Answer – same as light. About 300,000km per second. Sure, that’s fast. But having a conversation with someone, say, four light years away is going to be a tad tedious.

“Hi, I’d like to order the peperoni, please. With anchovies, no pineapple.” (Wait eight years)

“Sure. Would you like garlic bread with that?”

I think your pizza might be cold before it was delivered.

And yet, so often space opera ignores this fact of physics and has folks chatting from spaceship to planet, or planet to planet, as though they were using Skype back in the 21st Century on jolly old Earth. A case in point is the famous scene in The Empire Strikes Back, where Darth Vader’s Executor is chasing the Millenium Falcon through an asteroid field. Admiral Piett was delighted to be able to tell Vader the Emperor was on the line, so the star destroyer could be moved out of the asteroid field in order to send a clear signal. And then they had the little chat, the Emperor’s ominous figure dwarfing Vader, down on one knee, while he plotted betrayal.

Now, let’s think about this. The Emperor is on Coruscant, Executor is down in the Imperial boondocks, messing around near Hoth. I’m not suggesting the exchange was impossible. No, let’s put that another way. It’s impossible without some sort of futuristic device. Even within our own solar system, it takes anywhere from 3.4 – 21 minutes (depending on how close the planets are to each other) for a a signal to go from Mars to Earth.

It’s a known problem, though. Ursula Le Guin was the first to dream up a device which could enable people on different planets to converse in real time. She called it the ansible. The name has wheedled its way into the genre, rather like ‘hyperspace’. Elizabeth Moon wrote a whole series of books (the Vatta saga) around a company which specialised in setting up ansibles in orbit around inhabited planets, and maintaining them. And the subsequent danger when the ansibles were sabotaged, a bit like taking down the telegraph line across America in the Old West.

I don’t call them ansibles, but since my books involve much planet-hopping, I had to come up with something, which I suppose is an ansible by any other name. A multi-dim transmitter is a device which uses one of the many dimensions of space, a dimension which is not available to physical entities like ships, to transmit a signal from one place to another. They’re fitted to ships and planets have receivers.

Needless to say, if you don’t have access to an ansible or its equivalent, you can’t have a real-time conversation over a long distance.

Care to share your thoughts?

You could be excused for feeling fairly insignificant

picture of a glaxy clusterI’ve written a few posts lately about life, the Galaxy and everything. When you think we inhabit one small planet going around a pretty non-descript G class star in a spiral arm of the Milky Way galaxy, you could be excused for feeling fairly insignificant. In the scheme of things. After all, our run-of-the-mill galaxy is estimated to contain anywhere from 200-400 billion stars. That’s nine zeroes billion. 200,000,000,000 – 400,000,000,000.

But when you start looking at some of those amazing deep space photographs… Wow, just wow.

Those smudges of light are galaxies. The Hubble telescope took some very deep space photos, looking back in time to what is believed to be the beginning of the creation of the universe. Here’s the link. Please note, half way down the page it says this one shot shows an estimated ten thousandPicture of Star Wars Arkanis sector galaxies. In one little piece of sky. Let’s see now. 10,000 multiplied by 200,000,000,000 is 2,000,000,000,000,000. That’s a lot of stars. And that’s just a fraction, a tiny portion, of the galaxies out there.

Maybe, somewhere out there, is the galaxy far, far away, a long, long time ago. Suddenly it doesn’t seem so farfetched.

Time to call it a day?

Picture of pink elephant with clockTime. A clock on a wall, a calendar, numbers on the top (or bottom) of your computer screen, ticking off the days of our lives. (Gee, that’d be a good title for a show or something, wouldn’t it?)

This morning on Facebook I read a couple of discussions about time keeping. One was about the decimal system, how everybody but the US seems to have taken up metric measurement. Which seems especially odd since they use the decimal system for their money. Somebody, in a fit of flippancy, remarked we could have a ten hour day, with one hundred minutes etc etc and then said, yes but that wouldn’t fit in with year. Which it wouldn’t if a minute was the same in duration as a minute is now.

The second discussion was about the pagan origins of the names of the days of the week, which I’m sure everybody knows are based on Norse God’s names, plus a day each for the sun and the moon. That can be extrapolated into the pagan origins of the names of the months of the year. Although quite a few really are based on month number.

At the end of the day, we can’t go past the three overriding fundamentals of time measurement. On this planet, anyway.

  • The time it takes for the planet to revolve on its axis (day)
  • The time it takes for the Moon to orbit the Earth (month)
  • The time it takes for the Earth to orbit the Sun (year)

And we need to reconcile them. In earlier times, these cycles were extraordinarily significant for survival, since they dictated the amount of sunlight (daylight hours and the seasons) and tides. It’s how the ancients decided when to plant, when to harvest and when to celebrate, finally, the lengthening of the days and the passing of winter.

It’s hardly surprising that the Babylonian calendars were lunar based, that is, 28 days. Our 7 day week is one quarter of a month. Our ancestors probably came up with a duodecimal (base 12) system because 12 is so easily divisible by 2, 3, 4, 6 and 12. Thus 12 months, a 24 hour day, made up of 60 minutes, made up of 60 seconds. This is fine at a micro level, but it doesn’t fit the length of the year, so the length of months had to be juggled so that the end result was 365 days. In fact, the lengths of months were juggled to fir the needs of the solstices and equinoxes. And later, every four years we add a day because the orbit actually takes 365 ¼ days.

All in all, it’s an arithmetic nightmare. Trust me on this. I used to be a computer programmer and date mathematics was awful. The only way to calculate date (a) minus date (b) is to convert the dates to the day (number) in the year. Thus 28 February is the 59th day of the year.

A decimal time system would seem to be eminently sensible. The French tried it, back in 1793, without success and that experiment is discussed on io9. In this case, tradition had the weight of inertia behind it, and the French reverted to the old hours in 1795 and scrapped the revolutionary experiment in 1806. Frankly, I’m not surprised. This decimal time system is artificial. It’s interesting that the French still stuck to 30-day months and 12-month years, though.

We COULD try a lunar calendar, with 13 months made up of 28 days, with an extra day at the winter solstice (say) to bring the number of days to 365. I think that would work. The solstices and equinoxes would be predictable and fall on a given date. Feel free to correct me if I’m wrong. And there’s no reason why we couldn’t trade in the old 24-hour day for (say) 20 hours or 25 hours. We’d have to adjust seconds and minutes to suit. 100 seconds in a minute, 100 minutes in an hour. The length of a week isn’t so much of an issue, since we don’t use it for much except how many days we work. Plenty of people do nine days on/nine days off and the like.

What do you think? Stick with the monster we know, or create a new time elephant?

500 million is a very big number

A picture of an exoplanet

This image was recently posted on Facebook’s “I Fucking Love Science” page. The guys there are happy to share, so here it is for those who missed it.

Yes, I know life doesn’t HAVE to be confined to the Goldilocks zone (the space around a star where liquid water could exist). After all, life doesn’t have to look like Earth life. And nobody is suggesting that ‘life’ means technology. And nobody is suggesting that there might be lots of excellent reasons why life didn’t form on these planets, or why beings like us couldn’t exist on those planets. I talked about this a bit here.

However. 500 million is a very big number. Let’s do something else totally unscientific and suggest that just 1% of those planets have life. That’s 50,000. Too optimistic? What about .01%. That’s 5,000.

Anybody want to lay bets that there is no life out there? No, me either.


A little bit of moonshine in the night

Picture of partial eclipseA lunar eclipse happened in my part of the world on 28th November, hard on the cosmic heels of a solar eclipse earlier in the month. As it turned out, the penumbral eclipse was a huge disappointment. No shadow across the moon’s disc, not even a reddening of the light. So the cirrus cloud partially obscuring the view didn’t matter much. We had moonshine as we always do and the photos were a fizz.

However, it got me to wondering about moons; ours, and other moons in general. To start with, let’s mention the eclipse – the truly spectacular solar eclipse that happened earlier this month. It was a partial eclipse in my part of the world, but even so it is a special event. But why is it so? The moon is tiny compared to the sun.

An extraordinary cosmic coincidence

The sun is about 400 times the moon’s diameter and about 400 times as far way from the Earth and that ratio means that when the moon comes between the sun and the Earth, that shadow is just about a perfect fit. Here’s a more detailed explanation. And coincidence it is. Evidence indicates that the Moon was once closer to the Earth and is gradually moving away, so enjoy your cosmic moment, knowing that in the distant future, there will be no total solar eclipse.

That factoid is not the only extraordinary thing about our moon. Not at all.

It’s not the largest moon in the solar system. In fact, going by this list it comes a creditable fifth after Ganymede (Jupiter iii), Titan (Saturn vi), Callisto (Jupiter iv) and IO (Jupiter i). Indeed, Ganymede and Titan are both larger than Mercury and let’s not talk about poor Pluto. Really, when you think about it, it makes perfect sense that the largest planets have collected the largest moons.

Except ours.

Why is this so?

I have in my possession a tattered little paperback, a collection of essays on astronomy by Isaac Asimov (Asimov on Astronomy, Coronet, 1974). One of the things I loved about Asimov, who had a PhD in chemistry and an interest in everything scientific, was that he could explain complex physics in a way that an interested amateur with absolutely zippo mathematical ability could understand. He wrote papers regularly for magazines and the like and subsequently, they were published in book form. This little volume is a treasure trove of scientific fact and some intriguing speculations. True, some of it is now dated, since it was published before the epic discoveries of Voyagers I and II. Pluto had not yet been demoted. And yet before it could be proved he predicted that many planets other than Saturn would have rings.

To get back to the point, one of these essays is entitled “Just Mooning Around” in which Asimov talks about the gravitational effects of the sun, the planets and the moons in the solar system have on each other. Without going into all the details of the paper, he talks about the ‘tug of war’  ratio, which argues that in most cases, the gravitational attraction of a planet on its moons is vastly greater than the pull of the sun on those same moons. There is also a kind of ‘goldilocks’ zone around a planet in which a true moon would exist (as opposed to loosely captured satellites like Neptune’s Nereid). A moon must be between a minimum Roche limit and a maximum ‘tug of war’ distance. For the mind-bending number-crunching, go read it yourself – I told you I can’t do maths. However, I can appreciate logic. And you will see it is so.

According to his theory, of the four innermost rocky planets, Mercury could not have a moon because it has no ‘goldilocks’ zone. The other three are highly unlikely to have moons because of the narrowness of the ‘goldilocks’ zone. And indeed, Mercury and Venus do not have satellites, and Mars’s Phobos and Demos are overlarge potatoes which are expected to disintegrate.

I see you jumping up and down. What about us? Earth and that thing up there?

Ah, Asimov argues that the Earth/Moon pair is not a true planet/moon relationship because the Moon is so much larger in comparison with its primary than any other such relationship in the solar system. By a long way. He suggests that the Earth/Moon combo is really a binary planet, waltzing its way around the sun. Of course, all planets with moons have a wobble in their orbit but the Earth/Moon shimmy must be quite pronounced. Certainly I don’t think there’s much disagreement these days that our Moon was derived from the same stuff as the Earth. This article suggests accepted theory is that a Mars-sized object collided with the Earth, aggregating the material and spewing off a portion which later formed the Moon.

The next thing you have to wonder is – how important is that massive moon to life on Earth? But that’s another topic, isn’t it?

Isn’t science wonderful?

What would you weigh on an exoplanet?

picture of an exoplanetI was reading an article from somebody, all enthusiastic about the exo-planets the Kepler probe keeps finding. They’re all many times larger than planet Earth even if they’re in the ‘Goldilocks’ zone. You know the one – not too close, not too far, just right. That is, a planet neither too close to its primary nor too far away, where liquid water could exist. My immediate reaction was ‘sure, but we’d weigh too much’.

Then I began to wonder how much more. I’m not a mathematician – never have been. In truth, I can’t add up to save my life. So I’m counting on you (ha ha) to correct me if I get this wrong.

I discovered this site and learned that gravitational pull weakens by the radius squared. So let’s say you weighed 60kg on planet Earth. Planet Gliese 581g is estimated at 2.6 Earth masses and 1.4 Earth radii. So yes, you’re going to weigh more on Gliese 581g, but not 2.6 times as much. If I’ve got this right, the increased diameter of the planet means you’ll weigh about 1.3 times as much – so about 78kg. That’s certainly not a huge imposition. And all of a sudden, I’m bouncing in my chair, going oooh oooh.

Here’s some estimated figures about Gliese 581g, taken from this fascinating website

Mass = 2.6 Earth Radius = 1.4 Earth  Temp = average surface temperature, so this place, at 10, is rather cooler than our 15 degrees (NASA’s figure from 2008), but the estimate of average temperature assumes an Earth-like atmosphere, which is a pretty big assumption. On the face of it the planet zips around its sun in a fraction of the time it takes ours, taking only 32 days as compared to 365. But that might not be the case, since the Gliesean day may be much longer than Earth’s. The figures don’t mention period of rotation, which I find a tad surprising. As a comparison, Venus’s ‘day” (the time it takes to rotate on its axis) is actually longer than its year (the time it takes to orbit the Sun.) (

So there you have it. I found out today that a candidate for Torreno (capital of the Coalition of Worlds in Morgan’s Choice) may be only 20.2 light years away. And with the shift drive of the future, that’ll be a place to add to your holiday plans.

Ain’t science grand?

Humans are such fragile entities

Picture of MarsThe more I read about the strangeness of our universe, the more I wonder if we, humanity, will ever colonise other planets. There’s not much chance we’ll settle on a diamond planet and I have to wonder how we’d go on many of the ‘earthlike’ planets already pinpointed. We are such fragile entities, we humans.

I’m in the throes of writing a sequel to my space opera Morgan’s Choice, which accepts the existence of political groupings of star systems into coalitions, federations and the like. Hey, I’m not special in that respect. Lots of SF writers have done the same thing, with great success – Elizabeth Moon, Jack McDevitt, Isaac Asimov etc etc and of course, Star Trek, Star Wars and the like. But how likely is it really?

Like all other animals we are closely attuned to our environment, more so than many of us actually realise anymore. In these days of electricity we can heat or cool our homes, spend half the night watching TV, or reading books, source food from all over the world so nothing is ever out of season, cross distances that took years in days. Yet we cannot escape the factors which shaped us.

I think there are five vital factors we will not easily overcome.

The first is our perception of time.

I use the word ‘perception’ advisedly, because time is something we measure for ourselves to put ourselves into context, if you will. But whether we think the sun is rising where we are, or setting, our bodies are built to expect a ‘day’ of twenty-four hours or so, because that’s how long it takes for the planet to revolve on its axis. What’s more, if we are suddenly wrenched from one time of day to another, as happens with long distance air travel, it takes time for our bodies to adjust. (It’s called jet lag)

Next is gravity, what we call weight.

We have evolved to suit the amount of force the planet exerts upon is. The advent of space travel and weightlessness has proved how important gravity is to our ability to function. Without gravity our bones lose density and muscles atrophy.

Then we move on to air.

Most of our atmosphere, what we breathe, is nitrogen, with twenty-three percent oxygen and a bunch of other gases in smaller quantities, including carbon dioxide. It also has a level of density. There’s more of it at lower altitude (see gravity). See what happens to mountain climbers if they climb before becoming acclimatised. Their bodies can’t cope. And if that mixture of gases changes past a certain level of tolerance, then what?

Then there’s temperature.

Humans exist in an apparently wide range of climates, providing they can find protection from the elements. But the range is actually not that wide in the scheme of things. This article in New Scientist speculates that global warming of only about 11° would render many places on our own planet ‘unliveable’.

The last factor is light.

Earth orbits a G class star which emits light towards the red end of the spectrum. We’re used to seeing colours in that light. If we lived on a world orbiting a cooler star with redder light, or a brighter star with more bluish light, we’d see colours differently.

Humans are adaptable. That’s why the species has been so successful. But even so, we’ve only ever had to adapt to the extremes of one planet. If humans are to venture to other planets I believe we will have two choices; terraform the planet into another Earth or modify the settlers to cope with the conditions. That would mean physically very different races of humanity occupying different planets. And here again, SF can offer plenty of examples. One that springs to mind is Moon and McCaffrey’s joint effort, Sassinak, where members of the Star Fleet have different body characteristics, depending on which planet they come from.

I admit I don’t take that route in my own writing. I simply assume all planets are earthlike, with only small variations in light, heat, time and gravity. I reckon I’m in pretty good company. Come on SF fans and writers, what do you do, what do you prefer?