Archive for March, 2011

Gravity, Part. 2

Posted in Space, Speculation with tags , , , on March 31, 2011 by davidnm2009

It’s all about the bones.

Your bones are a central part of your physiology. They hold your body up. They also help you to move, by giving your muscles something to push against. They also house the marrow that amkes your red blood cells. And, like all systems in the human body, evolution has optimised them for 1 g of gravity. How are they going to react to a hypothetical colony planet, with g=0.68? or 1.3? or 0.17 (if we’re talking about a Moon colony)?

I’ll be clear about one thing; at the moment, we don’t know for an absolute fact. But there is some evidence to suggest that there could be tears before bedtime…

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Gravity, Pt. 1

Posted in Science, Speculation with tags , , , on March 29, 2011 by davidnm2009

We’ve already talked – a bit – about the possible role air pressure might play in planetary colonisation. I didn’t do much more than dip my toe into what is by any standards a vast topic. You could loosely summarise it as ‘human beings function best at 1 standard atmosphere’ – surprise, surprise! However, there is also some flexibility – presumably, our pre-human ancestors did encounter big hills and mountains often enough for evolution to factor it in. Human settlements can and do exist at altitudes as high as ~5000 metres.

Gravity, however, is potentially a very different problem. It’s something that will be a fundamental property of any planet. It’s also something that isn’t amenable to human influence, short of some kind of completely-incomprehensible, borderline-magic type technology. But, irritatingly, it’s something that will have major health implications for any putative human society. So it can’t be ignored. One can imagine taking supplements to deal with chemical deficiencies in the local soil, one can imagine pressurised houses to deal with air pressure differences, one can imagine vaccines or perhaps genetic engineering to cope with local diseases – but you can’t really do anything about the surface gravity! (By the way, if you think I’m being absurdly glib in dismissing the other issues, you’re dead right! All of these would be major undertakings just by themselves…)

Now, a note before we go any further. Most of this series of articles will be me commiting the physicist’s cardinal error – speculating outside one’s own field! So, any errors you see in the medicine and the biology are most definitely not my sources’ fault, they are a consequence of my own faulty comprehension. (Incidentally, if we do have any biologists or doctors in the audience, I would be very interested in their views on this topic.)

First off, let’s start with a brief – and it will be brief! – overview of what gravity is from a physics perspective.

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Blurring the Boundaries

Posted in Astronomy with tags , , on March 22, 2011 by davidnm2009

Aaah, 2006. The year of the great Pluto debacle! I have to admit to having been left unsatisfied by the IAU’s resolution on whether or not Pluto can be said to constitute a ‘planet’. In the end they designated it a ‘dwarf planet’, a designation that smells faintly of the sort of confused fudges beloved of politicians. Science is supposed to supply clarity, and precision on definitions is important.

Except sometimes, one has to be careful with definitions. They can cause more trouble than they solve.

The basic problem here, I think, is more to do with human beings than it is to do with what’s going on in the sky. The human animal is a categorical one – we like to drop objects and phenomena into neat, tidy boxes. It’s probably a side-effect of the sort of pattern-recognition that enabled our ancestors to spot predators lurking in the bushes, and tell them apart from the prey they were stalking. All very useful, from an evolutionary point of view, but not a behaviour that always maps so well onto an untidy, messy universe.

In particular, I’m thinking about this in a brown dwarfs context.
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Star Formation In Pictures

Posted in Art, Astronomy with tags , , on March 20, 2011 by davidnm2009

Star formation is arguably the central astrophysical process. The only thing that could compete would be what we might call ‘universe formation’, but as far as we know, that’s only happened once. Star formation, however, is still ongoing. And star formation dictates everything you can see, from the stars in our skies to the shapes of galaxies. (And planet formation is effectively a side-effect of this process as well.)

So, this is a post about star formation. We’re going to follow a generic main sequence star through from its birth to its middle age. And there will be pictures:

(There’s a much, much larger version of this image available at this link, but beware – it’s huge!)

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Surprisingly Durable

Posted in Science, Social Concern with tags on March 14, 2011 by davidnm2009

Just a quick note – The Register has some commentary on the post-earthquake problems at the Japanese nuclear plants, the point being, that although what’s happened isn’t good, it could actually be rather a lot worse.

And, in fact, the surprise is indeed that it isn’t worse. What you haven’t heard amongst the media-frenzy of FUD is that the radiation leaks have actually been mild and only one of the containment vessels themselves has been breached (and that appears to be a minor incident rather than a major one). In fact, out of eleven reactors in the affected area, only three have had trouble.

So, actually, overall this incident is arguably a qualified success for nuclear safety. Bear in mind that the earthquake in question was five times – five times! – larger than the maximum for which any of these plants were devised. In fact, it’s now been rated as the 4th most powerful earthquake since records began. There simply is a limit to how much you can plan for an event that extreme.

Of course, you wouldn’t know any of this from listening to the mainstream media. They’re doing their best to add even more fear and panic to a febrile, horrible situation by wibbling loudly and repeatedly over the word ‘radiation’. It doesn’t helped that most media people (I use the word in its most generous sense) probably have no actual understanding of what radiation is, either.

(To clarify, so far almost all of the emissions from the reactors have been short-lived isotopes like Nitrogen-16. Short-lived here means a half-life of several seconds. Or to put it another way, in the time it takes you to sneeze, a good chunk of the emission has decayed into something boring and harmless. These sorts of things just don’t hang around long enough in the environment to be a major problem.)

So actually, I would contend that the news here is surprisingly good. Or at least, ‘surprisingly good’ compared to what you might reasonably expect in the aftermath of the fourth-most-powerful earthquake in more than a century.


Posted in Art with tags on March 12, 2011 by davidnm2009

I’m feeling some way from compos mentis at the moment – I seem to be in the early stages of some sort of mild flu bug. However, you don’t need to be too with it to fiddle around in Poser. So have a scene featuring some Space Marines getting a nasty undead-robot-type surprise:

The full version is here, with the entire scene.

Seeds for Optimism

Posted in Personal, Social Concern, Speculation with tags , on March 12, 2011 by davidnm2009

I’ve talked a lot on here about what I fear for our future. I thought instead, for once, it might be nice to talk about what I’d like to see instead. After all, whatever we do today, the future will arrive. And maybe having something to aim for will help. And let’s face it, I’m a bit too prone to glass-half-emptiness, so a look at more cheery possibilities is doubtless healthy.

So, I would like to see:

  • A lower population: It’s hard to see how our current numbers can be sustained for very much longer. Next year, the population is forecast to hit 7 billion. The typical population for a species of large mammals is something like 300,000 – 3,000,000. We’re too numerous by a factor of several thousand. A world with a population of (say) 1-2 billion instead still has enough people to support a decent quality of life, but not so many that it risks blue-screening the ecosystem.
  • Cleaner technology: There are all sorts of clean-tech ideas out there, and many of them could be implemented right here, right now. The reason why they’re not? A combination of vested interests who make money out of the status quo and also a public that seems to want to passively consume rather than seek out innovation.
  • And end to Big Oil: Let’s face it, the oil addiction is probably one of the worst mistakes we’ve made over the last century or so. The sad irony is, it was probably avoidable, too. Getting away from the rampant guzzling of petrochemicals would also do a wonder for the environment.
  • Democracy: should liberty simply be the privilege of the West? No, obviously not. There would be a lot to be said for a loose, democratic global federation. I say ‘loose’ and ‘federation’ as I don’t imagine it would a) be possible to establish a planetary unitary state or indeed b) actually a good idea. But one can imagine a future world existing as a confederacy of small-ish democracies, and being reasonably happy.
  • Capitalism: might be an interesting experiment to try. What we have at the moment resembles it in about the same way that a deformed moth resembles a dragon. (It’s fascinating how many advocates of Adam Smith haven’t actually read him – let’s not forget, folks, amongst other things he calls for a progressive wealth tax!) Also, commensurate with the above, we need to devise some effective means to build the ecological cost of goods into their economic one.
  • Colonies: I think colonies on other planets would be an experiment worth undertaking. The idea would be to establish self-supporting societies, rather than ‘cargo junkies’ permanently dependent on the next food-freighter from Earth, I might add. I would also like to see more progress in both human and astronomical space exploration.
  • Freedom of conscience and freedom of speech: things that exists today in places, albeit only in imperfect form. But I take it as perfectly obvious and perfectly reasonable that people should be free to practise their religious convictions (and indeed also not practise, if that is their choice) and that all people should be free to speak their minds as they choose. The only jusitifiable limitations on these are to prevent harm to others – and by that I mean physical harm. (Hurt feelings suck, I do agree, but none of us can expect to get through life without being offended every now and then. And it probably wouldn’t be healthy for us if we did.)

The funny thing is, I don’t see anything in that list that strikes me as inherently-impossible.