Saturday, 27 November 2010

Cassini Set For Enceladus Flyby

Our Solar system, the Sun and all those who sail with her, is pretty ordinary as far as we can tell.  There's a very average star surrounded by a few gas giants, some small rocky types and a fair bit of rubble.  Examinations of other stars have so far shown much the same setup and there's no reason to suspect our system is anything other than fairly mundane, with the possible exception of some interesting biology on the third rocky type.

And yet we still find fascinating things everywhere we look.  One of the funkiest ongoing projects is the Cassini Equinox Mission, a space probe orbiting Saturn and paying some flying visits to the attendant moons.  Cassini has been producing some stunning data over the last six or so years, some of it highly technical, and some of it simply very, very pretty.
Based on an original from NASA/JPL (cropped by author)

This, for example, is Enceladus, an ice moon with a diameter of about 500km.  There are two particularly interesting things in this image:

The stripes and flat areas are the first.  Look at almost any object in the Solar system that doesn't have a thick atmosphere (which Enceladus doesn't) and you'll find one main feature: craters.  Big craters, small craters, overlapping craters, craters inside craters...there's usually lots and lots of craters.  Everything in the Solar system is being constantly bombarded by lumps of rock, ice and metal left over from the original formation, and that leaves a few scars.  Even the Earth has a few big ones from objects that made it through the atmosphere.  Enceladus has craters too, but not as many as you'd expect.  There are big areas which are fairly crater-free, meaning that the surface is being wiped clean somehow.  The stripes are a clue as to how this is happening.

The second interesting thing in the picture is the fuzzy plume at the bottom of the picture.  Enceladus is too small to hold an atmosphere down, so what is the plume, and where did it come from?

The most likely solution to both curiosities, the plumes and the unusual surface, is that Enceladus isn't entirely frozen.  The suggestion is that under the surface shell of ice there is liquid water, possibly huge amounts of it.  The current theory is that because Enceladus' orbit isn't perfectly circular it's kneaded by Saturn's gravitational pull.  If you take a snowball, stick it in a plastic bag and crunch it about in your hand it'll melt fairly quickly, and that appears to be what's happening with Enceladus.  And a liquid ocean under the ice would produce tectonic activity very similar to what we see on Earth.  The icy crust will slide about on the water, crack open, melt and refreeze, potentially explaining the lack of craters.

This is where this article becomes a bit speculative.  There's no suggestion that there's life anywhere in the known universe other than on Earth, but we do have a few likely candidates:  hardy microbial life on Mars perhaps, or possibly even some funky methane eating organisms on Saturn's gigantic moon Titan.  One of the best bets however, is anywhere you find liquid water, which puts Enceladus firmly in the "just maybe" category.  We've got life on Earth which exists in a very similar environment, under the Antarctic ice cap for example, or deep in the ocean.  There might be nothing - Enceladus might just be a dead snowball hovering too far from the Sun.  The potential is certainly interesting though.

Cassini will be making another close pass on Enceladus this Tuesday (30th November, 2010), skimming past at a mere 48km.  Even if there's no extraordinary new game-changing data from the plucky little space probe, we should at least get some very pretty pictures back.

Tuesday, 23 November 2010

The PiSBN Project

[Jan 2015 update - thanks to Cliff Pickover for an unexpected Twitter boost to an old article - I should point out that his books on maths and science are excellent, I used to deal with them a lot as a science buyer at Blackwell's.  See also a followup at the end on ISBN10]

I don't normally apologise for being a bit of a geek.  There's a part of my brain that's into computers and space and science and all that, it's just the way things are.

But to be honest, even I cringe a little at my latest little project.  Sorry about this.

Pi is an interesting number.  It goes on forever, doesn't repeat itself, and appears to be entirely random.  And in an infinite, random sequence, you get every possible combination of numbers eventually.  Your phone number is in there somewhere.  And every book written, if you convert the numbers into ASCII.

Searching Pi for books like that would be stupid though, you'll burn up the best computers on the planet before you get anything worthwhile.  There is, however, a quicker alternative.

Almost every single book published since 1966 has an ISBN number.  These days they all start 978, then there's another ten digits.  The last one's a check digit made by multiplying the others up in a certain way.

So I wrote a program that searches Pi for ISBN numbers.  Then it checks them to see if the check digit is a valid one.  Then it looks the ISBN up on Google Books.

I got three hits in the first fifty million digits of Pi.  It took about ten minutes.  Actually, it took about three hours to write the thing properly, another hour debugging it, and a frustrated lie in the bath half way through.  And about six cups of tea.  Once it actually worked it was fairly quick though.

And so, ladies and gentlemen, I present for you edification and entertainment....

The first three books in Pi!

(Cue fireworks.)

At the four hundred and nine thousand, seven hundred and eighty third decimal place, we have:

Licentiate seminar on environmental engineering and biotechnology
by the Tampereen teknillinen korkeakoulu. Bio- ja ympäristötekniikka.
(Tampere University of Technology. Department of Biological and Environmental Engineering.) 

I have to admit that I haven't read this one, but I'm quite chuffed that the first book (well, journal) is something a bit geeky.

In second place, at the two million, one hundred and twenty thousand, two hundred and fourth place, is:

Sneeuwwitje en Rozerood
by Jacob Grimm

Or as it's known in English, Snow White and Rose Red.  And because the original is not covered by copyright you can get a copy from the excellent Project Gutenberg.  Not hugely geeky, but there is something wonderfully gothic and conspiratorial about one of Grimm's turning up.

And taking the bronze, at the three million, six hundred and thirty thousand and thirty third decimal place:

The healing knife
by George Sava

A curious sounding book written under a nom de plume by a "noted Harley Street Surgeon".

I'll bet you feel better now that you know what the first three ISBN numbers are in Pi?  I know I certainly do.

Sorry again.

2015 Followup
Bookish types will have recognised that I searched for ISBN13 versions - and that there's also a 10 digit version which was used until 2007 (coincidentally when I first worked as a bookseller, and witnessed much gnashing of teeth from people who had 40 years experience as booksellers or, worse, software suppliers to the book trade).

The 13 digit version was brought in to align the whole system with an over-arching barcode, the "978" was added to denote "bookworld" - books, magazines, journals, that kind of thing. Unfortunately, it also screwed with the check digit at the end, meaning that also had to be recalculated.  As a bonus, however, the new check digit could only be 0-9, while the ISBN10 version could also have a check digit of "10" which was encoded as "X".  This is the main reason I went with ISBN13 in my search, Pi doesn't contain any X's.

However, a search for ISBN10s would be far more profitable in terms of books discovered, even ignoring the missing ones with X's at the end. A quick and dirty guess would suggest thousands of times more, and now, the internet being what the internet is, somebody has run with it in a glorious way.

David Fiander has found a total of not three, not thirty, not three hundred, but 1,168 books in the first million digits, and he's posted a great big spreadsheet with all of them on it on his blog.  My thanks to him for turning this from a geeky little project into a geeky bigger project.

Tuesday, 2 November 2010

Trying to explain the weirdest idea in the universe.

This is going to sound utterly crackpot.

Sorry, but some of the big ideas can sound a bit weird.  To an atheist, the idea of a god seems a little out-there, and this is the flip side - an atheist suggesting something about the universe that not only might never be proved, but might not even be provable at all.

Or even wrong.

But hey, the whole ethos of science can be summarised by "I might be wrong, but what about...?", so I'm going to throw this idea out there and we'll see where we go with it.  So here we go, hold on tight, this is the big soundbite:

Mathematics might be real.

It's an idea that I've been throwing around in my head for a few years now.  It all started with physics, a subject which has been close to my heart since I first wondered just what the hell was going on.  For some reason physics seems to be very good at taking the stuff we see around us and distilling it down to a simple mathematical equation or, at the very least, one prefixed with "In a frictionless vacuum".  See, for example, gravity. 

Courtesy xkcd, prescient comedy god amongst men.

Drop any object, near any other object, anywhere in the known universe, and we pretty much know what's going to happen.  Newton got it right enough for everyday use, and Einstein's relativistic reinterpretation corrected Newton well enough to not only change our view of the structure of space and time, but also to run atomic clocks in orbit decades later.  This one little idea, using nothing mathematical beyond primary school maths (if the idea of a square root is still primary level) describes the vast majority of what happens in the range of any telescope we have.  One equation describes most things we can see.

Or let's take something else, like things bumping into each other.  Again, Newton laid the groundwork, and then James Clerk Maxwell refined the ideas with his theory of electromagnetism, and another huge lump of the universe was reduced to an equation.  Well, maybe three, but there's a lot of stuff in the universe.

By now things are starting to look a little suspicious.

It seems that everything we experience is a rough estimate (a fact that's easily demonstrated by a high speed cameras or electron microscopes), and that the closer we look the simpler things become in a way.  Take, for example, a book.  Prop one up on the far side of the room, as far away as you can.  Go on, I'll wait.., there's a book.  You can see that.  I'm sure you're well aware that it could be an optical illusion by a talented artist, but if you move around the room a little you'll prove to yourself that it's a real 3D object.  But it could be a clever film prop, so you can pick it up and flick through to convince yourself it's a real book.  Is it really the book it claims to be on the cover?  Well, read it and find out.

All of the time you're gathering new information, and yet the object you're observing becomes more simple.  As you look closer you see:

  1. An object that looks like a book, but could be a million other things.
  2. An object that looks like a book, or a very good effort at one.
  3. A book, one of countless billions.
  4. A book, by a specific author.
  5. A particular book by that author.
And so on and so forth.  As you look deeper and deeper you'll find a very small ASCII text file embedded on a paper based medium - a blank book plus an ebook.  Then you find yourself looking at molecules arranged in a particular way.  Then atoms.

When you get down to the subatomic level you're saying, in effect, "there's a quark here".  A quark can be described with just three numbers: the mass, the charge and the spin.  That's it.  You don't get big quarks or little quarks, you can't get a quark made from metal and a quark made from wood, you only get three numbers.  That's all a quark is, just three numbers.

Now we're not looking at a thing at all, just three numbers.  Add to that a few rules about what happens when these three numbers bump into another three and you're got something called quantum mechanics, and yes, it's really that simple.   Well...nearly.  The maths is a little tricky, but particle physics and quantum theory are both in effect just careful juggling of a few numbers, not objects.

It may be that we just don't know enough yet (see above, "science admits it might be wrong"), but it all seems to boil down to numbers.  Not objects, just numbers.

What we're looking at now is commonly called Platonism, after Plato's idea that maths is real, and that's absolutely what I'm supporting here, the idea that mathematical ideas are real in their own right.  We know Pythagoras' Theorem, and yet we're not able to build a mathematically perfect right-angled triangle.  We can get really close, but the best we can even theoretically manage at the moment is a triangle of Planck lengths - three by four by five of them.  And even then, it's still a bit hazy.  Maths is more perfect than reality can muster, but reality seems to be trying very hard indeed.

See, told you this was a bit of a wacky post.

For further reading, without much terminology and maths, see:

The Unreasonable Effectiveness Of Mathematics In The Physical Sciences
Eugene Wigner - a classic and readable academic paper on the subject, link courtesy of Buffalo State College, US

Neal Stephenson - a work of fiction covering the main themes and a beautiful work at that.  The inspiration behind this post in a way.