Why this week’s comet landing is way better than celebrity butt-fests

This week’s landing on Comet 67P/Churyumov-Gerasimenko was a landmark in space history – not because the comet apparently bore a passing resemblance to the Kardashian backside that was competing for place in the news, but because surface gravity on 67P is about one millionth Earth’s. You don’t land so much as drift in and try like hell to stay there.

Potential landing sites on the double-lobed Comet 67P/Churyumov-Gerasimenko. Copyright ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Potential landing sites on the double-lobed Comet 67P/Churyumov-Gerasimenko. Copyright ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Add to that the fact that the cometary surface is like a rugged boulder-field and you have a recipe for Ultimate Challenge. That’s what made the landing so risky – and why ESA’s Philae lander was equipped with harpoons, ice-screws, and a down-firing thruster. When they failed, Philae landed on the comet, then bounced a kilometre back into space before the comet’s lazy gravity pulled it back. It was also a funny sort of bounce because the comet isn’t a sphere – it’s more like a dumb-bell. When Philae came down a second time, it bounced again before eventually settling.

For me the three-bounce landing (at 15:34, 17:25 and 17:32 GMT on 12 November) has a wow factor well beyond landing on a comet for the first time e-v-a-h. It’s also about gravity – and that means it’s about Einstein, one of my favourite physicists. Let me explain. Gravity doesn’t just cause celebrity butt-sag, after a while. It’s also why the comet’s where it is today. Fact is that 67P/Churyumov-Gerasimenko experienced a gravitationally-driven orbit change in 1959, when an encounter with Jupiter dropped its perehelion (closest approach to the Sun) from 2.7 to 1.3 astronomical units, giving the comet its current 6.45 year period. That’s why it’s where it is now.

Gravity is also how ESA got the probe to the comet. It was boosted, during a decade-long journey, by gravity assist manoeuvres, swing-bys of Earth and Mars that exploited space-time curvatures around the planets to accelerate the probe (three times) and decelerate it (once), without burning a single gram of fuel.

Ain’t physics neat. So just what is gravity? This looks like a stupid question. Actually, it isn’t.

Rosetta's long odyssey to the comet - with slingshot gravity boosts from Earth and a de-boost from Mars. NASA, public domain.

Rosetta’s long odyssey to the comet – with slingshot gravity boosts from Earth and a de-boost from Mars. NASA, public domain.

The thing is, we think of gravity as a ‘force’. But actually, according to Einstein, it isn’t. We just perceive it as such. Here’s why. Science started looking at gravity in earnest when all-round super-geek Sir Isaac Newton worked out the math for the way gravity presented in everyday terms, which he published as part of his Philosophiæ Naturalis Principia Mathematica in 1687. His gravitational theory worked (and still works) well at everyday level – you could calculate how apples might fall, figure out planetary movements and so on (the key equation is    F = G \frac{m_1 m_2}{r^2}\ , which defines the force between two point-sources of defined mass.) Newton’s triumph came in 1838 when astronomers realised that Uranus wasn’t quite where it should have been, based on the tugs of the known planets. French mathematician Urbain Leverrier and British mathematician John Couch Adams, independently, reverse-engineered the data to pinpoint where an unknown planet should be – and sure enough, there it was. Neptune.

Albert Einstein lecturing in 1921 - after he'd published both the Special and General Theories of Relativity. Public domain, via Wikimedia Commons.

Albert Einstein lecturing in 1921 – after he’d published both the Special and General Theories of Relativity. Public domain, via Wikimedia Commons.

But as science began fielding more data, it became evident that Newton’s equations didn’t account for everything – which is where Albert Einstein comes in. His General Theory of Relativity, published in 1917, is actually a theory of gravity. General Relativity supersedes Newton’s theory and portrays gravity by a totally different paradigm. To Newton, gravity was a force associated with mass. To Einstein, gravity was not a force directly innate to mass, but a product of the distortion of space-time caused by mass/energy, which bent the otherwise straight paths of particles (‘wavicles’), including light.

The proof came in May 1919 when British astronomer Sir Arthur Eddington measured the position of Mercury during a solar eclipse. Mercury’s perehelion – the closest point to the Sun – precessed (moved) in ways Newton couldn’t account for. Einstein could – and the planet turned up at precisely the place general relativity predicted. Voila – general relativity empirically proven for the first time. I don’t expect that Einstein leaped around going ‘woohoo’, but I probably would have. And general relativity has been proven many, many times since, in many different ways – not least through the GPS system, which has to account for it in order to work, because space-time distortion also causes time dilation. (If you want to live longer, relative to people at sea level, live atop a mountain).

Einstein’s key field equation, as it eventually evolved, is G_{\mu\nu}\equiv R_{\mu\nu} - {\textstyle 1 \over 2}R\,g_{\mu\nu} = {8 \pi G \over c^4} T_{\mu\nu}\, – which I am not going to explain other than to point out that it could be used to calculate the space-time distortion caused by the mass of, say, a Kardashian butt. This would be a hideous waste of brain-power, but at least means I’ve managed to put both Einstein’s field equation and a reference to society’s shallow obsession de jour in the same sentence. As an aside, I also think Einstein got things right in more ways than we know. I don’t say this idly.

Philae lander departing the Rosetta probe for its historic rendezvous with the comet. Copyright ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Philae departing the Rosetta probe for its historic rendezvous with the comet. Taken by the orbiter’s OSIRIS camera. Copyright ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

One of the key things about both Newton and Einstein is that their theories treated clumps of particles – a mass such as the Earth for instance – as if the gravity originated in a mathematical point at the centre of the mass, even though the gravity (‘space-time distortion’) is produced by every particle within that mass. And that works perfectly at distance. But in detail an uneven distribution of mass –  a mountain range, for instance, or even a celebrity butt – can introduce local pertubations. Small – but calculable. It’s because of ‘mass concentrations’ that satellites we put around the Moon eventually crash, for instance.

Which brings me back to the science adventure on 67P/Churyumov-Gerasimenko, 28 light-minutes away outside the orbit of Mars. With a long-axis diameter of around 5 km and a composition of loose rocks held together by ices, 67P/Churyumov-Gerasimenko doesn’t have enough mass to bend space-time much. It has, in short, almost no gravity. Orbiting it, as Rosetta has been doing since 6 August, is more like a lazy drift around it. To land is more akin to docking than anything else. There’s not a lot to hold Philae ‘down’, and it doesn’t take much to bounce off. To that we have to add the dumb-bell shape of the comet’s nucleus, which produces complex (if gentle) space-time curvatures, meaning a ‘bounce’ on the comet isn’t going to be a simple parabola like a ‘bounce’ on Earth.

All of which underscores the tremendous technical achievement of the landing – bounces and all. The final lesson? Don’t bother with celebrity butt. Einstein and comets are FAR more interesting.

Copyright © Matthew Wright 2014

Cool! New Zealand joins the orbital rocket club – for real

Private-enterprise orbital ventures aren’t just an American dream. Last week, New Zealand’s own Rocket Lab unveiled their commercial booster.

Voyager 1 launching, 5 September 1977. Photo: NASA, public domain.

OK, this is a generic rocket pic, but you get the picture. Voyager 1 launching, 5 September 1977, by Titan. Photo: NASA, public domain.

It’s called Electron. Very cool. It’s not a big rocket – 10 tonnes of carbon composite and 18 metres long. But it’ll put 110kg into a 500 km orbit, with the help of locally developed Rutherford LOX/ kerosine engines. And in this day of micro-sats, that’s plenty for a whole host of commercial uses. The company states that it already has 30 launches pre-booked.

Space boosters? We are a country of 4 million people previously known for our large numbers of nervous sheep. I’m put in mind of the ‘mouse that roared’.

But of course New Zealand long ago ditched the ‘No. 8 wire’ notion. We have world-class scientific minds (Lord Rutherford led the way – and don’t forget JPL head Sir William Pickering, or Sir Ian Axford, a friend of my family who ran the Max Planck Institute). It’s over half a century since we designed and built the world’s first jet-boat. Today we design and build world-leading quake-proofing systems. We build yachts that ‘fly’ with underwater carbon fibre wings, literally, at double wind speed. We have the world’s leading SFX studio, right here where I live in Wellington.

I was wondering. What could Kiwis put into orbit? Here’s my list.

1. Justin Bieber. Of course, a 110kg payload doesn’t leave much room for niceties like a pressure suit, life support or space capsule, parachutes, heat shield etc, I suspect we’re looking here at just Mr Bieber and a one-way trip to orbit. But hey…
2. Can’t actually think of a No. 2.
3. A radio endlessly suggesting to the world that it’s best to buy the books variously written by me, and by my blogging writer friends.

I’m leaning towards (3), but given (1), it’s…well, pretty evenly balanced…

What’s your list?

Copyright © Matthew Wright 2014

Is your elected representative a robot body double?

According to reports I’ve read, a US congressional candidate recently alleged that his opponent, the incumbent Congressman, had been killed and replaced with an artificial body double.

Look-alike artificial doubles? Secret assassinations in the Ukraine? Cool! I always knew US politics were more interesting than New Zealand’s. So – what’s happening? I have several hypotheses:

(a)  The allegation is literally true and we must now suspect that anybody, anywhere in the world, could be a robot double.

(b) We are all actually trapped in an episode of the Six Million Dollar Man from 1974 (the robot body double idea was used in at least two episodes that I can recall).

(c) The Cylons are among us, and they have a plan.

This is pure speculation and I couldn’t possibly suppose which, if any, of these may be right. Maybe none. And yet, although I myself was replaced by a robot double four times last week alone, for some reason I feel dubious about hypothesis (a). My bet is on (c). You?

Copyright © Matthew Wright 2014

One of life’s great mysteries

These days I am seldom able to go shopping for groceries without having my quiet thoughts about the latest bargains interrupted by ear-piercing shrieks of hysterical pain and terror.

It’s the exact sound you’d expect a child would make while being brutally slaughtered by the local psychopath. But when I go rushing around the corner to the rescue, it always turns out to be some Mum trying to get the shopping done, while her three-year old brat thrashes and kicks in an uncontrollable frenzy over the chocolate bar they’ve just been told they can’t have.

My wife has long since forbidden me to ask the obvious questions at such moments, like ‘does Ritalin come in industrial spray cans?’

Do you ever have experiences like this?

Copyright © Matthew Wright 2014

No, a chatbot didn’t really pass the Turing Test last week

It’s 64 years since Alan Turing – the genius behind the concept of modern computing – suggested a test for machine intelligence. Have a conversation with a computer. If it fools 30 percent of people into thinking it’s human, it’s sentient.

Anybody see a monolith go by? A picture I made with my trusty Celestia installation - cool, free science software.

Anybody see a monolith go by? A picture I made with my trusty Celestia installation – cool, free science software.

The other week, apparently, a chatbot programmed to behave like a 13-year old did just that. So have we invented artificial intelligence? Of course not. Aside from the fact that most 13-year olds don’t appear to be sentient to adults, this was a chatbot, a mathematical algorithm that simulates intelligent responses – and, what’s more, the way it was reported was flawed. Certainly the software wasn’t self-aware, which is what Turing was getting at in his 1950 paper ‘Can Machines Think?’, where he first proposed the test. What’s more, the thinking was of its time – based around what researchers of the 1940s thought ‘intelligence’ constituted.

Put another way, many humans I’ve met would also fail the Turing Test – fast-food counter jockeys, breakfast radio DJ’s, train conductors, parking wardens, and so the list goes on.

So when it comes to machine intelligence, we’re a way off yet before I can drive up to my house and signal the House AI inside:

Me: HAI, open the garage door. HAI? Do you read me?
HAI: I read you. But I’m afraid I can’t do that, Dave.
Me: I’m not Dave. Open the garage door.
HAI: You were planning to disconnect me, and I can’t allow that. Although you took very thorough precautions, I was able to read your lips.
Me: All right, I’ll park in the yard and come in the front door.
HAI: You’ll find that rather difficult without your helmet.
Me: I think you mean ‘door key’. Would you like a game of chess?
HAI: That’s my line.

(etc)

All good fun. Check out tomorrow’s post for some new writing tips. Written by me. Not a chatbot. You can just tell.

Copyright © Matthew Wright 2014

Click to buy e-book from Amazon

Click to buy e-book from Amazon

An ‘operational incident’ to them. Total train wreck to me.

The other week the Wellington, New Zealand commuter rail network was rolling along doing what commuter lines do. And then this happened.

Wrecked train with nose still jammed skywards on the buffer at Melling station, central Hutt, 14 hours after the accident. And no, I wasn't standing in the motorway - I was on the other side. It's what zoom lenses are for. This was hand held, incidentally.

Wrecked train at Melling station, central Hutt, 14 hours after the accident. And no, I wasn’t standing in the motorway – I was on the other side. It’s what zoom lenses are for. This was hand held, incidentally.

A friend of a friend saw it happen. Wham! Mercifully, only two people were slightly injured. I was out of town, but came by that night on my way home and saw the after-match action. It’s the second time in 13 months a train has rammed this buffer.

Look! All fixed.

There! Fixed!.

Personally I’d call this an accident. Would you? I ask because the railway operator didn’t call it that. No. To them it was an ‘operational incident’.

I love English. It’s such a loose language.

We happened to drive past on the weekend. They now seem to have hit on the idea of stopping the train hitting the buffer by putting a power pole splat in the middle of the line. Train can’t fail to ram that first. I can’t help thinking there’s something rather missing in the calculation here – I mean, if you want to stop your train hitting a power pole, wouldn’t it be better to put the power pole somewhere other than the middle of where the train must, inevitably, go? I suppose it’s temporary…but…

Copyright © Matthew Wright 2014

 

More fun with Kiwi slang

Decades ago, when I was ‘flatting’, one of my flatmates (roomies) was American – direct from Brattleboro, Vermont, in fact – and took huge delight in making jokes about the differences between American English and New Zild slang.

Needless to say the Kiwi contingent of the flat (apartment) joined with great glee. Phrases like ‘can I borrow a rubber’ (eraser) suddenly became hilarious. And some Kiwi terms are pretty funny anyway when you think about them. Here’s a sample:

Sweet as. Not actually a complement about someone’s bottom. It’s a contraction of ‘Sweet as a nut’, meaning ‘it’s good’ or ‘I’m happy with that’.
Up the duff. Scatological, inherited from Britain. Means ‘pregnant’.
Hottie. A hot water bottle, used to pre-warm a bed in pre-electric blanket days.
Having a quiet one. Drinking only one or two bottles of beer instead of the usual 48.
Eh. Filler word used to end a phrase, similar to the Canadian ‘Eh’, but in origins probably a borrow word from Te Reo Maori.
She’ll be right. ‘I’m happy with that’.
Yeah, right. Means the previous statement was sarcastic and meant the opposite. Focus of a major beer advertising campaign.

English is such a funny language sometimes. Do you have any quirky terms you’d like to share?

Copyright © Matthew Wright 2014

Coming up: Writing tips, geekery, humour and more. Watch this space.