Is Comet Siding Spring going to turn our Mars probes into shredded tinfoil?

Shiver in your shoes, Martians! This month – specifically, 19 October at 18:28 Zulu – Comet C/2013 A1 ‘Siding Spring’ makes its closest approach to Mars. The nucleus, a few kilometres in diameter, will come a smidgeon under 120,000km from the red planet.

Mars from the Siding Spring nucleus at closest approach - a picture I made with my trusty Celestia astronomy package.

Mars from the Siding Spring nucleus at closest approach – a picture I made with my trusty Celestia astronomy package.

That’s close. Though not as close as once feared. When the comet was first discovered by Robert H. McNaught in January 2013, using the 20-inch Upssala Schmit telescope at Siding Spring observatory in New South Wales, it was thought likely to hit Mars. It was only later, after multiple observations and cross-checks, that the orbit was refined.

Good news is that this is a tremendous opportunity – and there’s a fleet of orbiting satellites up there for the purpose.  Two, the US MAVEN and India’s Mars Orbit Mission (MOM) – arrived just last week. That puts a lot of instruments in close proximity, and the Indians have plans to use MOM to check for methane on the comet as it brushes past. The Mars Reconnaissance Orbiter will use its HIRISE camera to look at the comet nucleus and activity. Mars Odyssey will check out the coma. MAVEN will make a range of observations with eight different instruments. Even the rovers on the ground, Curiosity and Opportunity, will point their cameras at the sky – Curiosity’s ChemCam, which can pick up the composition; and Opportunity’s PanCam, which will give us a visual from the surface of Mars.

More shenanigans from my Celestia software. This is a view looking from inside the coma towards Mars and the Sun at closest approach.

More shenanigans from my Celestia software. This is a view looking from inside the coma towards Mars and the Sun at closest approach.

Bad news is that this fleet of satellites took years to get up there, cost billions of dollars – and are basically irreplaceable. The nucleus won’t get near Mars. But the coma of dust and debris surrounding it will. Estimates are that during the several hours it takes Mars to pass through the comet’s coma, the planet will be peppered with about five years’ worth of normal meteor activity. It’s all small stuff – nothing more than 1cm diameter, most of them only fractions of a millimetre. But the relative speed is 56 km/sec (200,000 km/h). That’s – uh – impressive. At that speed a 1 gram mass has a kinetic energy of 15,680,000 joules, or 4.35 kwH. In human terms? Enough to run a domestic fan heater on high for a couple of hours. Woah! And that’s just one particle. There are going to be a LOT of particles skidding past Mars.

More Celestia fun; a picture I made of planetary orbits at the moment of Siding Spring's Mars encounter.

More Celestia fun; a picture I made of planetary orbits at the moment of Siding Spring’s Mars encounter.

Precautions have included adjusting orbits so the probes will be on the opposite side of the planet from the comet 100 minutes after closest encounter, when the dust is estimated to reach its highest density. The MRO shifted its orbital parameters to that end on 2 July, while Odyssey did so on 5 August and MAVEN on 9 October. Still, that’s not a complete fix – they’ll travel back around into the danger zone soon enough. Other precautions include pointing the spacecraft so more delicate components are shielded by less crucial elements. And MAVEN will be put into a partial shut-down mode. Once the danger’s past, they’ll restart the science.

By 22 October, according to mission timelines, it’ll all be over. And, if the cometary debris hasn’t shredded them into tinfoil, they’ll be back to their normal work exploring the red planet.

Is Earth in any danger? None whatsoever. Even if we were at closest approach to Mars, the comet wouldn’t affect us – but as it happens, we’re nearly a quarter-turn away from Mars in any case, just at the moment. That’s not the issue – the issue is the several billion dollars worth of science equipment we’ve got around Mars at the moment, its survival – and the science we’ll get from them during this once-in-a-lifetime opportunity.

Copyright © Matthew Wright 2014

Apocalypse now: why we must fear a Carrington storm

On 28 August 1859, British astronomer Richard Carrington noticed something unusual on the Sun. A flare, larger than anything he’d seen before.

Solar flare of 16 April 2012, captured by NASA's Solar Dynamics Observatory. Image is red because it wa captured at 304 Angstroms. (NASA/SDO, public domain).

Solar flare of 16 April 2012, captured by NASA’s Solar Dynamics Observatory. Image is red because it was captured at 304 angstroms. (NASA/SDO, public domain).

Three days later, Earth lit up. Aurorae erupted as far south as the Carribean. All hell broke loose in telegraph systems across the world. Lines began spraying sparks. Operators were electrocuted. Other telegraphs worked without being switched on.

Later, we figured it out. The sun ordinarily blasts Earth with a barrage of fast-moving protons and electrons; the solar wind. Most is deflected by the Earth’s magnetic field – particles are trapped by the field, forming the Van Allen radiation belts.

Flares add to this in two ways. The first is through intense electromagnetic radiation – a mix of X-ray frequencies produced by Bremmstrahlung, coupled with enhanced broad-spectrum radiation as a result of synchotron effects – both of them slightly abstruse results of relativistic physics. This strikes Earth, on average, 499 seconds after a major flare erupts in our direction. We’re safe on the surface from the effects; the Earth’s magnetic field and atmosphere stops even radiation on a Carrington scale. In 1859, nobody noticed. But today, astronauts on the ISS wouldn’t be safe. Nor would our satellites.  So aside from the human tragedy unfolding in orbit, we’d lose everything associated with satellites – GPS to transaction systems to weather to Google Earth updates and everything else. Gone.

Buzz Aldrin on the Moon in July 1969 with the Solar Wind Experiment - a device to measure the wind from the sun. Public domain, NASA.

Buzz Aldrin on the Moon in July 1969 with the Solar Wind Experiment. (NASA/public domain).

It gets worse. Some flares also emit a mass of charged particles, known as a CME (Coronal Mass Ejection). Seen from the Sun, Earth is a tiny target in the sky. But sometimes we are in the way, as in 1859. The problem is that a CME  hitting Earth’s magnetic field compresses it. Then the CME passes, whereupon the Earth’s magnetic field bounces back.

The bad juju is the oscillation, which causes inductiion on a huge scale. Induction is a principle of electromagnetics, discovered by Michael Faraday in September 1845 when he moved a conductor through a magnetic field, generating electricity down the conductor as long as it moved. It also works vice-versa – a moving magnetic field induces electricity in a stationary conductor. And electricity can be used to create magnetism. We’ve been able to exploit the effect in all sorts of ways. It’s how electric motors and loudspeakers work, for instance. Also radio, TV, bluetooth, ‘wireless’ internet broadband. Actually, pretty much everything. When inducing an electric current with magnetism, the strength of current is a function of (a) the size of the conductor, and (b) the flux of the magnetic field. Maxwell’s equations apply. The longer the cable, the more current generated in it. That’s how aerials work – like the one in your cellphone, ‘wireless’ router, laptop – and so the list goes on.

Now scale it up. Earth’s magnetic field moves, generating electrical current in all conductive material. Zzzzzzt! That’s why so much current was generated down telegraph lines back in 1859 – they were immense aerials.

Geothermal steam from the Taupo system is used to generate power - up to 13 percent of the North Island's needs, in fact. The techniques were developed right here in New Zealand.

Geothermal power station at Wairakei, New Zealand. This generates up to 13 percent of the North Island’s needs. Note the power lines – vulnerable to induced voltage in a Carrington event.

Fast forward to today. Heavy duty devices like a toaster or kettle don’t contain enough conductive material to induce voltage that will fry them during a CME event, and that’s true of most appliances – though your phone or computer might be damaged, because microprocessor chips and hard drives are vulnerable to very small fluctuations. Personally, if I knew a Carrington storm was coming, I’d unplug my computer at the CPU (the power cable acts as an aerial). But none of it will work afterwards anyway. Why? No mains power. That’s the problem – the power grid. Those 220,000 volt lines. They’re plenty big enough to suffer colossal induced voltages, as are the cable windings inside the transformers that handle them. Power grids around the world go boom.

Yes, we can rebuild the system. Eventually. Estimates suggest a minimum of five months in the UK, for instance, to get enough transformers back on line. Always assuming they were available, which they might not be if every other country in the world also wanted whatever was in stock. In any case, the crisis starts within hours. Modern cities rely on electrically pumped water. Feeling thirsty? Maybe you’re lucky enough to live near a river. You struggle through crowds dipping water. Struggle home with a pan of muddy liquid. No power – how do you boil it? You have a barbecue. What happens when the gas runs out?

Now think about everything that relies on electrically pumped water. Nuclear power stations.  Their diesel generators are not designed to run for weeks or months. Think Fukushima. Over and over. I am SO GLAD I live in nuclear-free New Zealand.

This isn’t speculation. A CME-driven grid burn-out already happened to Quebec in 1989. Luckily the solar storm wasn’t colossal. Studies suggest that 1859 storms occur every 500 years or so, but we’re learning about the Sun all the time, and that may change. We had near-misses from dangerous CME’s in 2012 and earlier this year. We’re vulnerable.

A CME might not take down the whole planet. All depends on its size. But it could still do colossal damage. A study in 2013 put the potential cost of another Carrington storm at $US2,600,000,000,000. If you stacked 2.6 trillion US $1 notes, one on top of another, the pile would be 291,200 km tall, which is a shade over 75 percent the average distance of the Moon. That’s without considering the human cost. But there are ways to ameliorate the issue. Including shutting down the grid and disconnecting things if we get warning. If. The take home lesson? Remember the Carrington storm. Fear it.

If you want to read about how we might cope after a big CME, check out the novels by New Zealand author Bev Robitai. Sunstrike and Sunstrike: The Journey Home.


Copyright © Matthew Wright 2014


Finding another Earth isn’t easy. Unfortunately.

Are you looking for a second Earth? We need to – humanity is on the fast track to ruining our one.

Simulated Exo-Earth. A picture I made. Apart from the fractal artefacts, does anybody notice what's wrong with it?

Simulated Exo-Earth. A picture I made. Apart from the fractal artefacts, does anybody notice the science issue that I didn’t correct?

Of course it’s not an easy task. A planet discovered the other week with the help of Kiwi astronomers underlines the problems. Four astronomers here in New Zealand contributed data to the OGLE microlensing follow-up network program in 2012. The results were published recently – and the good news is, OGLE found a planet.

OGLE, incidentally, stands for ‘Optical Gravitational Lensing Experiment’. An apt acronym. It works by exploiting a quirk of Einstein’s theory of relativity – that mass distorts space-time. Massive stars bend light around themselves, acting as ‘lenses’ and enabling us to point a telescope at the massive star, and so detect faint objects passing directly between us and them, that we wouldn’t otherwise be able to observe. The gravity lens around the distant star is known as an ‘Einstein Ring’, and the method is usually used to pick up planets orbiting in the ‘halo’ of a star – the debris orbiting it, like our Oort Cloud. These are known as Massive Compact Halo Objects (MACHOS). Cool or what?

Anyhow, back to the news. The planet is called OGLE-2013-BLG-0341LBb, and it’s about 3000 light years away in the constellation Cassiopeia.

The good news?

- It orbits its sun at 0.8 AU – nearly the distance of Earth (yay!)

- It’s about Earth sized – mass is thought to be only twice ours (yay!)

- That doesn’t imply twice our surface gravity (yay!) [I can't calculate it unless I know the radius and density of the planet, which I don't, but if density is the same as Earth, average 5.5 g cm <exp>3, then the surface gravity won't be double because surface gravity is also proportional to the radius. Just saying.]

- It’s orbiting just one star in a binary pair (Tattooine, sort of – yay!)

Let me illustrate mass vs surface gravity. Although it has a mass 14.5 times that of Earth, 'surface gravity' on Uranus is just  89 percent that of Earth. That's because the radius is about 4 times Earth's. I made this picture with Celestia.

Let me use Uranus to illustrate mass vs surface gravity. Although it has a mass 14.5 times that of Earth, ‘surface gravity’ on Uranus is just 89 percent that of Earth. That’s because the radius is about 4 times Earth’s. I made this picture with Celestia.

So is this Earth 2? Well, if I were you I’d take warm clothes. The bad news is that the star is a red dwarf, 400 times less energetic than the Sun, so the planet has a surface temperature of 60 degrees Kelvin – in centigrade, a chilly -210 degrees. (Booooo!)

The search for Earth-like planets has got exciting lately as we’ve developed the tech to discover them. Problem is, the gear is not good enough to image them directly. We can’t learn much other than the size and orbital distance – from which we can derive its year, mass and temperature. If we’re lucky, we might also get a handle on its atmospheric makeup, via spectrography as it transits its sun.

For these reasons, usually when we detect a planet that’s otherwise in the ‘goldilocks’ zone, we don’t know whether it’s actually like Earth. It might be like Venus – runaway greenhouse with sulphuric acid, crushing atmosphere and oven-like temperatures. We don’t know. Don’t forget, if astronomers 3000 light years away were using the same techniques to analyse our solar system, they might conclude there were two Earths here from the planetary mass and orbital data.

The way things are going, of course, we’re likely to end up with two Venuses. Venuses? Venii? You know what I mean.

And it’s a worry.

Copyright © Matthew Wright 2014

Flying saucers and other aerial crockery

A UFO was caught over the South Island the other week by an Australian film crew. By “UFO” I mean “unidentified object” which was “flying”. We don’t know what it was – and the objects could have been an artefact of the video.

Jupiter rising over Io - a picture I made with my Celestia installation

Jupiter rising over Io – a picture I made with my Celestia installation

Needless to say, I am certain they weren’t alien spacecraft, any more than any other UFO is.

I can hear the howling. ‘But the universe is big, surely other planets must have life?’

Sure. Space is enormous.  No doubt life’s emerged elsewhere. But – again – it doesn’t follow that the aliens have developed civilisation, jumped into spacecraft, and flown here. It particularly doesn’t follow that they’ve done so merely to lurk mysteriously on the edge of our vision, violating cows, revealing themselves to lone witnesses on dark country roads, and so on. Or that they’d be big-headed, big-eyed, child-bodied versions of us with an ethical view that fixes the faults of western society.

The fact that lay-people presented with partial evidence can’t explain an observed phenomenon doesn’t prove it’s an alien spaceship. The fact that science can’t explain it from partial data doesn’t, either. That’s false-premise logic.

I’ve seen plenty of weird aerial stuff myself. The best was over Wellington in April 1986, when I spotted a slow-moving fireball parallel to the southern horizon, shedding sparks. I knew what it was. The thing was moving in the direction I’d expect from the usual orbital paths, the only ‘unidentified’ part was whether it was US or Soviet.

Spacewalk to assemble the ISS, 12 December 2006. New Zealand is below - North Island to the right, South to the left. My house is directly under the aerial centre-frame. Photo: NASA, public domain, via Wikipedia.

Spacewalk to assemble the ISS, 12 December 2006. NASA, public domain, via Wikipedia.

To me the phenomenon of ‘space aliens’ is a product of the way western culture is conditioned to think. The trigger was the mid-twentieth century assumption that Earth was archetypal and that every world capable of supporting life would bear one intelligent species, probably a bipedal hominid. In due course, this would become civilised, space-faring and visit other worlds. Just like Europe’s explorers during the age of exploration.

It is no coincidence that we decided aliens were visiting just as we began to take spaceflight credibly. The idea emerged in June 1947 when US pilot Kenneth Arnold reported nine boomerang-shaped objects paralleling his aircraft near Mount Rainier. A journalist misquoted that as ‘saucers’, which promptly became the shape of the interlopers thereafter. The origin of that shape as a journalists’ misquote was rather lost amid the flood of blurred photographs of aerial lampshades that fringe enthusiasts were subsequently able to provide as proof of their own encounters.

Blue sunset on Mars - for the same reason skies are blue on Earth. An approximately true colour image by the Spirit rover at Gusev Crater, 2005. Photo: NASA/JPL, public domain.

Blue sunset on Mars – for the same reason skies are blue on Earth. NASA/JPL, public domain.

These 1950s-era aliens came from Mars or Venus and looked like us, only with handy super-powers such as telepathy. Alas, the Mariner and Venera probes of the 1960s revealed Venus was a runaway greenhouse oven – and Mars was a cold, cratered world without breathable air. Luckily it turned out, after that discovery, that the aliens really came from well-known stars on the school science curriculum, like Aldebaran. Then in 1978 Stephen Spielberg’s Close Encounters of the Third Kind hit the cinema, and the current alien trope followed.

You get the picture.

My take? We have had civilisation for an eye-blink against the age of the Earth. It may only last another eye-blink, by that scale. Who says aliens have the same capability at the same time? They might have flourished and gone a billion years ago. Or their time might be a billion years in the future.

Space is also immense. Who says they’d find us anyway? Or that we could be important? To give that a sense of proportion, our sun’s invisible, without telescopes, from just under 60 light years.* I’ve heard it argued that ‘they’ could hear our transmissions – TV, radio, radar and so on. Actually, we’re just as invisible that way too. In theory I Love Lucy – which began transmission in 1951 – has just reached the planet we photographed, orbiting Beta Pictoris, 63 light years away. Actually our broadcasts, even high-frequency radars, don’t get that far because of the inverse square law, coupled with natural background radio noise. Our stuff’s lost in the static. Yet our galaxy is 100,000 light years across. Feel small? You should. And if aliens did arrive, would we recognise them as life? Or be able to communicate? They’re alien, remember. Maybe they’d be too busy talking to their own kind – you know, other algae.

Put another way – sure, we see stuff in the sky we can’t explain. But that doesn’t mean it isn’t explicable. Or that ‘aliens’ are among us.


Copyright © Matthew Wright 2014


* Geek time. Muahahahaha. Stellar brightness is measured by magnitude, an inverse scale in which lower is brighter. The true magnitude of a star is its absolute magnitude. But this fades with distance (inverse square law), so its visual magnitude, the brightness we see from a distance, is less. This is known as the apparent magnitude. Any star of apparent magnitude greater than about 6 is invisible to the average naked eye. The distance where the apparent magnitude (m) fades to invisibility can be calculated from the absolute magnitude (M) using the distance modulus equation r = 10<exp>((m-M)/5+1) where r is the distance in parsecs. If you apply that to the Sun, absolute magnitude 4.83, you discover it fades to apparent magnitude 6 at about 57 light years, which is about 0.057 percent the diameter of the galaxy.



My hypothesis that English is a loose language

I’ve always thought English is a loose language. Take the words ‘theory’ and ‘hypothesis’, for instance. Even dictionary definitions sometimes mix their meanings up.

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 the Special and General Theories of Relativity. Public domain, via Wikimedia Commons.

Scientifically, the word ‘theory’ means a ‘hypothesis’ that has been established to be true by empirical data. Take Einstein’s two theories of relativity, Special (1906) and General (1917). We call them ‘theories’, by name, but everybody with a GPS-equipped cellphone or GPS system encounters proof that Einstein was right, every time they use it.

This is because GPS satellite clocks have a correction built into them to cope with Special Relativity time dilation that occurs because they’re moving at a different velocity than the surface of the Earth. It’s miniscule –  6 millionths of a second loss every 24 hours. There’s also the need to cope with General Relativity time acceleration relative to the surface of the earth, because they’re in orbit, putting them further away from the mathematical centre of Earth’s mass than we are on the surface of the planet. That totals 45 millionths of a second gain every 24 hours.

If all this sounds supremely geeky and too tiny to worry about, millionths of a second count,  because its on differences at that order of magnitude that GPS calculates positions. If the net relativity error of 39 millionths of a second every 24 hours wasn’t corrected, GPS would kick up positional errors of up to 12 km on the ground. Einstein, in short, was totally right and if we didn’t use Einstein’s equations to correct GPS, we’d be lost. Literally. Yet we still call his discovery a ‘theory’.

Hypothesis,on the other hand, is the idea someone comes up with to explain something. Then they run tests to figure out the rules. Take gravity. Everybody knew it existed. However, Newton figured he could come up with rules – his hypothesis. Once Newton had a hypothesis, he was able to run experiments and sort out actually how it worked – creating his theory of gravity.

Neptune. A picture I made with my trusty Celestia installation (cool, free science software).

Neptune. Discovered by mathematics, thanks to Newton’s theories. A picture I made with Celestia (cool, free science software).

One of the reasons why these explanations are called ‘theory’ is because science sometimes finds refinements. Einstein’s theory of General Relativity is also a theory of gravity, integrating the extremes of time and space Einstein described in his Special theory. It replaced Newton’s theory. But that didn’t mean Newton was wrong in the terms he observed and described. On the contrary, his equations still work perfectly for the things around which he developed the theory.

So in the strictest sense, ‘hypothesis’ means ‘how we think things work’, while ‘theory’ means ‘how we’ve shown things to work’. Science sometimes creates supersets of theories, like onion skins, that explain things differently – but usually don’t invalidate the core of the earlier theory.

And my hypothesis, which I think should be elevated to theory status on this evidence, is that English is a pretty loose language. Thoughts?

Copyright © Matthew Wright 2014


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The science behind this year’s blood moons

Well, the first ‘blood moon’ of 2014’s come and gone. I missed it – the night sky where I live was socked in with 10/10 overcast at an altitude of about 200 metres.

US Navy photo of a total lunar eclipse in 2004, by Photographer's Mate 2nd Class Scott Taylor. Public domain, via Wikipedia.

US Navy photo of a total lunar eclipse in 2004, by Photographer’s Mate 2nd Class Scott Taylor. Public domain, via Wikipedia.

Still, I’ll have another chance on 8 October. And another on 4 April 2015. And a fourth on 28 September that year.

Although unusual, it’s not a unique occurrence to have four eclipses in quick succession. Technically they’re known as a tetrad.

The reason why eclipses are a bit erratic is interesting. A lunar eclipse is simple enough – the Moon passes through the shadow of the Earth. The reason lunar eclipses don’t happen every 27 days, as the Moon orbits the Earth, is because the Moon doesn’t always pass through the shadow when it’s ‘behind’ the Earth relative to the sun. It would if everything was lined up flat on the same plane – but it isn’t.

In fact, the Moon’s orbit is tilted relative to the ecliptic – the plane in which Earth and Sun orbit. The tilt varies between 4.99 and 5.30 degrees. The two points at which the orbit intersects the ecliptic are known as ‘nodes’, and they move around the Moon’s orbital path – technically, ‘precess’ – at a rate of  19.3549° annually.

For an eclipse to occur, the node (‘ascending’ or ‘descending’) has to coincide with the point where the Moon would pass through Earth’s shadow (which is on the ecliptic). That happens every 173.3 days. An eclipse is possible at that time, though again, the orbital mechanics don’t always mesh exactly.  There are more factors than just ecliptic and orbital angle. Earth’s shadow has a dense part (umbra) and a less dense part (penumbra). Sometimes there is only a partial eclipse. Sometimes it’s total.

Colour photo of the Moon taken by the Galileo probe in 1990 - a view we never see from Earth. The - uh - 'dark side' is to the left, fully illuminated. NASA, JPL, public domain.

Colour photo of the Moon taken by the Galileo probe in 1990 – a view we never see from Earth. The – uh – ‘dark side’ is to the left, fully illuminated. NASA, JPL, public domain.

The interlocking mechanisms of orbital mechanics – the way Earth, Sun and Moon all move in a complex dance of planes, angles and distances – means we end up with circumstance where strings of lunar eclipses – like the current tetrad – cluster. Between 1600 and 1900, for instance, there were no tetrads. But this coming century, there will be 8 of them.

So why red? The answer is one of the reasons why science is so cool. If you were standing on the Moon during a lunar eclipse, you’d see the Earth as a dark circle rimmed with fire – the light of every sunset and sunrise happening on Earth, all at once.

It’s red because of Rayleigh scattering – the way that the atmosphere scatters particular frequencies of light. I won’t repeat the explanation here – check out my earlier post.  Suffice to say, when sunlight passes through a horizontal thickness of atmosphere, the red wavelengths are what emerge – and those red light wavelengths refract into the shadow of Earth, lighting the Moon in blood-red hues.

So when you see a ‘blood moon’, what you’re actually seeing is the reflected light of every sunrise and sunset on Earth, all at once.

And that, my friends, is the really neat thing about those eclipses. Harbingers of doom? To me it’s cool science, on so many levels.

Copyright © Matthew Wright 2014


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The Big Bang theory wins again. So does Einstein.

It’s a great time to be a geek. We’re learning all sorts of extreme stuff. There’s a team led by John Kovac, from the Harvard-Smithsonian Center for Astrophysics, who’ve been beavering away on one of the fundamental questions of modern cosmology. The secret has demanded some extreme research in an extreme place. Antarctica. There’s a telescope there, BICEP2, that’s been collecting data on the cosmic background temperature. Last week, the team published their initial results.

Timeline of the universe - with the Wilkinson Microwave Antisotropy Probe at the end. Click to enlarge. Public domain, NASA.

Timeline of the universe – with the Wilkinson Microwave Antisotropy Probe at the end. Click to enlarge. Public domain, NASA.

The theory they were testing is as extreme as such things get and goes like this. Straight after the Big Bang, the universe was miniscule and very hot. Then it expanded – unbelievably fast in the first few trillionth trillionths of a second, but then much more slowly. After a while it was cool enough for the particles we know and love today to be formed. This ‘recombination’ epoch occurred perhaps 380,000 years after the Big Bang. One of the outcomes was that photons were released from the plasma fog – physicists call this ‘photon decoupling’.

What couldn’t quite be proven was that the early rate of expansion – ‘inflation’ – had been very high.

But now it has. And the method combines the very best of cool and of geek. This early universe can still be seen, out at the edge of visibility. That initial photon release is called the ‘cosmic microwave background’ (CMB), first predicted in 1948 by Ralph Alpher and others, and observed in 1965 by accident when it interfered with the reception of a radio being built in Bell Laboratories. That started a flurry of research. Its temperature is around 2.725 degrees kelvin, a shade above absolute zero. It’s that temperature because it’s been red-shifted (the wavelengths radiated from it have stretched, because the universe is expanding, and stuff further away gets stretched more). The equation works backwards from today’s CMB temperature, 2.725 degrees Kelvin, thus: Tr = 2.725(1 + z).

The COBE satellite map of the CMB. NASA, public domain, via Wikipedia.

The COBE anisotropic satellite map of the CMB. NASA, public domain, via Wikipedia.

The thing is that, way back – we’re talking 13.8 billion years – the universe was a tiny fraction of its current size, and the components were much closer together. Imagine a deflated balloon. Splat paint across the balloon. Now inflate the balloon. See how the paint splats move further apart from each other? But they’re still the original pattern of the splat. In the same sort of way, the CMB background pattern is a snapshot of the way the universe was when ‘photon decoupling’ occurred. It’s crucial to proving the Big Bang theory. It’s long been known that the background is largely homogenous (proving that it was once all in close proximity) but carries tiny irregularities in the pattern (anisotropy). What the BICEP2 team discovered is that the variations are polarised in a swirling pattern, a so-called B-mode.

The reason the radiation is polarised that way is because early inflation was faster than light-speed, and the gravity waves within it were stretched, rippling the fabric of space-time in a particular way and creating the swirls. Discovering the swirls, in short, identifies both the early rate of expansion (which took the universe from a nanometer to 250,000,0000 light years diameter in 0.00000000000000000000000000000001 of a second…I think I counted right…) and gives us an indirect view of gravitational waves for the first time. How cool is that?

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.

What’s a ‘gravitational wave’? They were first predicted nearly a century ago by Albert Einstein, whose General Theory of Relativity’of 1917 was actually a theory of gravity. According to Einstein, space and time are an entwined ‘fabric’. Energy and mass (which, themselves, are the same thing) distort that fabric. Think of a thin rubber sheet (space-time), then drop a marble (mass/energy) into it. The marble will sink, stretching the sheet. Gravitational waves? Einstein’s theory made clear that these waves had to exist. They’re ripples in the fabric.

One of the outcomes of last week’s discovery is the implication that ‘multiverses’ exist. Another is that there is not only a particle to transmit gravity, a ‘graviton’, but also an ‘inflaton’ which pushes the universe apart. Theorists suspect that ‘inflatons’ have a half-life and they were prevalent only in the very early universe.

There’s more to come from this, including new questions. But one thing is certain. Einstein’s been proven right. Again.

Copyright © Matthew Wright 2014

Coming up: More geekery, fun writing tips, and more.