Wednesday, October 5, 2011

What’s wrong with the Universe?

For centuries now mankind has been pretty sure it knew what the Universe was made of – gas, dust, stars, planets, galaxies, hamburgers – those were considered to be the main constituents of the cosmos. Some of the dust and gas may have been a little hard to see, some of the galaxies were so far away that their light was incredibly faint by the time it reached the Earth, but essentially we knew what the raw ingredients were (apart from the burgers but who cared, they tasted so good).

For the last hundred years or so we have also had a good working model of the way the Universe came into existence and how it has evolved since – the famous Big Bang theory (the scientific hypothesis, not the TV show). This says that at some point in the past (around 15 billion years ago) the entire Universe came into existence at a point, exploded outwards and has been expanding ever since. This latter conjecture has been verified experimentally numerous times by measuring the so-called red shift of other galaxies as they rush away from each other. The effect is analogous to the way a train whistle or a siren appears to change in pitch as the vehicle approaches and then recedes from an observer (a phenomena known to physicists as the Doppler effect).

Sound waves from a moving vehicle distorted by the Doppler effect (Image credit  Charly Whisky)

Of course in much the same way as a ball thrown directly upwards on Earth will slow down due to the effect of gravity as it rises higher and higher, it was understood that the rate of expansion of the Universe would slow down over time. What would happen once the rate reached zero was unclear, this depended on how much matter the entire Universe contained. Nonetheless the slowing of the expansion was taken as given.

Imagine the surprise of two separate groups of physicists therefore when studies they were carrying out to determine the distances to a class of exploding star known as Type 1a supernovae indicated that the rate of this expansion was not slowing down, in fact the total opposite, it appeared to be speeding up. This would be like throwing a ball straight up into the air only to see it speed up faster and faster and fly off into space! Both groups initially doubted their own findings and it was only when they became aware of the work of the others that they were able to accept that they had discovered a new phenomenon, rather than having made some huge experimental error.

A supernova remnant, or possibly a giant cosmic space pizza
(Image credit NASA)

In fact their findings are now so well accepted by mainstream science that three of the men have been awarded this years Nobel prize for physics, usually reckoned to be a good indication that you are on the right track with your work.

In order to explain this result a mysterious and so far unobserved mechanism was proposed, currently going by the name of Dark Energy – the name being chosen to indicate that we don’t really have a clue what this consists of. It is hoped that future observations by instruments such as the James Webb Space Telescope (due for launch in 2018) will shed light (literally) on the answer, until then there are a range of weird and wonderful ideas being bandied about as explanations.

The sum total of human knowledge about exactly what comprises dark energy

Of course this is all great news for physicists, the more cynical amongst us may well feel that ‘discovering’ something huge yet invisible is a great way to guarantee future employment and funding for massive science projects such as the JWST or the LHC, but of course physicists are far too na├»ve and innocent to ever cook up such a scheme – aren’t they?

Thursday, September 29, 2011

Why am I an astronomer?

You may live next door to one and not even realize it.
It is possible you have put those late night noises down to cats playing in the backyard, or maybe caught a glimpse of a furtive, well wrapped-up figure lurking in the shadows at some ridiculous time of night. Assuming you didn’t call the police you have probably gone to sleep none the wiser as to the true nature of this elusive figure.
If so, it is quite likely that you share your street with an amateur astronomer.
People who pursue this most esoteric yet rewarding of hobbies are dedicated, curious (in both senses of the word) and scientifically literate individuals who get an uncommon satisfaction from observing or photographing the night sky.
Almost everyone has a casual interest in the stars, it is virtually impossible to be outside on a clear dark night and not glance up at the sky and wonder what you are looking at. Many people can probably identify a couple of constellations, maybe the Plough/Big Dipper (the name depends on which side of the Atlantic you call home) or majestic Orion, his glowing sword hanging down from his belt. Unfortunately this is probably as far as they take it, realizing that more detailed familiarity with the cosmos calls for spending long, often cold hours outside in the dark and even, heaven forbid, reading some books with quite long words in them!
For those who do take this hobby to a more serious level the rewards are seldom financial. In fact the costs of equipment can rapidly spiral to literally astronomical levels, once so called ‘aperture fever’ (the urge for ever larger telescopes) takes hold there is no potential end in sight. It is however possible to enjoy the night sky without selling your wife/house/Ferrari, although it has to be said the latter two are entirely superfluous once you have your eye glued to a telescope in the hunt for some faint nebula or galaxy. A wife is of course completely indispensible, who else is going to bring you cups of tea at 2 am when your toes have turned into ice cubes and you dare not head indoors for fear of ruining your dark adaptation?
(I realize that I am making some hideously un-politically correct and possibly misogynistic assumptions here but I think it is true to say that men outnumber women in the world of amateur astronomy by probably ten to one – I have no theory as to why this is, I think it may ultimately boil down to a ‘boys and their toys’ love of gadgets but I stand to be proven wrong.)

This is clearly Photoshopped or else taken from the brain of an amateur astronomer while they slept

So why do I number myself amongst this small band of antisocial individuals?
Ever since childhood I have had a fascination with optical instruments of all types, doubtless due in part to having a father who made spectacle lenses for a living, but also I think because I was born just in time to witness the first moon landings – I have very distinct memories of watching the early black and white shots of astronauts descending the ladder to set foot on that alien world.
Early experiments with discarded lenses and toilet roll tubes were less than spectacular successes but nonetheless proved that a telescope of some sort was required. When I was about 15 I procured a copy of a small book written by a gentleman called Reg Spry (a friend of Patrick Moore) called ‘How to build your own telescope’. This was a revelation, I saved up my cash and purchased a 6” mirror from David Hinds, a well respected UK manufacturer. With the addition of a couple of four foot long planks of wood, some plastic parcel binding strip and the drive shaft of an old Ford Escort I soon became the proud owner of a Newtonian reflector.
Optically it was superb, unfortunately the hardest part of observing anything now became the challenge of actually locating it in the eyepiece. Even at low powers the field of view of a telescope is miniscule, it is like trying to aim a rifle at a full stop about half a mile away. This, coupled with the light pollution that came with living in a big city in the UK meant I was mostly restricted to the moon and planets as targets. Nonetheless I persevered and was sometimes rewarded with a glimpse of a faint distant object in the eyepiece. This would of course necessitate my mother being called outside for a look, since she was not the dedicated geek I had become by this stage she would usually oblige by quickly running outside for a look before returning to the warmth and comfort of the house. Astronomy in the UK, especially in the winter, can be a chilly experience!

The archetypal amateur astronomer, the amazing Sir Patrick Moore

Last year I was fortunate enough to move to the USA, California to be specific, and as you can imagine the weather conditions here are ever so slightly more conducive to the pursuit of my hobby. Not only are the temperatures much higher on average but that bane of the astronomer, namely the cloud, is far less in evidence. Astronomy is one outdoor hobby which is utterly impossible to pursue, no matter how high the dedication of the individual, once a bank of thick low cloud rolls in for the night. I lost count of the number of lunar eclipses or meteor showers which I had no chance whatsoever of seeing due to inclement meteorological conditions.
So why have I stuck at it all these years?
Partly it is the thrill of actually seeing with your own eyes something which many people may have read about or even seen a photograph of – maybe the rings of Saturn or a bright nebula.
Partly it is the intellectual satisfaction of realizing that the photon of light which has just entered your eyeball has been travelling, in some cases, for literally millions of years – in fact the thing that you are ‘seeing’ may no longer exist.
But ultimately I think it is because astronomy, like no other science or hobby, gives you a true perspective on how small and insignificant we are in the cosmic scheme of things, and while you are at the eyepiece straining to catch a glimpse of some desperately faint gas cloud, or gazing in awe at the cloud belts of Jupiter, the petty squabbles of the human race and the stresses and strains of daily life vanish from your mind, if only temporarily, as you float out there in space next to the stars.

Friday, September 23, 2011

So who is this Higgs guy anyway and why is he a boson?

If you have been following the story of the LHC in any way over the past few months you cannot fail to have seen the name ‘Higgs boson’ bandied about a great deal. The phrase ‘God particle’ is also used, especially in the more tabloid press who probably think it makes for better headlines. Personally speaking the latter name makes me shudder but I can understand why they like to use it, although the reason usually given for the origin of this name is incorrect. The name ‘God particle’ has nothing to do with any deity-like power it may have, but rather comes from the fact that one of the early scientists who wrote about it wanted to call it the ‘goddamn particle’ because it was proving so elusive, but his publishers would not let him use the phrase, which was then shortened to ‘God’.
One of the foundations of modern physics is the so called ‘Standard Model’. This is the name for a way of describing all of the known (and theoretically predicted) particles which go to make up the everyday matter we see around us (rocks, trees, burgers – all the important constituents on the Universe). You will have heard of some of these particles – electrons, protons, neutrons are all well known and understood – electrons are what move down a wire when an electric current flows, neutrons play a major role in the production of nuclear energy and so on.
Many of the constituents of the Standard Model however are much more mysterious and less well known. Most of these have been detected in particle accelerators around the world, many had in fact already been predicted theoretically before they were ever ‘observed’ experimentally, and most of the time they turned out to have just the mass and energy that the theorists had calculated they should.
There is still one major gap in the experimental evidence however, and this gap is expected to be plugged by the Higgs boson.
Peter Higgs is an English physicist who wrote down the equations describing the way in which most of the matter in the Universe is endowed with mass, the mechanism requires the existence of a specific super heavy particle, now known as the Higgs boson.

Peter Higgs, the man who started all the trouble in the first place (Picture credit Gert-Martin Greuel)
A boson is just the name for a group of fundamental particles which play the role of transmitting forces from one place to another (there are currently considered to be four fundamental forces in the Universe – the weak nuclear force, the strong nuclear force, the electromagnetic force and gravity).
The most famous boson is the photon (the same one that Starfleet makes its torpedoes out of). Photons are fairly well understood and easy to create, just switch on a light bulb and billions of them come flooding out every second, some of them impact your retina and you detect them as light.
The Higgs boson has proven a little more elusive, in fact the LHC was constructed with the specific task in mind (amongst others) of creating and then detecting this particle.
This is all marvelous stuff, science being done the way science is suppose to be done – someone draws up a theory, then an experiment is done to test the theory, hopefully results are found which conform to the theoretical predictions and everyone can go home for tea happy in the knowledge that the world is the way they thought it was.
The only trouble is that after nearly two years of operation of this gargantuan experimental apparatus there hasn’t yet been one single Higgs boson spotted. There have been a couple of false alarms but they have turned out to be statistical errors in the data, so far not one single verifiable Higgs particle has been detected. Does this mean that physics as we know it is bunk?
Does this mean that the LHC is a whopping failure?
Far from it – in science a negative result can often be more informative in the long run than actually finding what we set out to prove in the first place. There are still a few corners where the Higgs could be lurking, but they are growing fewer day by day, it is expected that by Christmas 2011 there will be a definitive answer one way or the other as to whether or not this particle exists.
Bearing in mind the news reported yesterday about the possible contravention of the long standing speed of light limit this is proving to be a fascinating time for physics, especially for physicists themselves.
Watch this space…

Thursday, September 22, 2011

Faster than the speed of light?

Major news channels such as the BBC are reporting a seemingly incredible result from the Large Hadron Collider (LHC) - in case you have been living at the bottom of a coal mine for the last few years and haven't heard of this amazing machine it is the largest particle accelerator ever built by mankind. 

One of the huge detectors at the LHC - notice the person standing lower center     (Image credit CERN)

It consists of a circular underground tunnel, 17 miles in circumference, which contains an evacuated (i.e. has no air in it) tube, around which sub-atomic particles such as protons can be fired.
As they whizz their way round and round the tube they are steadily accelerated by huge superconducting magnets (magnets operating at temperatures so low that they have virtually no electrical resistance and can therefore sustain huge magnetic fields). This allows the particles to be taken up to speeds very very close to the speed of light (no particle with mass can ever reach or exceed the speed of light - well, that's what Einstein told us and we have always believed him, until now at any rate, but more of that later). 
There are actually two bunches of these particles, each bunch travels in opposite directions around the LHC, a bit like two trains going round and round in circles but each on slightly different tracks. Once the scientists are ready for their experiment to actually begin they cause the two particle groups to collide - it is as if someone switched a signal on the train tracks and caused the mother of all head on collisions.

The first recorded neutrino collision

This collision causes the particles to crash head on into each other and annihilate in a huge (by sub-atomic standards anyway) flash of energy. As dear old Albert told us, E=mc^2 - that is to say the energy which a particle (be it a proton or a porpoise) has by virtue of its mass is equal to the mass of the object times the square of the speed of light. Now the speed of light is by itself a pretty large number (around 300 million meters per second or about 671 million miles per hour!) so you can imagine that squaring this number (multiplying it by itself) gives an utterly humungous figure for E. This large value of E is the reason that atomic bombs produce such massive amounts of energy, the conversion of even a tiny amount of matter directly into energy gives a huge net energy output.
So, back in the LHC this collision produces energy and a shower of particle fragments flying every which way. Some of this energy can turn directly back into matter, but often matter of a totally different nature to the protons we started with.

Albert Einstein before he became rich, famous and crazy!

This is ultimately the whole point of the LHC (and other similar, albeit smaller colliders the world over). It is like taking two pieces of rock and banging them together to see what is inside, it is only by smashing stuff up at this level that we can find out what the Universe is actually made of. 
The analogy with rocks is flawed in that rocks don't spontaneously change into bananas when they are broken apart by collision with each other, but the sub-atomic (or 'quantum') world  is so strange by everyday standards that analogies seldom tell the full story. You just have to accept the word of a lot of people much much smarter than you and I who have been doing this stuff for a long time.
One of the side experiments which they have been running at the LHC for the past couple of years involves sending a beam of neutrinos (very light, very fast sub-atomic particles) from one place to another. The original point of this was to investigate the way these neutrinos can spontaneously change from one type to another along the way (told you the quantum world was weird). As a by product of this experiment, by very carefully measuring the time taken to travel from one place to another, and by very accurately measuring the distance between the two locations, physicists are able to measure the speed of the neutrinos. They were therefore more than a little shocked to find out that it appears as though the neutrinos are travelling ever so slightly faster than the speed of light.
One of the cornerstones of modern physics is the assertion, first made by Einstein, that nothing with any mass can travel at or above the speed of light, no way, not ever. This 'cosmic speed limit' has become utterly entrenched in modern physics, in fact most of reality as we know it depends on this fact being true. If it were not, you would theoretically be able to see events before they had actually taken place - is your head hurting yet?
So there are four possibilities here: 

  • Albert had it wrong all those years ago
  • The piece of string the physicists used to measure the length of their experiment was a bit shorter than they thought
  • The physicists should not have bought their stopwatch at Wal-mart
  • Albert was mostly right but the neutrinos are doing some new and funky stuff that we have never seen before
Personally my money is on the last possibility, but only time will tell. The scientists have published their findings because despite having checked and rechecked their results until their brains are ready to explode (and that takes some doing for physicists) they can't find any error in their analysis. They are hoping that releasing this information to the larger scientific world may let someone else come up with a reasonable explanation i.e. they cocked up their calculations and we can all breathe a sigh of relief because Einstein is still the biggest smartass who ever lived.
Alternatively they have discovered something new and utterly amazing, in which case everything we thought we knew about everything is utter codswallop and we need to go back and start all over.
Only time will tell, keep reading this blog to find out...


LHC breaks lightspeed barrier?