Practical Physics And The Robbins-Henry Feline Transport System

Henry, Official Blog Cat, just walked out of his enclosed litter tray and into the living room.  This took The Julia somewhat by surprise, mainly because she'd locked him outside five minutes before.

Is this, perhaps, because cats are sneaky little blighters and can worm in through windows and sneak into their litter trays when you're not looking?

Or is it because I've invented a cat teleporter?  It's quite simple.  You know the whole Schrödinger's Cat thing?

The idea is that the cat can be both alive and dead at the same time.  Well that's not quite the whole story.  The cat's medical status is a bit vague anyway.  Schrödinger was no vet*, you see, he never really specified what he meant by dead.  Lack of mew?  Cardiovascular failure?  Brain death? Advanced decomposition?

What he actually meant was the chain of events that leads to a dead cat.   Or a live one for that matter.  He was objecting to the idea of an atom being in two places by trying a bit of reductio ad absurdum.  If an atom can be in two places at once, he said, that means that there's two different universes that flow out of it.

Imagine, he said, that there's a particularly important atom, one that we're going to look at.  We know that if we look at the atom in one minute's time then there's a 50% chance the atom will have decayed while we waited:

Once we start the clock running we have two possible results:  in one future chain of events the atom doesn't decay and nothing happens.  In the other future chain of events the atom decays, the Geiger counter goes "click", the relay opens, the hammer falls, the bottle smashes, the poison spills and the cat dies.

Schrödinger's argument was that between the clock starting and us looking to see if the cat was alive or dead, both chains of events were valid according to the maths, that there was nothing in quantum theory which prevented two different realities, or chains of events, from both being perfectly possible as far as we know.  He believed the universe had to follow a single chain of events, and one only, and the maths should show this.

He was wrong, as most of the pioneers of quantum theory were at some point, in fact there's still a good possibility that they all got together at what's called the Solvay Conference and decided to be wrong together.  They all met in Denmark, Schrödinger and Planck and Einstein, Eddington and Bohr and Born, and put together the "real world" description of what's going on in the maths of quantum theory.  It's called the Copenhagen Interpretation, and there's still a fair chance it's wrong.

They decided that particles exist as wave functions, wibbly-wobbly "stuff", to steal a phrase.  When any of these wave functions interacted with anything else, they "collapsed" and became  a single, measurable particle.

So where does Henry come in with his litter tray and teleportation ability?

Well go back to the chains of events which led to Schrödinger's cat being alive or dead - it doesn't have to involve boxes and poison and hammers.  Just because you have a Nobel Prize in physics it doesn't give you a monopoly on inventing strange cat-based scenarios, any of us are allowed to do it.

So the Robbins-Henry Theorem suggests that there are two, equally likely chains of events which lead to  Henry (Official Blog Cat) either being in his litter tray and being outside.  All you have to do to transport the cat from outside the house to inside the litter tray is to have one single, perfectly random interaction with a single atom go the other way.  OK, you might need to go tweak the universe in precisely the right time and place to set off a realistic chain of events, but it's possible in theory.  And if you don't observe the cat from the moment you prod that particular atom to the moment you look at the litter tray (or outside) and find the cat, the Copenhagen Interpretation suggests it could be, and therefore is, in both states.  There is a single wave function which is called Henry, and until I look outside or at the litter tray the Henry Wave Function is in both.  When I look it collapses instantly into one of the two Henrys, and either way he's bloody pleased with himself, what with mastering teleportation and all.

But this is the argument from the point of view of Schrödinger's beliefs and the Copenhagen Interpretation.  There's another way of looking at it.

Hugh Everett III suggested that the wibbly-wobbly stuff of a particle was, in fact, an ever expanding cloud of every possible particle, essentially lots of "might be" particles all superimposed on each other.  Many particles, which when we look at the wibbly-wobbly cloud, becomes a single particle.  What happened to all the others?  Everett's suggestion is that they're still around somewhere.  Not here, obviously, that would make the entire universe one blazing ball of energy appearing from nowhere**, but somewhere else.  And given that every particle in the universe appears to behave like this, it's going on a lot, with every tick of time.

The only explanation that springs to mind is the idea of a multiverse.  Many universes, all existing at once, with every possible chain of events played out.

So we open Everett's box and have a look at Everett's cat, and what do we see?  Either a dead cat, or a live cat, big deal.  The only extra information we've received is which particular universe we're in a minute after we started the experiment.  The explanation from Everett's point of view is obvious to the point of being mundane.  It's not some wacky feline paradox that will be mentioned 77 years later on The Big Bang Theory, it's just kind of obvious.

Personally, I reckon there's a hint there.

So how did Henry's (OBC) teleportation display work according to Everett?  Well, it's entirely possible that when you don't have enough information to decide which universe you're in (cat inside or out) that you can legitimately be said to be in both.  Until something happens which makes you change your mind, both possibilities are true.  You're in one of two universes, the cat is in one of two universes, and until you meet neither of you know where either of you are.

This brings about a particularly mind-blowing suggestion from the edge of physics:

You're in many universes at once, which are all exactly the same except for the location of the cat.  In all of them identical copies of you are wondering exactly the same thing, "where's the bloody cat?".  These different versions, which are identical in every way until they find the cat, exist in the same state an atom does, they're all part of a big wibbly-wobbly "You".

So, with that in mind, let me pose a question.  When you wonder where the cat is, and imagine he may be outside, or in his litter tray, or under the couch, or hiding behind the curtains, then what is more likely?  Is your brain creating multiple simulations of reality, in seconds, which all conform to likely cat-locations, or are the various different versions which make up the wibbly-wobbly-you simply comparing notes?

I've no idea why it's always cats with physics by the way, and I'm sorry.  I'm a dog person, but the behavioural  psychologists wouldn't have me.



* He should have taken lessons from Richard Feynman, who once decided to keep his brain ticking over outside physics by learning biology.  He went down to the University library and asked for a map of a cat.

** That does sound spookily familiar though...

The Hunt For The Higgs - Why So Long?

[EDIT: The Higgs was "discovered" with two independent observations averaging 4.9 Sigma around a week after I posted this.  4.9 ....pah.[/EDIT] 

The Large Hadron Collider's search for the Higgs boson continues.  It's been running for a few years now, gathering an unprecedentedly big amount of data, and everything seems to be pointing at a discovery being announced towards the end of this year (2012).

So the obvious question is, if they're expecting to discover the Higgs in November, why not just skip to whatever's on the LHC calendar for November 1st and save a whole bunch of time and money?

It's all down to the way the experiment works.  A hadron is simply a particle which is made of quarks, such as a proton or a neutron - the LHC uses protons because they carry an electrical charge, meaning you can use magnets to accelerate them and focus the beam.  Two "packets" of protons are sent whizzing round the LHC in opposite directions and smashed into each other in any one of several detectors, which are simply huge digital cameras with a few specialist add-ons.  When they smash into each other the protons are broken apart and a whole bunch of "debris" comes flying out and is picked up by the detectors.  The whole setup is essentially based on Einstein's famous equation, "E=mc²" and something called a "conservation law" which simply says that the accounts have to match up, you always get exactly the same amount of mass/energy coming out as you put in.

Now the Higgs boson, if it exists, is far heavier than a couple of protons, but there's a trick that can be used here.  If any object travels quickly enough then it becomes more massive, some of the energy of the motion is converted into mass, which is precisely what "E=mc²" actually means.  So 2 protons can equal a Higgs, as long as they're moving quickly enough.

So far so good, take two protons, bang them together hard enough, and out pops a Higgs.  Except it's never that simple is it?

The problem is that two protons can also equal a lot of other things.  There's a whole zoo of other particles, muons and pions, W+ and Z- particles, gluons, electrons and the mysterious neutrino, a particle that comes very close to not existing at all.  The list goes on, and you can get any combination of particles from any collision, as long as the accounts match up at the end of the day.  It's impossible to intentionally create a specific type of particle from any given collision.

A common analogy is to take a few thousand grand pianos and blow them all up with a few kilos of Semtex.  The job of the physicists at the LHC is to take all of the wreckage and work out how many pianos there were and exactly how a piano works in the first place.

Imagine you've just got a job at the LHC - you are now in charge of working out how many keys there are on a grand piano.  So on day 1 you blow up a piano and manage to piece together 85 keys, but there's a few bits left over, so it might be 86, 87 or 88.  The next day you blow up another piano and from the various bits you conclude there's 91 keys, but you think a few of them might have landed in a nearby river, so it might be fewer.  The evidence from the third piano suggests somewher between 87 keys and 90.  Carry on like this and eventually you'll find there's just one number that is common to all experiments, 88 keys, which as it turns out is the right answer.

So even though each individual experiment produces wildly different results and is difficult to get an answer from, on average they point to the right result.  This is what's happening with the search for the Higgs.  There are plenty of "candidate signals" where a physicist can point at a spike on a graph and say "that looks like a Higgs", but they're never sure, there are simply too many possible errors or alternative explanations.  As they gather more and more data, however, they get a better overall picture.  The more data, the more reliable the result is considered.

This reliability is measured in "sigmas", a statistical term.  One sigma means you can be approximately 68% sure about the measurement, two sigma is 95% accurate, three sigma is 99.7%.  If you have a three sigma measurement you're officially allowed to upgrade it to an "observation".

For a scientific "discovery" you need an overall confidence of five sigma, you need to be 99.999999% sure that it's not an error.

So this is what's keeping the Big Announcement on hold for the moment - many scientists at the LHC will quietly admit that they've "probably" seen the Higgs boson already, but "probably" isn't good enough for science.  They need a five sigma signal overall, and the only way to get that is to gather more data.  And to do that they need another five months or so.

Battlefield 3 - Zero Stars

I've been a fan of Electronic Arts' Battlefield series for a few years now.  Battlefield 1943 was the first one I played, and whilst it was limited in weapons and landscapes I still have to rate it as one of the best computer games I've ever played.  It's one of those fantastic games that is open enough to allow you to develop your own tactics and strategies, and the satisfaction of playing as part of a tight team with players from all over the world is something else.

Battlefield: Bad Company 2 came next.  It's a more modern version, more weapons, more maps, but much the same game overall.  The added "rush" mode which splits the two teams into attackers and defenders is a great addition and takes the whole thing to a new level.

So I was quite excited to hear Battlefield 3 was coming out.  More new maps, more new weapons, more brilliant!  Except it's not.

Don't get me wrong, it was pretty good for the first month, I was enjoying it.  And then it stopped working. 

Within a month of release it required an update.  Nothing unusual there, it's fairly common, but this required a 2 Gigabyte update.  This is clearly crazy, it implies that nearly 50% of the game required replacement.   Looking into it a bit further it wasn't all replacement code - in fact the update to the code itself was pretty minor and would have taken a few minutes.  Most of the "update" turned out to be extra maps which you could pay £15 to activate. 

But I don't want the extra maps.  I don't want to pay £15 more, I just want my game to work.  You don't have to pay the money of course, you can just download the extra content and leave it taking up 3% of your hard drive.  You do, however, have to download it.

This is a ridiculous situation - a 2Gb download of junk data to continue playing a game you paid £35 for last month?  That works out at over a pound a day before EA disabled my copy.  I certainly won't be giving them any of my money, ever again.



So I'm not a fan of a game that doesn't work.  It gets worse.


I tried to ask EAs help system if there was a way to download the update without the extra content.  They refused to talk to me because my "date of birth was wrong".  Six months and a few emails later and I've finally managed to use the Data Protection Act to get the information they hold on me.  Guess what?  My date of birth is correct on their system, so I've got no idea why they won't talk to me.


In summary, the game lasted 30 days, cost me over a pound a day and I had to use legislation just to get them to talk to me.

Mystery Fireplace Dots

Here's an interesting puzzle for you.  We got back to Misfit Cottage this evening after a few days away, and there were a bunch of small black dots in front of the fireplace.  

They were all roughly the same size, dry, and fairly circular.  They're a jet black powder.

So what were they?  I've got an answer to follow, but it was an interesting puzzle I thought I'd throw out there. 

Bring Back The BBC Micro!

I remember when our school got a computer.  It was sometime around 1984, and I was about 8.  It was a BBC Micro (or maybe a model B, I've never been much of a hardware buff).   They were fantastic little machines made by Acorn for the BBC, who through a stunningly insightful move had initiated the BBC Computer Literacy Project, something that without a doubt is a significant factor in the lives of many computer professionals today.  And a good few amateur hackers, which is equally good.

Google's own Eric Schmidt recently lambasted Britain's computing education, and unpleasant as it is to hear he's absolutely right.  By the time I hit high school, the momentum built up by the BBC had faded.  We were taught to use word processors, spreadsheets and databases.  I don't recall doing any programming at all.  From what I've heard not a huge amount had changed.  Far more emphasis is placed on the use of applications than is on actual programming.  It's akin to a craft and design class showing you a chisel and then spending half an hour teaching you how to use a chair.

But back to the BBC Micro, the little silicon hero at the centre of this minor diatribe.

It was really quite brilliant.  This is pre-GUI remember, so Mrs Bott had to sit a wide-eyed eight year-old down in front of a black screen with a little white cursor, and explain to him that this was the future.  I knew that of course.  This was a TV that could do what I told it, I was living in one of my Asimov novels (the Lucky Starr series in fact).

And we programmed, us eight year olds.  Through a simple cursor on a screen, and some basic shell level commands, we made things happen.  Turtle was a particular favourite - part programming language and part game, you could control a little cursor on the screen that drew lines.  You could move forward and rotate the cursor.  I don't recall the exact syntax, but it was something like:

FW10,R90,FW10,R90,FW10,R90,FW10

That would give you a square.  At this point we'd realise there was a quicker way, and were introduced to loops:

{FW10,R90}4

Did exactly the same.  And, of course, we'd all compete to make the best circle we could without killing the machine, so that's a basic knowledge of hardware limitations and the effect of big loops.  We were eight!

So why, I demand to know in an overly theatrical way, was I next sat down in front of a plain old terminal in 1994?  Ten years later?!  In a university physics class?  If I'd known at the time I'd have been bloody furious, ten years is forever when you're eight.

What happened in the meantime?  The school only had the one computer, and a lot of children, and no computing teacher.  They did the best they could, but there was never a chance of getting more than the odd hour on it, and you need more than that to really get into it.  Then I programmed the video for my parents a lot, and did a lot of whining about them buying me a computer.  Eventually, when when the cost/whining ratio hit a critical point, they bought me a Commodore 64, and I got to grips with BASIC.

By the time we had the mandatory-aged-14 classes on how to type and save a file I was fairly quickly convinced that computing education in schools had missed the point.

What would have been useful?  A bare bones computer the whole way through.  A basic UNIX style terminal with BASIC, maybe Perl.  Oh, the things we could have done and learned.

The thing is, these days that's possible.  If any kid wants to learn programming they should have free access.  Hell, we could easily provide a single decent computer for the school, and a lot of dumb terminals for the pupils to log in through.  But no GUI, that's the important point.  No windows (certainly no Windows), no mouse, nothing.   Certainly no internet.  Give them Lynx for Christmas perhaps.

We've lost sight of what made the brilliant programmers Britain boasts today.  It wasn't Windows and Word, don't be silly, those weren't even around when our greatest and brightest were learning.  It's a free reign.

Give them root access - give them a virtual machine.  Give them Perl and pwd and Apache.  Give them shell scripting and apt-get and sudo.  Give them SSH and vi and/or emacs.  Just give them a bloody computer and let them learn!  Yes, they'll break the computer.  And most of them won't want to admit it, and try to fix it themselves.  And some of them will manage it.  The ones that don't?  Well it's only a virtual machine after all, just reset it. 

It's not difficult (unless you're old enough to be an MP) and it's certainly cheaper than most of the nonsense spent by government these days.  How many virtual machines would a cool billion buy?  Cos that's what we spend on no trams these days.

Like A Neverending Circle, Like A Wheel Within A Wheel

So, physics is cool again [BBC News].  This happens every so often, and as far as I can tell there's a chaotic element to the cycle, but it's generally on the order of decades.  Professor Brian Cox seems to be taking a large amount of the credit and/or blame this time around, and it's partly deserved.  He's clearly passionate about the subject and puts it across very well to a lay audience (although his colleague Jeff Forshaw [YouTube] is the one to look out for if you want relativistic hyperbolic geometry to be fun!)

I don't think physics is cool because Brian Cox is involved though, eloquent as he is.  In fact, I think Brian Cox is fairly famous at the moment because he happened to be there at the right time.  The very beautiful Wonders Of The Solar System, for example, wouldn't have been made if there hadn't been a public enthusiasm for physics in the first place.  Take a look at America, where Carl Sagan's classic series Cosmos is currently being re-made.  I bet America hasn't heard of Brian Cox, let alone D:ream, and yet physics is kicking off there as well.

It's a cyclical thing, and it's always huge.  Take a look at Einstein as a classic example.  He was one of the first modern superstars, a moniker that is remarkable fitting,  truly famous across the globe, and yet most people had very little idea what he'd actually discovered.  A few decades later we had Richard Feynman, then Stephen Hawking.  It seems all you have to do to be a famous physicist is break the mould a little.  Playing a musical instrument aso seems to help;  step forward Dr Brian May PhD, and one of the greatest rock guitarists to have ever lived.  I also maintain, against much opposition, that Wayne Rooney and others like him are great physicists, even if they don't know how they do it.  So they only work with dynamics under 1g and narrowband air resistance?  Well, everybody has to specialise.

There's something deeper to physics-cool than celebrity endorsement and TV documentaries though.  Physics is cool because it makes you look smart.  Everybody seems to have a strange impression that physicists are particularly intelligent, that it's a subject for geniuses.  That's generally quite wrong, it's a remarkably simple subject if you get your head around the rules of the game.  It is exceedingly good at making you look smart though. 

I've lost count of the number of times I've "cleverly" fixed something using what I learned in physics classes at the age of 15.  Problem with the ice machine in the pub?  Well, that's a transformer, I recognise the coils, and it's making that grid of wires hot because electricity does that, and they melt the sheet of ice that comes from there.  But that wire is broken...

Shazzam, free drinks for the night and a reputation as a super-genius thrown in. You get to look like The Doctor and Sherlock thrown into one. Steven Moffat is clearly a physicist at heart.

Physics is cool because it gives you some very solid ground to stand on when you need to build an argument.  You know the basics, you can rule out daft ideas at a stroke and concentrate on what's actually real, in front of you, and how you can use it.  If you are faced with a problem you've never seen before you've got a head start, because you understand the rules the problem has to obey.  Sometimes, just sometimes, you solve a problem by going right back to first principles, and that feels particularly cool.

Smug Mode: On

Last September, at the height of the Old Town Mouse Season, I posted some  observations that the mice in our flat seemed to have developed a distaste for poison laced grain, and suggesting that evolution of some description was going on.  ("Mice, Chickens, Eggs & Evolution")

Now I'll point out once more that what I do on this blog isn't actually science.  I have fun exploring science, yes, but very little I do is actually science.  The mouse thing sort of got close - there were repeated observations and the vaguest semblance of data gathering, but it was all very wooly.  "Anecdote is not a synonym for data" is a phrase you'll hear a lot.  "Correlation is not causation" is another.  The mouse thing wasn't science - an interesting angle to explore the basic idea of evolution from, but not science.

But now some real scientists with proper notebooks and letters after their name have taken the idea and turned it into proper science. They even got it published in a journal, Current Biology.

What they've discovered isn't precisely the same as my hypothesis.  I wrote:

For some reason or another they didn't go for the free food. Maybe it was the smell, maybe the colour, maybe they just didn't like the taste - maybe they're refined mice and expect more presentation than a small plastic tray.

Whereas Song, Endepols et al wrote:

Polymorphisms in the vitamin K 2,3-epoxide reductase subcomponent 1 (vkorc1) of house mice (Mus musculus domesticus) can cause resistance to anticoagulant rodenticide

Or, if you prefer, the mice have naturally bred a resistance to warfarin, the poison often used on them, rather than not even eating it in the first place.  It's actually a better tactic, because then they get free food as well.  I love it when the best laid plans come together.