Questions From Friends (Part 2) - Radiation & Radioactivity

Another slightly-cheaty post from me, unashamedly based on an email conversation with a friend who writes Fan-Fiction.  If you're unfamiliar with the genre, it's generally an extension of an established fictional world, for example Harry Potter or Clarke's Space Odyssey series - anything you want in fact, it's a fan-driven and fan-written culture that has sprung up because people love the characters and setting, and want to explore it further.  Sadly, lawyers love getting involved, even when (as is normal) it's all done on an amateur basis and for free, which is why you're not getting a link to the final fictional result of this discussion.

I received an email containing the following request:

[Let's imagine] a new processing chip has flooded the market...it's actually
radioactive, but a thin coating of plastic has disguised this fact.
(Yeah yeah, point is, it will leak eventually.)

However, by a series of improbable coincidences, the radioactivity is
discovered a week after launch by a scientific gentleman, actually
scanning for evidence of radioactivity from a difference source.

What, exactly, does the scan pick up? I mean, I know it picks up
radioactivity - like a Geiger counter - but if I want to refer to that
radioactivity in scientific muttering, what do I say? Unstable
isotopes? Fission activity? Help!! Is there useful vocabulary I can
drop in?

Cool.  I wish all fiction authors would put so much thought into their technowaffle, as it's officially called.  I'll point out that, much as I love it, Star Trek in all its forms is one of the worst perpetrators of Bad Technowaffle.  (Red Dwarf, on the other hand, is one of the best.)

So, my reply, which was written as an informal email if you spot any glaring errors in style or content:

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[General personal salutations deleted]
 There are three basic types of radiation, alpha, beta and gamma.  All are produced by the decay of atomic nuclei, according to some very beautiful quantum mechanical magic which I'd love to go into but will omit for brevity (give me a shout if it's useful).  Particular nuclei (eg Carbon 14 or Uranium 235) omit a particular type or types of radiation when they break up (decay) and produce "daughter products" which are themselves radioactive, so they decay producing their own particular type or types and so on, until you have stable isotopes left (or just ones with a very long half-life).

An isotope is simply an atomic nucleus with a particular number of neutrons.  Carbon, for example, is defined as any nucleus with six protons, and the normal stable form has another six neutrons, hence Carbon 12. Carbon 14 has eight neutrons, and according to quantum wibbly stuff is more unstable and likely to decay.

Alpha radiation is simply a Helium 4 nucleus, the most common low-mass "chip off an atom" that is produced.  It's by far the biggest and heaviest lump that's ejected when a nucleus decays, and it is generally fired off at very, very high speed.  It can do a hell of a lot of damage to entire cells when it smashed into them, so it's very dangerous in the body.  However, because it's so big it's fairly easy to stop.  A sheet of paper, or indeed a thin film of plastic/resin, will stop it in its tracks.  This is what all the decontamination showers are about, washing off the contamination which produces the alpha before you can accidentally ingest or inhale it, it's relatively harmless on the dead outer skin layers (you can safely hold a piece of refined uranium in your hand), but when the source gets into the living cells inside the body it really kicks off.

Beta radiation is a high speed electron. It's not an electron that existed in the atoms in the first place though, it's made out of the leftover energy from an atom breaking up, and some of that leftover energy also gives it a hefty kick of kinetic energy.  Beta is the more benign of the three in some ways - it can be stopped by a thin piece of metal, an inch or so of wood, that kind of thing.  Beta will mess with atoms when it hits them, so it can cause mutations and hence cancers, and as it can penetrate a few millimetres of flesh you don't want to have any long term exposure - however, that's never stopped us worrying about cathode TV screens - cathode literally means "spits out electrons at high speed" - they're just electrically created beta radiation, and if you leave a Sellafield radiation badge sellotaped to a TV screen overnight and leave it playing it will detect enough radiation to get you removed from your job while they investigate! (My dad did it with his old badge when he left - you'd probably face a real risk of cancer if you did it for a month solid. As long as you're an inch or so from the screen you're fine for centuries.)

Gamma is the odd one out - it's not even matter, it's just a photon of light.  Just like radio, infra red, light, UV and so on, but with particularly high energy (in other words, a very short wavelength).  Different isotopes produce gamma with different energies, it's a very direct E=mc^2 demonstration: The energy (and therefore wavelength) depends directly on the amount of mass the nucleus loses when it splits, and that depends on which isotope it is - I'm getting quantum again...
Gamma can penetrate anything up to a few inches of lead, it's insidious, nasty stuff that's very difficult to escape.  It carries so much energy that it can kick electrons out of atoms, which changes their chemistry and really screws with the body's functions.  If you want to kill a lot of people in a nasty way with very little defence against it then gamma rays are what you want.  (Although SF would suggest at this point you would face an army of very big, very muscular and exceedingly pissed off green people...)

(There is a fourth kind, high energy neutrons as released in neutron bombs, but I've only just realised this and won't comment until I've read up on it and found it was first published in the 1920s!)

So...relevance to Silicon chips with a coating of plastic.  If your geiger counter picks up anything significant it won't be alpha.  You also need something which has a long enough half life to be of danger to the consumer, and most of the unstable Silicon isotopes decay in milliseconds, so they're out.  What is a good candidate, however, is Silicon 32.  It has a half life of 153 years, so it's going to be "live" for several human lifetimes.  It decays by beta, so you've got something which would be hindered by a plastic layer, but could be a danger with a little poetic license (eg silicon carrying current, ie a chip, boosts the beta).  Alternatively, people could be exposed in another way, like exploding chips (would only need to be a puff of Magic Blue Smoke) or, as Gerry suggests, "people licking them - there's nothing geeks like more than fission chips" - he says you're free to pinch that if you aren't already using it as the title)

First article on Si32 that popped out was one on geochronology - it's produced by cosmic ray impacts in the atmosphere. http://www.sciencedirect.com/science/article/pii/S187110140900017X

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So there you go.  That's how much thought and research goes into what ended up being about 1% of the storyline of an amateur piece of fiction done purely for fun.  There are certain science fiction books that you can pay actual money for which don't do the job half so well.

The Naming Of Timelords

With apologies to T.S. Eliot.

The Naming of Timelords is a difficult matter,
It isn't just one of Moffat's odd games;
You may think at first I'm as mad as a hatter
When I tell you, a Timelord must have THREE DIFFERENT NAMES.
First there's the name Gallifreyans use daily,
Such as Luton, Graffito, Salpash or James,
Such as Chovor or Jobiska, Rynde or Bill Bailey--
All of them sensible everyday names.
There are fancier names if you think they sound sweeter,
Some for the gentlemen, some for the dames:
Such as Doctor, The Master, The Rani, Romana--
But all of them sensible everyday names.
But I tell you, a Timelord needs a name that's particular,
A name that's peculiar, and more dignified,
Else how can he keep up his time reputation,
Or control his TARDIS, or cherish bow ties?
Of names of this kind, I can give you a quorum,
Such as Rassilon, Ao, or Pandak The First,
Such as Yassinbur, or else Apeiron-
Names that never belong to more than one Timelord.
But above and beyond there's still one name left over,
And that is the name that you never will guess;
The name that no human research can discover--
But THE TIMELORD HIMSELF KNOWS, and will never confess.
When you notice a Timelord in profound meditation,
The reason, I tell you, is always the same:
His mind is engaged in a rapt contemplation
Of the thought, of the thought, of the thought of his name:
His ineffable effable
Effanineffable
Deep and inscrutable singular Name.


With thanks to the Gallifreyan Conlang Project for the names.  All real, apart from James. And Bill Bailey's so obviously a Timelord I'm leaving him in.  Seriously, check T.S. Eliot's original, he's snuck himself in there. 

The Discrepancy

Ladies, gents, bots, potentially sentient networks, a guest post.

This is brought to you by Richard Tee (@RichardTheGeek) after a Twitter discussion on the subject of Dark Matter and Dark Energy and whether or not they're a whole big ugly cheating fudge.  The post below is Richard's take on the matter, the long rambling bit of fiction in the menu on the right entitled "The Discrepancy" is my attempt, I thought I'd give "making it all up" a go seeing as a clear and coherent argument was in such good (single malt loving) hands.

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The internet. For a computer scientist with a hankering for physics, the internet can be a fun (and scary place).
The other day, I was involved in a very good Twitter Chat with two online friends, the subject of which was the concept of dark matter and dark energy.
As one of my personal heroes Dr. Richard Feynman once said “It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong.” – well Dr. Feynman I couldn’t agree more – sadly many people in modern cosmology think otherwise.

Why do you ask? Simple – we are wrong.

Before you hang me out to dry, kindly let me explain.

In the study of the universe, we have come across a slight problem – it seems that given our current equations and theories, we cannot account for roughly 96% of the matter that we think SHOULD be in the universe. In other words, the more we find out, the more it seems we don’t know … all the visible matter in the universe only adds up to 4% or so of the total amount of matter that should be out there!

If you haven’t guessed this is a problem.

So, what was the solution to this problem? Simple: Say that the remaining 96% of the “stuff” out there is simply, “dark” and thus not visible nor detectable by conventional means.

Simple right? … not quite.

A recent study from the AMS (Alpha Magnetic Spectrometer) was searching for positrons – which it found … that wasn’t the problem, the problem was that an expected results showing a “drop off” for dark matter was not present. Furthermore, given the nature of how we think dark matter behaves, we would expect it to be non-isotropic, meaning concentrated towards the direction of the galactic center. This was not the case: In fact it was nice and uniform.
So what does this mean? Nothing really. That in itself is a bad thing for the dark matter/energy group.
Of course, I am not saying that dark matter and dark energy doesn’t exist, but having it represent 90+% of the universe is a bit … far fetched.
Why am I so against dark matter/dark energy as the solution to our cosmological problems? It seems that it is just bad science.
Basically, as Feynman said, if the theory APPEARS correct, it can be assumed as long as the data supports it – at which point we need to re-write our theory to support the new data. This doesn’t seem to be the case of dark matter/energy. The observations seem to contradict our theory, and thus to “fix” the theory we happen to mention that it only accounts for 4% of what we can see.

The analogy I can make is spending. It is like a teenager saying they manage all their money very well … out of every $100 they keenly save $4, and the other $96 is unaccounted for… Would you let them manage your finances?

We may find out that one day, dark matter and dark energy are in fact present in very high quantities in our universe. However my gripe is that the fact that few people seem to be demanding a simpler and less exotic solution to the problem.
Ladies and Gentlemen, it is time to erase the blackboard and start from scratch on this one.

@RichardTheGeek

Questions From Friends (Part 1): Is Our Universe A Simulation?

I've had a couple of interesting geek-type questions from friends recently, and as Twitter is a bit too limited for long explanations this is probably the place to explore them.

The first question is from Twitter's @LoisAnnounces, an expert on both cultural geography and asking awkward philosophical cosmology questions:

@_thegeoff So lattice quantum chromodynamics- space as 4D? But does this prove we're living in computer gen. universe?arxiv.org/abs/1210.1847
— Lois Jefferys Jones(@LoisAnnounces) April 25, 2013

(For those not familiar with the link, arXiv is a "pre-print server" where draft versions of physics papers are published, allowing free access to anybody who wants it - a very good system which other subjects are starting to follow.)

The paper in question, "Constraints on the Universe as a Numerical Simulation" by Silas R. Beane, Zohreh Davoudi and Martin J. Savage (BDS) (direct link to the PDF) builds on the ideas presented in a famous paper published by Nick Bostrom of Oxford University, entitled "Are You Living in a Computer Simulation?".

The central crux of Bostrom's argument is that if Moore's Law continues then at some point in the future we'll have enough power to simulate, to the last particle, entire chunks of the universe, from whole molecules (now/near future) to biological cells, multicellular organisms and even, in the distant future, whole cities, planets, galaxies or, at the limit, a whole universe.  He then goes on to ask what the odds are that we're living in the "one original universe" or one of the countless simulations that an advanced civilization could create - the implication being that the odds are in favour of some variant on a "Matrix" scenario - we're all probably living in a computer simulation of some description.

While this makes for a very nice bit of philosophical theorising, it's not actually definitive in any way - what's needed is some sort of test before we all start learning Kung Fu, wearing lots of black leather and attempting to escape from our digital world.  This possibility of performing such a test is the main theme of the BDS paper (which, I should point out, is well beyond my limits in many ways!)


A great many "simulations" exist in physics - in fact, it could be argued that a good definition of physics is "the search for the simplest possible way to make a universe that matches ours".  From Newtonian mechanics to relativity, string theory and dark matter, all physics really is is a series of computer programs which seem to accurately mirror the universe around us (precisely why we can develop programs like this is a different, and equally fascinating question), and the specific "program" in the BDS paper is something called lattice quantum chromodynamics (lQCD), which thankfully is easier to explain than it is to actually do!

There is no Theory Of Everything at the moment (well, string theory might be, but nobody knows yet), so physicists tend to work on their own little subsets of reality in the hope that everything can be joined up later.  lQCD is a technique that deals solely with quarks, the particles which make up most matter, but doesn't include electrons (in other words there's no chemistry in this program) and also doesn't handle time, gravity or light in any meaningful way, so it's not a complete simulation.  The basic technique is to create a lattice, a grid of points in space, and give it a starting position with all the quarks in various positions, then run the simulation to find out what happens.

It's a remarkable powerful technique, and seems to match reality extraordinarily well.  It also has another interesting feature, which is that it's very efficient - in fact, it may be the most efficient way to simulate this small chunk of reality, and this is where it gets interesting.

The universe tends to do things as efficiently as possible - for example, there aren't, as far as anyone can tell, two different systems to make gravity work and to handle the conservation of angular momentum, one necessarily implies the other, it's all tied up in the one theory.  Space and time are another example - once thought to be two entirely separate entities, Einstein's work a hundred years ago led to the realisation that they were two sides of the same coin.  So, the BDS paper asks, could the universe actually be running on lQCD?

They've taken a simple, effective form of lQCD and assumed the universe plays by exactly these rules - and then they've done the classical science thing of asking what that universe would look like if this was the case.  Obviously, yes, it will be very similar to ours, that was the whole point of developing lQCD in the first place, but this is never a guarantee - Newton's law of gravity stood for several hundred years before we found a mismatch between it and reality.

The main prediction they find is related to the "GZK cutoff", a complicated way of saying there should be a maximum energy for any cosmic ray particle hitting the Earth.  This is something that is predicted by many theories, and the big test for many of them is exactly where this cutoff applies - something which is still unclear.

The nice thing about the BDS paper is that they're able to relate the GZK cutoff to the actual spacing of the lattice in lQCD - if our universe does run on lQCD then we can potentially discover this, and even find out some of the settings under universe -> file -> preferences.

So, returning to the original question, are we living in a simulation?

We're back to philosophy here - specifically the identity of indiscernibles. Let's assume that the universe does actually use lQCD - this doesn't actually imply a simulation scenario.  Yes, it could be a simulation, but it could equally well just be "the way things are".  Mathematical models crop up all over the place; plants grow in fractal structures, cicadas mate on a prime-number based pattern of years and the Golden Ratio seems to be behind many features in the natural world, but this doesn't mean there's some sort of Grand Simulator furiously tapping away on a keyboard.

If the universe obeys a "program" such as lQCD it doesn't have to mean there was a programmer, just as the existence of Pi doesn't imply the physical existence of a mathematically perfect circle (which, ironically, is impossible under lQCD).

Long story short? I can't put it any better than the great Randall Munroe, of xkcd.com (yet again).

StarKites Taina Review (12m)

For those who don't know, I'm a bit of a kite fanatic.  Having started on sport kites (the little hang-glider shaped things) I moved onto powerkites, then kite landboarding and have been a keen kitesurfer for many years - to the extent that I moved a few hundred miles partly based on kitesurfing opportunities (but mostly to keep the girlfriend happy, honest!)

Recently I was offered the chance to review a new brand to the UK, a company called StarKites.  To be honest, I was a little skeptical to start with, there's a lot of new entries to the kite market each year, and most of them are cheaply manufactured close-copies of the big and established names.  Not the case with StarKites however, I was pleasantly surprised though....full review follows:

StarKites Taina 12m Review

Background

I was sent a Taina 12m and Nex bar and lines which had seen around a years use as demo kit.  I have not received any incentive or gift in exchange for this review other than a loan of the kite for a couple of weeks.  What follows is my honest opinion of the kite without any bias towards or against the manufacturer or distributor - I had never flown any StarKites product before.

I weigh 10st / 65kg and I'm 5'8" / 1.75m tall.  I started kitesurfing with a Flexifoil Strike (C-kite), spent several years on a Peter Lynn Venom and for the last year and a half I've been flying Flexifoil Ions, Mk II and III.  I normally ride in fairly choppy conditions with anything up to head-high waves when there's good swell.  I'm mostly into freeride (back/front loops, carving transitions, jumps with grabs and rotations) and some wave riding which I'm trying to improve at!  I don't really go for wakestyle tricks.

Out Of The Bag

The bag itself is essentially a 50 litre rucksack with a doubled-over liner to allow it to expand and store the kite with the struts still inflated if necessary.  There's a separate outsite pocket for bar and lines, and a second zipped entry at the bottom of the bag which can be used for storing a wetsuit, towel etc.  Reasonably heavy duty cordura and plenty of zips and straps to keep things in place.  No metal components at all, so you're not going to end up with rusted zips.  It's red and black, if that kind of thing bothers you.

First impressions of the build quality on the kite are good.  The stitching is tidy, with white thread on black fabric making any problems or unravelling easy to spot.  Reinforcement patches are used in all of the high-stress areas and there is a lightweight plastic "bumper" on the center of the leading edge to give a little extra protection during ground handling.  Cordura is used on the tips of the struts to protect against wear.  All in all it's not a heavyweight, "indestructable" build, but it's perfectly adequate and results in a nice lightweight kite that should stand up well to everyday use. 

There's a simple and fairly long bridle for the main lines with a pulley on each - both pulleys were already showing signs of getting jammed with sand and salt and the pulley wheels showed wear from the line running over them rather than turning.  This will always be a problem with using pulleys on the beach, but did not seem to affect the flying characteristics in any way, from the looks of it the pulleys will "fail" pretty quickly without regular maintenance, but even then they should continue to function without any problems.

The rear lines attach to one of three different settings on the wingtip allowing you to tweak turning speed and bar pressure, with the middle setting being the ideal all-round setting as far as I'm concerned.

The Look

I'm not all that bothered about graphics and colours, as long as the kite is bright enough to make out against the sky or sea and easy for a search and rescue team to spot!  This particular model comes in brown and yellow with black leading edge and struts and some white detailing - works fine for everyday use, but in an emergency I'd like some reflective panels built into the wingtips.  The girlfriend is more into visual styling, so I'll leave the aesthetic comments to her:  "It's not brown, it's more of a bronze/burgundy.  70s retro, I like it, and the big star logo".  So there you go.

There was a tiny amount of colour bleeding visible on the white panels, but nothing to bother about unless you're planning to enter your kite into the equivalent of a classic car show.  If you want a pretty kite to show off on the wall then buy a Rok, this is for kitesurfing and it's going to get wet and stuffed in a bag at some point!

Bar & Lines

The bar and lines are generally very simple - four generic colour-coded lines (red=left, white=right) which have the power/rear line attachments reversed so you can't get them the wrong way around.  The depower strap is the simplest possible pull-pull strap arrangement and works well.  The line leaders are polyurethene coated to protect against wear - they do, however, make winding/unwinding the lines a little awkward and aren't really necessary.  The bar ends are nicely rounded, enough to safely wrap the lines without them falling off but not enough that it's likely to catch on a harness mid-kiteloop!  The bar itself seems to be carbon with a one-piece aluminium insert in the center (although it's difficult to tell without stripping the coating off!) and the hole in the middle is nicely machined, it's not going to go eating your depower line.  Most components seem to be very bog standard generic items making replacement and/or repair cheap and very easy.

Safety Systems

The primary safety is a departure from the simplicity of this kite.  It's a large plastic and metal construction with a vaguely cone shaped release - unfortunately the cone points away from you, so cold, wet and tired hands tend to slip on it, you need a reasonable grip to activate it in a hurry.  The metal components may well suffer in time - the setup I was using was already showing patches of rust in places, and the plastic has become worn leaving ragged edges where the safety line runs through.  It works, but personally I'd rather go with a simpler pin-and-loop or Flexifoil style top-hat arrangement. 
  Don't get me wrong, it works well enough, but it's a departure from the "Keep It Simple" ethos of the rest of the setup, and an unnecessary one at that.  I can't help but wonder if it's related to various international standards which require a maximum release force of X under a total pull of Y, something which has resulted in companies producing overly complicated safety systems in the past.
  Curiously, the primary safety also has "Total Weight: 35kg-90kg" embossed on it - this is confusing.  In climbing and rope access it's common to quote a safe working load and/or maximum load on equipment (something that could be useful in kitesports), but this is clearly something different.  I'm assuming it's the weight of the rider, and that it's actually rated at forces far higher than 931 Newtons (95kg) because otherwise it would have popped every time I jumped with it.  Nice try, but confusing and potentially misleading.
  The primary releases the kite onto a single front line allowing the kite to flag out and pretty much giving a 100% kill on the power - the kite inverts and falls to the ground. 
  The secondary safety is the pin-tucked-into-a-tube type - it works well enough and let's face it, it's rare to use this anyway.  The leash is fairly standard shock cord with a couple of lightweight stainless steel clips which look like they'll fail under a load of 100kg or so, which is a good thing.

In Flight

The first thing you notice is that this is a pure-bred bow kite, as far removed from a C-kite or hybrid as you can get.  If you try to fly the Taina like a C-kite you'll be very disappointed, the power generation through the window and ability to depower it by driving it to the edge are very minimal, and completely swamped by the depower range on the bar, which has so much throw it's silly.  I'd estimate that the power delivery is 70% on the bar and 30% from the kite's speed through the window, the complete reverse of a C-kite.  You don't get the explosive power and never-ending grunt, but what you do get is a kite that is very, very easy to fly in a wide range of conditions.

Close to a stall this kite still produces a lot of power, meaning the upwind performance in nasty choppy conditions is very good - if you've spent much time on a landboard you'll be familiar with getting upwind by trundling along fairly slowly, well you can do the same on the water with the Taina.  It does love a bit of apparent wind, but you don't have to build up some speed to get upwind - you can if you want, and it's still the preferred method, but you can pootle upwind while avoiding the worst of the chop if you need to.

When properly lit up the Taina performs very nicely indeed.  The power builds comfortably and the depower range means you rarely feel overpowered, although this is a double edged sword for relatively short people like myself - to fully depower the kite you've got to reach forward so far you end up in poo-stance rather than leaning back and edging against it, which isn't the ideal situation - I'd shorten the depower line and sacrifice some of the depower for a little ergonomics if this was my main kite.  People with longer arms will love it though.

I never had the chance to try the kite in flat water, but I suspect it's an absolute beast when lit up - upwind performance at speed should be very good, and low wind performance should be at least respectable - other reviews suggest it's far better.

Jumping

Smooth, easy and very forgiving.  It's not a wrench into the air as you get with some kites, just a nice firm hoist upwards with lots of float.  Again, you don't need to really wang the kite back hard, just give it a reasonably purposeful turn towards the zenith and then pull the bar in and up you go.  The quick turning speed means you don't have to crank the bar over to redirect the kite, just keep the bar pulled in with your leading hand and that's enough to bring the kite around.  I've not tried a kiteloop with it, but I'd imagine it's a fairly pleasant experience.

Stability

I managed to Hindenburg the Taina once, after messing up a jump and landing well downwind of the kite.  In relatively normal situations overflying simply results in the kite sitting back a little and drifting back into the power zone without any drama - great for newbies and wave riders who won't have to worry about catching up with the kite.

It eats gusts for breakfast - you certainly know about them through the bar feedback, but there's rarely enough of the gust transmited through the main lines to put you off balance, and again, the long throw and depower range come into their own.  My first session with the Taina was in fairly gusty conditions (~18mph gusting to the high 20s, maybe touching 30) and I never even adjusted the depower strap after I was up and moving on the first run.  Landboarders flying inland will appreciate this if they like flying LEIs.
 
 

Relaunch

I tried testing the relaunch twice, once on purpose once after wiping out. Both times the kite relaunched itself before I really had to try - very easy.

Marks out of 10

Build quality - 8
Launching - 7
Stability - 9
Safety - 5
Power - 8
Jumping - 9
Waves - 8
Freeride - 8
Freestyle - 6
Wakestyle - 4
Ease of use - 8
Newbies - 9

Overall - a solid 8.5 out of 10, a really nice kite for somebody who wants to do a bit of everything, whether on water, land or snow.  It's not the highest performance kite I've ever flown, but kites designed for pure speed, power or whatever are invariably pigs to fly.  This is aimed at the average rider (which, statistically, most of us are) and does a very good job of it.

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.