Lovefilm voucher codes: 2 free months

Posted in Random on July 10th, 2013 by Andy

Lovefilm_logo_V401920778Since getting a smart TV we’ve been trying out streaming from Loveflim and Netflix. We’re pretty happy with both to be honest.

If you’re thinking of trying it out I’ve got Lovefilm voucher codes for two free months:

  1. Go to
  2. Enter code: YGCH6GMEN
  3. You’ll get two free months of streaming or disks (or both), if you cancel before they bill you for the third month it won’t cost you a penny.
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MicroSD storage madness

Posted in Computers, Random, Stupid trivia, Tech on May 18th, 2013 by Andy

 An giant 19070s hard the size of a man compared to a tiny microSD card sitting in someone's palmThis is a pretty mad picture. I remember the first PC I owned had a 202MB hard drive, a size that just seems laughable compared to that microSD card.

So where does it all end? Will we eventually be able to pack the entire internet into a pinhead? Physics wonks tell us there is a maximum theoretical amount of data you can squeeze into a finite amount of matter,  but it’s a lot. For the microSD card given above it works out to about 567 bits, which is about 6.2 trillion trillion trillion trillion trillion MB.

It turns out that the capacity of hard drives has been growing at an exponential rate over time:

Capacity of hard drives over time. Note the logarithmic scale...

Capacity of hard drives over time. Note the logarithmic scale…

So, if they keep growing at this rate when would that microSD card sized storage device max out? Well, if the biggest microSD you can get currently is 64GB then I make it 132 years. And what could that microSD card fit on it? Well, the entire data storage of Earth in 2013 is around 735 exabytes, and that would take up a smidge over 0.000000000000000000000000000000000000000001% of the space on this “perfect” microSD card.

So clearly things can get even smaller, and store even more. Watch this space.


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The Liberator isn’t a gun, it’s a dangerous toy

Posted in Random, Tech on May 17th, 2013 by Andy
A man firing a 3D printed handgun

Cody Wilson of Defense Distributed test-fires his comedy “gun” thing

American 3D printing anarchists Defense Distributed have caused a bit of a flap in media and official circles with the release of the Liberator, a 3D-printable handgun. But how disruptive is this thing really?

What is the Liberator?

It’s a single shot handgun, completely 3D fabbed from plastic except for a metal firing pin (aka: a nail). The model demonstated so far was in .380 calibre.  It’s the spiritual descendant of nasty self-maiming tools the FP-45 Liberator and the Deer gun. The manufacturers claim that it democratises access to firearms, by allowing anybody to fabricate a real gun at home. I’m going to tell you why that is a really, really bad idea.

Can you make a gun out of plastic?


While many modern firearms do make extensive use of polymers, they use tough high-impact plastics properly formed by processes like injection moulding that guarantee strength. They don’t use 3d printing, for a good reason. Crucially, they also don’t use plastic for any of the actual working parts of the weapon exposed to high stresses.

The Liberator has a plastic frame and trigger mechanism, which is absolutely fine IMO. Unfortunately it also has a plastic barrel and chamber, which is just stupid. This is made worse by the fact that’s it’s constructed using additive manufacturing (aka 3D printing) where parts are built up by extruding layers of thermoplastic. This combination of process and materials is inherently weak, meaning the weapon will be inaccurate,  underpowered and dangerous to use.

Inaccurate and underpowered

Firearms are gas-operated. When the primer of a cartridge is struck it burns the propellant inside the cartridge and this generates expanding gas. This gas pushes the bullet out of the cartridge and down the bore, where spin is imparted to stabilise it once it leaves the barrel.

The gun disassembled into it's parts

The Liberator is built from 19 ABS components, a nail, and some very misguided intentions.

The Liberator’s plastic chamber is in fact more elastic than the brass of the cartridge it holds (brass elastic modulus = 100+GPa, ABS = 2.3GPa) so the chamber will not restrain expansion of the brass due to the rising pressure of the burning propellant. In a normal firearm the brass cartridge and lead bullet are constrained by the much less elastic steel chamber. This process is called obturation and is important for forming a tight gas seal so that as much energy as possible is imparted to the projectile.

On top of this, the Liberator’s extremely short barrel means that any gases that do start pushing the bullet along the bore will only have a very short time to transfer energy. Short barrels result in lower muzzle velocities, and since stopping power (ie: kinetic energy) is proportional to the square of velocity this means that short barreled firearms lack stopping power. Half the muzzle velocity will only carry one quarter the kinetic energy. And the Liberator’s barrel is really, really short, robbing the .380 cartridge of any stopping power.

It’s interesting to note that Defense Distributed have not published any chrono readings from their test firings. Were they to so I suspect you would find the Liberator is severely underpowered and dangerously useless for self-defence. Or crime, for that matter.

To make matters even worse the barrel is unrifled, and even if it were rifled the soft plastic would be unable to cut into a soft bullet to impart spin. This means the bullet emerges slowly in a pretty random direction, probably starts tumbling all over the place, and goes anywhere except where you’re pointing it. Not too useful given that you only get one shot.

But a crap gun still beats a knife right?

It should be noted that the original FP-45 Liberator from WWII (built to a higher spec than this one) was estimated to have an maximum range of no more than 25ft, and effective range was more like 10 feet. That’s about spitting distance. Police forces teach their officers that a knife-wielding attacker is dangerous to a gun-wielding cop at around 21ft, a figure the Mythbusters seem to have backed up with some playing around of their own.

Bottom line, the Liberator is no more effective than a knife, and probably somewhat less than an axe, a baseball bat, or any number of seriously lethal devices you can pick up completely legally, such as a chainsaw. Besides not being able to actually do its job, there’s a strong likelihood that it’ll blow up and plant bits of plastic in your eyes and face when you pull the trigger. Indeed, when Defense Distributed tried to fire a rifle calibre cartridge (5.7x28mm) from one it blew up on the first shot, which just goes to show these jokers have no idea what they’re doing. Did they even run the numbers on the chamber pressures before building it? I’m guessing not.

Should it be banned?

Not because it subverts firearms laws or allows criminals to tool up. Personally I’d be quite happy with criminals 3d printing themselves a Liberator if it meant they ween’t carrying better weapons, such a knife (or maybe a spoon).

However, I predict that some fool will fab one and injure themselves badly with it very soon. It’s dangerous to fire and good only for making a loud noise. You could build a more effective weapon with hardware from your local DIY store. 3D printing mongs Defense Distributed claim this gun is a revolution in civilian access to firearms. If that’s true then Lego is a revolution in building houses.

By all means, download and print one for a laugh if you want, but whatever you do don’t fire it.


Some testing done by the New South Wales police, during which (surprise, surprise) one of the two guns they printed blows itself apart:

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World of Tanks: panzer fun for the masses

Posted in Computers, Random on August 14th, 2012 by Andy

Most massively multiplayer video games let you play as an elf, or a soldier, or a wizard. World of Tanks one let’s you play as a tank. Yes!

A German panzer moves down a road in a  rural setting

Achtung! Very large Panzer!

World of Tanks is a freemium MMO wargame from Russian treadheads The game is a 3Gb download (Windows only), and it’s completely possible to play totally for free, tightwad players aren’t nerfed. Gameplay is team-based deathmatches, mostly a 15-a-side capture-the-flag scenario.

So what’s it like? Fun and hard. Combat is very tactical, you’ll have to make use of cover, concealment and scouting to survive, and teams that mutually support each other tend to wipe the floor with those that play as individuals. Even very tough tanks can be taken down by coordinated teamplay, and running around madly looking for trouble is generally a quick way to wind up with your panzer a flaming wreck.

You’re allowed several tanks in your garage. This is essential as if your ride is knocked out (which it will be, a lot) then it’s not available for use until that game ends, which can be up to 15 mins. Tanks of all types, tank destroyers and assault guns, and self-propelled artillery are all available, and the arty is actually quite fun to play as it gives you an aerial view of the battlefield. German, Russian, British, Russian and US vehicles are available, and teams will be a mix of nations.

The tanks themselves are initially early or pre-WW2 models, and as you progress up the tiers they tend to work their way through the war years, with puny early war Panzer I’s giving way to the mighty Panther. All the famous vehicles are there: Shermans, T34-85s, Tigers, StuGs and even some Cold War heroes like the M48,  T54 and T62 at the top tiers. In addition there are quite a few prototypes that never saw actual combat in the World of Tanks lineup.

Several tanks lined up in a field

Actual in-game shot showing the UI. You’ll have to keep track of ammo, relative team composition and strength, and the minimap to avoid becoming flaming wreckage.

Injecting some cash into your account can buy you extra spots in your garage, better ammo, bling for your tank, or even whole new tanks. Some of these aren’t available through the normal tech tree, but all premium tanks suffer the fairly significant drawback of being unable to take upgrades. I haven’t bothered to pay for anything myself, but what’s worth doing is to slog your way through the tutorial battles, as you’ll be given a premium tank and a good crew for your trouble. This gives a nice insight into what combat is like with a better vehicle than you’ll have initially. You can use that premium tank to train crews for other vehicles.

Experience is scored in battles for damaging enemies and for spotting them, which rewards reconnaissance as well as violence. XP can be spent on upgrades, eventually unlocking new vehicles. However, I’ve found it’s not compulsory to pick up better vehicles as soon as they’re available. Some of the lower tier vehicles are excellent fun to play, and shunning the upgrade gives you the opportunity to concentrate all XP into improving the crew’s skills, which is just as important as having a good tank.

Observation and scouting play more of a role in World of Tanks than most games, as you can only see enemy that yourself or an ally in radio range have spotted, and they can vanish completely if they give you the slip. A well-concealed tank destroyer can easily lie in wait and ambush unwary foes, and a safely distant artillery piece can engage targets under observation by scouts without those scouts having to give away their position. Using cover and terrain well will give a tactical advantage that will win firefights.

A T34-85 tank painted like a New York taxi

This T34-85 used to be around the corner from where I lived. They didn’t let me drive it or have go on the guns 🙁

The number one mistake I see in the game is the tendency for people to charge at the start of the match, generally the folks who do this end up dead within a couple of minutes, with the more cautious and clever fighters claiming their scalps. Retreating is a valid tactic, pushing on against a disadvantage rarely pays off, as the teams are generally closely balanced. Since neither side has an overall advantage the only option is to try and create local mismatches. Tactical errors will be ruthlessly exploited but battles are normally a simple matter of attrition, as a successful flag capture tends to only happen once enough of the enemy have been knocked out to allow several tanks to advance onto the objective together. Cheeky loners slipping through the lines don’t tend to live long unless their team mates reward their impetuosity with immediate reinforcements.

Overall the gameplay is varied, and rewards a range of tactics. Some tanks are extremely quick and make good scouts, while some have powerful guns but are slow or weakly armoured. Some are genuine monsters that strike fear wherever they go, but these also attract a lot of unwelcome attention, and no one is invulnerable. The maps are good, with terrain varying from street fights, desert, mountains, coastal and maps with a good mix of terrain. Just driving around can be fun, and there’s plenty to look at.

If you can spare a couple of hours, swallow the 3Gb download and go take a panzer for a drive.

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Does making the battery for a hybrid car take more energy than the car saves?

Posted in Green, Random, Tech on April 13th, 2011 by Andy
A Humvee

Some folks on the internet have actually tried to claim that a hybrid car uses more energy than a Hummer. Lol!

I recently heard someone trot out a factoid i’d heard before a couple of times:

The battery on hybrid cars takes so much energy to produce that it’s actually greener to drive a normal car.

As a Prius owner myself I wondered; could this be true?

Toyota have been rather tight-lipped about the exact details of Prius battery manufacture, although this is probably just because they consider their Hybrid Synergy Drive technology commercially sensitive (at least while they’ve got such a lead in the hybrid market over their competitors)

So let’s take a guesstimate at some numbers and see how it stacks up:

A new Prius starts at about £20,845. Let’s be generous to the sceptics and say that making the battery is a whopping 20% of the sticker price of the car (it’s likely much less than this). That means it costs £4169 to make a battery. Again, lets humour the sceptics and say that 90% of the cost of the battery manufacturing process is energy and that Toyota pays the equivalent of 5p/kWh. That puts the energy consumed during manufacture at 270GJ. That amount of energy is equivalent to a little over 1800 gallons of petrol. Toyota rate the hybrid drive as offering an improvment of about 25mpg over a standard drivetrain (using figures from the Auris vs Auris Hybrid), even if that’s only 15mpg in reality then a Prius would only take 27,200 miles to make back the energy used making the battery. Remember, those numbers I chose are extremely pessimistic, it’s likely that the real break-even point was much sooner.

Toyota’s warranty on their hybrid batteries is eight years, so unless you don’t think you’re going to put 27,000 miles on the clock in that time, a hybrid will reduce the amount of energy your driving consumes.

So bottom line: even a rough calculation of the energies involved does not support the claim that building batteries for hybrid cars is more wasteful than driving a conventionally powered car.

If you want to play around with the numbers, you can download this spreadsheet.

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What would really happen if SETI discovered an alien signal?

Posted in Random, Space on January 12th, 2011 by Andy
Alf holding a telephone

" 1 to be taken to our leader, press 2 to strip-mine Earth for its natural resources..."

We’ve seen it all in the movies enough times: finally we get proof that we’re not alone. But how would it really go down?

Fortunately head alien-botherer from SETI Seth Shostak has given us some the inside skinny in his excellent book “Confessions of an Alien Hunter“, which I highly recommend if you’re a fan (and even moreso if you’re a critic) of SETI

The government would cover it up, right?

Nope. The first thing that would happen if an astronomer discovered an candidate signal is get another astronomer on the other side of the world to check it. This eliminates the possibility that the signal is anything boringly local like air traffic control, the military or a satellite. The parallax view offered by a remote observer would confirm that the signal really does come from a far off point. The bottom line is that by the time the signal had been confirmed as alien, no one government could silence it. The genie would be out of the bottle.

And even if they did try and cover it up, somebody would just put it on Wikileaks and the press would snap it up.  There’s no way you could cover up a discovery of this magnitude.

Ok, so we’d immediately start to decode the signal?

Er, no. Despite the enduring image of Jodie Foster in Contact sitting by a dish wearing headphones, the reality is that SETI processing is all done automatically, by computers. An unfortunate side effect of the mathematical transformation they do while scouring the background noise to find blips is that it averages everything. Obviously averaging everything destroys the actual information, although it will alert you to the fact that you’ve got a signal in the first place. That’s a bit of a pain, but it’s the best we can do.

Right, so we’d just point our dishes in the same place, and get the signal again?

Um, no again. Unless the signal came from our immediate neighbourhood, or was stupendously powerful, we’re unlikely to be able to extract any information from it, even if we detected it.

You can detect radio signals at much weaker strengths than you can extract information from them. You can see this when you scan for wifi signals with your laptop. You can detect lots of hotspots, but the signal isn’t necessarily strong enough to let you form a reliable connection. The wifi base station can pump out as much data as it wants, but your little antenna just isn’t up to the job. It’s likely to be ditto with signals from little green men.

So how would we decode it?

We’d build a bigger antenna. A MUCH bigger one. More likely, we’d actually build a behemoth made up of massive numbers of smaller dishes all working together. How big? A 1971 NASA study estimated a thousand 100m dishes, which is big boys’ engineering. Once we’d built all that, we would have enough receiving power to grab a good signal.

So what happens if the signal stops before we’ve built this mega-receiver?

We’re screwed. This is entirely possible if the signal wasn’t meant for us, for example if the original signal was Earth being inadvertently swept by the beam of some long range communication between a moving object and another point. Whoever coughed up the cash for building the receiver would probably be pretty pissed off.

Ok, so let’s say we’ve got the message. What would ET want to say?

We really don’t know. We know the kind of things we’d put in a message: some basic maths and chemistry, a map, some cultural tidbits, and a nice cheery hello. But we really shouldn’t try to second-guess the contents of a message. It would be logical for the initial message to be simple and easily understood, and based only on knowledge that a civilisation would require to receive it in the first place (ie: roughly the technological level of the early 20th century). Building radio receivers requires a certain understanding of maths and physics, and since the laws of physics are the same everywhere there should be at least some common knowledge between any two civilisations that can control radio waves. Using that body of knowledge as a kind of crib sheet for constructing a language to communicate in would seem the best strategy. Or not, maybe ET would rather beam their soap operas at us.

When will the signal arrive?

Well, if you’re a pessimist you’d say: never. We’ve been looking up for decades now and we’ve heard almost nothing of interest. Coupled to the fact that nobody from out there has ever been proved to have shown up here, despite having many billions of years to have evolved enough to do so, it’s entirely possible that there’s just nobody out there. Or at least that life is so laughably rare that finding another civilisation is almost impossible.

If however you’re of a more cheery, optimistic inclination you’d say: soon. The massive rise in computer power in recent years has enormously enhanced the ability of SETI scientists to scour the heavens. Their surveys are going from sporadic peeks at a select few stars to massive sweeping sky surveys. It’s not unreasonable to say that within a few years we’ll have checked all the good candidates, and that within a few decades we’ll have comprehensively searched the entire sky for all the viable frequencies. If ET is phoning Earth at all, we’ll see them.

Why “The Singularity” is bollocks

Posted in Random, Tech on February 20th, 2010 by Andy
A graph of the number of blades per razor over time

The logic behind the "singularity" applied to razor blades. Personally I think there might be something in this one...

There’s a lot of nonsense talked about the supposedly looming “technological singularity“. For the uninitiated, this is based on a principle called Moore’s Law. Broadly speaking, Moore’s Law states that every couple of years, computers get twice as fast for the same cost. The impressive thing is that in the 40 years or so since Gordon Moore first cooked it up, it’s been remarkably accurate, even though the tech has gone through changes he could never had foreseen.

What gets all the singularity nuts excited is the idea of what happens next. According to Moore’s “Law”, computers will get smarter and smarter, until eventually they’re smarter than us, and begin (according to the singularity folks) designing themselves at a rate we couldn’t match. The machines take over, humanity becomes irrelevant, etc, etc.

Except that’s a load of bollocks, and here’s why:

In the real world stuff never continues to grow exponentially forever. Projections based on unbridled exponential growth are the mathematical equivalent of perpetual motion machines. It’s called a Malthusian growth model, after a bloke who made some very dire predictions about world population back in the 19th century. Lucky for us, the complete lameness of this type of model meant that the world didn’t implode under the combined weight of humanity, and the mathematicians went back to the drawing board. The result was a new, better model they called the Logistic model, which acknowledges the idea that even if something can grow at an exponential rate for a while, eventually forces that may have been too small to notice begin to slow the growth rate. This model has been far more successful at accurately modeling real-world processes.

Sure the idea of the singularity is fun, but the less sexy reality is that your wrist watch is unlikely to ever be able to out-smart you, let alone usurp your position at the top of the food chain by creating it’s own army of super-intelligent wrist watches. Moore’s Law will eventually break down, machines will stop getting smarter so quickly, or even stop getting smarter at all.

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Why I have enough light bulbs for the next 404 years

Posted in Random on January 18th, 2010 by Andy
A human skeleton

A picture of me the next time I buy light bulbs

UK electricity companies are in the habit of sending out packs of free energy saving lightbulbs to their customers. It’s one way they satisfy their climate change obligations to government. During the course of a couple of house moves i’ve ended up getting sent 3 packs of four bulbs each, so 12 bulbs in total.

Now, I already had five spare bulbs, so that means i’ve got 17 spares kicking around now. We currently use eight low-energy bulbs around the house, and i’ve yet to have one die in about three years of use. If one blew tomorrow, that would put my usage at 0.042 bulbs per year. If they all blew, that would mean 2.67 bulbs per year. So in the very worst case scenario I have 6.37 years before I have to buy stock up on bulbs again. If you take the lowest estimate, i’ve got enough for 404 years.

I mean, free stuff is great, but I think i’m pretty much sorted for light bulbs now. If you’re listening power companies: you can stop sending them now. If you feel you have to send us free stuff, alcohol will do nicely.

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Merry Christmas everybody!

Posted in Random on December 25th, 2009 by Andy
Possibly the most awesome Christmas tree ever.

This is probably the most awesome Christmas tree ever.


Battletech ahoy!

Posted in Random, Tech on December 8th, 2009 by Andy

Not content with possesing enough conventional firepower to squish pretty much anything on the battlefield, the US military seems to now be plundering the future for cool new tech to waste people with. Next up on the US military’s agenda: autonomous walking battledroids. No really.

It turns out walking is actually a pretty practical way of getting around over rough terrain, so DARPA is flinging money at tech labs who can build them a droid that can lug heavy loads across rough ground. Presumably these poor bots would end up doing the jobs that the humans find difficult and dangerous, such as resupply and EOD. They’re kind of creepy, but i’ll bet they’d be popular with the meatsacks that would be doing these jobs otherwise.

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