it's incontrovertible really: the bbc exists, and it relies on a tax that is unenforceable unless the television detector van is real, and the television detector van seems to be impossible… so our idea of what is possible must be wrong. stop reading if you see a flaw here.

so, in 2006, the bbc was once again faced with an interesting r&d problem, with what seemed to be ample financial and non-financial incentive. if lost media could be found, it would not only be great for the bbc's image, but they could make a pretty penny by doing so.

it quickly became apparent that this problem could not be solved with just the bbc's own funds, but this was not a problem. the larger copyright industry was all too happy to chip in. with so much demand and only one hope for supply, the market could tolerate a very high price.

and it turns out they placed their bets on just the right organisation. it turns out that, in 1952, the bbc had created a small side-channel within the television licensing unit that enabled minor violations of causality. a fact of course that must be concealed from the public.

the skeptics were in fact always right: the television detector van does nothing. it's just a normal van.

and yet, it never has a false positive. why? how could the bbc figure out if someone had a television so reliably?

well, it's an easy problem with the fullness of time.

it's very easy to deny, on the spot, that you have a television. it's very easy to prevent them being able to tell if they drive past your house at predictable times. but if the television licensing unit is after you, eventually they'll find concrete evidence. you'll slip up.

it is after all, the most normal thing in the world to own a television. it had enormous cultural impact in the 20th century. nobody can plausibly deny they own a television forever. it'll get to you eventually. it'll show. somehow, the truth will come out.

the problem is, well, time. in 1952 the bbc faced an existential threat. they couldn't figure out if someone owned a television fast enough. the time they were spending investigating television ownership cases was more expensive than the eventual fees recovered. they bled.

now, at this point you might think the answer is simple. the british government should simply give the bbc the power to break into people's homes and check if they have televisions. or, to simply use general taxation.

but the new conservative government knew this would end them.

in the end, the bbc was only able to extract a tiny concession: if they could find a way to detect television ownership that never had false positives, that would never be incorrectly wielded against a good, middle-class home-owning tory voter, they could fast-track enforcement

but as we know, it's very hard to guarantee no false positives. while this let them immediately enforce the outcome of their investigation, the time needed to investigate was still a problem, so it shouldn't be so useful, right?

this is where small causality violations come in.

the details of how they did it are lost to us now, known as they were only to a tight circle of dead british men who, for obvious reasons, never spoke of it to outsiders.

but what they did, we do know: they found a tiny and very limited side-channel in the fabric of reality.

this side-channel allowed them to leak a single bit of arbitrary data backwards in time, over a span of at most a few weeks. the cost to doing so was quite high: willing participants at both ends are needed, they need physical space and some amount of time, and special equipment.

a single bit of data means all that can be conveyed is “0” or “1”. or, in another interpretation, “no” or “yes”.

for the bbc's television licensing department, this single bit of data was the answer to the question: “after investigation, did the person have a television?”

knowing all this, you probably start to see how they solved their licensing enforcement problem.

if you had “reverse parallel construction” on your bingo card, congratulations! that's exactly the principle.

in the usa, it is widely believed that cops engage in “parallel construction”. this is when they do blatantly illegal shit to obtain evidence, which shouldn't be admissible in court. but then, using the evidence, work backwards to find a legal way they “could have” gotten it.

you then, well, lie to the court and say that the evidence you have was arrived at in this plausible, legal manner. it might not even entirely be a lie, because you could re-obtain the evidence via that legal path. and that's how you get away with illegal surveillance.

what the bbc television licensing department did was essentially the same idea, but with a fun twist. they didn't use invented traditional evidence gathering to cover up surveillance… they used invented surveillance (the vans) to cover up future traditional evidence gathering.

if someone was a difficult case who didn't immediately slip up or confess, this was no problem. they could spend weeks, or maybe months investigating them, but by leaking the outcome of the future investigation to the present, they could enforce immediately with no false positive

now, we all know about the problems with anything adjacent to time travel. if they were stealing the outcome of a investigation from the future, and then using that information to immediately enforcing the outcome, won't that mean the investigation never ends up happening? indeed

but, luckily, television license enforcement happens to be a simple enough problem that it works out neatly here.

the timeline forks at the point they ask the future about the investigation outcome. the first time around, there is no answer, and they investigate.

the second time around, they get the answer and immediately enforce the result. in the process of enforcement, they find out that, indeed, the person has a television, so there is no painful penalty for a false positive. weeks later, they send back the same answer. a neat loop.

it's so neat. well, it's too neat. it is not something you should be able to do. they were probably able to get away with it because television licensing is so inconsequential, and they managed to obfuscate the process so that licensing staff wouldn't know the power they had.

so, right, the lost media problem. you might see where this is going.

in 2006, some of those dead british men i spoke of earlier were still alive. they had spent more than half a century living with the knowledge of what they had done, resisting the temptation to use it again.

well, actually, we don't know if they resisted the temptation. i only know about two timelines: the one i'm writing this in, and the one i talk about in this story. it is possible that there are many timelines where they did succumb to temptation, and had to undo it.

so far i described these people as resisting temptation. but, like anyone else who discovers a way to leak future information into the present, they of course immediately devised and implemented a scheme that would give them the option of doing insider trading, if they wanted.

i said that they could leak one bit of data backwards in time, over a timespan of a few weeks. that sounds quite limited, but that's if you only pay the time, space and people cost once. with several people you have several bits. pay it repeatedly and the timespans can be chained

that makes it start to sound practical. but consider: this scheme is designed for insider trading. it is a conspiracy! the number of participants must be kept small to avoid detection, and for trading on information from the far future, they need to be committed for a long time.

the television licensing enforcers have it easy: they want very little information (yes or no), on a very short timespan (weeks), and since they have have had the actual meaning of their actions concealed from them, they can be employed in large numbers without problems.

suppose you want to convey a large message, with enough information needed to, say, save old doctor who episodes from being destroyed, so they can be found in the future. a message needs hundreds of bits, coveyed over many decades. you need a huge and long-lasting conspiracy.

well, the original insider trading conspiracy of old british men who worked in r&d was not large enough for this. it was a handful of people, in it for life for the fun of it. with regular meetings over a few decades, they could convey only a few bits of information back in time.

but, they had just enough bits that they could retroactively bootstrap a larger conspiracy if necessary. you don't need a lot of bits to do insider trades. if you can make a successful trade, you can hire more people for your conspiracy, and now you have more bits. virtuous cycle

the only problem with this scheme is now you have to maintain a multi-decade insider trading conspiracy with exponential growth in membership over time.

so, finally, what happened in 2006? well, you can probably guess at this point what occurred in many essentially identical 2006es: the tiny conspiracy of old men tried to use their half-century-long chain of side-channels to reach back a few decades and prevent media being lost.

but we don't live in a timeline where they succeeded, because… well, co-ordination problems are hard?

there could be a timeline where they do succeed, but i think a conspiracy of (at least) hundreds maintaining a causality loop of decades is just too big.

ok i'm done