How To Beat Your Future Self

“If you know the enemy and know yourself, you need not fear the results of a hundred battles.” – Sun Tzu
^{(and yes, he actually said this one)}

The first of my posts to make it to the Thought Experiments category!

One of, if not arguably my favourite videos of all time is by Wifies, a Minecraft YouTuber, called Can I Trap Myself? It’s a great watch and I would argue (if you’re into Minecraft content) you should watch it before reading this for context. But the description sums up the video topic very well: “You can’t evade it, even if you know it’s coming.” Wifies essentially wants to create a structure or challenge that a future version of him cannot steal a diamond block from in 15 minutes.

Past Wifies (and by past, I mean the one which built the structure) explored various methods, including brute force, randomly switching between multiple types of prison, and skill based challenges to make the possibility of breaking the diamond block in 15 minutes near zero. He even set up an arguably unbeatable trap – a stasis chamber that would teleport his Future (and by future, I mean the one who attempted the challenge) self to the world border millions of blocks away, that would go off nearer to the end of the challenge, so that there was no way Future Wifies could travel back in time.

But Future Wifies still won, as he had the knowledge of everything Past Wifies had done before, including building the stasis chamber, and he did this by ironically building another stasis chamber that would teleport him back straight to the prison right after the first one went off. This is how the video ends… but the topic struck a chord within me. Can you actually beat your Future self?

The Rules

Before we answer that, we should probably set some parameters – aka rules. We aren’t limited to Minecraft like in the original video, but the basic concept is the same. There is a challenge that we have to set, that although isn’t outright impossible (including breaking the general laws of physics) is designed specifically so a Future version of You cannot beat it. Their preparation time begins the instant you start the challenge, where the narrative flips from Past You to Future You.

Now I can think of a million things that Future Me probably can’t do in my puny lifetime – say, survive a nuclear bomb impact at ground zero. But let’s give the Future version an upgrade to make this a real challenge. Firstly, they have near-infinite lifetime and infinite resources at hand – infinitely better than Past You, a real glow up. In addition, their dedication to win matters more than their life.

A final rule before we begin: neither Past nor Future You can have “outside help” after they’ve prepared. As soon as Future You begins and the timer starts ticking, no-one else can intervene. Now we’ve defined the parameters, let’s try and imagine how wimpy Past You stands a chance against Future You.

Amateur Attempts

Let’s imagine the challenge is to obtain a diamond like in the video. A real life one this time＼(⁀▽⁀)／ We’ll store it in a metal safe box and lock it using various simple methods. Here’s a blast to start us off: rig the box so that if you attempt to open it, two tonnes of plastic explosive littered around it will explode – a “self destruct” mechanism.

Now most regular people would struggle with this, but Future You doesn’t even sneeze at that. Turns out with their infinite amount of time they’ve built a suit that can withstand the explosives. Or they’ve become a bomb expert and learnt how to disarm the bomb without even entering the room. Or they’re just a really lazy person and decide to wait a few thousand/million/billion years for the circuitry or even the bomb parts themselves to decay away, the metal box to rust to nothing. Either way, Future You barely yawns with a challenge so trivial, millennia upon millennia to bypass your measly explosives.

Other basic traps like locks, walls, throwing our box underwater etc. don’t fare much better. As long as the challenge is possible, with enough time Future You will prevail. .

So if we can’t protect the diamond physically, how about digitally?

Hashing Our Way

One of the most common forms of encryption is SHA-256. We can take a piece of data, like a string of characters (a sentence perhaps)? and, using a function, generate something called a hash. What’s that, you ask?

A hash function like SHA-256 maps data (that can be any length) to a fixed length, using some complicated math. The key here is that once you have the result (the hash) it should be basically impossible to use it to go back to the input. Here’s the result of a SHA-256 hash, which returns a hexadecimal 64-digit number:

inp = "my blog is the best blog on the internet!"
# ... code that runs SHA_256(inp)
result_hash = 1fd1d57e8694ba07e2bb15df2af14447e696044c62e01d996fc0797fca79f240

And if you changed just a few things in the input, such as capitalising two letters, you get a completely different result from the SHA-256 hash:

inp = "My blog is the best blog on the Internet!"
# ... code that runs SHA_256(inp)
result_hash = 3c9c5a4fc55b122ef16a972d45f07266b15c4fb176da70eb4455652ea2c2e855

SHA-256 is called a one-way function for a reason. There are 2²⁵⁶ unique hashes in SHA-256, around a 100 quadrillion quadrillion quadrillion quadrillion quadrillion. That’s so large that you could estimate trying to brute force, by trying every combination, would take trillions of times longer than the existence of our universe.

But… Future You has infinite time to try every one of these 2²⁵⁶ combinations, but if they were trying to be economical, they wouldn’t spend that much time. They would instead build a quantum computer to solve hashes exponentially quicker than we can today, nothing but a blip of time for our opponent.

Yeah, we’re going to need a different approach.

Thinking Outside the Box

Past You must be pretty close to giving up at this point, but Future You isn’t a quitter, so we can’t quit either.

The limitation of the laws of physics bounds some of the more creative ideas you may have had. For example, someone suggested a biometric lock to me when presented with this puzzle. Biometrics is most commonly seen in day to day life on your mobile phone login screen – via a fingerprint scanning or face scanning. There’s a good chance you’ve run into one at an airport security stall. Unfortunately for us, Future You has our fingerprint too – so you would have to remove your own fingerprint after you made the lock, which would be quite painful, and useless anyways, because Future You has infinite time to create future technology to bypass the biometrics.

Defining a challenge as possible means we can’t just give them an impossible challenge either, like finding a diamond that doesn’t exist, or asking me to go outside. So we’re going to need to work on a technicality to come out on top.

Here’s my suggestion: a paradox.

The most famous paradox involves the fun suggestion of time travel. If you could travel back in time, and kill your grandfather before he and his partner gave birth to your parents, you wouldn’t have been born, right? But that means you couldn’t have travelled back in time to kill your grandfather! This paradox is named – you guessed it – The Grandfather Paradox.

It has many suggested solutions, including three which we will explore here. Let’s set the challenge to this paradox and check the solutions out.

• Solution 1: You CAN kill your Grandfather. This causes a loop in time, called a ‘closed loop’ – your grandfather is alive, you are born, you go back in time and kill your grandfather, which means you weren’t born, which means your grandfather is alive, which means you are born… and so on. In this scenario, Past You has won – your grandfather hasn’t really been killed, as by killing him Past You, and by definition Future You, doesn’t exist, which means he hasn’t been killed. Brain bending. 

• Solution 2: You CAN kill your Grandfather. But this causes a split of timelines – think the multiverse theory. In the universe where your Grandfather is killed, you aren’t born, and the timeline continues without you in it. Therefore Past You never sets the challenge, therefore Future You never wins the challenge! Aka, going back to the past affects a new future. Meaning, we’ve still won the challenge!

• Solution 3: You CAN’T kill your Grandfather, called the Novikov Self-Consistency Principle, and it basically states that any attempts to influence future events still causes them to play out exactly like they do. Aka – you can’t change history. Future You can’t kill your Grandfather no matter how hard Future You tried – the event never happened, so you can’t make it happen. This one invalidates our challenge, as it becomes impossible to complete the challenge.

This might be our best answer so far! No matter what technologies Future You develops, they can’t beat a paradox – that’s the definition of a paradox. As long as it’s possible for Future You to travel back in time, then this idea holds up! Talk about thinking outside the box, we’ve done it!

Right?

Solution 3 complicates things. Future You has to invent time travel to complete the challenge here. If they’re not successful, the challenge is invalid and we’re back at square one. And if they are successful, they’ve just invented time travel, so they go back in time, but if the Novikov Self-Consistency Principle is true, then the challenge is invalid and.. you know how it goes from here. So we only win based on it being false; if it’s true, we’re stuck without an answer.

Pretending the Box doesn’t exist

Future You has been buffed so much it’s hard to see how we can exploit their capabilities or provide a challenge so strong they can’t beat it. But we do have something they don’t have, as highlighted by our time travel tricks, assuming self-consistency turns out to be true. We can affect their past, and they can’t.

If you decide to steal a car before the challenge begins as Past You and end up in jail, Future You has to get out of jail before they begin. You decide to place yourself in the middle of Antarctica right before the challenge starts? Future You has to make it out of Antarctica before they begin. If they die on the way out, the challenge wasn’t technically impossible – we made the conditions of the challenge more favourable to us before we started.

Future You’s prep time, no matter how long it is, can’t break the laws of physics either.
Let’s just navigate ourselves to a black hole light years away and start the challenge to say, get a diamond on Earth the instant before we fall over the event horizon.

The challenge is still possible – we aren’t doomed yet – but unless Future You learns how to travel at the speed of light in the millisecond between the time Past You starts the challenge and Future You passes the event horizon, we’re in the clear finally.

Ironically, the best answer to the question of how to beat your future self, is to end yourself. (￣ ￣|||)
Thanks for reading, and I’ll see you in the next one.