Assassin's water bottle - expert

PRE-ORDER only – Assassin's Water Bottles will be delivered in Q2 of 2025. 

The official assassin's water bottle with poison measurements AND Schrodinger's cat bottle

• Assassin’s water bottle
• Schrödinger’s cat water bottle
• Knight’s Tour sleeve
• Asteroids sleeve
• Braids sleeve
• Steve Mould mini poster
• Michael Stevens mini poster
• Unique P3M1 logo sleeve

The official Assassin’s bottle with poison measurements:

What is a poison? LD50 is an acronym for "median lethal dose" and refers to the amount of a substance that is lethal to half of a group of test animals. The Assassin's water bottle provides a series of measurements with approximate LD50s of francium, the Brazilian wandering spider venom, antifreeze, mercury, and orange juice (yes, too much of anything is a bad thing). The LD50s are based on Steve Mould’s body weight and translate into how many Micro (10^-6), Kilo (10^3) or Mega (10^6) Steves it can kill. Each side can hold up to 450ml of liquid, with a combined volume of 900ml.

Schrödinger’s cat water bottle:

You must not use the Assassin’s water bottle to store poison, despite what the name might suggest. If you did, one side of the bottle would be deadly while the other would not. The fate of the person or animal drinking from the bottle would depend on the unobserved actions of the pourer. Which is reminiscent of some thought experiment involving a cat. This bottle incorporates a cat head design which is half white, and half black - half dead, and half alive. It also has the Steve Mould, Vsauce and Curiosity Box logos.  Each side can hold up to 450ml of liquid, with a combined volume of 900ml. 

When demonstrating the magic trick we recommend you cover the bottle with a sleeve to hide the two compartments. Steve has unique stories for each sleeve:

Knight’s Tour sleeve:

If you place a knight on an empty chess board, it’s possible to visit every square on the board exactly once and end up back where you started, only making legal knight moves. That’s called a knight's tour. It works for an 8x8 grid of squares but it’s not guaranteed for other sizes of board. Specifically, if the board is an odd number of squares wide and an odd number of squares tall, it can’t be done. UNLESS you curl the board into a cylinder and allow the knight to make moves that jump across the seam. In other words, in a cylindrical universe the knight’s tour is possible even on an odd x odd board. Sometimes. This sleeve shows a solution for an 11x9 board.

Asteroids sleeve:

In the classic arcade game Asteroids, when you fly off the left edge of the screen you reappear from the right. In other words, the Asteroids universe is topologically equivalent to a cylinder. So we put it on one.  “But hold on,” I hear some of you say, “if you fly off the bottom, you reappear from the top, so the Asteroids universe is a torus.” That’s true but where would I have put the spout on a doughnut shaped water bottle?  Can you figure out why the score is 852655?  

Braids sleeve:

Alexander's Theorem states that all knots can be represented as a closed braid. In other words, any knot, in the mathematical sense, can be arranged into a ring of intertwined threads with no thread reversing direction around the ring. What a beautiful thing to embed on a cylinder!  The first knot, drawn in white, isn’t really a knot at all, it’s the unknot: just a loop of string.  The coloured knots represent all possible knots up to a crossing number of 3 (knots 3₁, 4₁, 5₁, 5₂, 6₁, 6₂, 6₃ in Alexander–Briggs notation). The last knot in black doesn’t fit the sequence. It’s the 9₄₆ knot, and it’s included on this sleeve because it is my favorite! See if you can spot it in my Elastic Knots video.

The P3M1 logo sleeve:

There are only 17 different wallpapers. Which is to say, there are only 17 planar symmetry groups. My favorite is called the p3m1 group, which is almost what is shown on the logo sleeve. If all the logos were the same, it would be p3m1. But by sharing the logos between me and Michael, I have broken that symmetry. Which is what good artists do. I’m not sure what the symmetry group is now.

Steve Mould and Michael Stevens mini posters:

At expert level you also get mini versions of the engineering prints showing how the bottle works. Size: 8.27 inches by 11.67 inches (A4) each and unsigned.