One of my pastimes is to consider impossible inventions. Mentally walking through the design, construction, and use of these inventions is a way to unpick a stuck brain.

I’ve annoyed many a coworker with the cliché question of whether they would choose to have a time machine or a cloning machine. Personally I’d take the time machine. Unless it’s of the Primer units. Now that China has banned time travel and scientists in Hong Kong have cemented this ban with scientific proof that time travel is impossible, a new folly is required.

Of late the subject has been magnetism. Let’s purposefully misunderstand science and imagine that you can reach into a magnet and take out the power to attract one class of object to another. Take that power and inject it into something—anything—and see how that works out for you. It’s like using the force, except less convenient. Glass of water out of reach and you want to grab it? Find another cup and magnetically attract the water glass over to you.

The problem is, in the world of magnetism opposites attract. If you separate the concept of magnetism from the pesky science that makes it work you have the burden of finding the negative with which to attract the positive.

So the question is, what’s the opposite of a sandwich?

Answers have included miso soup, empanadas, salad, hair gell, eye glasses, dancing, and “a sandwich painted in antimatter”. What I like about this question is that to produce an answer you must first choose an angle. If soup is the opposite of a sandwich, this implies that essential sandwichness is being solid. Hot chocolate might imply that a sandwich is solid and savory, therefore the opposite should be liquid and sweet. Answering “eye glasses”, on the other hand, implies that essential sandwichness is more basic and primarily about being edible, whereas glasses scarcely are. A sandwich painted in anti matter is another thing altogether: how would you make it? What would it look like? What would happen if the sandwich and the anti-sandwich collided?