> There is only one combination of sand particles that looks like your sand castle This is very wrong. Each grain of sand is interchangeable for a start, and y

> There is only one combination of sand particles that looks like your sand castle This is very wrong. Each grain of sand is interchangeable for a start, and you can change the sandcastle in an infinite number of ways that would be imperceptible to an onlooker. Same with the puzzle example.