Mathematics. The 52 cards in a playing card deck can be arranged in many ways! 52! = 80,658,175,170,943,878,571,660,636,856,403,766,975,289,505,440,883,277,824,000,000,000,000 is so unimaginably large that it dwarfs almost every large number encountered in everyday science. ⊕ If you shuffle a deck thoroughly, the exact order you create has almost certainly never existed before in the entire history of the universe. It is also overwhelmingly unlikely that anyone will ever produce that same order again. ⊕ There are far more possible deck arrangements than there are stars in the observable universe. ⊕ There are vastly more possible deck arrangements than there are grains of sand on Earth. ⊕ Imagine placing one unique deck arrangement on every atom in Earth. You would run out of atoms almost immediately. Even if you assigned one arrangement to every atom in the observable universe (about 10^80 atoms), you'd still be using only an infinitesimal fraction of the possibilities. ⊕ Suppose a trillion (10^12) people each shuffled a deck one billion times every second, and they continued for the entire 13.8-billion-year age of the universe. Together they would still have explored only an utterly negligible fraction of all possible arrangements. ⊕ If every possible arrangement were printed as a single page in a gigantic book, the book would be so enormous that no conceivable physical library could contain it. ⊕ The odds of guessing a particular shuffled deck are approximately the same as picking one specific atom from a collection containing many trillions of observable universes' worth of atoms.