Is the expression Biblical in origin? Abbreviated? Scientific? I have seen all three forms of this one written, and I could almost see a logical argument for each version; however, only one is correct.
To clear up the confusion, “up and at ‘em” is the proper form, as in “up and at them.” The colloquial idiom means, in essence, “it’s time to get moving.” It has nothing to do with Adam’s existence in or out of Eden, and it has nothing to do with quantum physics.
Exactly how long the expression has been used is unclear, but records show its usage at least as far back as letters by Katharine Mansfield (1919) and beyond that by a general at the Battle of Waterloo (1815).
When you say it, you don’t have to know the spelling, but when you write it, precision is essential. Unless you’re going for a witty pun (The Up and Atom Chemistry Department Softball Team?), it’s time to get “up and at ‘em” right.