Several paranormal and supernatural series have “shifters” now, humans that can turn into other creatures, animals or otherwise. Unlike weres – werewolves, werecats and werecoyotes that can only shift into one form and often are affected by moon phases – shifters can take on multiple forms.

My question, however is this: conservation of mass. To make this example simple, the modern Avengers Hulk (“Son, you gotta condition”) doesn’t make sense whereas the old Bill Bixby and Lou Ferrigno tv “Hulk” did. Why? Because you can imagine something getting a little bigger, but where does the mass of something ten times larger come from? How is all that energy stored, and where does it go when it isn’t in use?

Both “True Blood” and the Twilight movies make use of shifters. In Twilight, the wolves appear four times larger than their human counterparts. In “True Blood,” Sam can shift into a fly! Where does 160 pounds (wringing wet) disappear to unless that’s going to be a HUGE fly? Just as incredible is Sam’s ability to find jeans that fit him perfectly every time he shifts back to human form no matter where he is, but I digress.

So, does it strain credibility when a character shifts shape into a creature too large or too small to be believable? Yes, its magic or mysticism or whatever, but does it help suspend disbelief when the shifting is done into something of approximately the same size and perhaps relative shape?