Spells

I know that we have some pagans on this board, but I don't know if you guys are in the habit of casting spells or not (I really don't know much about Wicca or any other pagan type belief). Anyhow, this question is directed to anyone who happens to feel like discussing it.

So has anyone ever cast a spell on someone or attempted to cast one? Did you actively wish someone harm when you cast it? Or was it more like a prayer that they just get what they deserved, whatever that might turn out to be? Does anyone believe that an individual has the ability to influence the cosmos by casting a spell? What about the karmic repercussions on the spell caster? My philosophy has always been that what we send out usually comes back to us sooner or later in one form or another.

Personally, I don't believe in spells, but last night I was talking to a man who has a degree in physics and he told me that he has met people who are actually able to cast very nasty spells on other folks. He also said it always seem to catch up with the spell caster, ultimately. I was surprised that such a rational person could believe in such an irrational thing as magic. He started to explain it in terms of string theory and I got lost.

Thoughts, anyone?