Woah… that’s a philosophical one 🙂 ! There are lot’s of examples of how energy can’t be created or destroyed… like this:
Or in my research, fusion… we convert mass into energy using Einstein’s E=mc^2 formula. Also, in supernovas (when stars die) you can get energy converted back into mass!
But why is a much harder question. There are some really tricky theorems about this (e.g. http://en.wikipedia.org/wiki/Noether%27s_theorem). It’s to do with the ‘symmetry of time’ which means that the laws of physics do not change with time… and somehow that implies the conservation of energy!
Nice question! 🙂 Sorry I can’t give a clearer answer.
What chaos if it could be …… all our laws of physics would be overturned and nothing would remain the same from one day to the next. Not sure I’d like this kind of world……although if energy is related to mass we would never run out of fuel, food would be sufficient for all, and we’d have the best cure to obesity ever!! Hmmm 😉
Great answer for Jack 🙂 I would add that our main purpose is to be able to ensure that we can reuse some of the energy rather that just wasting the valuable resources we have. It is amazing to know that all types of energy get transferred and gets to go on a journey from one form to another … wish I could do that! Okey, maybe not since I don’t want to be either nuclear or heat 🙂