|MadSci Network: Physics|
In quantum mechanics, there is an uncertainty principle between energy and time -- the briefer the time span, the more uncertain the energy is for that span. Longer time spans allow for a more accurate energy measurement. Sometimes popular science accounts imply that this uncertainty means that energy is not conserved on very short time scales. This is incorrect; quantum mechanics still implies energy conservation.
If future experiments at the Large Hadron Collider (LHC) find that energy is not conserved during a high-energy particle interaction, physicists will not throw out conservation of energy as a fundamental principle. It is too well established, on both experimental and theoretical grounds. Instead, physicists would probably use those results to infer that some energy has gone somewhere else, where we cannot measure it. (Perhaps into Hidden Dimensions!)
Try the links in the MadSci Library for more information on Physics.