What does 100% efficiency mean? Does that mean that for some power delivered to the LED load there is a (near) 100% efficient conversion to visible light ("photons")? Would that mean the LEDs operate with practically no heat generation?
And yet you won't find any shortage of people who will call you a terrible, terrible naysaying pessimist if you dare to voice the prediction that an efficiency jump like from incandescents to CFL or from CFL to LED won't ever happen on top of state of the art LED.
You're probably thinking of heat engines. Extracting 100% efficiency from a heat source is impossible. That doesn't mean that near-100% of non-heat energy can't be converted to another energy type. Eg resistors pretty much convert electricity to heat at a 100% "efficiency" rate..
Please explain how this is. It seems like something could convert all energy to light without generating heat and while conserving total energy & mass...
Well, the law they're referring to states that rather than just conserving energy and mass you also can't have a process that lowers entropy. Although it's unclear how this is relevant because, if anything, converting kinetic energy to light increases entropy, or at the very least doesn't decrease it.
