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.well to be fair LED based lights, while still not anywhere near 100%, are many many orders of magnitude more efficient.
In physics light refers to electromagnetic radiation of any wavelength. While it is typical for people to think of light as just the part we see the truth is infrared, down to near-dc and ultraviolet on up to gamma rays and beyond is all light.
Heat , or in this case since its radiated heat we really mean "heat transfer" takes three forms, well technically 4 but the fourth one is kinda obvious and i wouldnt say really counts.. those are
Convection : the flow of a gas or fluid, such as hot air rising, that causes the heat to move along with the medium that is moving that contains it.
Conduction: The movement of heat through direct physical contact. For example if you hold onto a metal rod and heat one end eventually the end your holding will also get too hot to hold.
Advection: this one is a cheat, lets ignore it, but its where you pick up something hot and put it somewhere else.
Radiation: This this is where an object gives off its heat as Infrared light. If you sit in front of a camp fire on a cold day and feel its warmth, the vast majority of that warmth is from the IR light of the fire.
Now we are ignoring advection for the obvious reasons. As for convection, well the inside of a lightbulb is a vacuum, so there is no air to allow for convection of heat off of the filament (where the heat is being generated). Conduction makes a little bit of sense as there is a physical path from the filimat to the base of the light bulb. But because it is a very thin long metal wire that has very little contact with the filament the effects of this are negligable.
That leaves us with just radiation... Therefore when we talk about a light bulb then any heat it produces, is heat in the form of light. So saying most of the energy goes to heat and not light isnt correct, heat **is** light. but you would be correct if you said that the portion of light given off as heat is not **visible** light :)
No problem, it is a common mistake. Its just it if we take light to mean only visible light (as is sometimes the case) the entire logic breaks down, as you already pointed out :) So glad we could set that back on track.
@ravenclaw
Honestly, i'd imagine quite a few people at spacex would use the term "light" to specifically and exclusively mean visible light, at least in casual conversation.
Typically one needs to infer if they use light to mean visible light or all light.
So its really not a hard mistake to make and can just as easily say its my own fault for not being more explicit, even if the technical definition of light is not just the visible spectrum.
@Science