so far we've looked at conduction and convection and both of these methods need particles to transfer heat but heat manages to get to us from the Sun and there's definitely no particles in space it's a vacuum so how does the heat from the Sun get to us well it travels as radiation infrared radiation or heat radiation to be precise so let's look more at this process of heat transfer of radiation we actually find that different colors are better at emitting heat than others now all hot objects emit heat radiation and this is a physics term of hot what it essentially means is any object above 0° Kelvin or - 273° c that's what US physicists mean by hot so anything above that emits heat however it will also be absorbing heat radiation and it's only if it's hotter than surroundings that it's actually going to be emitting heat overall so let's add some boiling water to this Cube to make it hotter than the surroundings and let's see what happens first let's look at the shiny silvery side we can see that's really rubbish at emitting radiation there's hardly any waves coming out of there at all if we then turn to the white shiny side we see that's only marginally better still pretty rubbish at emitting radiation the matte white side slightly better but still pretty rubbish let's go round to the shiny black side and we see all of a sudden that is emitting a fair bit of heat now but now if we turn around again and we see the matte black side we can see that is going like crazy that is emitting loads of heat radiation and we can see from this that matte black is the best color at emitting heat radiation so what color is going to be best at absorbing heat radiation we've seen that matte black is definitely the best emitter what color is going to be the best absorber so it's a really easy experiment for this we have a nice heat Source in this form of a fire and we can stick using just some wax to marbles onto a couple of plates one plate with a shiny surface and one plate with a matte black surface so whichever surface absorbs the most heat radiation is going to melt the wax the fastest and therefore the marble will drop quickest so which one do you think it'll be well let's look and see what happens well first off I can notice that the shiny silvery surface is reflecting away all of the radiation the matte black surface seems to be absorbing all that radiation so I'm going on the oh there we go the matte black fell off way in advance of the shiny silvery one the shiny silvery one's still pretty stuck on there and we can see why it's because matte black is absorbing all that radiation shiny silvery is reflecting it so what's the key information for us to have here well when heat needs to transfer across a vacuum the only way it can do it is by radiation we've also seen that Matt Black is the best absorber and emitter of radiation and that's why if we want something to heat up really really quickly or something to cool down really really quickly we color it matte black we also saw that shiny silvery surfaces were the worst at both absorbing and emitting radiation and that's why if we want something to stay hot or if we want something to stay cold we use a shiny silvery surface