• Question: what is light

    Asked by eringracecooke to Christina, Jess on 28 Jun 2013.
    • Photo: Jess Bean

      Jess Bean answered on 28 Jun 2013:


      Scientists at the moment argue that light from the sun is both a wave and a particle at the same time!

      Light waves are what we think of as normal ‘sunbeams’ that are what causes rainbows and what means we can see. It is light waves that reflect off things into our eyes that let us see things, as well as colours.

      Scientists a few 100 years ago realised that when they did experiments, light sometimes acted as if it was a solid thing. As in you could count the ‘particles’ of light in a beam of light. It is released from the sun in tiny chunks of energy called ‘photons’.

    • Photo: Christina Pagel

      Christina Pagel answered on 28 Jun 2013:


      The study of quantum physics (or quantum mechanics) all boils down the study of light as a particle AND a wave and how light interacts with atoms (mainly through electrons). Light seems to be one of the most fundamental things in the universe and we grow up taking it for granted… it carries energy from one part of the universe to the other, it’s closely bound up with electromagnetism, it’s the only thing whose speed looks the same whatever speed you’re going at….

      I think that whatever light is, it’s not something we can describe using language but we can describe it in equations… but even those equations only really tell you what light *does* – ie how it interacts with things and the effect it has on things – and not what it *isMATOMO_URL

      So when describing what those equations mean so we are forced to say things like “it’s both a wave and a particle” because under certain conditions it behaves like it’s one or the other (and we know what waves and particles *are* and not just what they *do*). And sometimes light just behaves as if it’s both a particle and wave at the same time (and we have no idea what that *is*)!

      If that all sounds very confusing then don’t worry – it is confusing! and it confuses everyone. Richard Feynman (one of our greatest physicists ever who studied quantum theory and light) once said “If you think you understand quantum mechanics, you don’t understand quantum mechanics”…

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