• Question: what substance emits the greatest amount of light?

    Asked by to Daren, Lynne, Phillip, Simon on 18 Jun 2014. This question was also asked by .
    • Photo: Lynne Thomas

      Lynne Thomas answered on 18 Jun 2014:

      This depends on what you mean by giving out light. The sun is one of the brightest things that affects us on earth – that is because it is very hot and so a process called nuclear fusion causes the hydrogen to turn into helium. This gives out a lot of heat and light as a consequence.

      On earth, we make high powered light sources called lasers. These contain some clever optics but also use crystals of different compounds depending on the colour that you want and how strong you want the light to be. Often a lanthanide element like Neodymium is put into a crystal of another compound like yttrium lithium fluoride (Nd:YLF) and yttrium aluminium farnet (Nd:YAG) in very small amounts and this is what allows the light to be generated. But there are loads of other types of crystal that can do this too. We can make lasers that are powerful enough that if you got in their way, they could burn right through you!

    • Photo: Simon Redfern

      Simon Redfern answered on 18 Jun 2014:

      Following on from Lynne’s answer, there is a new kind of experiment called an X-ray free electron laser that produces a huge but very short burst of light that can be used to find out where atoms are in solids, liquids and gases, and how they are arranged with respect to each other. There is one working in California at the moment, and another one that is being built in Hamburg in Germany and which European scientists will be able to use. It is very exciting because it opens up a whole new way of looking at the world around us with much brighter light than we have had before. More about it here http://www.xfel.eu/

    • Photo: anon

      anon answered on 18 Jun 2014:

      The big bang as the biggest light ever – you can still see traces of it if you look deep enough into the universe!

    • Photo: Daren Fearon

      Daren Fearon answered on 18 Jun 2014:

      Lynne, Simon and Jenny have all given great answers for this but did you know Diamond Light Source produces light that is 10 billion times brighter than the sun!

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