FRED AN­SWERS YOUR QUES­TIONS

Australian Geographic - - Geobuzz -

We are told the Uni­verse be­gan as an incandescent gas ball that cooled dur­ing mil­lions of years to form gal­ax­ies, and so on. Where was this heat dis­si­pated? Not in space, because we know it is empty.

Jeff Lewry, Bowna, NSW

The Big Bang’s heat must still be around, physi­cist Ge­orge Gamow first noted decades ago. Ob­ser­va­tions of the Cos­mic Mi­crowave Back­ground Ra­di­a­tion, which per­me­ates the Uni­verse, bear that out to­day. We in­ter­pret this as the Big Bang’s flash, seen at a look-back time of 13.8 bil­lion years and stretched into mi­crowaves by the Uni­verse’s ex­pan­sion. Far from being empty, space is full of pho­tons of ra­di­a­tion, 99 per cent of which orig­i­nated in the Big Bang. The rest is mostly starlight.

If you have a space ques­tion for Fred, email it to edi­to­rial@aus­geo.com.au

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