6 Things you may not know about the afterglow of the big bang

The ‘afterglow of creation’ – commonly known as the cosmic background radiation – is the left-over heat from the fireball of the big bang in which the Universe was born 13.7 billion years ago.

It provides a unique insight into our Universe’s infancy - a ‘baby photo’ described somewhat dramatically by Stephen Hawking as 'the discovery of the century, if not of all time' and by experimentalist and Nobel Prize winner George Smoot as ‘like seeing the face of God’. Here are a few more little known facts about the cosmic background radiation.

1. It's the oldest fossil in creation

It comes from a time just 380,000 years after the Universe burst into being.

2. It’s the coldest thing in the Universe

It is has been cooled by the expansion of the Universe to just 2.725 degree above absolute zero – the lowest possible temperature – so it appears not as visible light but stretched out into short-wavelength radio waves, principally microwaves.

3. It carries with it a ‘baby photo’ of the Universe

The splotches on the ‘photo’ show the locations where the smooth stuff of the big bang fireball is for the first time beginning to curdle into clusters of galaxies.

4. It accounts for 99.9 % of all the particles of light, or photons, in the Universe

Remarkably, only 0.1 per cent is tied up in the light from the stars and nebulae and galaxies. If you were in space with ‘magic glasses’ that showed microwaves, you would see the whole of the Universe glowing brightly with the big bang afterglow just as if you were inside a light bulb.


5. It's in the air around you - even in the room where you are now

It had absolutely nowhere to go since it was bottled up in the Universe, and the Universe, by definition, is all there is. Every cubic centimetre of space is currently being traversed by 300 photons from the big bang. Tune your TV between the stations and about 1% of the static on the screen is from the big bang fireball.


6. Its discoverers mistook it for the microwave ‘glow’ of pigeon droppings (yet still carried off the Nobel prize)

When radio astronomers Arno Penzias and Robert Wilson first spotted an unusual microwave signal by chance in 1965, they blamed it on birds. Pigeons were nesting inside their giant microwave horn at Bell Labs in New Jersey and had covered the interior with a “white dielectric material” (pigeon poo to you and me!).


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To find out more, read Afterglow of Creation by Marcus Chown (Faber & Faber, 2010).

A 'science for dummies' take on creation’ - The Times, 16 January;

‘The wonderful intro alone is worth the cover price. Witty and accessible science’ - Scott Pack (former chief buyer Waterstone's), meanmybigmouth blog, 10 February.

Also see www.marcuschown.com

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