The Science of Discworld Revised Edition

problem?’
    ‘Aren’t they going to crash into this world?’
    Rincewind heard the muted sounds of debate in the background, and then Ponder said: ‘The Archchancellor says snowballs don’t hurt.’
    ‘Oh. Good.’
    ‘We’re going to move you on a few million years now. Ready?’
    ‘Millions and millions of years of dullness,’ said the Senior Wrangler.
    ‘There are more blobs today,’ said Ponder.
    ‘Oh, good. We
need
more blobs.’
    There was a yell from Rincewind. The wizards rushed to the omniscope.
    ‘Good heavens,’ said the Dean. ‘Is that a higher lifeform?’
    ‘I
think
,’ said Ponder, ‘that seat cushions have inherited the world.’
    They lay in the warm shallow water. They were dark green. They were reassuringly dull.
    But the
other
things weren’t.
    Blobs drifted over the sea like giant eyeballs, black, purple, and green. The water itself was covered with them. A scum of them rolled in the surf. The aerial ones bobbed only a few inches above the waves, thick as fog, overshadowing one another in their fight for height.
    ‘Have you
ever
seen anything like that?’ said the Senior Wranger.
    ‘Not legally,’ said the Dean. A blob burst. Audio reception on the omniscope was not good, but the sound was, in short,
phut
. The stricken thing disappeared into the sea, and the floating blobs closed in over it.
    ‘Get Rincewind to try to communicate with them,’ said Ridcully.
    ‘What have blobs got to talk about, sir?’ said Ponder. ‘Besides, they’re not making any noise. I don’t think
phut
counts.’
    ‘They’re various colours,’ said the Lecturer in Recent Runes. ‘Perhaps they communicate by changing colour? Like those sea creatures –’ He snapped his fingers as an aid to memory.
    ‘Lobsters?’ the Dean supplied.
    ‘Really?’ said the Senior Wrangler. ‘I didn’t know they did that.’
    ‘Oh yes,’ said Ridcully. ‘Red means “help!”’ 1
    ‘No, I think the Lecturer in Recent Runes is referring to squid,’ said Ponder, who knew that this sort of thing could go on for a long time. He added hurriedly, ‘I’ll tell Rincewind to give it a try.’
    Rincewind, apparently knee deep in blobs, said: ‘What do you mean?’
    ‘Well … could you get embarrassed, perhaps?’
    ‘No, but I’m getting angry!’
    ‘That might work, if you get red enough. They’ll think you want help.’
    ‘Do you know there’s something else here besides blobs?’
    Some of the blobs trailed strands in the faint breeze blowing across the beach. When they tangled up on a blob gasbag, which put some stress on the line, the little blob on the end let go its grip on a rock, the line gradually shortened, and the gasbag bobbed onwards with its new passenger.
    Rincewind saw them on a number of blobs. The blobs did not look healthy.
    ‘Predators,’ Ponder told him.
    ‘I’m on a beach with
predators
?’
    ‘If it really worries you, try not to look blobby. We’ll keep an eye on them. Er … the Faculty is of the opinion that intelligence is most likely to arise in creatures that eat lots of things.’
    ‘Why?’
    ‘Probably because
they
eat lots of things. We’ll try a few big jumps in time, all right?’
    ‘I suppose so.’
    The world flickered …
    ‘Blobs.’
    … flickered …
    ‘The sea’s a lot further away. There’s a few floating blobs. More black blobs this time.’
    … flickered …
    ‘Well out at sea, great rafts of purple blobs, some blobs in the air …’
    … flickered …
    ‘
Great steaming piles of onions!
’
    ‘What?’ said Ponder.
    ‘I knew it! I just
knew
it! This whole damn place was just lulling me into a false sense of security!’
    ‘
What’s happening?
’
    ‘It’s a snowball. The whole world’s a giant snowball!’
    1 Wizards seldom bothered to look things up if they could reach an answer by bickering at cross-purposes.

TWENTY-EIGHT
THE ICEBERG COMETH

    THE EARTH HAS been a giant snowball on many occasions. It was a snowball 2.7 billion years ago, 2.2 billion years ago, and 2 billion years ago. It was a really cold snowball 700 million years ago, and this was followed by a series of global cold snaps that lasted until 600 million years ago. It reverted to snowball mode 300 million years ago, and has been that way on and off for most of the last 50 million years. Ice has played a significant part in the story of life. Just
how
significant a part, we are now beginning to appreciate.
    We first began to realize this when we found evidence of