Stardate Friday 20th April 2006 Issue 179

Crack kids science TV producer Jonathan Sanderson is back with a vital issue of the day. Pom-poms.

We've all made them, spending hour after tedious hour winding wool around flimsy bits of cardboard. It all seems like such fun when we're lured into starting, but five days later, as you're still winding away, frankly... the fun has worn off, hasn't it?

What if we said that you can make a pom-pom in about twenty seconds?  Not days. Not hours. Not minutes. Seconds. Wouldn't that be something?

No? Well, read on anyway.

What you need:

• A ball of wool.
• Big scissors.
• Somebody to work the big scissors for you, if you're not very good with them. Besides, you get to make the adults do the work for a change.

What you do:

1. Think about how you'd normally make a pom-pom: first, you'd cut two cardboard rings. Then you'd take a ball of wool, unravel it, and wind it around the rings. And keep going. And keep going. And keep... you remember that part, right?
2. But hang on a moment. That starts from wound-up wool (the ball of wool), and ends up as... wound-up wool (the pom-pom)! The arrangement of the wool hasn't changed at all! The only bits that count are tying the pom-pom off in the middle, and snipping the wound-up bits. The cardboard rings are a red herring too.
3. So all you really need to do is tie a really tight loop of wool around the middle of the ball, and then chop the top and bottom off.  If you try that with a small ball of wool it'll work perfectly well.
4. If your wool ball is larger, it'll be hard to tie the loop tight enough. The best thing to do is dig your thumbs right through the middle of the ball of wool so you start splitting it in half. Tie both sides off, chop off the top and bottom, and you'll have two pom-poms in a jiffy.

What's going on:

We worked this out while making The Big Bang for CITV a couple of years ago. We needed a dustbin full of pom-poms for something, and as we sat making yet another bunch, we started talking about quantum physics. If anything's going to make pom-poms exciting, it's quantum physics.

But the thing about quantum physics is this: several parts of the theory involve symmetries, sets of operations on microscopic particles that, taken together, leave the particle exactly how it started. Slowly it dawned on us that what we were doing to the wool was the same sort of set of operations - that is, we were spending hours achieving precisely nothing.

That's when we started applying the same sort of thinking to the wool, and realised that unravelling it was a complete waste of time, since we were only going to ravel it back up again over the next few hours.

Spotting patterns and similarities like this is, I think, one of the ways that science leaps forwards. It's only a shame that we had a breakthrough about... pom-poms.

While it’s always good to celebrate the achievements of science, it’s also interesting to reflect on the way that sometimes even the greatest minds have barked up the wrong tree. Ian Francis has been investigating a few of these wrongest of wrong ideas – and this week his subject is that old chestnut, the age of the Earth...

You’re How Old?

“It might be rude to ask someone’s age, but they don’t have to tell you. Should they keep schtum, you can always estimate and you’d probably be correct plus or minus up to 10 years.

Planet Earth has similarly tantalised scientists by refusing to directly reveal its age – but the history of our estimates of its age until recently produced figures that just kept on falling way, way short.

Earliest ideas about the age of the Earth were rooted in religious belief, and depending on your religion, could date the Earth from a few million years old to as young as a few thousand.

Geologists later tinkered with figures based on the number of layers of rock in a formation and an estimate of how long each layer took to be formed. These suggested a more ancient Earth than suggested by creation stories, but exactly just how ancient, they couldn’t say.

Then in 1862 the famous Lord Kelvin (a.k.a. William Thomson) weighed in, using ideas about heat transfer to estimate an age for Earth. He assumed it started off as a molten blob of rock and cooled steadily over the ages to its present temperature. He dated Earth to between 20 and 400 million years- an old Earth for sure, but an age that displeased biologists as it wasn’t a long enough timespan for natural selection to work its evolutionary magic. Like the biologists, geologists also reckoned this too young, but couldn’t say why or prove conclusively a more aged planet.

Another scientist (John Joly) came up with an estimate based on how salty the oceans were and how quickly erosion from the land dumped salt into rivers. Other scientists used astronomical techniques that also suggested an age like Joly’s of around 100 million years, so Kelvin’s figures looked reasonable in that light. But maybe they were too keen to side with the great man…

The discovery of radioactivity in 1896 killed off the idea of a ‘youthful’ 100 million year old Earth. This was a heat generating process that trashed assumptions made in Kelvin’s calculationsand wound the clock back to the presently accepted age of around 4.6 billion years …

For more info on how the Earth’s age is determined nowadays check out this site.

			Revision Decision Ian Francis rides again, as our in-house science teacher has been back on his cyber surfboard to find you another top-notch revision website... "Sciencepages began life as the humble online home of a school science department, but now offers its goodies to a wider audience. Despite the name, it's mostly chemistry on offer to the revising masses at GCSE, (although to be fair, there's also a little stuff for the key stage 3 National Tests as well as A level). It gets recommended by me today because of the neat selection of quizzes. These comprise 40 to 50 or so quick questions with model answers popping up at the click of your mouse. If you go 'eh?' when you see the answer it probably means you need to put extra time into revising that topic! As a bonus, it also features a smattering of revision notes, crosswords, a few PowerPoints, a nifty checklist to see what mark you're likely to get for your coursework, and a wee links list pointing you to some of the weirder websites out there."

			Squashed Frogs Here's another good site for teachers - recommended to us by Olga Papadopoulos. http://www.squashedfrogs.co.uk/ As Olga says, "It has lots of resources for lessons (filed according to Key Stage and then topic) including powerpoints, worksheets, games etc. It covers KS3-5 in all areas. It also lists lots of links to useful websites." And she didn't even mention the downloadable 'Element Bingo' cards or the Colouring In Factsheets for Light and Sound.  There really is a treasure trove of good stuff on this site - have a look Thanks for the tip, Olga!