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05/12/2008

For most religions, candles represent life in the living flame. As Christian Advent Candles burn for the 25 days until Christmas, I am reminded of another 25, forever linked to Christmas and also to science. In 1825 Michael Faraday became director of The Royal Institution in London and began the Faraday Christmas Lectures, still maintained to this day.

Faraday’s first Christmas Lecture topic was also his favourite, repeated at least 3 times in his life; “The Chemical History of a Candle”, so apt for Christmas. His book is now in print once again - probably no better Christmas present for a scientifically minded young person or perhaps more importantly, a modern science teacher?

Let me paraphrase the lectures as briefly as I can, to show the simplicity and richness in Faraday’s scientific method and its relevance in today’s scientific world.

A candle is made of a wax that usually contains paraffin, but which is clean and none staining. It has a wick which would burn up in a couple of minutes, but which in the wax candle, will last for hours? Why?

A match ignites the wick and immediately the wax just bellow starts to melt. Solid paraffin wax does not burn and neither does the liquid wax. However the liquid wax rises up the wick by capillary action. To test capillary action, stand a bunched up paper or cloth napkin in a saucer of water or wine and watch the liquid rise up the napkin. Let a towel hang over the edge of a bowl of water, with one end in the water. Quickly, the water travels up the towel, over the edge and forms a puddle outside the bowl.

Capillary action causes liquid wax to rise up the wick and vaporise as it gets hotter. Then at last it burns and sustains the candle flame. With inflammable liquids, it is the vapour that burns. In movies, when anyone sets light to leaking petrol, the flame hovers over the liquid fuel, but its heat creates more vapour and the flame gallops along the stream of fuel.

But wick, heat and inflammable vapour are not enough for the candle to burn. Place a glass over the candle and it goes out in seconds as the part of the air it needs for combustion - the Oxygen - is exhausted. The candle flame behaves like an invalid. They both need oxygen. Feed them pure oxygen and they are both invigorated. Without Oxygen nothing can burn. How do fire extinguishers work? They cut off the oxygen.

It is Oxygen that determines how the candle burns. Hot air rises and fresh air is drawn up the outside of the candle to replace it, keeping the outer surface of the candle cool. Under the flame, the heat produces a perfect bowl shaped pool of hot liquid wax at the top of the candle. But no Oxygen gets in and the flame sits above the liquid. The air which is 20% Oxygen, comes up the candle surface and bends into the flame, producing both the brightness and the characteristic shape of the flame. Place a card against one side of the candle, quite near the top and see how the flame is affected by receiving less rising oxygen.

But what happens to the paraffin wax vapour and oxygen as they burn? Hold a plate, upside down a few inches above a candle flame for a minute or so. A black spot of Carbon soot forms on the plate. Remove the plate and touch the spot with your finger - it is moist. The plate surface and the soot are wet. Where did the water come from?

Every time we burn fossil fuels, we are burning hydrocarbons. Oil, coal, gas, plastic, wood, paper, the food we eat (carbohydrate), and even ourselves, all contain Hydrogen, the element the Sun is made of, and Carbon.

Hydrocarbons with oxygen, burn vigorously. The smallest Hydrocarbon molecule is 4 very light Hydrogens with a single Carbon atom. Oxygen usually comes in groups of two atoms. Burn them and the Hydrocarbons split and they all get mixed up.

H H C H H

O O O O

when burned becomes

H-O-H, O-C-O, H-O-H

Two Oxygens each join to two Hydrogens to make two molecules of H₂O - Water.

The Carbon joins two Oxygens to form CO₂ which Faraday called Carbonic Acid.

Nothing is lost - Nothing is gained. But Energy is released as Heat - a classic Chemical Change, as explained in Dalton’s Atomic Theory. This simple experiment explains how life itself exists on Earth. Hydrogen on its own is so light it would disappear up into space. Burn Hydrogen with Oxygen and it can power rockets into space.

Locked together, Oxygen and Hydrogen form Water, the most vital substance on the planet. The moist parts of your body are Water. The solid stuff is mostly Carbon.

Dalton and Faraday wondered why, if burning things always produces CO₂ and H₂O, there is not a build up of H₂O and CO₂ in the atmosphere? They realised that plants reverse the process. Plants absorb water and die without it - large trees suck up water in huge quantities. But plants are not made of water. Plants are mostly Carbon.

CO₂ is half as heavy as air again. Hot CO₂ rises but soon cools and falls where the plants are waiting to gulp in all the CO₂ they can get. A Tree is 85% Carbon, which all comes from the atmosphere. But of all the plant life on earth, a massive 80% is in the Oceans, which must also absorb vast quantities of CO₂ to grow. The Carbon is fixed and becomes part of the plant, and the Oxygen is released back into the atmosphere, to maintain the balance.

Now man is capable of upsetting the balance, but with only 4% of all CO₂ being man made, the upset is amazingly slight and extra plant growth could more or less maintain the balance.

Today, there is a danger of science teaching being bogged down by fears of climate change and students being asked not so much to learn and enjoy science, as to spend the majority of science lesson time seeking ways to save the planet. This is all based on spurious fears of CO₂ being somehow dangerous, which I do not believe is true. CO₂ itself is not classed as a pollutant as it is as natural and vital as water. I am concerned that the damage to science teaching and to the future scientists we are producing could be immense if we continue to focus on this approach..

The 2008 Faraday Christmas lectures are to be presented by Prof Chris Bishop, who will take us on a hi-tech trek to explore the science behind the digital revolution in search of the ultimate computer. As with Faraday in 1825, the audience will be riveted and inspired by wonderful examples of man’s scientific ingenuity.

Merry Christmas.

Posted at 09:33 by Kevin Beckett | Category: Chemistry | Permalink | Email this Post | Comments (0)

04/11/2008

BEING SAT NAV SAVVY

Do you have a Sat Nav system in your car?

Now that everyone wants one, the price has dropped like a stone and they are incredibly cheap, especially when you consider just how clever the maths needs to be to make them work reliably. It was good old Galileo who worked out how cannon balls fly through the air and Johannes Kepler who worked out how planets move in ellipses around the Sun.

Then along came Isaac Newton who put the two ideas together and came up with Gravity and how that works.

Now, Newton’s maths is fine for building bridges and skyscrapers and working out how aircraft fly, but it just isn’t good enough to produce our Satellite systems. For that we needed Albert Einstein.

It was Albert and his relativity that threw a spanner in the works, relatively, when he said that a clock moving through space would move slower than a clock on earth.

Let me explain that, if I can. Light travels at 300,000 kilometres per second, which is very fast indeed. Einstein said, “If you look at a clock, you can see a second hand moving as it passes the time. What would happen, if while you were looking at the clock, you moved away on a beam of light? The clock would seem to stop moving and as far as you could see, it would be frozen in time. For you, on your beam of light, time would have stopped.”

We cannot travel at the speed of light but a satellite does travel at high speed and it is also travels some distance above the earth. So a GPS satellite’s clock does move slower --- and faster -- Ouch.

Well, clever old Albert came up with two separate theories of relativity. First Special Relativity and then General Relativity.

The GPS satellite system has 32 satellites at present of which between 8 and 10 are within sight of your Sat Nav at any one time. They travel in 6 different orbits, some 20,200 km above the earth at a speed of around 14,000 kph or about twice around the Earth in a day (only 1/77,000th the speed of light).

General Relativity says that a GPS satellite’s atomic clock will tick more rapidly by 46 microseconds (millionths) per day, because of its distance from earth and the weaker pull of gravity, whilst Special Relativity says that the same clock will tick slower by 7 microseconds a day because of its speed, compared to the speed of light. So altogether it is going 38 millionths of a second faster, per day.

To account for that, when it is launched, software onboard gives it an offset frequency of 10.22999999543 MHz instead of 10.23 MHz and that keeps it in perfect line with clocks on the surface of the earth.

This is just as well. You see, if the two clocks were out of sync by 1/1,000,000,000 of a second per day then your Sat Nav would be out by 1 ft or 30 cms, which is as accurate as it needs to be.

However, if the two clocks were out by 100 times that and still only 1/10,000,000th (One ten-millionth) of a second out, then your Sat Nav would be out by 100 ft or 30 metres, and you will be driving in your car with your relatives, on the wrong carriageway of the motorway.

You would also be going the wrong way, at which point, for you, time might suddenly and finally stop altogether, relatively.

Posted at 09:00 by Kevin Beckett | Permalink | Email this Post | Comments (2)

17/10/2008

FOLLOWING SCIENCE RELIGIOUSLY

If there is anything that has depressed me about science in recent years, it is the rise of the conflict between science and religion. There is nothing new in this situation. In fact, looking back through history is an excellent way of coming to terms with and tackling it in the classroom.

It has to be remembered that Darwin, like Copernicus, Galileo, Faraday and so many other great scientists, was a deeply religious and god fearing man. All of them followed science religiously, believing that a greater understanding of how the world works was a wonderful way of unravelling “God’s Onion” and of discovering just how miraculous the creation of the earth has been.

In around 1650, Blaise Pascal sorted out Odd and Probability. Pascal’s Triangle is an essential tool in teaching the maths of gambling or finance. When asked if he could calculate the odds that god existed, he said, “Although I cannot “prove” that god exists or that he doesn’t, it would be a supreme folly when I die, to arrive at the pearly gates and find that they wouldn’t let me in.” So he dropped mathematics and became devoutly religious for the rest of his life.

Most early scientists were deeply religious monks who felt that making scientific discoveries and building on the teachings of the bible was part of their job. The Venerable Bede who lived in County Durham, 673-735 introduced AD and BC, counting the years from the birth of Christ. He also saw that the moon caused the tides.

Much early science passed from religion to religion. The Hindus produced the decimal system and zero, which passed via Islam and Al Khwarizmi, to Christian Europe through Adelard of Bath and Fibonacci of Pisa. This, along with other Islamic ideas, brought Europe out of the dark ages into the Renaissance, the age of new learning.

Men of religion had strong scientific influence. Bishop Grossteste (no sniggering at the back, yes it does mean big balls) of Lincoln, suggested the universe may have started with a flash of light - the earliest Big Bang theory. His pupil, Friar Roger Bacon, spent 15 years in jail arguing that the church should adapt to new discoveries, even if they showed the bible to be wrong.

The greatest change came with the polish monk Copernicus (Copper Nickers when I was at school) who was part of the Popes team in the Vatican. The Greek idea of the Earth being the centre of the Universe didn’t tie in with the way the planets revolved. Surely God would not design something so complicated? At last he found that by placing the Sun at the centre, and making the earth just another planet revolving round it, it all fitted and was now simple to understand. His findings were published after his death and it was left to Galileo to try to prove the idea to the Pope.

One thing that really annoys me is the idea that the Pope and Galileo had a row. They didn’t. With his telescope everyone could see that the moon had mountains like the earth and was not a perfect sphere as suggested by the bible. Galileo knew the church couldn’t accept a theory that conflicted with the bible, so he went out of his way to find a middle ground, writing explanations that gave both points of view. However, someone suggested that Galileo was mocking the Pope and brought a charge of heresy. This set a problem. If Galileo was found “Not Guilty”, then the church (i.e. the Pope himself) would be guilty of heresy. So Galileo had to admit the charge. His punishment was as light as it could possibly be. He was placed under house arrest, but could choose where and which house he lived in - he moved three times before he died. Could it have been any more lenient?

Perhaps the finest example of Religion versus Science came from Isaac Newton who discovered Gravity and Joseph Priestley who discovered Oxygen. Both were Unitarians. In essence, as with all the religions, they believed in God, a grand creator. But they felt that all the religious ideas beyond that, have been designed and invented by normal men of the church, including the writings of the great religious works.

In today’s multi racial classrooms, surely their example is an ideal way of tackling the modern problems of religious differences. For many of us, religion is part of our family character, our roots and our upbringing. If people believe that there was a creator, and both science and our own daily observations surely suggest there had to be some guiding hand in producing life itself in all its glory, then perhaps a wonderful way to serve God, is to ignore our religious differences, and together through science, improve our understanding of how it all works?

Johnny Ball October 2008

The issue of science and religion arises in many triple science topics, particularly around areas such as The Big Bang, Evolution and Genetics. What are your views about discussing religious beliefs in science lessons? Please let us know

Posted at 11:03 by Kevin Beckett | Permalink | Email this Post | Comments (1)

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