Science: technoquest

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Q Why do blades in razors, which are many times harder than the materials they are designed to cut, become blunt? (Asked by schjm@unesco.org)

The fact that steel is much stronger than hair is largely irrelevant; water is much "softer" than rock, yet most of the Earth's surface has been moulded by the action of water. A blade is thin. The thinner the blade and the more regular the edge, the sharper the cut and the more often it has to be sharpened to maintain that sharpness. As the blade passes over the stubble on a person's chin, the hair knocks off individual atoms from the edge of the steel blade. As there are many thousands of hairs, it doesn't take long to dull the blade slightly. When we consider a blade to be dull, it has not really lost that much of its edge. Even if each hair only removes one atom, the blade can be dulled quickly.

Q Why does it always take longer to fly from east to west than from west to east? (Asked by Balraj Gill)

Because of the wind. Winds in the upper atmosphere always flow from west to east. If you are flying from east to west, you have to fly against the prevailing wind, which means the journey takes longer.

Q Why do plants such as hyacinths have such a strong scent? Is it because they are catering for dopey insects?

In wild flowers, scent is intended to attract pollinators. When plant selectors and breeders get involved, as with most or all of the garden forms, then colour, or scent, or shape, or doubleness of flowers often predominates. Scent sometimes "suffers" with selection for other features, and then they try to bring strong scent back. The chemicals themselves in scent may not be attractive to us - some flowers attract flies for pollination, and some of those smell of rotting flesh or halitosis.

Q The period of rotation of our Moon about its axis (its day) is the same as its rotation about the Earth (its year). Is that a coincidence, or is there some reason for it? (Asked by Dennis Leachman)

The two rotational rates are not a coincidence. The Moon is locked in what is known as a "synchronous rotation". The Earth raises body tides on the Moon - basically, it stretches it - which are about 20 times greater than body tides on the Earth. The enormous energy dissipation that results has slowed the rotation of the Moon, resulting in an equilibrium, where the Moon's rotation (27 days) is the same as the time it takes to revolve around the Earth. It is not unusual to see synchronous rotation in the solar system; some of the satellites of the outer planets (Jupiter, Saturn Uranus and Neptune) have become trapped in synchronous orbits.

Q Has life been created in the laboratory? That is, has anyone made a primordial soup in a lab, sent a spark through it and ended up with life? (Asked by Peter Marchese)

It has proven possible to produce some of the very basic units of life from basic elements. But to get those into the correct form and to produce the complex chemicals for life would be extremely difficult. It is very hard to produce the long stretches of DNA necessary even to code for the most basic of creatures. DNA has evolved to be copied; producing it from scratch is more difficult. Even if you do make the DNA, you then have to make all the proteins which form the DNA into chromosomes, and then all of the enzymes, nucleic acids, fats and carbohydrates which make up the cell. Then those chemicals have to be built into the structures that form the cell. Although it may be theoretically possible, the technology to be able to do it in the lab still evades us. There have been billions of years of evolution to make the creation of organisms possible. To try to replicate that in the lab is extremely inefficient. It's much easier to do it naturally.

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