Science: Technoquest

Q Is it possible to say how fast our galaxy is moving through the universe?

Yes, by measuring the apparent Doppler shift of the microwave background radiation - leftover "noise" from the Big Bang. Since that radiation is not moving, and we are, we can measure the motion of the Milky Way rather accurately. The current best number is that we are moving at about 600 km per second in a direction away from the constellation Cygnus.

An interesting, unsolved question is, if we are moving, what is pulling us? Astronomers say it is the "Great Attractor" - believed to be just a local imbalance in the galaxy distribution, with a relatively local cluster of galaxies invisible behind the (southern) Milky Way creating a local gravitational attraction.

Q What is the largest temporary structure that has been built at sea?

One of the Tension Leg Oil Drilling Platforms in the Gulf of Mexico. The latest one, apparently, sets the depth record for a drilling and production platform. It operates in approximately 1,300 metres of water and cost $1.65bn (pounds 1bn) to construct. The tendons anchoring it to the sea floor weigh 16,000 tonnes, the hull weighs over 23,000 tonnes and the deck over 22,400 tonnes.

Q In Britain, we can now buy gas from a variety of companies, but it all comes down the same pipes. How do the companies know how much to bill you?

The gas meter at your house registers how much gas you use, but not who supplies it. But this doesn't really matter. You have a contract with a certain gas company - the "provider" - that says you'll pay them for the gas you use. The provider has a contract with the company that owns the pipes, saying that it will put enough gas into the pipes to meet the demands of its customers.

The gas providers know how many customers they have and how much gas they are likely to use from the customers' gas meters, so they pump in enough gas to meet these demands.

The customers, in effect, receive a mixture of the providers' gases - but as it is the same product, that makes no difference. At the end of each quarter, the amount of gas the provider has pumped in, and the amount of gas its customers have used, is worked out. If the provider has not pumped in sufficient gas, it is fined by the pipe owners.

Q What is the volume of Wembley Stadium?

The surface area of the stadium is approximately 52,032 square metres. Its height is 38 metres, which gives the volume as 52032 x 38 = 1,977,216 cubic metres.

Q Where did [urban] Victorians get their ice?

They actually had ships bring it down from icebergs, glaciers, and so on, and then they brought large blocks of it. They kept it in cool rooms in their houses and chipped off bits as necessary. Needless to say, this was very wasteful and made the ice very expensive, so only the rich could afford it.

Q During the Second World War in North Africa, I came across several large man-made caverns underground. What were they? They were water reservoirs. Surface water is lost very quickly to the heat in North Africa so, many centuries ago, people built reservoirs underground in order to store water. Some still exist and can be found all over the desert.

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