Radiation alert!

In the wake of announcements that body scanners are to be used routinely in airports a television journalist today reported that there was concern over the risk of radiation. If passengers are really worried about radiation they would be well advised not to fly at all since flying increases exposure to cosmic radiation which can harm DNA and cause cancers. As one travels further from the surface of the earth the atmosphere becomes thinner and the magnetic field weaker and exposure to cosmic radiation increases. It is one of the major problems of space travel.
Thus, passengers flying at 30,000 feet in an aircraft confront a greater risk of harmful radiation than from an airport body scanner. The amount of radiation emitted by a scanner used for security purposes is negligible.
Perhaps people who have concerns should avoid areas of high natural radiation – Cornwall in the UK for example, or Yangjiang in China, Kerala in India, Guarapari in Brazil, or the area with the highest level of background radiation, Ramsar in Iran.
Doubtless the worries over body scanners will persist for as long as ill-informed reporters continue to make alarmist remarks.

What’s the time, Mr Wolf?

Perhaps you enjoyed this playground game when you were six or seven years old? It was a safe way to experience a frisson of danger and panic and an outlet for the demons that sometimes haunted childhood dreams. It maligned wolves but the knowledge of a wolf's true nature would come later in life, when innocent games would be replaced with more earnest pursuits. One child would volunteer or be chosen to be Mr Wolf. He would walk a little way off and turn his back on the rest of the group. Then the game could begin. The children would begin the sing-song chant.

'What's the time, Mr Wolf?'

After each question Mr Wolf would turn to answer them and the children would take a number of steps according to the time called out. Some children would take tiny steps, pretending fear, while others would show their 'courage' with huge strides.

'One o'clock.'

'What's the time, Mr Wolf?'

'Two o'clock.'

'What's the time, Mr Wolf?'

'Five o'clock.'

'What's the time, Mr Wolf?'

'DINNER TIME!'

At this point the children would scatter, screaming, but Mr Wolf usually managed to capture the nearest who then took his place and the ritual would start again.

Maybe the correct answer to the question is, 'It depends where you are in the Universe' for time is not constant. If you travel, for example on an aircraft, and then return you will have aged less than someone who hasn't travelled. This was proved by scientists who synchronised two atomic clocks, placing one in an aircraft and one in a stationary position. When returned the clock in the aircraft showed an earlier time than the stationary clock. (Atomic clocks are so accurate that they will lose only one second in tens of millions of years.)

So speed affects time. Gravity also has an effect. If a person could live at the top of Mount Everest the ageing process would be faster than for someone at sea level. There are some places in the universe that have incredibly high gravity. If it were possible to get inside a black hole, where gravity is so dense that nothing absorbed can ever escape, time would effectively stop. Furthermore, if one were able to inhabit a spinning black hole one would be able to view the end of the universe.

To stay forever young may be your dream while all around crumble into ruins but to do so you would have to travel phenomenally fast and the energy required would be enormous. It is not possible . . . but any space travel was unimaginable not so very long ago!