Good Questions: Time for a change

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TWO matters of universal concern fill this week's collection of instant enlightenment prompted by readers' queries.

Why do your fingers go wrinkly in the bath? (Elen Gwynne, age four, of Runcorn, Cheshire)

The simple answer is because the outer layer of the skin absorbs water, which increases its volume making it too big to fit your fingers without wrinkling. The extra water also makes it look whiter. The longer answer requires a more detailed look at the structure of skin.

The outer, cellular layer of skin is the epidermis; the inner, fibrous layer is the dermis. The epidermis, fortunately, is waterproof, though its own outer layer, the stratum corneum or horny layer, can absorb water. The stratum corneum is dead tissue whose scales are constantly being rubbed off and replaced by cells from below. It varies in thickness with the epidermis, which is thickest on the palms and soles of the feet. Which is why those are the bits that become most wrinkled in the bath - their thickness enables them to absorb more water.

Sources: Black's Medical Dictionary and a helpful consultant dermatologist called Jane whom we met at a party.

What is time? If time moves, how does it do so? Is it possible to objectify the 'present' when all appears to be 'past' and 'future'? (Nicholas Gough, Malmesbury, Wiltshire)

According to Parmenides and Zeno, in the 5th century BC, change is logically impossible, reality is motionless and time is an illusion. Buddha and Plato, while not going quite so far, thought that our lives in what we think of as time are at best second-rate conditions by comparison with Nirvana or Platonic Ideas. Heraclitus, however, considered time flow to be the very essence of reality.

More practically, Isaac Newton considered both space and time to be vast containers inside which all experiences are situated; Kant described them as 'pure intuitions' inherent in the sensibilities of observers. Space and time are only real as long as there is a human perspective to experience them.

Many of the problems in thinking about time are caused by our spatially based vocabulary. To say that time 'moves' is an extension of the normal use of the word. Movement, in its usual sense, involves a change of position relative to time. So what is time moving relative to? Are we to suppose a metatime scale relative to which time moves? And if so, how fast is that moving, and relative to what?

All this mess became easier to accept (though harder to understand) once Einstein produced the Theories of Relativity, which showed that the measurement of time, like space, depends on the motion of the observer. One of the simpler consequences is that simultaneity has no objective meaning. Events that are simultaneous to one observer may be temporally distinct to another. So what appears to me to be the present may be the past to someone whizzing past in one direction and the future to someone who sees me whizzing past in another.

Must go now. I've run out of time and space.

Principal source: Encyclopaedia Britannica.