If you were to tell a child playing with a horseshoe magnet and pieces of iron that his uncle has a much bigger magnet that can lift everything and everybody, the child would probably believe you and might even ask for a ride on the magnet. If a physicist were present at such a conversation, he or she-armed with knowledge and experience-would probably smile condescendingly. The physicist would know well that only a very few materials-such as iron or nickel-are strongly magnetic, while the rest of the world's materials are not; to be precise, the rest of the world is a billion (10(9)) times less magnetic. This number seems obviously too large to allow common substances (water, for example) to be lifted even by the most powerful magnets; a billionfold increase in magnetic fields can be found only on neutron stars. In this case, however knowledge and experience would mislead the physicist: In fact, all materials can be lifted by using magnetic fields that are rather standard these days. In principle, even a child can be levitated by a magnet, as we shall see below.
|Number of pages||4|
|Publication status||Published - 1998|