Magnetism Quotes

“In an age of modern evidence-based medicine, it might be thought that magnetic healing would have completely disappeared. Look in any modern bookshop and you will see that this is far from the case. Many have a generously stocked section entitled ‘Mind, Body, Spirit’ (though the classification ‘Utter Nonsense’ might be more appropriate) in which one can find numerous titles discussing magnetic healing or describing the supposed therapeutic power of crystals. In one such volume, I found the assertion (unsupported by any documented scientific evidence) that lodestones can be used to ‘channel energies’ and ‘reduce negativity’, and that they attack certain cancers and can combat diseases of the liver and the blood. Such specious claims would not be out of place in a book from the Middle Ages, but they can be found in books published in the 21st century. Irrationality is alive and well and sold in a bookshop near you.”
― Stephen J. Blundell, Magnetism: A Very Short Introduction

“But perhaps most of us all, magnetism has aroused humanity’s basic curiosity. The image in Figure 1 of the pattern produced in iron filings from a magnet shows an experiment that can be done by a child. But that experiment illustrates relativity (magnetic fields are a relativistic correction of moving charges), quantum mechanics (the Bohr–van Leeuwen theorem forbids magnetism in classical systems), the mystery of spin (it is electron spin which produces the magnetism), exchange symmetry (which keeps the spins aligned), and emergent phenomena (many spins doing what a single spin cannot). With this in mind, one cannot escape the conclusion that magnetism itself is emblematic of the mystery, the wonder and the richness of the physical world.”
― Stephen J. Blundell, Magnetism: A Very Short Introduction

“Spacecraft flying at distance from the Earth are particularly vulnerable as they are away from the protection of the Earth’s magnetosphere. A powerful solar flare in August 1972 occurred between the two last Apollo manned missions to the Moon. Had the flare struck during one of those missions, when the astronauts were outside the Earth’s protection, the radiation dose received on board could well have been fatal. Major solar flares are relatively rare events, but are a worrying risk for future manned space missions, especially to more distant destinations such as Mars where the extended journey time increases the likelihood of a catastrophic event en route. This is a useful reminder that planet Earth not only provides humans with an atmosphere which we can breathe but also a magnetic shield which protects us from deadly cosmic radiation.”
― Stephen J. Blundell, Magnetism: A Very Short Introduction

“The development of quantum mechanics in the 1920s motivated physicists to tackle all the unsolved problems of physics with the new methods and see if they worked (they mostly did). But what was the evidence for any of this new way of thinking?

The evidence that was persuasive at the time was a number of rather abstract physics experiments concerning the nature of atomic spectra or the interaction between light and metal surfaces. Each was important in its own way, but what ought to have played an important role in retrospect was something far, far simpler: the observation that magnets work. The crucial step was made by an unknown Dutch scientist called Hendreka van Leeuwen, and what she showed was that magnets couldn’t exist if you just use classical (i.e. pre-quantum) physics. Hendreka van Leeuwen’s doctoral work in Leiden was done under the supervision of Lenz and the work was published in the Journal de Physique et le Radium in 1921. Unfortunately, it subsequently transpired that her main result had been anticipated by Niels Bohr, the father of quantum mechanics, but as it had only appeared in his 1911 diploma thesis, written in Danish, it was unsurprising she hadn’t known about it. Their contribution, though conceived independently, is now known as the Bohr–van Leeuwen theorem, which states that if you assume nothing more than classical physics, and then go on to model a material as a system of electrical charges, then you can show that the system can have no net magnetization; in other words, it will not be magnetic. Simply put, there are no lodestones in a purely classical Universe.”
― Stephen J. Blundell, Magnetism: A Very Short Introduction

“Even though De Magnete was a technical treatise which dealt with rather abstract concepts, Gilbert’s work became a runaway bestseller and succeeded in confirming magnetism as a fashionable topic of conversation in the early 17th century.”
― Stephen J. Blundell, Magnetism: A Very Short Introduction

“The discovery of magnetism began with a type of rock. Magnetite is a mineral with chemical formula Fe3O4. It is commonly found in various locations around the world, although it gets its name from Magnesia, a region of central Greece (the names of the chemical elements magnesium and manganese, neither of which have anything much to do with magnetite, also derive from Magnesia). Many pieces of magnetite are naturally magnetized, probably due to lightning strikes, and will therefore pick up bits of iron. This mysterious property of what became known as magnets was known by the Greeks (it is mentioned by Thales of Miletus in the 6th century BCE) and also to the Chinese (there is a reference to magnetism in literature of the 4th century BCE).”
― Stephen J. Blundell, Magnetism: A Very Short Introduction