Labour’s persistent failure to address its electorate’s salient concerns is behind the protest vote, asserts DIANE ABBOTT
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How small is light?
Understanding how light can be fused with matter is the key to a major new technology — but researchers in Southampton have found a limit to how small you can go, write ROX MIDDLETON, LIAM SHAW and JOEL HELLEWELL
Waves of light are surprisingly big, only a very tiny bit smaller than the smallest thing we can see — a good gauge for imagining the size of light is a thread in a spider web
Washington’s lawless behaviour towards countries in the region it considers its ‘back yard’ should be condemned by all law-abiding people, says LUKE DANIELS
In part I of a serialisation of his new book, JOHN McINALLY takes a look at the early days of organising government workers
Colombia’s success in controlling the drug trade should be recognised and its sovereignty respected, argues Dr GLORY SAAVEDRA
The shadow lord chancellor has recently made a name for himself as an rabid hater of immigration – but there are exceptions to every rule, says SOLOMON HUGHES
Plaid Cymru’s front-bench spokesman on health and social services MABON AP GWYNFOR, in a two-part series, analyses the Caerphilly by-election and the wider political scene in Wales ahead of the 2026 Senedd election
LIGHT is a wave. But what is doing the waving? The abstract idea of a disembodied wave is extremely hard to conceive of. Just as you can’t imagine a wave in the ocean without the ocean, or a wave of a hand without a hand, it’s confusing that we would ever try to imagine a light wave without thinking about what the wave is travelling through.
In order to answer “what is waving,” the physicists who invented our modern description of light constructed the idea of the electromagnetic field. The field permeates every point of space in the universe, whether there is any matter or light at that point or not. The field at any point describes the amount and direction of electrical and magnetic force that is present at that place.
The wave that is light is a pulse of energy that passes in a straight line, carried as fluctuations in the electromagnetic field. Any point on the line undergoes a very quick change back and forth in the electric and magnetic forces as the light passes through. In fact the changing back and forth of the field is itself the light moving. Just like the way that water at the surface of a lake moves up and down as a ripple passes through the surface, and the movement up and down of the water is actually the ripple itself.
Why is it helpful to think about the wave-like nature of light? There are many effects that are easier to explain once you have the idea that light acts like a wave passing through a field.
One particularly striking feature is that when you imagine the light wave that passes through the field, it necessarily means that the wave takes up a certain amount of physical space.
The light wave has a length over which the light at any time is spread. To think about the water waves again, if you are on a boat bobbing up and down as waves pass underneath the boat, then the length of the wave is the distance between the peak of the wave you have reached the top of, and the next wave that you can see coming.
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