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Essentials : The Story So Far

Over many centuries physicists have developed ways of understanding reality, from the tiny to the enormous, the freezing to the fiery. Their quest? To explain of all nature with just one set of rules. It’s been a long journey, with many dead ends and setbacks. But some are hoping we’re nearly there. Today physicists know that there are four fundamental forces of nature. All [...]

Quantum Mechanics : What You See Is What You Get

Quantum mechanics was the most important scientific discovery of the twentieth century. It correctly describes everything we see around us with astonishing accuracy. It explains how all the atoms in your body behave, how molecules form and why things have colour. And it is needed to create the electronics that power your computer. Quantum mechanics was formulated in the 1920s and first [...]

Quantum Field Theory : All for One and One for All

Quantum field theory (QFT) extends quantum mechanics from single localised particles to fields that exist everywhere. These fields represent forces that permeate all of space and time. A familiar field is the electromagnetic field, which can be seen by scattering iron filings around a magnet. Another example is the gravitational field, which we see pointing towards the centre of the [...]

Gravity : The Cosmic Rollercoaster

Einstein’s general theory of relativity is our best notion of gravity. The presence of mass warps spacetime, creating the gravitational phenomena we observe. Currently we grasp many of its properties. We use it to study the expansion of the universe and precisely position GPS satellites. But sometimes the concepts break down. Gravity is the weakest of the fundamental forces. This [...]

Conflicts : Flies in the Ointment

We have described the two great theories of the 20th century: the gently curving world of general relativity and the bubbling sea of quantum mechanics. They enable us to study the physics of huge, heavy galaxies, and tiny, energetic atoms. But what about the boundaries? Can we model the beginning of the universe or the inside of a black hole? There, matter is squashed into a space so [...]