Wonders of the Universe - Brian Cox [45]
CERN / SCIENCE PHOTO LIBRARY
SUB-ATOMIC PARTICLES
Our understanding of the structure of matter has increased in the last century. Originally, atoms were thought to be the basic building blocks of life, but Rutherford’s famous diffraction experiment proved that matter consisted mainly of space, with each atom containing a very small dense nucleus surrounded by a cloud of electrons. Further investigation showed that each nucleus was composed of protons and neutrons and that each proton was composed of up and down quarks. We have now reached what is believed to be the smallest particles possible – scientists have now discovered that all matter is composed of 9 particles and 4 forces, plus the hypothetical Higgs Boson. The search for the basic building blocks of matter has used matter colliders, which can produce the very high energies that are required to recreate the temperatures in the early Universe, when these sub-atomic particles originally existed.
Nathalie Lees © HarperCollins
TIMELINE OF THE UNIVERSE: THE BIG BANG TO THE PRESENT
The history of the Universe can be split into several phases, according to the physical conditions that existed at the time. Things happened quickly in the first fractions of a second, when the Universe was filled with an intensely hot soup of energy and exotic particles. From this emerged the first protons and neutrons which were later to form the nuclei of the first atoms – mostly hydrogen and helium. After the emission of the cosmic microwave background, around 400,000 years after the Big Bang, the pace of events became more sedate. According to current understanding, the Universe will continue to expand forever, eventually fading into darkness in the unimaginably distant future.
Nathalie Lees © HarperCollins
The construction of all the chemical elements in the Universe can be illustrated with the most basic demonstration – so simple, it’s child’s play. To understand how the structure has emerged, all you need is a pot of bubble mixture. Blow one bubble and you have returned to the beginning of time, when all that existed in the Universe was the proton.
There’s a mystery at the heart of science for which, as yet, we have no explanation, and that is that this universe is simple. Underlying all of the astonishing complexity appears to be a magnificent simplicity, and nowhere is that simplicity more obvious than in the construction of the elements.
MATTER BY NUMBERS
Throughout human history the discovery and use of specific chemical elements has been intricately linked with the rise of civilisation. It is believed that copper was first mined and crafted by humans 11,000 years ago, and the specific characteristics of this metal ushered in a new age of technology and the transition from stone tools and weapons to metal ones. Four thousand years later it happened again but with iron which, even today, when mixed with carbon to form the alloy steel is the exoskeleton of industrial civilisation.
These two elements played a role in our history because of their particular physical characteristics. Copper was almost certainly the first metal to be used by humans; as it is such an unreactive chemical that it is one of the few metals that occurs naturally in its pure state. It is also very soft and malleable and so relatively easy to work into tools and weapons. When combined with another metallic element – tin – copper forms the alloy bronze; when combined with zinc it forms brass. Iron is, perhaps surprisingly, the most abundant element on Earth, and the fourth-most abundant element in the rocks of Earth’s crust. Although more difficult to extract and work with than bronze, iron is an excellent material for weapons manufacture as it is harder and lasts longer than bronze.
These two metals have had a profound influence on human history and sit just a couple of spaces apart in the periodic table. Iron (Fe) is element number 26 and copper (Cu)