Aylsham High Science - Further your knowledge

Biology

The Cell

First observed by Robert Hooke in 1665, cells occur in nature in a bewildering variety of forms. Every organism alive today consists of one or more cells: a single human body contains up to a hundred trillion of them. The first life on Earth was a single-celled organism which is thought to have appeared around three and a half billion years ago. That simple cell resembled today's bacteria. But eventually these microscopic entities evolved into something far more complex, and single-celled life gave rise to much larger, complex multicellular organisms. But how did the first cell appear, and how did that prototype evolve into the sophisticated, highly specialised cells of the human body?

Biology

Microbiology

BBC Radio 4 - In Our Time, Microbiology

We have more microbes in our bodies than we have human cells. We fear them as the cause of disease, yet are reliant on them for processes as diverse as water purification, pharmaceuticals, bread-making and brewing. In the future, we may look to them to save the planet from environmental hazards as scientists exploit their ability to clean up pollution. For microbes are the great recyclers on the earth, processing everything – plants, animals and us. Without microbes life would grind to a halt. How did we first discover these invisible masters of the universe? The development of microscopes in the 17th Century played a key part, but for a while science seemed stuck in this purely observational role. It is only when Louis Pasteur and Robert Koch began to manipulate microbes in the lab two hundred years later that stunning advances were made. These breakthroughs led to an understanding of how microbes transform matter, spread disease and also prevent it with the development of antibiotics and vaccines.

Biology

Fungi

BBC Radio 4 - In Our Time, Fungi

These organisms are not plants or animals but a kingdom of their own. Millions of species of fungi live on the Earth and they play a crucial role in ecosystems, enabling plants to obtain nutrients and causing material to decay. Without fungi, life as we know it simply would not exist. They are also a significant part of our daily life, making possible the production of bread, wine and certain antibiotics. Although fungi brought about the colonisation of the planet by plants about 450 million years ago, some species can kill humans and devastate trees.

Biology

Bacteriophages

BBC Radio 4 - In Our Time, Bacteriophages

Bacteriophages are the most abundant lifeform on Earth: the viruses that 'eat' bacteria. Early in the 20th century, scientists noticed that something in their Petri dishes was making bacteria disappear and they called these bacteriophages, things that eat bacteria. From studying these phages, it soon became clear that they offered countless real or potential benefits for understanding our world, from the tracking of diseases to helping unlock the secrets of DNA to treatments for long term bacterial infections. With further research, they could be an answer to the growing problem of antibiotic resistance.

Biology

Hormones

BBC Radio 4 - In Our Time, Hormones

Hormones, the chemical signals coursing through our bodies throughout our lives, produced in separate areas and spreading via the bloodstream. We call these 'hormones' and we produce more than 80 of them of which the best known are arguably oestrogen, testosterone, adrenalin, insulin and cortisol. On the whole hormones operate without us being immediately conscious of them as their goal is homeostasis, maintaining the levels of everything in the body as required without us having to think about them first. Their actions are vital for our health and wellbeing and influence many different aspects of the way our bodies work.

Biology

Plankton

BBC Radio 4 - In Our Time, Plankton

Plancton, the tiny drifting organisms in the oceans that sustain the food chain for all the lifeforms in the water and so for the billions of people who, in turn, depend on the seas for their diet. In Earth's development, the plant-like ones among them, the phytoplankton, produced so much oxygen through photosynthesis that around half the oxygen we breathe today originated there. And each day as the sun rises, the animal ones, the zooplankton, sink to the depths of the seas to avoid predators in such density that they appear on ship sonars like a new seabed, only to rise again at night in the largest migration of life on this planet.

Biology

The microscope

BBC Radio 4 - In Our Time, The Microscope

In the seventeenth century the pioneering work of two scientists, the Dutchman Antonie van Leeuwenhoek and Robert Hooke in England, revealed the teeming microscopic world that exists at scales beyond the capabilities of the naked eye. The microscope became an essential component of scientific enquiry by the nineteenth century, but in the 1930s a German physicist, Ernst Ruska, discovered that by using a beam of electrons he could view structures much tinier than was possible using visible light. Today light and electron microscopy are among the most powerful tools at the disposal of modern science, and new techniques are still being developed.

Biology

Immunisation

BBC Radio 4 - In Our Time, Immunisation

In 1717, Lady Mary Wortley Montagu, the wife of the British Ambassador to the Ottoman Empire, wrote a letter to her friend describing how she had witnessed the practice of smallpox inoculation in Constantinople. This involved the transfer of material from a smallpox postule into multiple cuts made in a vein. Lady Montagu had lost her brother to smallpox and was amazed that the Middle Eastern practice of inoculation rendered the fatal disease harmless. In Britain, the practice was unknown. Inoculation was an early attempt at creating immunity to disease, but was later dismissed when Edward Jenner pioneered immunisation through vaccination in 1796. Vaccination was hailed a huge success.

Biology

Enzymes

BBC Radio 4 - In Our Time, Enzymes

Enzymes, the proteins that control the speed of chemical reactions in living organisms. Without enzymes, these reactions would take place too slowly to keep organisms alive: with their actions as catalysts, changes which might otherwise take millions of years can happen hundreds of times a second. Some enzymes break down large molecules into smaller ones, like the ones in human intestines, while others use small molecules to build up larger, complex ones, such as those that make DNA. Enzymes also help keep cell growth under control, by regulating the time for cells to live and their time to die, and provide a way for cells to communicate with each other.

Biology

Mitochondria

BBC Radio 4 - In Our Time, Mitochondria

Inside each cell of every complex organism there are structures known as mitochondria. The 19th century scientists who first observed them thought they were bacteria which had somehow invaded the cells they were studying. We now understand that mitochondria take components from the food we eat and convert them into energy. Mitochondria are essential for complex life, but as the components that run our metabolisms they can also be responsible for a range of diseases – and they probably play a role in how we age. The DNA in mitochondria is only passed down the maternal line. This means it can be used to trace population movements deep into human history, even back to an ancestor we all share: mitochondrial Eve.

Biology

Rosalind Franklin

BBC Radio 4 - In Our Time, Rosalind Franklin

During her distinguished career, Franklin carried out ground-breaking research into coal and viruses but she is perhaps best remembered for her investigations in the field of DNA. In 1952 her research generated a famous image that became known as Photograph 51. When the Cambridge scientists Francis Crick and James Watson saw this image, it enabled them the following year to work out that DNA has a double-helix structure, one of the most important discoveries of modern science. Watson, Crick and Franklin's colleague Maurice Wilkins received a Nobel Prize in 1962 for this achievement but Franklin did not and today many people believe that Franklin has not received enough recognition for her work.

Biology

Parasitism

BBC Radio 4 - In Our Time, Parasitism

Parasitism, the relationship between parasites and hosts, where one species lives on or in another to the benefit of the parasite but at a cost to the host, potentially leading to disease or death of the host. Typical examples are mistletoe and trees, hookworms and vertebrates, cuckoos and other birds. In many cases the parasite species do so well in or on a particular host that they reproduce much faster and can adapt to changes more efficiently, and it is thought that almost half of all animal species have a parasitic stage in their lifetime. What techniques do hosts have to counter the parasites, and what impact do parasites have on the evolution of their hosts?

Biology

Photosynthesis

BBC Radio 4 - In Our Time, Photosynthesis

Photosynthesis, the process by which green plants and many other organisms use sunlight to synthesise organic molecules. Photosynthesis arose very early in evolutionary history and has been a crucial driver of life on Earth. In addition to providing most of the food consumed by organisms on the planet, it is also responsible for maintaining atmospheric oxygen levels, and is thus almost certainly the most important chemical process ever discovered.

Biology

Genetic engineering

BBC Radio 4 - In Our Time, Genetic Engineering

Out of the city of Cambridge in the mid century came DNA and out of Edinburgh at the end of the century came the cloning of Dolly the sheep. These two facts might well do more to change the world literally, and our view of the world, than anything else that has happened at any time. Genetics have become the conversation of our day and with the Human Genome Project lumbering towards completion, its power grows. But are the consequences likely to be destructive and will what we think of as a human being, a personality, or even a person, change uncomfortably and irredeemably?

Biology

Genetic Mutation

BBC Radio 4 - In Our Time, Genetic Mutation

A mutation is an error in reproduction between one generation and the next as the copying mechanism that allows you to inherit your parent’s genes goes awry. Mutations are almost always bad news for the organism that suffers them and yet mutation is also a giver of life. Without it there would be no natural selection, no evolution and, arguably, no life on this planet. It’s not unreasonable to see life itself as a mutation and to understand this may also hold the key to aging and disease. It is, in the Darwinian view of life, the raw material of evolution.

Biology

On the origin of species

BBC Radio 4 - In Our Time, Darwin: In Our Time, Darwin: On the Origin of Species

To celebrate the 200th anniversary of the birth of Charles Darwin and the 150th anniversary of the publication of On the Origin of Species, Melvyn Bragg presents a series about Darwin's life and work. How Darwin was eventually persuaded to publish On the Origin of Species in November 1859 and the book's impact on fellow scientists and the general public.

Biology

Evolution

BBC Radio 4 - In Our Time, Evolution

Are we continuing to evolve? If so, what are the signs and if not, why not? And those apes, so very very near us in genetic kinship, why are they so far away in so much else, and will they ever evolve? And is evolution necessarily progression? If so, does our apparent lack of evolution mean lack of progress? Also on the evolutionary front, could electronic devices discover the means of self-replication, and what will that mean for us? The march of the life sciences after the discovery of DNA accelerates by the year but what are the implications?

Biology

Fossils

BBC Radio 4 - In Our Time, Fossils

In the middle of the nineteenth century the discoveries of the fossil hunters used to worry poor Ruskin to death, he wrote in a letter in 1851, “my faith, which was never strong, is being beaten to gold leaf…If only those Geologists would let me alone I could do very well, but those dreadful Hammers! I hear the clink of them at the end of every cadence of the Bible verses.”The testimony of fossils over the ages has been remarkably eloquent when we have wanted to listen; and now with mass spectrometers, electron microscopes and secondary X-ray detectors, these long dead organisms can speak to us of the past in ways they never could before.

Biology

The late devonian extinction

BBC Radio 4 - In Our Time, The Late Devonian Extinction

The late devonian extinction was the devastating mass extinctions of the Late Devonian Period, roughly 370 million years ago, when around 70 percent of species disappeared. Scientists are still trying to establish exactly what happened, when and why, but this was not as sudden as when an asteroid hits Earth. The Devonian Period had seen the first trees and soils and it had such a diversity of sea life that it’s known as the Age of Fishes, some of them massive and armoured, and, in one of the iconic stages in evolution, some of them moving onto land for the first time. One of the most important theories for the first stage of this extinction is that the new soils washed into oceans, leading to algal blooms that left the waters without oxygen and suffocated the marine life.

Biology

The fish-tetrapod transistion

BBC Radio 4 - In Our Time, The Fish-Tetrapod Transition

Around 400 million years ago some of our ancestors, the fish, started to become a little more like humans. At the swampy margins between land and water, some fish were turning their fins into limbs, their swim bladders into lungs and developed necks and eventually they became tetrapods, the group to which we and all animals with backbones and limbs belong. After millions of years of this transition, these tetrapod descendants of fish were now ready to leave the water for a new life of walking on land, and with that came an explosion in the diversity of life on Earth.

Biology

Human origins

BBC Radio 4 - In Our Time, Human Origins

The story of human evolution is one that stretches back over five million years, and during that time there are reckoned to have been between fifteen and twenty species of hominid to have walked this planet. From the earliest (Genus) Australopithecus (Species) Anamensis through times when there have been several divergent pre-human species existing at once, we have now arrived at a period unique in the history of the earth when a sole human species, Homo Sapiens, is in evidence right across the globe.

Biology

The Neanderthals

BBC Radio 4 - In Our Time, The Neanderthals

In 1856, quarry workers in Germany found bones in a cave which seemed to belong to a bear or other large mammal. They were later identified as being from a previously unknown species of hominid similar to a human. The specimen was named Homo neanderthalis after the valley in which the bones were found.This was the first identified remains of a Neanderthal, a species which inhabited parts of Europe and Central Asia from around 400,000 years ago. Often depicted as little more advanced than apes, Neanderthals were in fact sophisticated, highly-evolved hunters capable of making tools and even jewellery.

Biology

Homo Erectus

BBC Radio 4 - In Our Time, Homo erectus

One of our ancestors, Homo erectus, who thrived on Earth for around two million years whereas we, Homo sapiens, emerged only in the last three hundred thousand years. Homo erectus, or Upright Man, spread from Africa to Asia and it was on the Island of Java that fossilised remains were found in 1891 in an expedition led by Dutch scientist Eugène Dubois. Homo erectus people adapted to different habitats, ate varied food, lived in groups, had stamina to outrun their prey; and discoveries have prompted many theories on the relationship between their diet and the size of their brains, on their ability as seafarers, on their creativity and on their ability to speak and otherwise communicate.

Biology

Echolocation

BBC Radio 4 - In Our Time, Echolocation

Some bats, dolphins and other animals emit sounds at high frequencies to explore their environments, rather than sight. This was such an unlikely possibility, to natural historians from C18th onwards, that discoveries were met with disbelief even into the C20th; it was assumed that bats found their way in the dark by touch. Not all bats use echolocation, but those that do have a range of frequencies for different purposes and techniques for preventing themselves becoming deafened by their own sounds. Some prey have evolved ways of detecting when bats are emitting high frequencies in their direction, and some fish have adapted to detect the sounds dolphins use to find them.

Chemistry

Kinetic theory

BBC Radio 4 - In Our Time, Kinetic Theory

Newton theorised that there were static particles in gases that pushed against each other all the harder when volume decreased, hence the increase in pressure. Those who argued that molecules moved, and hit each other, were discredited until James Maxwell and Ludwig Boltzmann used statistics to support this kinetic theory. Ideas about atoms developed in tandem with this, and it came as a surprise to scientists in C20th that the molecules underpinning the theory actually existed and were not simply thought experiments.

Chemistry

John Dalton

BBC Radio 4 - In Our Time, John Dalton

The scientist John Dalton was born in North England in 1766. Although he came from a relatively poor Quaker family, he managed to become one of the most celebrated scientists of his age. Through his work, he helped to establish Manchester as a place where not only products were made but ideas were born. His reputation during his lifetime was so high that unusually a statue was erected to him before he died. Among his interests were meteorology, gasses and colour blindness. However, he is most remembered today for his pioneering thinking in the field of atomic theory.

Chemistry

The electron

BBC Radio 4 - In Our Time, The Electron

The electron, an atomic particle that's become inseparable from modernity. JJ Thomson discovered the electron 125 years ago, so revealing that atoms, supposedly the smallest things, were made of even smaller things. He pictured them inside an atomic ball like a plum pudding, with others later identifying their place outside the nucleus - and it is their location on the outer limit that has helped scientists learn so much about electrons and with electrons. We can use electrons to reveal the secrets of other particles and, while electricity exists whether we understand electrons or not, the applications of electricity and electrons grow as our knowledge grows. Many questions, though, remain unanswered.

Chemistry

The proton

BBC Radio 4 - In Our Time, The Proton

The Proton, formed from three quarks close to the Big Bang and found in the nuclei of all elements. The positive charges they emit means they attract the fundamental particles of negatively charged electrons, an attraction that leads to the creation of atoms which in turn leads to chemistry, biology and life itself. The Sun (in common with other stars) is a fusion engine that turn protons by a series of processes into helium, emitting energy in the process, with about half of the Sun's protons captured so far. Hydrogen atoms, stripped of electrons, are single protons which can be accelerated to smash other nuclei and have applications in proton therapy. Many questions remain, such as why are electrical charges for protons and electrons so perfectly balanced?

Chemistry

The Neutron

BBC Radio 4 - In Our Time, The Neutron

The neutron, one of the particles found in an atom's nucleus. Building on the work of Ernest Rutherford, the British physicist James Chadwick won the Nobel Prize for Physics for his discovery of the neutron in 1932. Neutrons play a fundamental role in the universe and their discovery was at the heart of developments in nuclear physics in the first half of the 20th century.

Chemistry

States of matter

BBC Radio 4 - In Our Time, States of Matter

Most people are familiar with the idea that a substance like water can exist in solid, liquid and gaseous forms. But as much as 99% of the matter in the universe is now believed to exist in a fourth state, plasma. Today scientists recognise a number of other exotic states or phases, such as glasses, gels and liquid crystals - many of them with useful properties that can be exploited.

Chemistry

Chemical elements

BBC Radio 4 - In Our Time, Chemical Elements

The aim and challenge in chemistry, according to the Encyclopaedia Britannica, is the understanding of the complex materials which constitute everything in existence since the Big Bang, when the whole universe emerged out of the two elements of hydrogen and helium. For Aristotle there were four elements: Earth, Air, Fire and Water. Now there are one hundred and eight, sixteen of which are produced artificially, and none of which figure in Aristotle's original four. But they are all still elements - defined as substances which cannot be broken down, the building blocks of all life.Today we have the key to understanding these elements, the Periodic Table, which is a pattern embedded in nature and was miraculously discovered in a dream.

Chemistry

Absolute zero

BBC Radio 4 - In Our Time, Absolute Zero

In the early eighteenth century the French physicist Guillaume Amontons suggested that temperature had a lower limit. The subject of low temperature became a fertile field of research in the nineteenth century, and today we know that this limit - known as absolute zero - is approximately minus 273 degrees Celsius. It is impossible to produce a temperature exactly equal to absolute zero, but today scientists have come to within a billionth of a degree. At such low temperatures physicists have discovered a number of strange new phenomena including superfluids, liquids capable of climbing a vertical surface.

Chemistry

Early geology

BBC Radio 4 - In Our Time, Early Geology

A little over two hundred years ago a small group of friends founded the Geological Society of London. This organisation was the first devoted to furthering the discipline of geology - the study of the Earth, its history and composition. Although geology only emerged as a separate area of study in the late eighteenth century, many earlier thinkers had studied rocks, fossils and the materials from which the Earth is made.

Chemistry

The Cambrian Period

BBC Radio 4 - In Our Time, The Cambrian Period

In the Selkirk Mountains of British Columbia in Canada, there is an outcrop of limestone shot through with a seam of fine dark shale. A sudden mudslide into shallow water some 550 million years ago means that a startling array of wonderful organisms has been preserved within it. Wide eyed creatures with tentacles below and spines on their backs, things like flattened rolls of carpet with a set of teeth at one end, squids with big lobster-like arms. There are thousands of them and they seem to testify to a time when evolution took a leap and life on this planet suddenly went from being small, simple and fairly rare to being large, complex, numerous and dizzyingly diverse. It happened in the Cambrian Period and it's known as the Cambrian Explosion

Chemistry

Plate tectonics

BBC Radio 4 - In Our Time, Plate Tectonics

America is getting further away from Europe. This is not a political statement but a geological fact. Just as the Pacific is getting smaller, the Red Sea bigger, the Himalayas are still going up and one day the Horn of Africa will be a large island. This is the theory of plate tectonics, a revolutionary idea in 20th century geology that claimed the continents of Earth were dancing to the music of deep time. A dance of incredible slowness, yet powerful enough to throw up the mountains and pour away the oceans.Plate tectonics, the idea that the earth’s surface moved on a carpet of molten magma, constituted a genuine scientific revolution in geology. It explained why mountains appeared and why earth quakes occurred; it explained the curious distribution of fossils across the globe and finally solved the age old conundrum of why continents such as Africa and South America appeared to fit together like a giant jigsaw puzzle. Plate tectonics has made geologists, and many more besides, profoundly re-think what the Earth was, how it worked and how it related to all the things in it.

Chemistry

The KT boundary

BBC Radio 4 - In Our Time, The KT Boundary

Across the entire planet, where it hasn't been eroded or destroyed in land movements, there is a thin grey line. In Italy it is 1 cm thick, in America it stretches to three centimetres, but it is all the same thin grey line laid into the rock some 65 million years ago and it bears witness to a cataclysmic event experienced only once in Earth's history. It is called the KT Boundary and geologists believe it is the clue to the death of the dinosaurs and the ultimate reason why mammals and humans inherited the Earth.But exactly what did happen 65 million years ago? How was this extraordinary line created across the Earth and does it really hold the key to the death of the dinosaurs?

Chemistry

Seismology

BBC Radio 4 - In Our Time, Seismology

A massive earthquake in 1755 devastated Lisbon, and this disaster helped inspire a new science of seismology which intensified after San Francisco in 1906 and advanced even further with the need to monitor nuclear tests around the world from 1945 onwards. While we now know so much more about what lies beneath the surface of the Earth, and how rocks move and crack, it remains impossible to predict when earthquakes will happen. Thanks to seismology, though, we have a clearer idea of where earthquakes will happen and how to make some of them less hazardous to lives and homes.

Chemistry

Chromatography

BBC Radio 4 - In Our Time, Chromatography

In its basic form, it is familiar to generations of schoolchildren who put a spot of ink at the bottom of a strip of paper, dip it in water and then watch the pigments spread upwards, revealing their separate colours. Chemists in the 19th Century started to find new ways to separate mixtures and their work was taken further by Mikhail Tsvet, a Russian-Italian scientist who is often credited with inventing chromatography in 1900. The technique has become so widely used, it is now an integral part of testing the quality of air and water, the levels of drugs in athletes, in forensics and in the preparation of pharmaceuticals.

Physics

The Sun

BBC Radio 4 - In Our Time, The Sun

The object that gives the Earth its light and heat is a massive ball of gas and plasma 93 million miles away. Thanks to the nuclear fusion reactions taking place at its core, the Sun has been shining for four and a half billion years. Its structure, and the processes that keep it burning, have fascinated astronomers for centuries. After the invention of the telescope it became apparent that the Sun is not a placid, steadily shining body but is subject to periodic changes in its appearance and eruptions of dramatic violence, some of which can affect us here on Earth. Recent space missions have revealed fascinating new insights into our nearest star.

Physics

The life of stars

BBC Radio 4 - In Our Time, The Life of Stars

For Keats the stars were symbols of eternity- they were beautiful and ordered and unchanging - but modern astronomy tells a very different story. Stars, like everything else in the universe, are subject to change. They are born among vast swirls of gas and dust and they die in the stunning explosions we call supernovae. They create black holes and neutron stars and, in the very beginning of the universe, they forged the elements from which all life is made. But how do stars keep burning for millions of years, why do they self-destruct with such ferocity and what will happen to the universe when they all go out?

Physics

The death of stars

BBC Radio 4 - In Our Time, The Death of Stars

The death of stars, the abrupt transformation of stars after shining brightly for millions or billions of years, once they lack the fuel to counter the force of gravity. Those like our own star, the Sun, become red giants, expanding outwards and consuming nearby planets, only to collapse into dense white dwarves. The massive stars, up to fifty times the mass of the Sun, burst into supernovas, visible from Earth in daytime, and become incredibly dense neutron stars or black holes. In these moments of collapse, the intense heat and pressure can create all the known elements to form gases and dust which may eventually combine to form new stars, new planets and, as on Earth, new life.

Physics

Eclipses

BBC Radio 4 - In Our Time, Eclipses

Solar eclipses, some of life’s most extraordinary moments, when day becomes night and the stars come out before day returns either all too soon or not soon enough, depending on what you understand to be happening. In ancient China, for example, there was a story that a dragon was eating the sun and it had to be scared away by banging pots and pans if the sun were to return. Total lunar eclipses are more frequent and last longer, with a blood moon coloured red like a sunrise or sunset. Both events have created the chance for scientists to learn something remarkable, from the speed of light, to the width of the Atlantic, to the roundness of Earth, to discovering helium and proving Einstein’s Theory of General Relativity.

Physics

The planets

BBC Radio 4 - In Our Time, The Planets

Tucked away in the outer Western Spiral arm of the Milky Way is a middle aged star, with nine, or possibly ten orbiting planets of hugely varying sizes. Roughly ninety-two million miles and third in line from that central star is our own planet Earth, in thrall to our Sun, just one of the several thousand million stars that make up the Galaxy.Ever since Galileo and Copernicus gave us a scientific model of our own solar system, we have assumed that somewhere amongst the myriad stars there must be other orbiting planets, but it took until 1995 to find one.

Physics

Mercury

BBC Radio 4 - In Our Time, Mercury

We see it as an evening or a morning star, close to where the Sun has just set or is about to rise, and observations of Mercury helped Copernicus understand that Earth and the other planets orbit the Sun, so displacing Earth from the centre of our system. In the 20th century, further observations of Mercury helped Einstein prove his general theory of relativity. For the last 50 years we have been sending missions there to reveal something of Mercury's secrets and how those relate to the wider universe, and he latest, BepiColombo, is out there in space now.

Physics

Venus

BBC Radio 4 - In Our Time, Venus

Venus which is both the morning star and the evening star, rotates backwards at walking speed and has a day which is longer than its year. It has long been called Earth’s twin, yet the differences are more striking than the similarities. Once imagined covered with steaming jungles and oceans, we now know the surface of Venus is 450 degrees celsius, and the pressure there is 90 times greater than on Earth, enough to crush an astronaut. The more we learn of it, though, the more we learn of our own planet, such as whether Earth could become more like Venus in some ways, over time.

Physics

The Habitability of planets

BBC Radio 4 - In Our Time, The Habitability of Planets

How and where did life on Earth begin, what did it need to thrive and could it be found elsewhere? Charles Darwin speculated that we might look for the cradle of life here in 'some warm little pond'; more recently the focus moved to ocean depths, while new observations in outer space and in laboratories raise fresh questions about the potential for lifeforms to develop and thrive, or 'habitability' as it is termed. What was the chemistry needed for life to begin and is it different from the chemistry we have now? With that in mind, what signs of life should we be looking for in the universe to learn if we are alone?

Physics

The earth's origin

BBC Radio 4 - In Our Time, The Earth's Origins

Bishop Ussher, in 1654 arrived at an exact figure and specified it in his work Annalis Veteris et Novi Testamenti: He deduced that work on Planet Earth began at exactly 9am, on Monday 23rd October 4004 BC. The date was then printed in the margin of The Bible and preached from the pulpit, and right up to the nineteenth century to the left of ‘In The Beginning…’ was specified ‘Before Christ 4004’.Christian believers thought the creation story was solid as a rock…until the geologists arrived.

Physics

The Earth's core

BBC Radio 4 - In Our Time, The Earth's Core

The inner core is an extremely dense, solid ball of iron and nickel, the size of the Moon, while the outer core is a flowing liquid, the size of Mars. Thanks to the magnetic fields produced within the core, life on Earth is possible. The magnetosphere protects the Earth from much of the Sun's radiation and the flow of particles which would otherwise strip away the atmosphere. The precise structure of the core and its properties have been fascinating scientists from the Renaissance. Recent seismographs show the picture is even more complex than we might have imagined, with suggestions that the core is spinning at a different speed and on a different axis from the surface.

Physics

Aging the earth

BBC Radio 4 - In Our Time, Ageing the Earth

It was once thought that the world began in 4004 BC. Lord Kelvin calculated the cooling temperature of a rock the size of our planet and came up with a figure of 20 million years for the age of the Earth. Now, the history of our planet is divided into four great Eons: the Hadean, the Archaen, the Proterozoic and the Phanerozoic. Together, they are taken to encompass an incredible four and a half billion years. How can we begin to make sense of such a huge swathe of time? And can we be sure that we have got the Earth's age right?

Physics

Mars

BBC Radio 4 - In Our Time, Mars

Named after the Roman god of war, Mars has been a source of continual fascination. It is one of our nearest neighbours in space, though it takes about a year to get there. It is very inhospitable with high winds racing across extremely cold deserts. But it is spectacular, with the highest volcano in the solar system and a giant chasm that dwarfs the Grand Canyon.For centuries there has been fierce debate about whether there is life on Mars and from the 19th century it was even thought there might be a system of canals on the planet. This insatiable curiosity has been fuelled by writers like HG Wells and CS Lewis and countless sci-fi films about little green men.So what do we know about Mars – its conditions, now and in the past? What is the evidence that there might be water and thus life on Mars? And when might we expect man to walk on its surface?

Physics

Jupiter

BBC Radio 4 - In Our Time, Jupiter

Jupiter is the largest planet in our solar system, and it’s hard to imagine a world more alien and different from Earth. It’s known as a Gas Giant, and its diameter is eleven times the size of Earth’s: our planet would fit inside it one thousand three hundred times. But its mass is only three hundred and twenty times greater, suggesting that although Jupiter is much bigger than Earth, the stuff it’s made of is much, much lighter. When you look at it through a powerful telescope you see a mass of colourful bands and stripes: these are the tops of ferocious weather systems that tear around the planet, including the great Red Spot, probably the longest-lasting storm in the solar system. Jupiter is so enormous that it’s thought to have played an essential role in the distribution of matter as the solar system formed – and it plays an important role in hoovering up astral debris that might otherwise rain down on Earth. It’s almost a mini solar system in its own right, with 95 moons orbiting around it. At least two of these are places life might possibly be found.

Physics

Saturn

BBC Radio 4 - In Our Time, Saturn

In 1610, Galileo used an early telescope to observe Saturn, one of the brightest points in the night sky, but could not make sense of what he saw: perhaps two large moons on either side. When he looked a few years later, those supposed moons had disappeared. It was another forty years before Dutch scientist Christiaan Huygens solved the mystery, realizing the moons were really a system of rings. Successive astronomers added more detail, with the greatest leaps forward in the last forty years. The Pioneer 11 spacecraft and two Voyager missions have flown by, sending back the first close-up images, and Cassini is still there, in orbit, confirming Saturn, with its rings and many moons, as one of the most intriguing and beautiful planets in our Solar System.

Physics

Comets

BBC Radio 4 - In Our Time, Comets

Comets, the 'dirty snowballs' of the Solar System. In the early 18th century the Astronomer Royal Sir Edmond Halley compiled a list of appearances of comets, bright objects like stars with long tails which are occasionally visible in the night sky. He concluded that many of these apparitions were in fact the same comet, which returns to our skies around every 75 years, and whose reappearance he correctly predicted. Halley's Comet is today the best known example of a comet, a body of ice and dust which orbits the Sun. Since they contain materials from the time when the Solar System was formed, comets are regarded by scientists as frozen time capsules, with the potential to reveal important information about the early history of our planet and others.

Physics

The Kuiper belt

BBC Radio 4 - In Our Time, The Kuiper Belt

The Kuiper Belt, a vast region of icy objects at the fringes of our Solar System, beyond Neptune, in which we find the dwarf planet Pluto and countless objects left over from the origins of the solar system, some of which we observe as comets. It extends from where Neptune is, which is 30 times further out than the Earth is from the Sun, to about 500 times the Earth-Sun distance. It covers an immense region of space and it is the part of the Solar System that we know the least about, because it is so remote from us and has been barely detectable by Earth-based telescopes until recent decades. Its existence was predicted before it was known, and study of the Kuiper Belt, and how objects move within it, has led to a theory that there may be a 9th planet far beyond Neptune.

Physics

Exoplanets

BBC Radio 4 - In Our Time, Exoplanets

Astronomers have speculated about the existence of planets beyond our solar system for centuries. Although strenuous efforts were made to find such planets orbiting distant stars, it was not until the 1990s that instruments became sophisticated enough to detect such remote objects. In 1992 Dale Frail and Aleksander Wolszczan discovered the first confirmed exoplanets: two planets orbiting the pulsar PSR B1257+12. Since then, astronomers have discovered more than 900 exoplanets, and are able to reach increasingly sophisticated conclusions about what they look like - and whether they might be able to support life. Recent data from experiments such as NASA's space telescope Kepler indicates that such planets may be far more common than previously suspected.

Physics

Galaxies

BBC Radio 4 - In Our Time, Galaxies

Our galaxy is about 100,000 light years across, is shaped like a fried egg and we travel inside it at approximately 220 kilometres per second. The nearest one to us is much smaller and is nicknamed the Sagittarius Dwarf. But the one down the road, called Andromeda, is just as large as ours and, in 10 billion years, we'll probably crash into it. Galaxies - the vast islands in space of staggering beauty and even more staggering dimension. But galaxies are not simply there to adorn the universe; they house much of its visible matter and maintain the stars in a constant cycle of creation and destruction.

Physics

The Manhattan project

BBC Radio 4 - In Our Time, The Manhattan Project

Before the war, scientists in Germany had discovered the potential of nuclear fission and scientists in Britain soon argued that this could be used to make an atom bomb, against which there could be no defence other than to own one. The fear among the Allies was that, with its head start, Germany might develop the bomb first and, unmatched, use it on its enemies. The USA took up the challenge in a huge engineering project led by General Groves and Robert Oppenheimer and, once the first bomb had been exploded at Los Alamos in July 1945, it appeared inevitable that the next ones would be used against Japan with devastating results.

Physics

Nuclear Fusion

BBC Radio 4 - In Our Time, Nuclear Fusion

In the 1920s physicists predicted that it might be possible to generate huge amounts of energy by fusing atomic nuclei together, a reaction requiring enormous temperatures and pressures. Today we know that this complex reaction is what keeps the Sun shining. Scientists have achieved fusion in the laboratory and in nuclear weapons; today it is seen as a likely future source of limitless and clean energy.

Physics

Nuclear Physics

BBC Radio 4 - In Our Time, Nuclear Physics

Harnessing the enigmatic qualities of the atom’s tiny core brought us nuclear power and gave us The Bomb, a breakthrough with such far-reaching consequences that it moved the physicist Albert Einstein to say, “Had I known, I should have become a watch maker”.How can such outlandish power be released from such infinitesimal amounts of matter and what does the science of the nucleus tell us about how our universe is built? Nuclear technology provokes strong emotional and political reactions, but what are the plain facts behind its development as a science?

Physics

Radiation

BBC Radio 4 - In Our Time, Radiation

Over the course of the 19th century, physicists from Thomas Young, through Michael Faraday to Henri Becquerel made discovery after discovery, gradually piecing together a radically new picture of reality. They explored the light beyond the visible spectrum, connected electricity and magnetism, and eventually showed that heat, light, radio and mysterious new phenomena like 'X-rays' were all forms of 'electromagnetic wave'. In the early 20th century, with the discovery of radioactivity, scientists like Max Planck and Ernest Rutherford completed the picture of the 'electromagnetic spectrum'. This was a cumulative achievement that transformed our vision of the physical world, and what we could do in it.

Physics

The Photon

BBC Radio 4 - In Our Time, The Photon

Generations of scientists have struggled to understand the nature of light. In the late nineteenth century it seemed clear that light was an electromagnetic wave. But the work of physicists including Planck and Einstein shed doubt on this theory. Today scientists accept that light can behave both as a wave and a particle, the latter known as the photon. Understanding light in terms of photons has enabled the development of some of the most important technology of the last fifty years.

Physics

The laws of motion

BBC Radio 4 - In Our Time, The Laws of Motion

In 1687 Isaac Newton attempted to explain the movements of everything in the universe, from a pea rolling on a plate to the position of the planets. It was a brilliant, vaultingly ambitious and fiendishly complex task; it took him three sentences. These are the three laws of motion with which Newton founded the discipline of classical mechanics and conjoined a series of concepts - inertia, acceleration, force, momentum and mass - by which we still describe the movement of things today. Newton’s laws have been refined over the years – most famously by Einstein - but they were still good enough, 282 years after they were published, to put Neil Armstrong on the Moon.