A century of transistors, nuclear weapons and space

UNDER THE MICROSCOPE:TODAY I LIST 10 scientific discoveries of the 20th century that, in my opinion, have had the biggest effects on our lives.

1 The transistor:The transistor is a semiconductor device used to amplify or switch electronic signals. It is a vital component of almost all electronic devices, eg computers. The transistor has made miniature, yet highly complex, electronic equipment feasible. Today you can hold a more powerful electronic device in your hand than could be housed in a large building 50 years ago. The world we know would not be possible without the transistor.

2 Television:TV is a favourite leisure activity for most people. In 1927 moving images were transmitted for the first time from Washington DC to New York City. Today, everything is available on TV – news, sport, music, drama, arts, educational material, etc. Unfortunately, most people spend too much time passively watching light entertainment on TV.

3 The internet:The internet has coalesced into a single mass of information from which any connected computer can access information on anything under the sun. It is revolutionising many fields, eg education. Unfortunately, like TV, it is most commonly used for trivial or counterproductive ends, such as playing games or watching pornography.

4 Antibiotics:Alexander Fleming discovered penicillin in 1928, and in the 1930s Howard Florey developed penicillin for use as a powerful antibiotic, thereby revolutionising medicine. Antibiotics are chemicals that kill bacteria or stop their growth. They are widely prescribed in medicine to treat conditions such as bacterial meningitis, neurosyphilis, endocarditis, skin infections, burns, respiratory/ urinary/gastrointestinal infections, TB, pneumonia, anthrax, STDs, Lyme disease, bronchitis, severe acne, blood poisoning, and so on. Much of the pharmaceutical industry grew on the back of antibiotic production.

5 Birth control:Reliable birth control only became available in the 20th century. The contraceptive pill, introduced in the 1960s, contains hormones that block the release of a woman's egg in the monthly cycle, thereby preventing fertilisation and pregnancy. Birth control has had enormous social impact. The ability to control fertility without sacrificing sexual relations has allowed women for the first time in history to make long-term educational and career plans. However, many people argue that the easy separation of sexual activity from reproduction has also had negative consequences, such as increasing marital infidelity.

6 Nuclear weapons:The atomic bomb was developed by the Allies in the Manhattan Project (1942-1946). In 1945 the Americans dropped two atomic bombs to devastating effect in Japan, killing around 103,000 people within four months. Soon afterwards the Russians developed their own atomic bomb and the nuclear arms race began. This race ran until the late 1980s with the world looking on in fearful anticipation of the outbreak of a nuclear war that would end civilisation. Nuclear weapons remain with us as a testament to our immaturity as a species.

7 Space exploration:The development of rockets, telescopes and other technology that allow us to study the universe and travel into space has had an enormous influence on our imaginations and sense of our own significance and worth. The picture of the beautiful blue earth taken from the moon in 1968, shrouded in wispy clouds, standing out against the barren blackness of space, told us more about our place in the universe than all the books ever written on the environment.

8 Power-controlled flight:For most of human history people lived their lives in and around their places of birth. By 1905 Orville and Wilbur Wright had advanced their airplane design to the point where the aircraft could maintain a sustainable flight and land safety. Today we can travel from our local airport, at relatively little cost, to any place on earth.

9 Mass electrification:Prior to the 20th century, the population of the world lived without electricity. The economic and social progress made in the 20th century would have been impossible without universal access to reliable and affordable electric power. The Shannon Scheme for the Electrification of the Irish Free State was opened in 1929. It was executed by Siemens to harness the Shannon River and was one of the largest engineering projects of its day. It was a model for large-scale projects worldwide.

10 X-ray diagnostics:Although discovered by Wilhelm Roentgen in 1895 and immediately put to use in medical diagnosis, the use of X-rays in medicine didn't blossom until the 20th century. The ability to quickly visualise internal bodily organs and tissues without the need for invasive surgery or trauma is a wonderful boon.

Other authors’ lists of significant developments can be read on sites such as buzzle.com and toptenz.net.

William Reville is University College Cork’s associate professor of biochemistry and public awareness of science officer – http://understandingscience.ucc.ie