It's about Time: From Calendars and Clocks to Moon Cycles and Light Years - A History - Hardcover

Evers, Liz

Hardcover

ISBN 10: 1782430679 ISBN 13: 9781782430674

Verlag: MICHAEL OMARA BOOKS, 2014

Inhaltsangabe

Beautifully packaged, this book examines the people and places behind time's inventions, as well as reveals oodles of quirky facts related to timekeeping

From the ice-age recordings of moon cycles and the earliest calendars, to modern wristwatches and quantum clocks, time and its effects have always enthralled mankind. People have spent centuries developing new ways of measuring time, describing it and quantifying it, and such methods have given rise to some of the most technically and aesthetically beautiful devices ever invented. This book is a tribute to timekeeping in its many forms and takes in the most significant creations as well as countless time trivia. Peppered with time-related anecdotes and quotes, this is an essential handbook for anyone fascinated by the fourth dimension.

Über diesen Titel

Über die Autorin bzw. den Autor

Liz Evers is the author of I Told You I Was Ill and I Used to Know That.

Auszug. © Genehmigter Nachdruck. Alle Rechte vorbehalten.

It's About Time

From Calendars and Clocks to Moon Cycles and Light Years – a History

By Liz Evers, Greg Stevenson

Michael O'Mara Books Limited

Copyright © 2013 Michael O'Mara Books Limited
All rights reserved.

ISBN: 978-1-78243-067-4

Contents

Acknowledgements, 
Introduction, 
1. The Land Before Time, 
2. Marking Time, 
3. Keeping Time, 
4. The Best of Times, 
5. Modern Times, 
6. Future Time, 
7. Space–time, 
8. Thinking Time, 
References, 
Index, 

CHAPTER 1

The Land Before Time

Happy Birthday Planet Earth

In 1654, the Anglican Bishop of Armagh, James Usher, announced that the universe was created at six o'clock on the evening of 22 October 4004 BCE. He reportedly came to this rather definitive conclusion after years of studying the Bible and world history. This theory of the Earth's age was pretty popular right up to the nineteenth century, when the study of geology and Darwin's theory of evolution made it clear that the world was considerably older.

It is now widely believed to be 4.54 billion years old – or written out in full – 4,540,000,000 years old. That's a lot of years. The 4.54 billion figure has been reached using rather complex mathematics combined with the methods of 'radiometric' dating – which include radiocarbon dating, potassium-argon dating and uranium lead dating.

At its most basic, radiometric dating looks at radioactive decay. It compares the amount of a naturally occurring radioactive chemical component (isotope) and its decay products – we know, for example, that the radioactive component uranium decays to become lead, so looking at the amount of lead left in a rock one can calculate how much uranium there would have been to start with and so how long it has taken to produce the lead.

Applying these techniques to really, really old rocks and minerals – including meteorites and lunar samples – the magic figure of 4.54 billion has been reached and agreed upon. For now.

The oldest known terrestrial materials are zircon crystals found in Western Australia. These have been dated as over 4.4 billion years old. The oldest known meteorite matter is 4.567 billion years old. It is believed that our solar system can't be much older than these samples.

Which brings us to the time before there was an Earth, or a solar system to house it. To when our universe was born. The prevailing theory is that of the Big Bang, when the universe started expanding from a dense and hot state – and continues to expand into space, which is itself continually expanding.

The geologic time scale

Coming back down to Earth again, something called the 'geologic' time scale is used by earth scientists, geologists and palaeontologists to describe timings and events in our Earth's past. It relates time to 'stratigraphy' – the study of layers of rocks (stratification).

There are many wonderful examples of stratification bearing testament to the Earth's long history. Examples are found in chalk layers in Cyprus, the stunning Colorado Plateau in Utah, exposed strata on mountain faces in the French Alps, and the amazing Stratified Island near La Paz, Mexico, to name but a few.

The units used to describe geologic time are very long. They include Eons (half a billion years), Eras (several hundred million years), Epochs (tens of millions of years), and Ages (millions of years).

Taking it as read that the Earth is 4.54 billion years old, the deposits of our old pal zircon, the oldest known mineral, were found during the Hadean Eon in the Cryptic Era. This is when the Moon and Earth were formed. Between 500 and 600 million years later in the Eoarchean Era, simple single-celled life came into being, evidence for which is found in microfossils – that is, fossils which are not larger than four millimetres, and often smaller than one millimetre, and which can only be studied using light or electron microscopy.

Skipping ahead to the Proterozoic Eon, geologic evidence shows that our atmosphere became oxygenic (specifically during the Palaeoproterozoic Era some 2.05 billion years ago), then the first complex single-celled life, protists, came into being around 1.8 billion years ago.

It took another 1.2 billion years for the first fossils of multi-celled animals (worms, sponges, soft jelly-like creatures) to show up during the Neo-proterozoic Era (around 635 million years ago) and these evolved into yet more complex fishy creatures during the long Palaeozoic Era (between 541 and 255 million years ago). By the end of this Era the landmass known as Pangaea had formed, comprised of North America, Europe, Asia, South America, Africa, Antarctica, and Australia. Various reptiles and amphibians were roaming about and basic flora, mosses and primitive seed plants had developed, while a host of marine life flourished in shallow reefs.

Thence to the Mesozoic Era. During its Triassic, Jurassic and Cretaceous Periods (between 252 and 72 million years ago) the dinosaurs, first mammals and crocodilia appeared. Then flowering plants and all manner of new types of insects. Towards the end of the Cretaceous Period there were many new species of dinosaur (though not for long) and creatures equivalent to modern crocodiles and sharks. Primitive birds replaced pterosaurs and the first marsupials appeared. Plus atmospheric CO2 was close to our present-day levels.

Which brings us to our own Era – the Cenozoic – which started some 66 million years ago and is often referred to as the 'age of mammals'. In the early part of this Era, the dinosaurs were extinct (more on this to follow) and mammals were diversifying, but it would still be another 40-plus million years before the first apes, our evolutionary ancestors, appeared.

And it wasn't until just 200,000 years ago that the first anatomically modern humans appeared and only 50,000 years ago during the Holocene Epoch (which we're still in) that we started tinkering with stone tools.

The bottom line is the Earth is very old, and we are very young upon it. To put things in perspective, if you think of the age of the Earth as a 24-hour clock, the first humans appear just 40 seconds before midnight at 23:59:20.

Ice ages

Technically, we are still in an ice age. Admittedly at the tail end of it, the worst was over around 12,500 years ago. It began 2.6 million years ago, but the presence of ice sheets in Greenland and the Antarctic signal its continued existence.

The Swiss geographer and engineer Pierre Martel (1706–1767) was the first to posit the theory of ice ages. On a visit to the Chamonix valley in the Alps, he observed that the dispersal of boulders pointed to the fact that the glaciers had once been much larger, but had contracted with time. And this phenomenon was observable in other parts of Switzerland, Scandinavia and later noted in the Chilean Andes. But it wasn't until the 1870s that the theory was widely accepted as fact.

In addition to the erratic dispersal of large boulders, other evidence of ice ages comes in the form of rock scouring and scratching, valley cutting, the creation of small hills called drumlins and unusual patterns in the distribution of fossils.

There have been at least five ice ages in our Earth's history – and outside of these ages the Earth appears to have been free of ice, even at high latitudes. The first ice age was the Huronian, which is thought to have extended from 2.4 billion years ago...

Details zur Ausgabe

• Verlag: MICHAEL OMARA BOOKS
• Erscheinungsdatum: 2014
• Sprache: Englisch
• ISBN 10: 1782430679
• ISBN 13: 9781782430674
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 224
• Kontakt zum Hersteller: Nicht verfügbar
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