The 1800s ended with a number of unresolved problems. The Michelson-Morley experiment of 1887 had shown that space is not filled with Aristotle's aether. This meant there was no explanation for how light can travel through space, since waves usually need a medium to travel in, and would have as yet unknown implications for the nature of space and time.
"fixed stars that have been gradually wasted by the light and vapours emitted from them for a long time, may be recruited by comets that fall upon them; and from this fresh supply of new fuel these old stars, acquiring new splendour, may pass for new stars".
By the end of the 1800s, it had been suggested that the Sun could be fuelled by a chemical process, like combustion, yet even if the entire mass of the Sun were made of petrol, it would still only burn for about 7000 years*.
This was not considered a problem in the 1700s, when the age of the Earth was accepted to be about 6000 years. This was based on Irish Bishop James Ussher's argument that the world had been created on the 23rd of October 4004 BCE. Ussher had come to this conclusion by reading the bible and adding the male lineage from Adam through to Solomon. Beyond the time of Solomon, he cross-referenced the lineage of Kings with known historical data. Yet by the end of the 1800s, there was evidence that the Earth must be at least 35,000 times older than this.
The fossilised remains of unknown animals had been found for thousands of years, and were often only found in specific strata - layers of sedimentary rock or soil. In the 1790s, British geologist William Smith suggested that different strata have different ages, where one layer of rock or soil forms over another. He argued that if the same fossils were found in strata at different locations, then the strata are probably the same age.
British geologist John Phillips, used Smith's theory to show that there must have been at least three major geological eras: the Palaeozoic ('the Age of Fishes'), the Mesozoic ('the Age of Reptiles'), and the Cenozoic ('the Age of Mammals'). Phillips estimated that the Earth could be up to 96 million years old.
The remains of extinct dinosaurs were first correctly identified in England in the early 1800s. The first belonged to the herbivorous Iguanodon, discovered in Sussex by palaeontologist Mary Ann Mantell in 1822. The second was the carnivorous Megalosaurus, discovered in Oxford and identified by palaeontologist William Buckland in 1824, and the third was the armoured Hylaeosaurus, also discovered in Sussex, and first identified by palaeontologist Gideon Mantell in 1833.
British biologist and palaeontologist Richard Owen coined the term Dinosauria to encompass all three genera in 1842. Dinosauria is derived from the Greek words deinos, which is translated as 'terrible, powerful or wondrous' and the word sauros, which means 'lizard'.
Artist's impressions of Iguanodon, Megalosaurus, and Hylaeosaurus from the 1800s (these are no longer considered accurate). Image credit: Samuel Griswold Goodrich, Samuel Griswold Goodrich, & Benjamin Waterhouse Hawkins/Public domain.
British natural philosopher William Thomson, better known as Lord Kelvin, showed that it would take 20-40 million years for the Earth to cool to its current temperature from a molten state in 1897.
In 1898, Darwin's son, astronomer George Darwin, suggested that the Earth and Moon had once been part of the same molten mass but had broken apart. Astronomers now think that this occurred when it was hit by an object the size of Mars. George Darwin's theory showed that it would take at least 56 million years for the Moon to become tidally locked with the Earth, so that we only see one side.
Finally, in 1899, Irish physicist John Joly showed that it would take about 90 million years for the oceans to have accumulated their current salt content through mineral erosion.
2. 20th Century solutions ↑
We now know that the Earth is about 4.54 billion years old. This was first determined by American geochemist Clair Cameron Patterson using the radioactive dating of meteorites in 1953.
American astronomer Edwin Hubble estimated that the universe is about 9 billion years old in 1929. Hubble's calculations have since been refined to show that the universe is about 14 billion years old.
Mass = 2×1030 kg,
Rate of combustion =
Luminosity/Energy consumption during combustion=
3.9×1026/45×106= 8.7×1018 kg/s.
Mass/Rate of combustion=
2×1030/8.7×1018= 2.3×1011 s = 7,300 years.