Evidence for a beginning
The Age of the Earth
Toward the end of the 19th century new evidence was accumulating that the universe is not eternal and uncreated.
Ocean Salinity
The passage above from Ecclesiastes provided one of the first clues that the Earth is not ageless. All streams flow into the sea, yet the sea is never full. To the place the streams come from, there they return again. Streams start with fresh water from rainfall, but as they flow they leach salts out of the earth. Long before streams reach the sea they have measurable salinity. The saltiness of the sea is much greater than that of the streams. This is because salt does not evaporate when the Sun shines on seawater. Salt accumulates in the sea, but water does not. Clouds carry the fresh, unsalted water vapor over the land. When mountain slopes force the clouds upwards the water vapor cools, and the water falls as rain to feed the streams. Therefore the salt content of the oceans is always increasing.
In 1899 John Joly of the University of Dublin estimated the age of the Earth. He calculated that it would take 80 or 90 million years for the rivers to build up the sea’s salinity to its present value.[i] If the streams had been flowing forever then all the salts would be gone from the soil, and stream water would not have measurable salinity. The age Joly estimated for the Earth may be far from the true age, but one result is clear: The Earth is not eternal and uncreated.
[i] Badash, Lawrence, “The Age-of-the-Earth Debate,” Scientific American (August 1989), pp. 92–96.
In 1899 John Joly of the University of Dublin estimated the age of the Earth. He calculated that it would take 80 or 90 million years for the rivers to build up the sea’s salinity to its present value.[i] If the streams had been flowing forever then all the salts would be gone from the soil, and stream water would not have measurable salinity. The age Joly estimated for the Earth may be far from the true age, but one result is clear: The Earth is not eternal and uncreated.
[i] Badash, Lawrence, “The Age-of-the-Earth Debate,” Scientific American (August 1989), pp. 92–96.
Radioactivity
Other evidence for the finite age of the Earth came from the discovery of radioactivity. Certain elements are unstable and radioactive. Occasionally one of the nuclei splits apart spontaneously. The process of splitting is called fission. It often releases gamma rays.
The crust of the Earth includes some radioactive elements. They gradually decay into stable elements like lead. The decay releases energy that heats the melted rock or magma under the crust of the Earth. Non-uniform deposits of radioactive elements are partly responsible for heating and lifting parts of the Earth’s crust. They create volcanoes, mountains, and continents. Without them the Earth might have dry land only at the frozen poles, and most life would be aquatic.
The crust of the Earth includes some radioactive elements. They gradually decay into stable elements like lead. The decay releases energy that heats the melted rock or magma under the crust of the Earth. Non-uniform deposits of radioactive elements are partly responsible for heating and lifting parts of the Earth’s crust. They create volcanoes, mountains, and continents. Without them the Earth might have dry land only at the frozen poles, and most life would be aquatic.
Natural Radioactive Elements
The discovery of natural radioactivity is evidence that the universe and the Earth have finite ages. It shows that matter is not eternal and unchanging. If matter had existed for an infinitely long time, by now all spontaneous fission and radioactive decay would have ceased. If the Earth were infinitely old, eternally existing, and uncreated, then long ago all the radioactive elements would have decayed completely.
If the same processes produced the Earth and the rest of the universe, then the rest of the universe should also have a finite age. But, did the universe have a beginning? The answer began to come when we found out that the Earth is not the only part of the universe that has radioactivity. Astronomers discovered radioactive elements in the stars.
If the same processes produced the Earth and the rest of the universe, then the rest of the universe should also have a finite age. But, did the universe have a beginning? The answer began to come when we found out that the Earth is not the only part of the universe that has radioactivity. Astronomers discovered radioactive elements in the stars.
