Summarize advances over time in determining the age of the Earth, including the importance of the discovery of radioactivity.
For centuries, scholars, geologists, and astronomers sought to determine the age of the Earth. In 1862, physicist William Thomson determined the age of Earth based on the assumption that the Earth had formed completely from a molten object (Teichman & Stinner, 2003). Thomson calculated the time it would take for the near-surface temperature gradient to decrease to its present value and found the age of the Earth to between 20 million and 400 million years (Teichman & Stinner, 2003). However, many scientists had trouble accepting such as short age for Earth. In 1869, Thomas H. Huxley attacked Thomson’s calculations. Huxley argued that Thomson’s estimates were based on faulty assumptions. Herman von Helmholtz and Simon Newcomb, a physicist and an astronomer, calculated the age of the Earth based on the time it would take for the Sun to condense down to its current diameter and brightness from the nebula of gas and dust from which it was born. They carried out their calculations independently, and their values were consistent with Thompson’s calculations.
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Darwin’s son, George H. Darwin, proposed that the Earth and the Moon had broken apart immediately when they were formed. Based on the assumption of the amount of time it would have taken for tidal friction to give Earth its current 24-hour day. From his calculation, he determined the age to be 56 million, which proved that Thompson was on the right track (Sotirov & Savova, 2018). In 1892, Thompson had been made Lord Kelvin for his scientific accomplishments (Teichman & Stinner, 2003). Kevin used thermal gradients to calculate the age of the Earth and approximated it to be 100 million years. However, his estimate was invalidated because he did not realize the mantle of the Earth was convecting.
The discovery of radioactivity introduced another factor in the determination of the age of Earth. In 1989, Marie and Pierre Curie discovered the radioactive elements in polonium and radium. This upset the assumptions underlying most calculation of the age of the earth. The earlier assumptions assumed that the Earth’s and Sun’s original heat dissipated. However, radioactive decay meant that Earth’s and Sun’s heat continually replenished. Radioactivity overthrew older calculations, and provide a basis of new calculation in the form of radiometric dating. Radioactivity gave scientists and geologists the ability to research heat better. With this, radioactive decay provides better ability to calculate the age of objects.
What makes Earth a habitable, relatively stable environment within which we exist and survive? Review the early development of the solar system, including the Big Bang theory, to support your answer.
There are numerous factors that make the Earth a habitable, relatively stable environment within which human beings exist and survive. First, the location of the Earth in the Solar system or from the sun makes habitable. The Earth is at the right distance from the sun. Its location also gives the Earth the ability to remove excess carbon from the atmosphere. The second factor is the Earth’s magnetic field. The Earth is protected from harmful solar radiation by its magnetic field. The Earth also has the right chemical ingredients for life, including water and carbon, which makes it habitable as well as a relatively stable environment. The hydrological cycle gives the ability to regulate the climate of the Earth.
The reason the Earth has a climate is because of the big bang. According to the big bang theory, the Earth ended up the right distance from the sun. In other words, the Earth ended up in the habitable zone –not too hot, or not too cold. The Earth’s constant temperature keeps its atmospheric gases from escaping, which traps heat from the sun. This regulates the climate of the Earth, making it a habitable and relatively stable environment.
Alfred Wegener was a polar explorer and visionary. Describe how his early work was viewed with skepticism and how ultimately his theory of continental drift was proven.
In 1912, a German scientist, Alfred Wegener, proposed a theory that the continents once drifted apart –the Continental Drift Theory (Rhodes, 2017). Wegener suspected that the continents had once been joined. Wegener based his argument on the jigsaw fit of the continents. He drew from the field of geology, geophysics, zoogeography, and paleontology to strengthen his case. However, his work was viewed with skepticism and was heavily criticized. Other scholars viewed that his work crossed disciplines and that it lacked mechanism. However, Wegener kept the discussion of Continental Drift.
The Continental Drift Theory was proven by Jack Oliver, a geoscientist, in the 1960s (Rhodes, 2017). While studying earthquakes, Oliver was puzzled with seismic waves of deep earthquakes emanating beneath the Earth surface. Later, Oliver realized that the crust of the Earth was being bent down as well as pushed into the planet’s interior. Wegener’s idea is now accepted, thanks to the evidence presented in the 1960s of the spreading of the sea flow (Rhodes, 2017). Current studies have proved that volcanic activity of the mid-Atlantic Ridge and East Pacific Rise is capable of generating a lot of heat that can cause the sea to spread, as suggested in Wegener’s theory.
References
Rhodes, P. (2017). Dynamic Earth. [Online]. Retrieved from: https://www.geo.umass.edu/courses/geo105/Lecture%203%20DRIFT.pdf . Accessed 17 th August 2019.
Sotirov, A., & Savova, S. (2018). Forming of the moon. National Student Conference of Physics and Engineering Technologies. DOI: 10.13140/RG.2.2.18568.06408
Teichman, J. & Stinner, A. (2003). Lord Kelvin and the age-of-the Earth debate: A dramatization. Science & Education, Vol. 12, 213-228.
