The method geochronologists (scientists that date rocks) use to determine the age of the Earth is a method that requires the measurement of Argon-40 in rock samples. This method is called Potassium-Argon Dating. There are a few different types of potassium. The one we are interested in for this particular application is Potassium-40. It accounts for .0117% of all potassium. Potassium-40 has a half-life of 1.25 billion years. This means it takes 1.25 billion years for Potassium-40 to fall to half of its initial measured amount.
Now how are potassium and argon related? Well, when Potassium-40 begins to degrade, it will be degraded into Argon-40. The actual number that Potassium-40 will be degraded into is 11% Argon-40 and 89% Calcium-40. Now when rocks initially begin to form, let us use volcanic rock for example, there will already be a presence of Argon-40. Because the rock is still in a liquid state the Argon-40 will seep out because it is a noble gas. By the time the rock completely hardens all of the Argon-40 is gone and one of the important elements we are left with in our volcanic rock is Potassium-40. This stuff then begins to degrade and we start to have measurements of Argon-40 returning to the rock. We then take a sample and proceed to calculate how much Argon-40 we find in this volcanic rock. This becomes an indicator for how old the rock is because Potassium-40 will only degrade into a certain percent of Argon-40 over a period of time.
If you would like me to walk you through the actual equation used to calculate the age of rocks through the Potassium-Argon dating method, I can do so. It is basically high school math.
Now I am going to get into a bit of astronomy because it is also vital knowledge to possess.
It was found that it takes forty-two and a half hours for Io, a moon of Jupiter, to complete one orbit. Astronomer Ole Romer noticed Io would however immerge from a complete orbit later or earlier than expected, depending on the time of year. He realized that this variance occurred depending on the distance between Earth and Jupiter. Romer had just discovered that light does not travel instantaneously. It will take a longer amount of time for the light of an object to reach us when it is further, and a shorter amount of time when it is nearer. If I must, I can go into how we measure the speed of light and the distance to celestial objects, but I will only do that upon request.
The speed of light travels 300,000 kilometers per second or 1,080 kilometers an hour. Why do I suddenly bring up the speed of light? Well, because the speed of light is how astronomers measure great distances in astronomy and it also enables us to have insight to how our Earth came into being. Nobody wants to use 20, 30, or more digits in describing the distance to a celestial object in a paper or lecture. It would take too much time. And here is the perfect segue to describe exactly what the speed of light is. It is not only the measurement of distance, but also the measurement of time. Alpha Centarui is the nearest star system to us (we reside in the Solar System, which is our personal star system). It is 4.37 light years away. This means that it takes light from Alpha Centarui 4.37 years to reach us. Thus, we are seeing that star system as it was 4.37 years ago. Our star system, the Solar System, sits in a galaxy we have named the Milky Way Galaxy. It is approximately home to 300 billion stars. The nearest galaxy to our Milky Way is the Andromeda Galaxy, which is 2,538,000 light years away. This means that when we look at the Andromeda Galaxy, we are seeing it as it was 2,538,000 years ago.
Within our own galaxy we can witness the birth of stars in what we call a “Protoplanetary Nebula”. These nebulas also get referred to as stellar nurseries. These nebulas are the remnant gases of a dead star (a process that our own star, the Sun, will go through at the end of its life in about 5 billion years). Under the force of gravity and stellar winds, gas swirls around and collects very densely into one area creating a new star. Other gasses and elements also come together to form orbits of dust and rock around the newly formed star. These elements eventually collide and stick together, forming new planetary systems. By witnessing this in several stellar nurseries, we can essentially look into a visual record of how our own star system came into being and even measure the time it takes to form a star system.
So now we know how our planet was created, and we know how to date really old things. Through geology we can see visual records on the development of our planet. Modern day earth quakes give insight into the movements of the Earths plates, showing us how are continents move and evolve. Satellite imagery gives us the ability to map and study deep sea volcanoes and other structures and how they formed the land masses that we know of today. Volcanology, the study of volcanoes, gives us evidence and insights into how our atmosphere, oceans and lands were created, and of course eventually the development and evolution of life. Through biology, zoology, and botany, we can study the actual development of life on Earth and measure its changes over time.
There is so much science here, and what I have presented is a very elementary view of it. To really get a grasp of all this and to learn more, it really requires you to study these fields of science in great detail. What is so great about science is its scientific method. It is completely objective and open to change. However, in order to disprove something already proven or theorized by science, you must develop a hypothesis, acquire data that can be tested, perform your test/experiment, analyze the results, then be able to re-test it (if it cannot be re-tested then how can you find any actually truth to your claims/hypothesis?), analyze that data, draw a conclusion, submit it for evaluation and at which point debate and analysis of your data and testing’s will be judged for accuracy and authenticity, then finally through peer review your conclusion will be proved, disproved, or found to be requiring more data and testing. It is a long and often tiring experience, but it enables us to discover accurate truths. Despite the trials it puts scientists through, it is always thrilling to discover something new. Even if it completely goes against what you initially theorized or believed to be true. It is in discovery of new knowledge that drives a scientist and perpetuates the thrill of it all.
I would also like to add (because I have the feeling it may have been brought up at some point here, but I do not have the time to read every post), the most horrible thing anyone can do to the scientific method is say, “how do we know that conditions that exist today were the same when the Earth was being developed?” Skepticism is not a bad thing, but to dismiss all of the evidence and laws of nature as we know it is absolutely wrong. It is unobjective, and it completely works against the development of scientific knowledge. Evidence must be provided. There is a long man made history to the Bible that must be met with skepticism and evidence found through the artifact/anthropological/written record of time. Ignoring these things and allowing oneself to believe in any particular thing without sufficient data and analysis, pushes humanity into believing fallacies. There is no evidence to suggest that the laws of nature existed differently at another time in our development. I urge everyone taking part in this discussion and who are reading it to not negatively judge or dismiss scientific investigation or my attempt to be objective in my post. I also urge everyone to study the scientific method. It is among one of the most important discoveries and way of investigating the world in which we live and the Universe in which it resides.
I also implore that we all be respectful of each other and the time we take to discuss these important subjects. Less is achieved through hostile disagreement. It is also very beneficial to research things we believe to be facts before standing sternly with them. Education and objectivity are two of the most important things to discovery and civility.
