How do we know the age of the Earth? The Bible has records that show about a 6,000-year history back to the beginning. But for the evolutionist, billions of years is the assumption. Ask an evolutionist how he knows the Earth is this old and he will probably tell you something about fossils, rocks, and dating methods. Yet in most cases, people I’ve talked to know little about how these methods actually work.
No one has a time machine to go back and be an eyewitness of the origin of the universe, but a whole lot is riding on the accuracy of these claims. If Earth is really billions of years old, then the Bible must be inaccurate. But if the Bible is true then most of the secular truth claims are completely wrong. With so much riding on the age of the Earth, perhaps it is worth understanding these methods a bit better. In this series of articles I plan to summarize the basic ideas behind the major forms of dating and let you draw your own conclusions about their reliability. We’ll start with the most familiar, carbon dating, and later talk about other dating methods.
Most people know little about how scientific dating methods actually work, but a whole lot is riding on the accuracy of their claims.
Carbon dating is the most common method of dating ancient objects. It is almost a household word. But how does it work? In general, radioactive carbon 14 (C14) is created when nitrogen, high in the Earth’s atmosphere is struck by high energy particles from space. This C14 combines with oxygen and becomes the very heavy gas, carbon dioxide, which eventually sinks to the bottom of the atmosphere. There it is absorbed by plants as a natural part of their respiration process. These plants are eaten by animals and humans, and the C14 in them becomes part of our bodies and all the things we make out of animal and plant material.
This C14 is radioactive, unlike the normal carbon that forms the foundation of most of the chemistry in our bodies. Normal carbon has six protons and six neutrons for an atomic weight of 12, but C14 has more neutrons making it as heavy as the nitrogen it came from, with an atomic weight of 14. We call variations of elements that have the same number of protons but different neutron weights isotopes. The normal isotope of carbon is called C12. But the radioactive C14 isotope is unstable and slowly decays back to the original nitrogen over time by releasing the energy it absorbed when it was formed. Radiation detectors can pick up the faint energy being released and can estimate the amount of radioactive carbon that is changing back at any moment.
Radioactive decay takes time, and not all C14 takes the same amount of time to decay. In fact, observations of other radioactive isotopes that decay very quickly lead us to believe that each atom of a substance has an independent chance of decaying every moment, and some atoms take way longer than others to decay. We have estimated that it takes about 5,730 years for half of the radioactive carbon in a substance to change back to nitrogen. This is called its half-life, and the amount of time required is very predictable for the half-lives of all other shorter-lived radioactive substances in our experience.
But knowing how much C14 is in a sample now can only tell us directly how much longer it will be before all the radioactive carbon disappears. To find out how long it has been decaying, we must know how much was there in the first place (when the creature died) and use the loss of C14 to calculate the sample’s age.
The problems with carbon dating are not in the method but in the assumptions the method makes.
To discover the original amount of C14 in a sample we have to recognize that all the carbon in our bodies and in every living thing has come from the environment around us. And we can measure the relative amount of C14 to C12 in the environment today. So, to trust carbon dating, we must assume that this ratio has not changed significantly over the history of living things. We have to assume that the ratio in you and me and every living thing is approximately the same as what is in the environment, which is sensible. When we die, we have no way to keep up our carbon intake, so the ratio should shrink over time, eventually becoming undetectable in about 100,000 years.
Armed with an estimate of the original amount of C14 (from environmental measurements that we assume have always been true) and a measurement of the amount in an organic sample now, we can do a little math to determine how many half-lives of C14 have elapsed since the organic thing we are dating died. For more details on this process, a nice summary is here.
You can see, perhaps, why people are very confident of C14 as a clock for measuring the age of old organic objects. Carbon dating depends on objective measurements, observations of the environment, and math. What could go wrong with such a nice, neat solution? The problems are not in the method but in the assumptions the method makes.
Here are the assumptions C14 dating makes:
- The ratio of C14 to C12 has been constant over the history of the Earth.
- The radioactive decay rate has not changed significantly over time.
- The sample we are testing has not been contaminated by loss or addition of C14 between its death and our measurements.
These are very strong assumptions if you also assume a naturalistic worldview where things are very old and change very slowly over time at constant rates governed by natural laws. But if you believe in a living, active Creator who made the Earth and all of nature relatively recently, there are problems with these assumptions.
I’ll discuss those problems in a bit, but first I want to take a moment and underscore this very important point: The assumptions for this scientific measurement process depend entirely on the assumed truth of the naturalistic worldview. They do not prove this worldview, they simply require it to be true without proof. Evolutionists don’t like to admit that they start with anything but their observations and their own rationality. But right from the beginning, they have to assume a godless universe for their methods to work. Science always depends upon your assumptions, and the naturalistic worldview is the queen of assumptions.
But if we start out with Biblical Creationism as our worldview, we have reason to find problems with these C14 dating assumptions. First, it makes sense that C14 started being generated in the atmosphere near the beginning, but we have reason to believe the Earth was better protected from radiation earlier on because the Bible talks about people living in a different environment early on and living to long ages prior to the flood. Before the flood, there would have been almost no C14 in the environment, and almost none in living things. That means that pre-flood artifacts should have started out with significantly less C14 than more recent ones. Less C14 to start with means these assumptions make pre-flood artifacts appear exponentially older than they actually are.
Evolutionists¬†have to start out assuming a godless universe for their methods to work.
Second, while we have no evidence that the rates of decay have changed, we do know that the curse found in Genesis changed things fundamentally. Things decay now that didn’t initially. Death was brought into the world with the first sin. So we have reason to believe that God did indeed alter physical processes whose constant rates we depend on today. While sin and the curse may not have specifically changed the decay rate of C14, this same assumption is more suspect in other decay processes I’ll discuss in a later article.
Third, Biblical Creationists cannot assume that artifacts from before the flood were not tampered with. The global flood of Genesis definitely changed the mineral content of living things caught up in it. Many were fossilized by being injected with minerals that did not naturally occur in them. Naturalistic scientists consider the idea of a global flood ridiculous, but their worldviews are assumptions made without proof. Their ridicule of our worldview is based on their worldview, which is just arguing about assumptions.
A final note: radioactive carbon dating, even if it were totally reliable, is only useful for dating objects back 100,000 years or so. Beyond that the amount of C14 is too small to be reliably detected. Even if we were to be really generous and say we can date back to a million years, nothing older than that could be dated using C14 reliably. Thus, there is no way for evolutionists to claim, on the basis of carbon-dating alone, that dinosaur bones are 65 million years old, for instance. If anyone tells you that such ancient fossils were carbon dated, that is a sure sign he doesn’t understand the science he is spouting. So how do they come up with those old dates? They date the fossils by the rocks found with them. I’ll discuss rock-dating methods in future articles, but this is enough for now.
This article has been a very brief, non-technical presentation of carbon dating and some of the problems with it. For those interested in a more detailed analysis, I refer you to the Institute for Creation Research (ICR) website and this article. Until next time, remember that for evolutionary methods to work you must first assume their worldview. But if you start from the historical record of the Bible, all their assumptions fall apart.
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