We will take this bit by bit.
- 0:28 – the narrator states that most scientists regard the age of the earth as between 4.55 and 4.6 and then remarks that, if this is so accurate, why the 50 million year discrepancy? He then states “That seems like a lot.” 50 million divided by 4.55 billion is 1.09%. That is the standard error. This date range is made up of thousands of individual dates. The speedometer on your car is less accurate than that (standard error of 2.5%). In fact, in any statistical test a 1% standard error is considered is equivalent to saying that you are 99% confident that the results you have are accurate. 1% is not a lot of anything. Also carefully omitted from the narrative is that these dates are derived from at least five different kinds of radiometric isochron dating:
- Lead-Lead isochron
- Samarium-Neodymium isochron
- Rubidium-Strontium isochron
- Rhenium-Osmium isochron and
- Argon-Argon isochron.
- 1:52 – After a reasonably straightforward description of radiometric dating, the narrator then, while admitting that it is true that a decay rate can be measured using “observational science,” it requires “historical science” to tell how old the rock actually is. He states that in order to get accurate measures from rocks, one would have to know both the decay rate and the initial conditions of the rock, otherwise we cannot directly measure the ages of rocks. He asks “how do we know what the initial conditions were in the rock sample?” and “How do we know the amounts of parent or daughter elements haven't been altered by other process in the past?” and How does someone know the decay rate has remained constant in the past?" He then says “They don't.” This is false.
- Timothy Heaton, Chair of the Department of Earth Sciences & Physics at South Dakota State University writes this about the parent/daughter ratios:
Isochron dating bypasses the necessity of knowing the quantity of initial daughter product in the rock by not using that value in the computation. Instead of using the initial quantity of daughter isotope, the ratio of daughter isotope compared to another isotope of the same element (which is not the product of any decay process) is used as the comparison for isochron dating. The plot of the ratios of the number of atoms of the parent isotope to the number of atoms in the non-daughter isotope compared to the number of atoms of the daughter isotope to the non-daughter isotope should result in a straight line that intersects the vertical y-axis (which is the ratio of daughter to non-daughter isotopes). This point of intersection gives the initial ratio of daughter to non-daughter isotopes, which would also be the ratio in a mineral that crystallized without any parent isotope present.Here is a web site that shows how this plot works in graphic fashion. The narrator's hourglass analogy is, therefore, inaccurate. We don't need to know how much sand was in the hourglass to begin with, nor did we need to observe the process. The decay rate is well-known and invariate, which leads to his second statement.
- As far as the variation in decay rates of radiogenic isotopes goes, they have been shown to vary only 0.1% in response to outside influences (here, and here) and have been shown to vary significantly only under extreme laboratory conditions not found on earth.
Such a perspective is facile, as it completely disregards the fact that we reconstruct past events every day at all levels, from the simple act of encountering a broken glass on the floor with ice and water beside it (someone dropped a glass of water) to complex murder investigations in which no one but the murderer was present. No one questions the validity of these assumptions and they form the basis for much of what we do in life, including our entire criminal justice system.
Secondary to this notion that we can reconstruct the past is that the processes that occur today also occurred in the past. If I am digging in a field and encounter, at a depth of three or so feet, a series of horizontal metal beams that are four and a half feet apart with ties in between them, because I know that distance is the standard railway gauge, I can reasonably assume that what I have uncovered is part of an old railway. Was I there when they built it? No, but I didn't have to be to have a pretty good idea of what it is.
This is true not just of human constructs but also of natural formations. Because we have modern floods, hurricanes, meteorite craters and so on, we can identify these formations in the past.
This puts historical science and all of its reconstructive observational power on level footing with observational science. While Ken Ham and others at Answers in Genesis might say otherwise, it simply is not so.
It is amazing how much damage to scientific and academic integrity one can do in a three-minute video. Answers in Genesis is, apparently, up to the task.