science Feedback

ame: Shani Rupp and Emma Garthwaite Class Work #2

Physicists 1. The age can be seen through sampling the rocks. The rocks have

not changed since they cooled and other rocks were formed over them. 


2. The rocks get sampled through radioactive decay. When the rocks decay they show the unstable element. It is measured in half-life, so half of the time it takes the atoms left to decay. Since they can no longer escape. 


3. The way rocks decay has always been the same and will never change. Because we know the decay rate we can measure the age of the rock through calculations. 


Creationists 1. The discrepancy between 4.5 billion years and 4.6 billion years is

an incredibly long time––why such a large gap of uncertainty?


2. We weren’t there to observe the initial conditions in rock samples so we have no way to know what their base state was. We also weren’t there the entire time observing the rocks so we must make assumptions.


3. The amounts of parent or daughter elements may have been altered by other processes in the past affecting the rate at which they decayed.


4. How do we know that the decay rate has remained constant since the rock formed? Who’s to say it hasn’t sped up or slowed down during the time we have been able to observe and date their decay? 


Radiometric dating (shaky/unsupported and how they’ve been disproven)

1. Observational science how we look at things and calculate them can not always be specific because don’t know all the variables to keep it constant. 


1. Scientists have been able to disprove this with the theory of uniformitarianism––the idea that the same natural laws and processes that we can observe today have always operated the same way everywhere and everywhen in the universe. Uniformitarianism can be observed in the sedimentation observed in rock formations both on Earth and on Mars (sedimentation takes millennia if not millions of years to develop into the deep layers that are observable today) as well as through the formation of volcanic islands over time. While we do may not know all of the variables we do know how the rocks are behaving currently and so can infer through uniformitarianism that they have always behaved in the same manner.


2. Historical science and that it deals with things in the past and because it happened in the past it can not be re-tested. To measure a rock you need both observational and historical, because of that there can only be assumptions of how old a rock is. 


b. Though we have not been able to observe the rock’s entire history, scientists can determine the age of a rock, again, using the theory of uniformitarianism as well as radiometric dating.

3. How do we know the initial conditions of the rock? How do we know there was no alteration done to the rock throughout the past, that could change the elements (that give us the dating of the rocks). How do we know the decay rate has not changed throughout the past?


c. While we cannot know the exact initial conditions of the rock, scientists can infer them through radiometric dating by observing the rate of decay of uranium in zircon crystals. The rate at which uranium decays is a consistent lessening exponential slope (as measured by looking at its half-life) and no other process can alter that rate. If a rock was crushed or heated or eroded, the uranium within it would still decay at the same rate.