There is no reason to expect that the rate of decay of a radioactive material is largely constant,<ref>At least one example of a change in the rate has been observed in laboratory experiments. See Walker, 2000.</ref> and it was almost certainly not constant near the creation or beginning of the universe. | There is no reason to expect that the rate of decay of a radioactive material is largely constant,<ref>At least one example of a change in the rate has been observed in laboratory experiments. See Walker, 2000.</ref> and it was almost certainly not constant near the creation or beginning of the universe. |