Re:DNA has a 521-year half-life (2012)
by ReaLNero on Saturday February 05, 2022 @10:38AM
(#30222100)
A half-life of 10,000 years means the fraction (0 to 1) of healthy bonds at year t can be modeled by (1/2)^(t/10000). To have 1% bonds broken, it would take an expected 145 years.
EDIT: Fixed the numbers, my bad!
[ Parent
| on HN ]
>>> log(0.99, (1/2)**(1/10000))
144.99569695122509
Re:DNA has a 521-year half-life (2012)
by jdmoreira on Saturday February 05, 2022 @10:47AM
(#30222190)
I don't understand this. Does half-life even say anything else about the probability distribution?
aren't you assuming specific distribution here?
It's not a terrible assumption to make. We just need to assume[1] that the decay events are independent, that is, every bond flips a coin every 500 years and if it comes up heads, it breaks, independent of what the other bonds do. That is, the process is inherently "local", individual bonds having no way of knowing what the other bonds are doing.
[1] It may be a bit worse in the long run, since if many bonds break, the higher order DNA structure gets damaged and that may change the rate of decay experienced by individual bonds (?).
half lives (specifically, the "decay" of any individual thing is stochastic but the aggregate of many molecules models exponential decay (in radioactivity. I have no idea what happens in a complex mash of DNA)
Re:DNA has a 521-year half-life (2012)
by stocknoob on Saturday February 05, 2022 @11:38AM
(#30222806)
This shows the importance of mental gut checks.
If indeed 1% break after 15 years, then 10% (ignoring compounding) break after 150 years, and 50% after 750 years. That doesn’t square with a half life of 10,000.