If plastic was made in 1907 how do they know it may take up to 1000 years to decompose?
In: Chemistry
Imagine you only had the first half of a video of an ice cube melting. Can you extrapolate what happens in the second half of the video, and how long it will take?
We did experiments. Put it under really intense heat and ultra-violet lamps, packed it into material with enzymes and microbes, etc. We took lots of measurements at how fast the material breaks down, and projected it outward. Plastic doesn’t last 1000 years and then one day falls apart, it is affected by the environment and steadily breaks down, in a predictable fashion.
You don’t need to time me over the course of a 100 mile drive to tell if I’m going 100 miles an hour. You can simply measure how long it takes me to go one mile and multiply that by 100.
IRL the vehicle measures how fast the wheels are rotating. Knowing the circumpherence of the wheel allows the vehicle to compute how far you would go at a given speed in an hour. It doesn’t take an hour to calculate that.
Same thing with plastic. You can measure how much it decomposes in one year, and determine how many more years (approximately) it would take to break down all the way.
There’s a lot of patronizing answers on here but it’s a fair question.
Basically, you assume that a certain plastic decomposes by a physical and chemical process which we understand and can quantify in a mathematical model.
Then you do some algebra using the equations that describe that model and, voila, you have your answer.
Of course this assumes there are no other processes that affect decomposition that aren’t captured in the initial model.
I can explain this like you’re actually five.
You have five pieces of candy, and every minute you eat one. So how long will it take to eat all of them? That’s right, 5 minutes total.
We can do the same for this math problem, we measure how long it took to eat one candy to estimate how long it takes to eat the others without even having to eat them.
You know how when you are downloading/copying/transferring files on your computer, it says how long it’ll take, even though it isn’t completed yet. Calculation is based on how much competed over a short period of time, much like plastic decomposition can be observed in a few years, to determine how long before it’s mostly broken down.
I read a comment about a plastic engineer that said that plastic doesn’t take up to 1000 years to decompose. May have been bullshit.
He said something like the stabilizers that help the plastic not break down don’t take up that much to decompose.
There are different types of plastic, and they all break down eventually. I’d believe the thousand years is a generalization, isn’t it?
It has been explained below – but it just made me think of an even more absurd example: we have experimental evidence, that the half-life of proton (which is, simply speaking, the typical time it takes for a proton to decay) is at least 1.67×10^34 years, even though that’s 24 orders of magnitude longer than the existence of the Universe, so it’s … pretty damn sure nobody has watched a proton that long! It’s simply because there is a *lot* of protons to watch and particle decay happen randomly, so even if the average time is unfathomably long, if you watch enough protons, one would be almost guaranteed to decay in an accessible time frame if their half-life were “short” enough. (We still do not know whether they decay at all, this is just as close as we come experimental get to saying that they don’t as we can.)
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