I found it hard to word but like for example when shaking choccy milk how does the chocolate syrup know to spread evenly in the milk, and like other stuff to like when mixing alcohol with stuff. So like how does stuff already evenly or does it not and we dont know?
In: Chemistry
Particles of syrup and particles of milk scatter at random, without “knowing” anything, and yet, as a result, they end all mixed up really well. Why is that, you ask? It’s just that possible configurations where milk particles are all on one side and syrup particles are all on the other are few, while configurations where they are all mixed are plenty. **There is nothing more to it.**
See it for yourself, by simplyfing things a bit. Say you have a cup with just 4 particles (2 milk and 2 syrup):
X : *syrup particle*
O : *milk particle*
[ – – – – ] : *the cup, with 4 slots for a particle*
Let’s list *every* possible configuration for the particles to be in the cup:
1: [ X X O O ]
2: [ X O X O ]
3: [ X O O X ]
4: [ O X O X ]
5: [ O X X O ]
6: [ O O X X ]
See? out of 6 possible configurations, only in 2 (n.1 and n.6) the milk and the syrup are well separated. In all the others, they are pretty much all mixed up.
If you repeat this with 6 particles (3 O and 3 X), you’ll see that the disproportion gets bigger. There are 20 configurations now in the list of possibilities, and in only about 4 of them the milk and the syrup are more or less separated (like [XXXOOO] or [OOXOXX]). In all others, they are mixed up pretty well (like [OXXOXO] or [XOXXOO] or [XOXOXO]).
Try 8 particles next. The list of different configurations gets quite longer (they are 70), but only maybe 6-8 of them are well sepatated (depending on how you count them exacly).
And so on. The more particles you use, the more configurations are possible, and, proportionally, fewer and fewer of them are *not* all mixed up.
Your *real* milk and syrup cup is a bit more complex, but the exact same principle applies. It has many many many particles (it takes around 25 digits to write down that number), and the number of possible configurations is unimaginably large (don’t even *try* to write it down in the normal way). The important point is, only in a unimaginably tiny proportion of them the milk and sirup are well separated: in all the others, they are all mixed.
So, it is absurdly unlikely that you just end up in one of the incredibly rare well-separated configurations. Note that there’s no “real” physic law against these configurations. They can legitimately happen, just as much as any other configuration. It’s just that there’s so few of them, compared to the total number, that it’s basically impossible that you ever stumble upon one.
This is what is called the principle of *increasing entropy*, and it shapes the universe. Believe it or not, it even determines that time flows in a direction (“past” is not the same directon as “future”).
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