Early in the 1950s a Russian chemist by the name of Boris Belousov
reported one of the weirdest reactions that has ever been seen in chemistry.
It was a reaction that seemed to not be able to make up its mind.
Let me show you.
Now I'm pouring in a little bit of hydrogen peroxide into this mixture, and you can see
that yellow colour as iodine is produced.
Then it turns deep blue.
And then the whole process goes back to yellow again.
I mean, this reaction flip flops between these yellow and blue states.
To the chemists who read the report, this seemed a complete outrage.
Could this reaction actually represent a violation of the second law of thermodynamics?
Let me explain:
In a typical chemical reaction in which A is reacted with B,
what we might do is get some kind of product.
And in this case you can see this beautiful pink colour.
Well, that reaction is effectively over.
We've formed the product, and that's it.
And when chemists think about a reaction like this, they imagine that the reaction is travelling
through a landscape,
from the starting materials, high up in the mountains,
down to the much lower energy, much more dispersed plains where the product lies.
This ball provides a really good analogy of the way in which this second chemical reaction
went.
When we place it at the top, and as the reaction proceeds,
the reaction essentially rolls down the slope until it reaches the bottom.
And when the ball is at the bottom we all know there's no prospect of it ever coming
back up to the top,
and the same applies to our pink solution.
Our pink solution has reached the bottom of that chemical slope.
Now what Belousov discovered, was not a simple reaction,
in which A and B are combined and simply form a product.
What he'd seen was the path that his chemical reaction was taking on the way down the slope.
Now the way to illustrate this is not to use a ball, but instead to use one of these simple
toys,
this is called a slope walker.
What he does is he walks down the slope effectively going yellow, blue, yellow blue,
just like our reaction.
But in the end he gets to the bottom.
And at that point our reaction is over.
And therefore this is no violation of the second law.
We have a reaction which starts at the beginning and finishes at the end.
When we look back at Belousov's reaction, we can see that it's now gone a steady blue.
The reaction is over.
And in many ways this reaction that Belousov found, are a metaphor almost for life itself.
The action takes place on the slope while the energy flows.
But ultimately, everything comes to an end.
Everything finishes.
Everything dies.