I'm 32 and today was the first time I've heard the expression 'upset the apple cart' used. It was on reddit and the context was:
"Once again, my colleague Stephen Hawking has upset the apple cart. The event horizon surrounding a black hole was once though to be an imaginary sphere. But recent theories indicate that it may actually be physical, maybe even a sphere of fire. But I don't trust any of these calculations until we have a full-blown string theory calculation, since Einstein's theory by itself is incomplete."
Looking it up I found that it means to 'cause trouble, by spoiling ones plans' or 'to disorganize something, especially established plans.'
So, my question is: is there an implied meaning behind this idiom?
Does it mean that Stephen Hawking is basically talking a bunch of smack that goes against the established theory of whatever they're talking about and causing trouble because it gets a lot of press, thus, upsetting the apple cart?
Or rather, that there is some established theory, but Stephen Hawkings brilliant ass self came up with something that is making them reconsider whatever it is they'[re talking about, thus, upsetting the apple cart.
Or third, is it just impossible to tell without further context.
Best Answer
Upset the apple cart is an idiom which means changed the established order of things.
It is a reference to the way that carts for selling apples are traditionally stacked in a neat and orderly manner. This keeps the round(ish) apples from rolling out of the cart and all over the floor.
If you pull an apple from the wrong spot, the entire neat stack will fall apart and you have "upset the apple cart."
The metaphor implies that by making a drastic change to people's understanding or way of doing something, it causes a chain reaction where other assumptions have to be re-examined.
In the case you've mentioned, it means that Hawking's discovery was so radically different from previous assumptions that it forced us to look at accepted paradigms and question their validity. He basically disproved something accepted as a basic assumption, and it has thrown many other basic assumptions into question.