The trolley problem is something that has previously passed me by, however, following extensive research (i.e. Googling) all is clear, I think.
In short, the trolley problem is a thought experiment in ethics/morality. Do you pull the lever? Do you push the heavy man? Confused?
Well, the rationale behind this ethical dilemma is explained well in the piece below from wired.com, which looks at how this will relate to autonomous vehicles and the way in which they will handle/be instructed by their computers to deal with difficult/ethical driving decisions out on the road.
This has the potential to be an absolute minefield and only time will tell how autonomous vehicles will deal with these real life situations. And then how those judgements will be dealt with in law when the inevitable happens.
Anyway, back to working out whether I will throw the big man off the bridge...
To understand the trolley problem, first consider this scenario: You are standing on a bridge. Underneath you, a railroad track divides into a main route and an alternative. On the main route, 50 people are tied to the rails. A trolley rushes under the bridge on the main route, hurtling towards the captives. Fortunately, there’s a lever on the bridge that, when pulled, will divert the trolley onto the alternative route. Unfortunately, the alternative route is not clear of captives, either — but only one person is tied to it, rather than 50. Do you pull the lever?