What is exactly causing the current worldwide depression?

[Ser Clegane]

The original financial crisis was for real - the following overall economic crisis is largely based on psychological ripple effects, i.e. everybody (companies and private households) is afraid that things might turn out really bad and therefore refrains from making any spendings that are not absolutely necessary right now to beon the safe side (e.g., private households will postpone investments for a new car or TV for 1-2 years, companies will not buy machinery, build new plants or will hold back R&D investments).
This "holding back" is currently leading to a very real and sharp economic downturn.

If you have enough cash right now and don't have any reasons to worry about incoming cash (e.g. because your job is absolutely secure and will not be affected by a downturn), now might be a very good time to spend money on a new car or new furniture as you are very likely to get some nice discounts.