Why are interest rates so low?

That's an official statistic (US Bureau of labor statistics) that is, in all reality, fiction. Might want to look at ANY other analysis, other than the announced statistic. Like simply comparing the (est) population to the (est) jobs. Turns out it's more like 10% at best, but that's not the end. Yahoo, Experian, Amazon, etc. The vast majority of the tech employed have become contractors. At least be reasonable enough to do your research.

Saying GDP has increased is another statistical mischaracterization. There has been some very clever manipulation by the USG (http://seekingalpha.com/article/1368001-u-s-governments-new-...).

You seem to be woefully glib about topics you haven't been following. Growth hasn't helped the situation as there hasn't been much at all, if any. Rigid financial systems have failed and will do so again if the interest rate (inevitably?) spirals out of control. The executive branch talking heads and investing-in-debt schemes have been paying off for the last few years. It's been increasingly difficult to determine what lengths the fed will go to, in stabilizing the economy and maintaining a positive spin.

It makes people think they are wealthier, which amounts to the same thing. I'm not saying people are logical in this respect; I'm just saying that it happens, or at least that Keynes claimed that it happens. (I actually don't really disagree with him in principle; I'm not sure the effect in practical terms is as significant as he appeared to think it was.)

> Money is a real thing, is a medium of exchange and there is a demand for it.

These are actually two different things, not one. The use of money as a medium of exchange is different from the use of money to store value over time.

Demand for money as a medium of exchange can become arbitrarily small by allowing prices to fall as economic efficiency improves. Keynes appeared to think this was a Bad Thing, but AFAIK he never actually demonstrated why, he just asserted it without proof and everyone believed him. Certainly there are examples where the price of a given quantity of some good (such as a given amount of computing power) has dropped by many, many orders of magnitude, without any discernible negative impact. So an obvious alternative to printing more money so there's enough medium of exchange is to require less of the medium of exchange for each transaction.

The use of money to store value over time is what really creates significant demand for money. However, printing money in order to satisfy this demand defeats the purpose, because it reduces the value of money.

> the preferred Keynesian way of stimulating the economy is by fiscal policies (investing from the government), and not by “printing” money, but that is not possible in Europe or the States because politics

This is a good point, yes. However, I would add that the reason why the fiscal policy "solution" is not politically acceptable in Europe or the US is that was tried (in the 1930s during the Great Depression, and again to an extent after World War II) and didn't work, because governments are atrociously bad at picking the right investments. So now governments prefer to print money and hand it to private investors, who, while they are still bad at picking good investments, are at least less bad at it than governments. (But there are still other bad side effects, such as an economic meltdown once in a while.)

[2] http://www.amazon.com/dp/1442175958