What's the problem if Mechanics stop lubricating the engine?

    Now is around 5 years since we faced the 2008 crisis. Everyone has tried to push the economy back up to the pre-crisis level, especially US Federal Reserve (FED), which now the world puts the spot light on, because America is the biggest country in terms of GDP (Gross Domestic Product).....I'd like to elaborate more why right now America is the hottest country in terms of investment.
     When a country faces a crisis, it means the economic engine becomes unsmooth and, sometimes, might even get stuck. The reason is because people delay their spending due to the fact that they want to save the money in case they are laid off. So, when the economic engine is working roughly, we need a mechanic to lubricate the engine. The mechanic here is the government (fiscal policy) and central bank (monetary policy).
     Typically, a government and a central bank will collaborate on improving the economy. However, government has overspent for the past several years; therefore, a government did not have enough power to lubricate the economy's engine, thus all responsibilities falling to central bank.
     During the 2008 crisis, central banks of every country put all their effort to keep the economy from falling down, but FED had the largest power; consequently, we need to consider FED because what the FED do will affect the whole world.

Ben Bernanke (Federal Reserve Chairman)

     So, what is the lubricant in my meaning? It is....."Money". The economy engine is driven by "money".
     There are many ways a central bank can inject the money into the economy, but the main tool is adjusting interest rate down. Let's see how it works......

When interest rate is down > people is tempting to borrow more because of the lower cost, such as housing loan > Then, people use that money to hire contractors to build their house > Then, constructors pay their workers a salary > Then, workers go to shopping at department store > .... This cycle will be iteratively going on and on, and economy then come back on track.

Food for thought!! Imagine that the first group of people in the cycle above did not borrow the money. What would happen?...... There would be no cycle!.....economy would get stuck!!!

     Okay, we com back to the point that why FED is on the spotlight now. Now, there is an issue that FED will put less lubricant on the economy. In other words, FED will decrease the amount of money FED injects in the economy, because FED believes that, now, economy is strong enough to stand on its own feet. Investors around the world are afraid that the economy will go down owing to this operation. In terms of investment, investors are more risk averse, and start to draw their money back from risky assets (e.g. stock) ......Last month (August), if you notice, stock markets around the world started to face a correction. The currency's value in emerging countries tumbled around 10% because the money flew out of the country. So, you might not be able to expect much at the end of this year.