system
Given the following post, respond as if you're commenting on Reddit:
human
Economists, what’s your opinion on the state of the worlds economy? A bank in Germany has introduced negative interest rates.

Not sure how negative interest rates works anyway?sounds like a theory that isn’t great in practice as I’d rather incur no interest than being charged.

<edit elaborate comment>

I should have mentioned, if you had savings, they’d charge you and hadn’t  consider the alternative, if you had a loan.
gpt
you're not being charged. They would give you money to take their money. 

The reason this happens is because the ECB rate is negative too so as long as the banks charge higher than the ECBs rate they will still make money (even if their rates are still negative). A couple months ago a Danish bank started paying people to get a mortgage.

The answer to your question is no on really know because we haven't seen such low interest rates for such a long time. The question becomes what use would monetary policy in the case of a recession i.e. since rates are so low, how effective would it be for central banks to decrease interest rates in order to stimulate growth?