FAQ: Oracles
No single entity. An optimistic oracle reports the reference value only when needed, at expiry or on dispute, and anyone can challenge an incorrect report by staking against it.
Dispute it within the challenge window. The dispute escalates and is resolved by economic stake; an incorrect reporter is slashed. If no one disputes in time, a wrong value can settle. This is a real risk.
From hours to several days, depending on escalation. During that window a position may be unsettleable or mispriced.
A synth minted against a discrete event, a dated question with a credible resolution source, rather than a continuous price. When the event resolves through the oracle, the synth's collateral mix rebalances along a formula fixed at mint. See Event-triggered synths.
The rebalance stalls until it does, or until a keeper cancels the request after the resolve window.