The Ethereum Beacon Chain
In Ethereum 2.0, the purpose of the beacon chain is to allow nodes to add blocks to the blockchain. The beacon chain is divided into epochs and epochs are divided into slots.
Each epoch consists of 32 slots. Each slot is 12 seconds long. Hence, each epoch is 6.4 minutes long (32 * 12 seconds). In each slot, a block is created (if no proposer misses its assigned slot).
The participants in this consensus mechanism are called validators. Validators have two tasks:
- Create and propose blocks: then they are called block proposers
- Vote for proposed blocks: Then they are called attestors.
In every slot, a proposer publishes a block. Each slot should contain one block. But a slot may be empty if the proposer doesn’t publish a block. For example, this can happen if the proposer is offline at the slot time. Proposers are selected pseudo-randomly through an algorithm called RANDAO. This is also where the name of the beacon chain comes from. Like a lighthouse (beacon) the RANDAO emits random values.
The probability of being selected as a proposer from all registered validators depends on the stake the validator has locked away. The higher the stake, the better the chances of being selected. Block proposers receive a reward for their service.
Proposers and validators are selected two epochs in advance. So they have time to prepare themselves for their upcoming duty.
Validators can exit the beacon chain anytime. But there is a waiting period after submitting the exit request. This time is currently four epochs.
