Phase 0 of Ethereum 2.0 is scheduled for activation at a tentative time in 2020. Upon activation, the update will enhance the security of Eth 1.0 due to the Finality Gadget feature.

Finality Gadget
It is the view of Alex Stokes, an analyst, that Finality Gadget will largely buffer the network against external attacks making it economically hard for etched ETH transactions to be reversed in a majority attack. During Eth 2.0, a transaction will only be reversed if a third of proven staked ETH is burned.

The Beacon Chain
Forecasts from various analysts place Phase 0 implementation in the second half of 2020. However, no one is sure as it the nature of development in open source platforms. Phase 0 of Ethereum 2.0 will entail the activation of the Beacon Chain.

The Beacon Chain is the main “system chain” of Serenity’s sharded blockchain. In simple terms, the Beacon Chain will coordinate hundreds of other Ethereum blockchains called shards as envisioned in the final workable version of Ethereum 2.0.

Ethereum and the Casper Protocol
Then, Ethereum would have shifted from the Proof of Work–that is currently in use, to a Proof of Stake consensus algorithm where miners would be replaced by validators where Casper will resolve initial problems faced by early PoS systems of “nothing to stake”. However, the first implementation of Casper will leverage Proof of Work to verify and add new blocks to the new blockchain.

The Finality Gadget will factor in the consensus of Phase 0 of Ethereum 2.0 to further enhance the security of the original, Ethereum 1.0 chain.

In this way, the Ethereum community can derive value right from the first day of the activation of the Beacon Chain with improved security during transition: