After the successful merger of the Goerli testnet, it now appears that the Ethereum merger may take place in September.
During Thursday's consensus layer call, ethereum core developers discussed a possible date for the merger. According to a document circulating among ethereum developers, possible dates for the ethereum mainnet merger include September 15th, 16th or 20th.
The Ethereum merger will see Ethereum move from proof-of-work to proof-of-stake, and it will be split into two upgrades: Bellatrix and Paris. Bellatrix will start the merge process and get everything up and running (at one epoch height on the beacon chain). Paris upgrades occur when a certain Terminal Total Difficulty (TTD) is reached on the execution layer, which is related to the hash rate of the network.
During the conference call, the core developers came to a rough consensus on the dates for two major upgrades. The Bellatrix fork of the Ethereum mainnet has an Epoch of 144896 and is expected to be completed around September 6. There is a 14-day period between the Bellatrix upgrade and the mainnet merger. This is the length of time that will elapse before the network reaches a certain Terminal Total Difficulty (TTD), which in turn activates the merge. Paris is upgraded to September 15th - TTD tentatively set at 58,750,000,000,000,000,000,000. However, nothing is certain until it is codified into the client version. Adjustments may be made in the coming days and weeks. Some dates may also change due to block times and hash rate fluctuations.
For the merge date, two scenarios are discussed in the document. The first scenario is: a Bellatrix upgrade on September 1st, followed by a merge on September 15th about two weeks later. The second scenario is: Bellatrix upgrade occurs on September 6th and the merge occurs around September 20th. Given that the Bellatrix upgrade date is September 6, the second scenario is more likely.
The developers will revisit these dates and estimates during next week's all-core developer call.
FAQs
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Terminal Total Difficulty (TTD)
The total difficulty is the sum of the Ethash mining difficulties of all blocks up to a certain point in the blockchain. Terminal Total Difficulty is a specific value of total difficulty that will be used as a trigger to execute clients to turn off their mining functions so that the network can transition to Proof of Stake.
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Bellatrix and Paris upgrades
Merging is a two-step process. It starts with the network upgrade Bellatrix on the consensus layer, triggered by Epoch height. Next comes the transition of the execution layer from Proof-of-Work to Proof-of-Stake, Paris, triggered by a specific total difficulty threshold (called Terminal Total Difficulty (TTD)).
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Why are Terminal Total Difficulty (TTD) dates estimated so widely?
The volatility of difficulty per block increment makes estimating the TTD window harder than estimating block or epoch heights, so a wider range is expected. Users should be aware that this will also occur with the transition of the mainnet due to changes in the proof-of-work hash rate.
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Merger complete
Once the execution layer exceeds the TTD, the next block will be produced entirely by beacon chain validators. Once the beacon chain completes the block, we consider the merge complete. Assuming normal network conditions, this should happen 2 epochs or about 13 minutes after the first post-TTD block!