How to grasp the “accurate time” of Ethereum merger? TTD Learn more...

In September, we will witness the completion of the Ethereum "merger" together.

"Merge" is one of the important steps in the Ethereum 2.0 upgrade process. Specifically, it is a "merger" of the main network and beacon chain proof-of-stake systems before launching the "shard chain", which will make "mining" a thing of the past on the Ethereum network.

In the past, blockchain network upgrades were usually scheduled to occur at a certain block height, so it could be estimated relatively accurately that they would occur on a certain day. However, this time, the Ethereum "merge" was not based on a specific block height, but was executed according to the terminal total difficulty (TTD) announced by the Ethereum Foundation.

TTD is the total difficulty required for the final block to be mined before Ethereum transitions from PoW to PoS, so the "merge" completion time is affected by the difficulty of each block and the real-time computing power .

In other words, the time for the completion of this merger can only be estimated by time period. For example, the Ethereum Foundation announced in its announcement on August 26 that the "merger" will be completed between September 10 and September 20.

According to OKLink’s Ethereum merger countdown, the overall progress of the merger has exceeded 98%, and there are about 9 days left before the merger is completed . So during this waiting period, let’s learn how to estimate the completion time of the Ethereum merger.

Image source: www.oklink.com/zh-cn/eth/merge

Ethereum’s “merge” has been successfully tested on three testnets, Ropsten , Sepolia , and Goerli . Consistent with the merge process on these three testnets, the merge of the Ethereum mainnet and the beacon chain will be carried out in two steps.

Consensus layer network upgrade, codenamed Bellatrix

The upgrade is triggered by a specific "epoch". The epoch height is an integral part of the Ethereum consensus layer network block authentication mechanism. One epoch height contains 32 "slots", each of which can only create one valid block. Within the time limit of each epoch height, the verification node will randomly process transactions and pack several transactions into blocks and put them into the slot. The beacon chain Bellatrix upgrade is scheduled to be carried out at epoch height 144896 , which is 19:34:47 Beijing time on September 6.

Paris Upgrade: Transition from PoW to PoS

This upgrade is triggered by a specific Terminal Total Difficulty (TTD), which is currently set to 587500000000000000000000.

The exact date of reaching the set TTD directly determines the specific time when the merge is completed, so when the set TTD is triggered is the key to estimating the Ethereum merge time .

A simple estimation method is to calculate the difference between the current TTD and the target TTD, and then divide this difference by the average block difficulty. In this way, we can calculate how many blocks need to be mined before reaching the target TTD. Finally, multiply the calculated number of blocks by the average block time to roughly get the remaining time before the merge.

That is: (target TTD-current TTD)/average block difficulty*average block time

However, this method is not accurate enough. To estimate TTD more accurately, you can refer to the method introduced by Mário Havel in his technical blog. Of course, you can also refer to bordel.wtf and 797.io/themerge to get more accurate time directly.

Finally, after the total difficulty of Ethereum's execution layer reaches or exceeds TTD, the subsequent blocks will be generated by the beacon chain verification nodes.

That is to say, after the first block that touches TTD is generated on the mainnet/execution layer, the verification node on the beacon chain will take over the baton and quickly confirm the block. After confirmation, the merged transition is considered complete.