This is technically inaccurate and is not how #IBC transfers work. Here's what's wrong and how it **actually** works https://twitter.com/cosmosibc/status/1351848634149556226

This model assumes that 1) the chain runs a light-client of the other chain, which doesn't. It only stores the light-client state (latest height and parameters) and the consensus state (Merkle root, validator set hash, timestamp) for each height in order to validate proofs.

2) Light clients are instead run by IBC relayers (not mentioned), 3rd party operators that run light-clients for each chain and update their light-client and consensus states by submitting block headers. They also listen to events in order to relay IBC packets that contain txs

3) Regarding the transfer itself. The tweet also states that all tokens are locked upon sending, which is false. This is only the case if the tokens are transferred to a chain forward in the timelines of the transfer, the receiving chain effectively mints vouchers for the token.

The second transfer case is when tokens sent backward in the timeline of transfers. These tokens are burned on the sending chain and unlocked in the receiving chain

What do I mean by the "timeline of transfers"? Consider the following set of connecting chains and their corresponding native token:

@cosmos Hub ( $ATOM ) <-> @ethermint (PHOTON) <-> @binance chain ( $BNB )

Alice sends 10 $ATOM from @cosmos hub to Bob's account in @ethermint:
a) $ATOM locked on the Hub and transfer packet is sent
b) IBC packet with the transfer details relayed to Ethermint
c) ATOM vouchers (ibcATOM) minted on Ethermint

This is a forward movement

Bob pays 1 ibcATOM to Alice:
a) ibcATOM **burned** on Ethermint, transfer packet sent
b) IBC packet relay
c) 1 $ATOM unlocked on the Hub

Now, imagine that Charlie on @binance chain received $ATOM and $ATOM vouchers from Alice and Bob too. Are these tokens the same? NOPE. Tokens relayed through different routes are not fungible ! This also applies to relays on the same route but on different channels!

The UX on the #interchain is hard! We are working to make it easier by implementing chain registries on top of IBC and collaborating with stakeholders to solve these challenges https://twitter.com/jack_zampolin/status/1350130122565668865

Follow me for more about IBC, client UX, and interoperability! My DMs are open