Can someone please explain the meaning of "neutrino" within the lightning network? Rene Pickhardt wrote the below quoted comment in another thread about whether a mobile wallet can be both a full lightning node and wallet at the same time.


  I have many lightning nodes running but they all need to at least communicate with a bitcoin full node at this time. Most of them share the same bitcoin full node. So yes you could have a lightning node running on your phone that talks to a bitcoin fullnode somewhere else. The game changes when neutrino is fully working (I think it is still not integrated to bitcoin core) – Mar 4 at 22:03


Could someone give more precise explanation -

1)  What is this "neutrino" referred above?  

2)  When is it expected to fully work, on what is timeline dependent?

3)  And to what extent/how would this "neutrino" change the "Game" as implied above?  What effects would it have on the way lightning works?
Building on the great answer by Andrew:


  1) What is this "neutrino" refered above?


Where as BIP 37 generates a client side Bloom filter including the HD wallet addresses, BIP 157/158 "Neutrino" creates a server side [can be any Bitcoin full node] Golomb-Rice filter including all transactions in a valid Bitcoin block. You are no longer querying if a specific transaction is in a block, which might reveal which transactions you are interested in, but rather you query which transactions are in a block, and then you download the interesting blocks from another node. Every valid block has only one correct BIP 158 filter, and you can thus cross reference against several different nodes.


  2) When is it expected to fully work , on what is timeline dependent?


I don't know how fast the core process will integrate BIP 157/8 [probably in two weeks?!], but because this is not a consensus critical change, it can be implemented by individuals much earlier. For example, Wasabi Wallet is creating Golomb-Rice filters on the centralized Wasabi back-end server, the individual wallets are checking which block contains their interested transactions, then the wallet is downloading that block on the Bitcoin P2P network over tor, or from your own full node. This provides great privacy improvements, as neither the Wasabi back-end nor the P2P network know exactly which blocks [due to tor / your own node] or addresses [due to BIP 157/8] you are interested in.

Further, Lightning Labs has a testnet version of their app which is running Neutrino, their implementation of BIP 157/8.


  3) And to what extent/how would this "neutrino" change the "Game" as implied above? What effects would it have on the way lightning works?


As Andrew points out, running your own full node and verifying the entire block chain is the best practice for both security and privacy. With SPV proofs you inherently "trust the miners" that the chain with most accumulated PoW is valid. "Inverted" block filters protect wallet privacy and is a great improvement to address filters. I'd say that in all regards: Own full node >>> Golomb-Rice filters > Bloom filters.