It's tricky to track the progress of growth, as Lightning isn't easily measured in that way. While one source may say ~1500 nodes, others may say ~2000. At the time of posting, for example:
http://shabang.io/ currently lists 1560 nodes and 14260 channels
https://graph.lndexplorer.com/ says 1818 nodes, 5796 channels
and
https://rompert.com/recksplorer/ 2133 nodes, 5864 channels
As such, all statistics should be treated strictly as estimates.
as for lightning network it is growing fast because there are a lot of people interested in it but it is not yet complete nor safe to use it for serious purposes. that will also take time.
Technically, at the beginning of project’s development, Satoshi Nakamoto, bitcoin’s father, imagined as a future possibility of lightning network to be built on payment channels. His idea is shortly described as the payment channel could be locked by related parties and their latest balances is the most recent transaction which shall be announced and stored in the BTC blockchain. In terms of payment channel, L.N allows its users to carry out their payment directly rather than announcing their transactions worldwide. Moreover, the related parties can effectively avoid expensive and time wasting interactions with btc blockchain by self –tracking their payments. In case of conflict happening which relates to balances on the L.N, the latest valid state recorded by parties to the blockchain could be sent by each party in order to automatically judge the fraud (if any)
Indeed. The current implementations of Lightning do seem similar to
ideas Satoshi discussed privately. But, unless I'm failing at using the forum's search function, I can't see that Satoshi ever used the word "channels" here on the forum. Slightly curious, but then it seems Satoshi
had a habit of bouncing ideas off a select few people in private before implementing them.