Well hold on now. Would it be possible, technically, if for example he lived in a small village with a computer and a landline but without internet, and he had a fax machine, could he not develop a method of connecting the reconfigured fax to a node (which has internet access) through that landline and the node would broadcast to the blockchain? Technically he would be sending Bitcoin payments without internet connection.
That would certainly be possible, although there are probably easier ways of doing it than reprogramming a fax machine.
I'm not even sure you can reprogram fax machine easily either due to signed firmware requirement or unusual programming language used to create the firmware.
Hi everybody
about this thread, I hope it's useful to remember that propagation time / mining interval ratio is of huge importance regarding forks/reorgs and so double spending issues, but also underline that it has a role in setting sufficient conditions about safe honest/byzantine nodes ratio... so an offline scenario is highly risky considering a Nakamoto Consensus network as a whole. I guess sharding could be a plan-b, but I'm currently not expert enough to speak about it, and more important it wouldn't be BTC anymore (at least not as we know it now)
But in practice, amount of stale/orphan block is very low. Based on BitMex monitoring tool[1], there are only 46 detected stale block since 20-08-2020[2].
[1]
https://forkmonitor.info/notifications[2]
https://forkmonitor.info/feeds/stale_candidates/btc.rss