In life, the most direct path is not always the fastest, the shortest, or the one that involves the least effort. There can always be obstacles. The same occurs in the Lightning network, which works as a second layer of Bitcoin, and through which hundreds of bitcoins are sent between thousands of nodes with channels open to each other.
In this huge interconnected network, satoshis (the smallest unit of bitcoin or BTC), travel until they reach their final destination, inclining to choose the shortest, fastest or cheapest way in commissions. But what if we can use all of these options at once? Will it be possible to travel several paths at the same time to reach the same common goal? It seems like an approach to quantum physics, but with the Lightning network it is possible to fulfill this thesis.
To achieve this, researchers propose a mathematical and probabilistic solution that allows estimating which are the best routes on the Lightning network to send bitcoins. But, in addition, they propose split that payment and send your fractions separately, testing live which are the best available routes to consolidate said transaction.
On July 13, the document “Optimally Reliable & Cheap Payment Flows on the Lightning Network” or, in Spanish, “Optimally Reliable and Cheap Payment Flows on the Lightning Network” was published. This is the work of the researchers René Pickhardt and Stefan Richter, published openly (open source) and partially sponsored by the Norwegian University of Science and Technology (NTNU), as well as peer review.
All roads reach Bitcoin
Andreas Antonopoulos, Bitcoin educator, and René Pickhardt, Lightning developer, recently participated in an episode of the podcast WhatBitcoinDid, moderated by Peter McCormack, where they discussed Lightning scalability and this specific solution, among other topics.
Antonopoulos, known for simply explaining complex Bitcoin concepts, said that this would be one of the biggest innovations of the moment, and that it would allow sending potentially larger payments than what is usually sent in Lightning.
René Pickhardt (top right) and Andreas Antonopoulos (bottom) in one of the most recent episodes of Peter McCormack’s What Bitcoin Did (top left). Source: What Bitcoin Did.
For a year there has been a technology in the Lightning Network called Multi-Path Payment. With this, instead of sending payments through a set of Lightning channels or a single route, now what we can do is divide them into small fractions and send them through different channels and routes.
(…) How do you divide this payment? What channel to use to send all the fractions? These are the questions, the problem of finding the best possible route, which are the basis of the enormous innovation that René (Pickhardt) has achieved with his research (…).
Andreas Antonopoulos, popularizer on Bitcoin.
Multi-route payments were reported by CriptoNoticias at the end of 2019, as a solution that allowed sending a payment through several channels with multiple users as its final goal.
But now, what is sought is use several channels to reach the same common goal, or a single final direction. This is done for the purpose of sending large amounts of bitcoins using each and every one of the best options or channels available, when there is only one single recipient of the payment.
For his part, René Pickhardt explained that he was very surprised when, in a simulation, he noticed that he could send a large amount of bitcoins through Lightning, thanks to the results of the algorithm he designed to compute which are the best channels to use to trace. the payment route.
Pickhardt argued that the larger is the payment in bitcoin, the greater the probability that Lightning will not be able to process it, due to the limited capacity of the channels.
The channels of the Lightning network have the ability to send or receive as many bitcoins as their nodes have deposited. In September 2020, CriptoNoticias reported how a Lightning channel had been created with a capacity of up to 5 bitcoins, which implies that this amount can be received or sent through it without problems, when before it could only be sent on-chain, that is, , on the main chain of Bitcoin.
So, in the simulation model, Pickhardt noticed how, when making a payment, a user chose the channel that charged the lowest commission. What the researcher proposes is to use the probability theory and probabilistic functions to optimize the search for “routes most likely to be successful” to send the payment.
Antonopoulos commented on the podcast that he found it fascinating how can ‘scatter’ a payment or ‘flood’ the Lightning network with transactions. Pickhardt explained that this is a mathematical flow problem, so it was correct to refer to this as a “flood” of payments through network channels.
What we did was divide the amount into 250 different fractions, very small amounts, and send them to someone. When we created these Multi-Party Payment Streams (MPPs), and shipped them, we found that 75% of the balance sent reached its destination on the first attempt, the rest was returned to us. What we did was use the information collected with confirmed and declined payments, to adjust our estimate of the health of the network, and then run the second round of payments. In total I had to do this in four rounds to be able to send these bitcoins on the Lightning network, and I don’t think anyone has done it before.
René Pickhardt, Developer.
For his part, Antonopoulos pointed out that if we wanted to send 0.5 BTC on the Lightning network, to give an example of a large amount for this second layer, it would be convenient to divide the payment into 20 parts and pay less commission, than to do it in two parts and pay more.
A method still in the experimental phase
At the moment there are no applications that integrate this method as part of their native functions, but it is expected to continue to develop in the future.
Pickhardt received a donation of EUR 10,000 each from Antonopoulos and McCormack, as support to continue his journey as a Lightning developer.
Regarding Lightning, during the month of June the network exceeded its numbers in terms of channels and available nodes, as well as the amount of circulating bitcoins, reported CriptoNoticias. There are currently more than 22,830 nodes, 56,600 channels and 1,840 BTC circulating on the Lightning network, according to 1ML.