“Computer models cannot explain how dust particles stick together due to gravity. As grain size increases, so does the mean collision velocity, which would cause grains to break into smaller pieces.6 Simulations show that meter-sized particles have the highest drift speeds, about 100 m/s. This makes it quite challenging to grow to larger than meter sized objects, since collision speeds of this order will rather destroy the bodies via fragmentation or erosion.6,8
Theorist have been glossing over this problem for decades. The Swinburne University of Technology website is typical in this regard, saying, “While the mechanism is not yet fully understood, the grains will eventually become kilometre-sized planetesimals.”9 Once they reach that size, gravity can take over. But nobody can figure out how to go from dust to a small planetoid at least one kilometer in diameter.”
Read more here: https://creation.com/do-dust-rings-grow-into-planets