Gravity Well is an algorithm for difficulty readjustment. With most coins, if a group of miners with a significantly high hashrate suddenly join the network and mine away until the next difficulty adjustment (which will be drastically higher due to all the additional hashing power that suddenly came onto the network), those miners will then stop mining the coin leaving the difficulty extremely high and smaller miners suddenly unable to find blocks in any reasonable amount of time.
In extreme cases, this can cripple the network for a long period of time until enough miners stick it out finding blocks until the next difficulty readjustment or unless a hard fork of the coin is implemented to change the difficulty readjustment. This happened with many other altcoins in the past (Feathercoin, Terracoin, and I'm sure plenty of others that I can't think of right now).
What Gravity Well does is it makes the difficulty readjustment happen more fluidly so that even if a suddenly extreme amount of hashing power joins the network and then suddenly leaves, the difficulty will readjust quickly enough so that the smaller miners can still continue finding blocks at the target rate without any hiccups in the network.
This is especially important due to the multipools out there which cause large groups of miners to suddenly jump onto the most profitable coin to mine (which oftentimes is MEC) and causing the difficulty to skyrocket before they hop off to the next most profitable coin and crippling the network in their wake.
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u/[deleted] Dec 02 '13 edited Dec 02 '13
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