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In Avengers: Age of Ultron when the Avengers are all taking turns trying to lift Mjolnir from the coffee table, Steve Rogers is shown moving it about half an inch or so but not actually lifting it. Presumably whatever enchantment there is on Mjolnir that determines "worthiness"( "whosever wields this hammer", and all that) doesn't do grey areas i.e. someone can't be almost worthy of the power of Thor. Either they can lift the hammer or they can't. If this is as the case, why was Steve not able to lift Mjolnir completely off the table, since presumably if he can move it at all that means that he is in fact worthy?