Is there a massive gravitational force outside of the observed universe?

Theory states that the observed universe is expanding, presumably from a massive explosion such as the big bang, however, is it possible that the observed universe is not expanding under its own explosion force, but is being drawn further and further away from an observer due to a massive gravitational force... show more Theory states that the observed universe is expanding, presumably from a massive explosion such as the big bang, however, is it possible that the observed universe is not expanding under its own explosion force, but is being drawn further and further away from an observer due to a massive gravitational force outside of the observed universe?
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