Because humans cannot observe space beyond the edge of the observable universe, it is unknown whether the size of the universe in its totality is finite or infinite. Estimates suggest that the whole universe, if finite, must be more than 250 times larger than a Hubble sphere. Some disputed estimates for the total size of the universe, if finite, reach as high as 10 10 10 122 megaparsecs, as implied by a suggested resolution of the No-Boundary Proposal.