In 1995, Matt Visser suggested that there are many wormholes in the universe if cosmic strings with negative mass are generated in  early universe. On the other hand, some physicists such as Frank Tipler , Kip Thorne suggested how to make arificial wormholes.
In 1995, Matt Visser suggested that there are many wormholes in the universe if cosmic strings with negative mass are generated in the early universe. On the other hand, some physicists such as Frank Tipler and Kip Thorne suggested how to make artificial wormholes.
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