theories for traveling to the past . The first method is wormhole travel . Wormhole theory is a theory that states that black holes are connected to another opening in space . Hence , by entering blackholes , people could travel another location in space at different periods . Another theory is Frank Tipler ’ s theory . According to this theory , if humans can create an infinitely long cylinder with extremely high density like the density of stars , and rotate the to cylinder at a fast speed , people can
Unfortunately , both of these theories have various flaws . For the wormhole theory , scientists have not witnessed an actual wormhole in space . Furthermore , several years after the introduction of wormhole theory ; they realized that even though the formation of wormholes is possible they could only last for a few seconds and are in small sizes . For Frank Tipler ’ s theory , it is impossible to actualize it or perform it in the real world . create a hole for traveling to the past .
In conclusion , in theory time travel is possible in both directions : present to future or present to past . However , all the theories for time travel are impossible to actualize in real life . Therefore , the great scientist Stephen Hawking ’ s saying “ Time travel might be possible , but if that ’ s the case why haven ’ t we been overrun by tourists from the future ?” was correct .