Three travel paths: wormhole, black hole, light speed. Time flow also has different speeds in different spaces, which is the key to future time travel. Einstein once realized that the flow of time should be slow in places. For example, every spacecraft has precise clocks, but they run three billionths of a second faster than clocks on Earth every day.

Hawking therefore believes that a time machine that takes humans into the future is theoretically feasible. The required conditions include wormholes, black holes in space, or spacecraft traveling at speeds close to the speed of light. Wormhole: A passage through the fourth dimension.

Hawking believes that time travel means that we have to pass through the fourth dimension, which is time. The wormhole envisioned by scientists is a passage through the fourth dimension. Hawking said that wormholes are all around us, but they are too small to be seen by the human eye. Everything in the universe will have holes or cracks, and this basic law also applies to time. Time also has tiny cracks and gaps.

Although in theory, it is possible to travel through wormholes, from a practical point of view, it is actually very difficult to achieve. First of all, the scientific community has not been able to determine the specific location of the wormhole. At the same time, the shape of the wormhole is also unknown, and the wormhole may not be a hole. Secondly, even if we find a wormhole, how we can enter the wormhole is still a huge problem.

Scientists have long ago proposed that the Earth and other stars or other galaxies are not only maintained through gravity, but also need to be maintained through some special structures. The special structures may be mysterious celestial bodies such as black holes and white holes.