Is a time machine possible? When will the time machine be invented?

Probably, only when the speed of an object exceeds the speed of light, there is no need to worry about breaking the law of cause and effect, because Hawking pointed out that when you go back in time and change history, there will be a branch in the world, and that branch will have another direction of development, which is the parallel universe theory, that is, there are infinite universes. For example, if you fall in love with your mother when you were young, then in another world, your child will be born. And when you kill her, you don't exist in some universe.

A time machine is theoretically possible.

Stephen Hawking mentions it in A Brief History of Time. However, he needs to artificially create wormholes and so on, and I guess the time machine can only exist in theory. Because the energy required to create wormholes and other substances is greater than the sum of all the energies in the universe.

Possibly, because Einstein once proposed the special and general theory of relativity, when a person travels at the speed of light, time has almost no effect on a person, so it is possible to create a time machine, but our speed must reach the speed of light.

No way, Einstein was a fool, in fact, even if he was fast enough, he could only infinitely bring time close to zero, but not turn back time.

Yes, because there is -energy, that is, e=+ or -mc2

The parallel universe was proposed to avoid destroying the law of cause and effect

It can never be, human beings can't achieve such an ability, even if the space-time tunnel really exists, human beings can't create such a space-time machine, because it's very unrealistic, maybe everyone watches more science fiction movies and naturally has such an idea, but the fact is the truth after all, human beings may have some incredible inventions in the future, but it is almost impossible for human beings to move time forward and backward, first of all, the time machine is a kind of substantial object that can distort space, and this situation has not yet been discoveredThe operation of the time machine is completely beyond the three-dimensional space we live in now, that is to say, if there is really a time machine, then the time machine will take us to the four-dimensional space, so I didn't even think about it, but maybe one day we may accidentally encounter the natural transformation of time and space, if we enter this time and space, it may take us to the past or the future, but this is just a naïve idea, but with the progress of science, we may be able to develop an object beyond the speed of light, If such an object is developed that exceeds the speed of light, it may be a step forward in the invention of the so-called time machine.