Journey to find time machine (last part)

A tunnel that passes through a hill is naturally shorter than the surface path. Similarly, a wormhole can be a shorter path than the usual path in space.

In scientific fiction, wormholes are sometimes called stargates, which provide a shortcut between two points far apart in space. Going through a hypothetical wormhole, you will probably arrive later on the other side of the galaxy. Wormholes naturally fit in with general relativity, in which gravitational fields bend both time and space. Theorists gave a space with structures connected by wormhole " tunnels ". A tunnel that passes through a hill is naturally shorter than the surface path. Similarly, a wormhole can be a shorter path than the usual path in space.

The wormhole concept was used for an imaginary device in Carl Sagan's Contact novel, written in 1985. Immediately after Sagan, Kip S. Thorne and his colleagues at the California Institute of Technology sought to prove it, whether Whether a wormhole is suitable for mainstream physics or not. Their starting point is a wormhole similar to a black hole with a terribly attractive field. But there is a difference here, the way into the black hole will not lead anywhere, and a wormhole will have both in and out.

Wormhole time machine

In order for the wormhole to travel, it must contain what Thorne calls eccentric matter. This material will produce an antigravity to counteract the massive gravity of a large mass system. Gravitational feedback, or gravitational repulsion, can be generated by negative energy or negative pressure. Negative energy states are known to exist in certain quantum systems. That said, Thorne's bizarre matter is not disproved by the laws of physics, although Thorne is still unclear about whether there are enough antigravitational materials to stabilize the wormhole.

As soon as Thorne and his colleagues realized that, if a stable wormhole was created, then it could be ready to become a time machine. When an astronaut passes through it, he will not only go to another place in the universe but also go to another point in time, future or past.

In order for a wormhole to function as a time machine, one of its mouths could be placed near the surface of a neutron star. The gravitational field of the star will slow down time in a wormhole mouth so that the time difference between the wormhole's mouths will gradually accumulate. If both mouths are placed in appropriate places in space, this time difference will be kept stable.

Suppose that the difference is 10 years. An astronaut travels through the wormhole in one direction and jumps to 10 years later in the future. Another astronaut went in the opposite direction and returned 10 years ago in the past. By flying quickly to return to the starting point in normal space, the second astronaut could return home before the time he entered the wormhole. In other words, a closed loop in space can become a closed loop in time. There is a limit, the astronaut cannot return to the time before the wormhole was first created.

The difficult problem in creating a wormhole time machine is how to first get a wormhole. Perhaps space is naturally sequenced by such structures, they are remnants of Big Bang. If so, a super civilization could use them. On the other hand, wormholes can exist naturally in extremely small sizes, about the size of the so-called Planck length. In principle, such a tiny wormhole can be stabilized by an energy pulse and to some extent it will be enlarged to usable sizes.

Paradoxes

Assuming that we can overcome the technical difficulties, the construction of a time machine will encounter unacceptable levels of causal paradox. These paradoxes arise when time travelers try to change the past, this is obviously impossible. Consider the case of a time traveler coming to the future one year later and reading a new mathematical formula on the Tia ray for example. When he returned to his original time, he would teach that recipe to a student, and the student wrote it in one

Wormhole model.
(Photo: casa.colorado.edu)

The article was published in Tia . Of course, that article is the reader's journey. Then the question is: where does the recipe information come from? Not from the astronaut, because he had read it, not from the student, because he had learned it from the astronaut. Information does not seem to come from anywhere, not at all.

The dreadful consequences of time travel have led some scientists to definitively abandon the idea of ​​it. Stephen Hawking at Cambridge University has proposed a " chronological defense conjecture ", considering the causal rings as " outlaw ". Since the theory of gravity is known to allow causal rings, the protection of the chronology will require some other factor to interfere, to prevent travel to the past. What could that factor be? There is a suggestion that quantum processes will participate in this rescue. The existence of a time machine will allow particles to return to their past. Calculations imply that quantum turbulence will damage the wormhole.

The chronological protection is still guesswork, so time travel is still possible. The final solution to this problem may have to wait for the successful unification of quantum mechanics with gravity. We can even imagine that later generations of accelerators would be able to create wormholes at the subatomic level. They can survive long enough to make nearby particles fly into causal rings. This is still far from Wells's imagination about time machine, but it will permanently change our picture of physical reality.

Journey to find time machine (part 1)