Zhang Tie learned that he had become a father one morning...
It was entirely a sudden intuitive feeling. With the human defensive line in Selnes War Zone on the verge of collapse, he thought of how many days it had been since he last contacted his family. Having been busy all night, Zhang Tie took out the remote-sensing crystal his elder brother had given him after getting up the next morning. When his mind entered the crystal, he quickly sensed the steady-frequency vibrations coming from the other end. Those vibrations indicated that someone on the other side had been continuously monitoring the crystal—whether his elder brother was personally keeping watch or had assigned someone else to do so, he did not know. Since Zhang Tie was in the war zone, he could not possibly do nothing but keep an eye on the remote-sensing crystal at all times. Therefore, unless the two had arranged it beforehand, Zhang Tie was generally the one to contact Zhang Yang first.
Very soon, after Zhang Tie transmitted an identification code phrase he had agreed upon with his elder brother through vibrations of varying lengths, an identifying code came back from the other end only a few dozen seconds later. It was Zhang Yang.
Their identities were confirmed at once.
Immediately afterward, a series of vibrations of varying lengths came from the core of the remote-sensing crystal.
As Zhang Tie memorized those vibration frequencies, he used the decoding method he had agreed upon with his elder brother to translate their contents in his mind. Once one became familiar with how to use a remote-sensing crystal, as long as the people at both ends understood each other, it was an extremely convenient means of communication, even if it could not compare to speaking face-to-face. It was somewhat