Zhang Tie learned that he had become a father one morning...
It had been a complete whim of intuition. With the Human defense line in Selnes collapsing, he realized he had not contacted his family for many days. After being busy all night, Zhang Tie got up the next morning and took out the remote-sensing crystal his elder brother had given him. As soon as his mind entered the crystal, he quickly sensed the fixed-frequency vibrations coming from the other end. Those vibrations indicated that someone on the other side had been constantly watching the crystal. He did not know whether his elder brother was personally keeping watch or had assigned someone else to do so. Since he was in a war zone, he could not possibly do nothing but monitor the remote-sensing crystal at every moment. Thus, 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 agreed upon with his elder brother through vibrations of varying lengths, an identification code came back from the other side only a few dozen seconds later. It was Zhang Yang.
Their identities were confirmed at once.
Then, a series of vibrations of varying lengths came from the core of the remote-sensing crystal.
As Zhang Tie memorized those vibrations, he used the decoding method he had agreed upon with his elder brother to translate their meaning in his mind. Once one became familiar with using remote-sensing crystals, as long as both sides understood each other well, this method of contact was extremely convenient, even if it could not compare to speaking in person. It was somewhat like the instant transmission of information through mobile phones or telegraphs before the Great Cataclysm. However, compared with mobile phones