Time and Communication in the Multiverse: How to Synchronise Clocks and Transmit a Signal

This article addresses the fundamental problems of time and communication during interuniversal transitions within the framework of the Infinite-Dimensional Multiverse Model (IDM). The author demonstrates that time in different universes may flow differently, and synchronisation of clocks between universes by direct methods is impossible. This creates serious limitations for mission planning: it is impossible to determine the duration of the expedition, compare data from different worlds, or coordinate actions between the probe and Control. Synchronisation strategies are proposed: internal metronome (relative time), atomic clocks (require calibration in the target universe), local time measurement (via changes in constants and spectra), beacon signal (requires communication), and quantum synchronisation (theoretically possible but technically difficult). The recommended approach is combined: synchronisation before launch, recording the moment of transition, measuring local time after transition, and establishing a conversion factor. Special attention is paid to the problem of communication. Electromagnetic signals cannot leave the brane; the only signals capable of passing through the bulk are gravitational waves and vacuum fluctuations, but their practical use is limited by the current level of technology. Four communication strategies are introduced: "Buoy" (data storage with subsequent transmission upon return), "Beacon" (periodic signal transmission), "Relay" (a chain of devices along the chain of universes), and "Courier" (physical return of the probe with data) — the only reliable method. Practical recommendations are given for different generations of probes and piloted missions. The article is a practical supplement to the step-by-step expedition procedure and is linked to the concept of the "Echo Sounder of Knowledge."