It is said that one can travel to the astral spheres while still in the physical body. How is it that the silver cords do not get entangled, because there must be many people doing it, particularly unconsciously in sleep?

The explanation and the understanding of this lie in knowledge of frequencies. Each physical body has its own unique ‘frequency band’ and the astral body, while having a frequency rate many millions of times greater, nevertheless is a harmonic of earth frequencies. There is no likelihood whatsoever of the confusion mentioned. If you were to tune into a radio station in New Zealand, that is what you would get, there would be no confusion. Radio and television station frequencies do not clash or blend with one another, and neither do the personal frequencies of astral beings.