Answer
When the Bhagavad-gita describes the soul as immovable, it does not mean that the soul does not transmigrate from one body to another. Rather, it means that the soul never deviates from its constitutional position.
The soul is eternally a servant of Krishna. Whether one serves Krishna directly and willingly as a devotee, or indirectly through material desires and the senses, the soul's intrinsic nature as a servant of Krishna never changes. In that sense, the soul is immovable.
Similarly, devotional service is eternal. Paramatma, who receives that service, is eternal, and the soul itself is eternal. In their pure state, none of these are dependent on material concepts such as time, space, or energy.
While living in the material world, however, we function within time and space. Whatever comes within our control—our body, mind, abilities, possessions, and circumstances—should be engaged in Krishna's service. By doing so, we become situated in our constitutional position.
As for the dimension in which the soul exists, it cannot be understood materially. It is inconceivable. The actual nature of the soul and the spiritual dimension is beyond material perception and speculation.
The Krishna Book also explains that time (kāla) is an external energy under Krishna's control. Time operates differently at different levels of existence. For example, what is one moment for Lord Brahma may correspond to one year for human beings. Similarly, one day and one night for Brahma have entirely different durations from our experience.
Time itself remains a great mystery, even for modern science. Scientists continue to study it but do not fully understand its nature as an aspect of the external energy.
Modern physics demonstrates that time is not absolute. Through the well-known example of the twin paradox, one twin travels in a spacecraft at nearly the speed of light while the other remains on Earth. When the travelling twin returns, only a few minutes may have passed according to his clock, whereas many decades have passed on Earth. This illustrates that time slows down depending on the relative frame of reference.
Thus, time behaves as part of the fabric of the material energy, much like the dimensions of length, breadth, and height. Modern science now speaks of space-time, recognizing that time and space are interconnected rather than completely separate.
The Śrīmad-Bhāgavatam goes much further by describing the structure of time through concepts such as the kāla-cakra (the wheel of time), with its spokes, rims, and divisions. These descriptions suggest profound realities that future scientific research may gradually begin to appreciate.
Perhaps one day scientists will recognize that many truths they struggle to discover have already been explained in the Vedic scriptures. Details such as the three rims, the 360 joints, and other descriptions of the wheel of time are unlikely to be arbitrary; they point to deeper principles of creation that are yet to be fully understood.
