Apart from a very small number of exceptions, it is IMPOSSIBLE for a departed soul to communicate with those on Earth through a medium or even to see or have any knowledge whatsoever of what is going on here. Even without going into complex metaphysical explanations, the truth of this assertion can easily be seen if we consider the following . . .
The place (or rather the state) of Heaven – called by the Tibetan name of Devachan in Theosophy – is one of supreme and perfect bliss and paradise. As such, logic tells us that no sorrow or even the slightest shade of pain can be experienced therein.
But if departed souls are able to “look down” or “return in spirit” and see all that’s going on on Earth and especially in their homes, what kind of bliss or paradise can that be? Thus, according to the doctrine of the Spiritualists, we unfortunate human beings are not liberated from the sorrows of this life even by death!
Imagine a departed mother looking down upon, or invisibly visiting, or automatically being attuned with, her former home, in the days, weeks, months, and years after her passing and observing and feeling – completely helplessly – the sorrows, the sadness, the suffering, the mistakes etc. of her dear loved ones, from whom she is now severed by death and unable to help, comfort, or contact. Or what about her eventually witnessing her widowed husband finding new love in the arms of another woman? Can any of this be bliss?!? That would be even more hellish than life on earth.
Thankfully, Nature is kind enough to create an impassable chasm between the Heaven state and the Earth state, so that those who have passed on are entirely out of the reach of physical existence and of individuals on the physical plane. A further and more expanded explanation of this is given in the articles When We Die and Death and The Afterlife which can be read by clicking on the title links.
* The above article is an excerpt from The Danger and Deception of Channelling. The “very small number of exceptions” referred to above are explained in the “When We Die” compilation.
T H E O S O P H Y 
This offers nothing but some Law of Nature explanation that is entirely subjective, who knows the Laws of Nature other than maybe inklings of intuition? How do we know anything after all? Specifically who has come back from the dead to tell us all of this? There is literally no explanation for why a soul can’t visit our realm other than it goes to another realm and isn’t in contact with the one we are living in currently. I am not saying there is no truth in this but it’s really short and asking you to just take this face value.
Thank you for your comment Sarah but the article is not asking anyone to take anything at face value. Theosophy always emphasises the importance of spiritual and mental independence and freedom of thought and belief.
Just as Buddha famously told his listeners not to accept anything he taught unless they had thought it over in detail and found that it accorded with their own reason and intelligence, so it is with the teachings of Theosophy.
The article is “really short” (as you say) because, as it says at the bottom, “The above article is an excerpt from “The Danger and Deception of Channelling”.” That and other articles on this site, including the other ones referred to at the end, provide further information and details if people want to consider these things in further depth.
And as for the question of “who knows the Laws of Nature” and “How do we know anything after all?” Theosophy maintains that there are advanced human beings who have reached a high degree of spiritual perfection and perception, enabling them to have direct experiential insight into the mysteries and inner workings of the Cosmos. Such individuals are known as Masters of Wisdom.
Their Philosophy or “Esoteric Doctrine” “is the uninterrupted record covering thousands of generations of Seers whose respective experiences were made to test and to verify the traditions passed orally by one early race to another, of the teachings of higher and exalted beings, who watched over the childhood of Humanity. That for long ages, the “Wise Men” of the Fifth Race, of the stock saved and rescued from the last cataclysm and shifting of continents, had passed their lives in learning, not teaching. How did they do so? It is answered: by checking, testing, and verifying in every department of nature the traditions of old by the independent visions of great adepts; i.e., men who have developed and perfected their physical, mental, psychic, and spiritual organisations to the utmost possible degree. No vision of one adept was accepted till it was checked and confirmed by the visions – so obtained as to stand as independent evidence – of other adepts, and by centuries of experiences.” (H.P. Blavatsky, “The Secret Doctrine” Vol. 1, p. 272-273)
But please don’t feel that you’re being asked to believe and accept this…that’s entirely up to you.
But before you dismiss the whole of Theosophy completely, why not find out more about it? If you read “Theosophy – An Explanation and Overview” at https://blavatskytheosophy.com/theosophy-an-explanation-and-overview/ you might be pleasantly surprised.