This ray of Light is like a vertical pillar of Light, which flows down through all dimensions, through all the bodies, down to the physical. This is the Central Channel of the body, which goes along the spine of the physical body. In fact, the spine is the physical manifestation of the Central Channel. This Central Channel is the presence of our Soul incarnated as the lower self, it exists in all bodies simultaneously, it is what creates all our bodies, and it is what connects our bodies with each other and with our Soul. This is why the main chakras are located along this Central Channel :
This is traditionally called the shushumna channel. The two intertwining serpents, masculine and feminine, ida and pingala, are born from the shushumna, from the Central Channel.
Energy is constantly flowing along the Central Channel, both downwards (from Soul to the lower self) and upwards (from lower self to the Soul). This is what makes us alive, and in a way it is the wire that the Soul uses to connect to the body and drive the body.
In truth, all the Souls are One, so the Sun is One, and the Central Channels of all beings all come from the same Source. Soul and body are two parts of One whole, spirit and matter are two parts of One whole, everything in creation is part of One whole, parts of One organism which is life itself : Life is One whole, Source or God/Goddess is Life as a whole, there is nothing outside the One.
So another metaphor to describe this, is that the Souls and all life is all one ocean, and our bodies and everything we see are just waves in that ocean. The waves appear to stand out but they are still just parts of the ocean. It is all One.
Kundalini, is energy coming into the Central Channel which is not expressed, and therefore lies asleep, dormant, at the base of the spine. The reason the energy is not expressed is because of amnesia, of forgetting who we truly are, and also because of suppression of expression in society.
We are usually born with amnesia of who we are as Souls and who we are as the One ocean. Therefore we tend to not express fully our true nature. This is reinforced by suppression of expression in society, from youngest age we are usually pressured one way or another to behave a certain way, to speak a certain way, to think and feel a certain way, etc.
For example it is suppressed to dance or move the body in unusual ways in public, to sing in public, to fully express how we truly feel, to hug for too long time, etc, we are supposed to stay in line and just say 'I'm ok'. Fully honest sexual expression is especially suppressed. And people usually do not fully process their emotions, we may feel sad or angry and because it is not usually allowed to fully feel it with others, because people around are usually suppressing and rejecting the expressions of others one way or another, the energy is rarely fully flowing, fully released. Even expressions of joy are often suppressed and condemned for no valid reason. Therefore many people can not really cry or laugh or dance or express themselves anymore, they can put a very convincing mask if they want, they can mentally force themselves to smile and laugh and dance, but usually the expression is shallow, forced, it does not involve the whole being. Because the more we accumulate energy within which has not been expressed, the more difficult it becomes to genuinely express in new situations, and so people give a fake smile when they are unhappy, and can not fully laugh when they are really happy.