The universal energy, called Shakti in Sanskrit, resides in every human being and is known as kundalini. Shakti is the active aspect of the Absolute (Shiva).
When kundalini awakes, it rises from the base of the spine in the mooladhara chakra through the central channel (sushumna) and unites with Shiva at the top of the head in the sahasrara (crown chakra). When this union of Shiva and Shakti happens, a nectar-like coolness begins to flow. It is as if it were coming from hundreds of moons. Thus, the individual Self merges into the universal Spirit — the subtlest union of the masculine and the feminine within. This ultimate union of Shiva and Shakti occurring at the top of the head is called yoga, samadhi, Self-realization, enlightenment, liberation, moksha, nirvana, kaivalya, emancipation, or truth.
A mere awakening of the kundalini is not enough; it must rise to the sahasrara. Only then can the union, called a full kundalini awakening, take place.
In his book, Raja Yoga, Swami Vivekananda (1863 —1902) describes the kundalini rising: “When that Kundalini awakens, it tries to force a passage through this hollow canal [Sushumna], and as it rises step by step, as it were, layer after layer of the mind becomes open and all the different visions and wonderful powers come to the Yogi. When it reaches the brain, the Yogi is perfectly detached from the body and mind; the soul finds itself free.”
Kundalini is located in the subtle body, not in the physical body.
What Does It Feel Like?
To know what the rest of sleep feels like, you have to go to sleep. In the same way, if you want to truly know how a kundalini rising feels, you have to have your own experience.
Actually, it is my kundalini awakening experience that led me to write my book, Building a Noble World.
Given below is the description adapted from my book, Building a Noble World, along with the following link to my previous answer on Quora:
My Awakening Experience
In 1974, I was at a transition point in my life. I had just graduated with a master’s degree in Accounting from the University of Illinois at Urbana-Champaign and moved to Chicago in search of a job. I heard Swami Muktananda (known as ‘Baba’) was speaking at Northwestern University in downtown Chicago on September 13, 1974, so I decided to attend his talk. At this time in my life, I had never even heard the word ‘Kundalini,’ and I could never have imagined the drastic and wonderful turn my life would take after meeting Baba.
The talk was already in progress when I arrived, but I was nevertheless inspired by Baba’s words. After his talk, I joined the line formed to meet him. When I reached him, I whispered, “Baba, I don’t have a job.” At this, he raised his right hand in a gesture of blessing and said, “Mil jayega” (“You will get it”). I bowed down my head with utmost reverence and felt blessed. As I left the auditorium, I received a pamphlet describing a phenomenon known as Kundalini. Intrigued and desiring to know more, I resolved to visit Baba again the following day.
On the morning of my September 14, 1974 visit, when my turn came, I bowed my head before Baba, but as I was getting up, he gently took my arm and ushered me to sit beside him on the raised platform. Honored, I sat silently on Baba’s left side as people in the line moved forward to meet him. During this time, I found an opportunity to ask, “Baba, when will I get the job?” He replied, “You will get the job immediately after your Kundalini is awakened. Take the meditation program. It will be free for you.”
I did as I was instructed. The meditation program took place on Monday evening, September 16, 1974 — the day I would regard as the greatest day of my life. The hall in Lake Point Tower was filled to capacity as Baba delivered his meditation talk to a rapt audience. The program began with an opening statement from Baba: “Today’s subject is meditation. The crux of the question is: What do we meditate upon?”
I clearly remember sitting cross-legged on the floor while listening to Baba’s words. I was near the front row and at the edge of the center aisle with my eyes closed, quietly focused on my breathing. I recall Baba saying, “Kundalini starts dancing when one repeats Om Namah Shivaya.” I mentally repeated the mantra, which was charged with Baba’s spiritual energy. My breathing became heavier. Suddenly, I felt a powerful force rising within me. The intensity of this rising Kundalini force was so tremendous that my body lifted from the floor and fell into the aisle, causing my glasses to fly off.
As I lay there with my eyes closed — my breathing was suspended — I could see a continuous fountain of dazzling white lights erupting within me. These brilliant lights were brighter than the sun, though no heat came from them. I was experiencing the thought-free state of “I am.” I was overwhelmed with the realization that “I” have always been, and will continue to be, eternal. While experiencing this eternal “I am” state of supreme consciousness, I was fully conscious and completely aware. No words can describe this ultimate experience. For the first time, I really understood what the word “eternal” meant.
At that moment, Baba delightfully shouted from his platform, “Mene kuch nahi kiya; kisiko shakti ne pakda” (“I didn’t do anything; the Energy has caught someone”). Then he continued, “I [Baba] am like a radar. When something happens, I come to know of it immediately.”
The dramatic awakening of Kundalini in me frightened some people in the audience, but Baba reassured them saying, “Do not be frightened. Sometimes Kundalini gets awakened in this way, depending upon a person’s type.”
Within me, the brilliant white lights disappeared, giving way to a cooling experience. It was a blissful cooling state as if it were emanating from hundreds of moons. As I was still experiencing this ethereal state of indescribable celestial bliss, Baba commented on the inner state that I was experiencing: “Ab mere me aur isme koi antar nahi raha” (“Right now, there is no difference between his state and my state”).
As Baba returned to his talk on meditation, the intense coolness gradually receded inside me, and slowly I became aware of my physical body once again. I felt a slight pain at the base of my spine, but the sensation was dulled by another realization: Baba had become my guru the very moment I experienced my eternal nature. My heart was overcome with tremendous gratitude for Baba’s divine grace.
A short break followed Baba’s talk. During this break, I walked up to Baba and fully prostrated before him, to offer my deepest gratitude. Baba’s face lit up with joy as he patted me on the back. He told me to share my experience with others and to read his book (titled Guru at the time. It has since been republished under the title Play of Consciousness). “That’s why I wrote this book, Guru,” Baba explained, because this experience was meant to be shared.
I visited Baba every day at Lake Point Tower until he left Chicago. I shared many moments with Baba in those following days, and he continued to bless me with advice and wisdom until he departed on September 20, 1974. Just three days after he left, on September 23, 1974, I found an accounting position at CBS, a well-known television company in Chicago. Baba’s blessing came true.
In the Wake of My Awakening Experience
My life changed forever—I was completely transformed—with my Kundalini awakening. That experience of divinity vastly improved my quality of life and altered the way I view myself and the world. I look upon every person as a relative of my innermost consciousness. I see everything in the universe—from the smallest blade of grass to the largest star—is linked through a common, fundamental, pervasive energy called consciousness.
The same consciousness that exists within me exists within everyone. With absolute certainty, I understand now that both my physical body and my mind are coverings over the innermost “I am” awareness. This awareness is eternal, beyond birth and death, and it will exist even after my earthly body is gone. Just as rising and setting are illusions of the sun, birth and death are illusions in this “I am” awareness.
I frequently see a tiny blue light. Sometimes I see it with my eyes shut and at other times with my eyes open. This has been happening ever since my rebirth on September 16, 1974, and it continues to be my most sublime experience.
I kept going back and forth to Baba until he left his physical body on October 2, 1982, on the full moon night of Sharad Purnima. Looking back at my life, I would say, “1974 to 1982 were the most valuable, golden years of my life.”
I am forever grateful to Baba for my new awareness, for now, I do not merely believe in my Self; I know it to be absolutely true.
Kundalini awakening is true homecoming – you experience your original spiritual nature (atman). The individual is like an iceberg and homecoming is like an ocean. An iceberg is nothing but water at a very cold temperature. The sun rises and the iceberg melts with the hot atmosphere. There is no more the iceberg — no more individuality. It has become one with the ocean.
I feel blessed to be gifted with Kundalini awakening. What happened to me is the birthright of every human being. Have full faith in your innermost being. Explaining what a firm faith can do, Swami Muktananda (1908-1982) said, “I receive so many letters from people who were reading Play of Consciousness and received shaktipat from the book. They put the book against their hearts and began to meditate.”
You ask: How do you know kundalini rising has happened? Just as right now you know that it has not happened, so also you will surely know it has happened when kundalini rising does happen.
May you revel in your own inner Self!