The Science behind Life after Death
Dr K K Aggarwal
President Heart Care Foundation of India
As per Chhandogya Upanishad death is not instantaneous but an active process. The first to stop functioning are the five Karmendriyas. They are elimination (payu or excretory organ), reproduction (upastha or sexual organs), movement (pada or the locomotor organ), act of grasping (pani or the organ of action the hands) and speech (vak or the speech organ). As per Upanishad, when these five Karmendriyas stop functioning, it is called 'Vakvriti'. They stop functioning in sequence and speech is the last function to go.
In medical science, the first question we ask is " can the person speak?". If yes, the process of death has not started yet.
The next to go are the five sense organs called Gnanendriyas. They are smell (ghrana or nose), taste (rasana or tongue), vision (caksu or eyes), touch (tvak or skin) and ability to hear (srota or ears). The Jnanendriyas also stop functioning in sequence and the last to go is hearing,
In medical sciences, the next question to be asked is whether the person can hear or not.
Once the ability to hear has gone, the next to go is 'Manas" which includes mind, Intellect, Memory & Ego.
When both the Jnanendriyas & Manas stop functioning, the situation is called 'Manovriti'. In this phase, the person cannot speak, hear and think.
Once the vakvriti and manovriti stop functioning, the next to stop functioning are the five Pranas. Prana Vayu (the upward moving force of the chest region responsible for respiration); Apana Vayu (the downward moving energy of the sacral region connected with the functions of excretion and reproduction), Samana Vayu (the laterally moving energy helping in digestive functions); Udana Vayu (the energy that compress and causes deglutition and separates physical body from astral) and finally the Vyana Vayu (the energy moving in circles in the entire body and responsible for circulatory system).
These 'Vayus' too cease functioning with the 'Vyana Vayu' being the last to cease. Once all five Vayus cease to function it is called "Pranavriti".
Therefore, medically the third question to be asked “is the patient breathing?” and if yes, is the circulation on.
The above sequence also explains the difference between the “brain stem death” and “death”. In brain stem death the Prana Vayu cease to function but other vayus continue to function.
Once the Prana stops functioning, the Pranavriti merges with Tej (Tejas, lose control of temperature regulation) and these merge in Sat (Sath). With that life comes to an end.
The “Sat” may be taken as a state when the consciousness or the life force leaves the body.
At any stage, before “Tejas” merges with 'Sat" death is reversible. Before pranavritti by putting a person on ventilator and at Teajs by creating therapeutic hypothermia.
In Ayurveda there are three terms called Prana, Tejas (Tejesvi Bhava) and Ojhas (Ojhasvi Bhav). They represent the life forces and are consistent with the above observations. The nearest equivalent to Tejas is control of metabolism and temperature regulation. Till the tejas is under control, life force cannot cease to function.
Medically or naturally if hypothermia develops, Pranavriti cannot merge with the Tejas, the life force can be kept preserved for a long duration. A person can be revived later by bringing back the body to a normal temperature and with proper resuscitation. In modern medicine it is called therapeutic hypothermia.
A person whose functioning of Karmendriyas, Jnanendriyas, Mans and Prana have stopped and if put in a state of therapeutic hypothermia, can be revived later after re-warming and cardiopulmonary resuscitation.
The above sequential process also can explain the “near death” experiences. They depend at which stage the person was revived.
For example, if a person gets revived at a stage of vakvriti he or she may recall experiences related to the motor organs. If the person gets revived at a stage of Manovriti, he or she may recall experiences of both motor and sensory organs as well as experiences related to mind, intellect, memory and ego and if the patient gets revived at the stage of Pranavriti, he or she may recall the near death experiences linked to motor organs, sensory organs and breathing.
The process of death therefore is Vakvriti merging into Manovriti, Manovriti merging into Pranavriti and Pranavriti taking the heat of the body (Tejas) and merging into 'Sat' and the 'Sat' merges into “Brahamand” in the atmosphere. [Chandogya Upanishad 6.15.1]
Samadhi is a state of oneness in body mind and the soul. The process of Samadhi also involves the above process starting with control of Karmendriyas, then Jnanendriyas, followed by control of the mind (manas), then the control of prana and finally the control on metabolism (tejas) and lowering of body temperature. At this state the life force can be preserved for a long period and the person can revive back even after months. Samadhi has been practices by Rishi Munis in Vedic literature but in natural environments on the hills.
Food is Brahman
Motor organs, sensory organs, Prana, (the life force) and all formed by the food we consume.
When Ghee & oil in the food gets digested, it gets divided into three parts: The “crude” part makes bone, the middle part makes bone marrow and the subtle part makes the Karmendriyas (Vak).
When the nonfat part of the food is digested, it too gets divided into three parts: The “crude” part makes the feces; the “middle part” Manas and the “subtle” part Jnanendriyas.
When the liquid part of the food is digested, it also gets divided into three parts. The “crude” part gets converted into urine, the “middle” part into blood and “subtle” into Prana.
This explains the process of fasting. A person can live without air for three minutes, without water for three days and without food for three weeks. The first effect of fasting unto death is cessation of speech then hearing and then the prana.
The above is true in non-Samadhi state. In the state of Samadhi your metabolism may be so slow that you may live longer without food. Even today many Jain Munis live without food for months.
Life after death
As per Upanishads the ‘Sat' or the life force, called consciousness remain in the atmosphere.
After a variable period of time it will fall on to the earth through the rain drops when (the RNA & DNA) gets taken up by the food grains. Therefore, the term “food is Brahman”.
When the appropriate father & mother eats that food, the life force enters in the ova & the sperm and from there the new life begins. (Soul never dies Bhagavad Gita 2.20]
This process of new birth is just the reverse of the process of death. In the process of death, the first to go is Vakriti or speech and in the process of birth the last to come is Vak or speech.
This, explanation, though is difficult to explain in terms of modern science.
The science of Karma:
Karmas in Vedic knowledge are described in three terms: Sanchita Karma, Prarabdha Karma Agami Karma.
Every action result in a reaction. Action & the resultant reaction together is called a Karma. The end result can be positive or negative, depending upon the resultant reaction.
As per Vedic literature, the net negative Karmas get accumulated and needs to be neutralized either in this birth or in the next birth. At the time of death, all the resultant accumulated negative Karmas, which remains to be neutralized, constitute Sanchita Karmas.
If the Sanchita Karmas has a high burden, then some of them, as an installment, gets constituted as Prarabdha Karmas which one needs to neutralize in the coming birth.
Therefore, when a person is born, he is born with pre-defined Prarabdha Karmas. These need to be neutralized and faced in this life and the left over Sanchita Karmas to be faced in subsequent birth unless some of them are neutralized by this birth by good positive Agami Karmas.
Agami Karmas are day-to-day Karmas of this birth. If the net result of positive & negative Agami Karma is positive, they can neutralize the Sanchita Karma that form the basis of Vedic saying and recommendation of keep doing the good job. It also resolves the myth that if one’s destiny is pre-defined in terms of Prarabdha Karma, why should one do good jobs.
According to Buddhism, one is born to suffer as per the number of Prarabdha Karma at the time of birth. Buddhist Philosophy says that suffering exist, there is a reason for that suffering and one can live and make modifications to enjoy that suffering.
The purpose of life, therefore, should be to live our Agami Karma in such a way that they not only neutralize our Prarabdha Karma, but also the Sanchita Karma.
According to Bhagavad Gita, whatever you think throughout your life, will be your thinking at the time of death and whatever is the thinking at the time of your death, will be the type of womb you will get in the next birth [Bhagavad Gita 8.6, 8.7].
As per Prasna Upanishad  whatever one's thinking, with that one enters into prana. Prana joined with fire (udana), together with the soul, leads to whatever world has been fashioned by thought.
The thinking at the time of death decides which Karmas will form the installment of Prarabdha Karma. Therefore, thoughts at the time of death decide the destiny of birth in the next generations.
So as per Bhagavad Gita, one should be in a positive state of mind at the time of death. If spontaneous positive thinking is not possible, then every effort should be made to convert negative into positive thinking.
According to Bhagavad Gita, the best time to die is Uttarayana, before full moon in a day light or in an atmosphere of Yagna. The bad time to die is Dakshinayana, before Amawasya, in the night or in the dark.
To convert bad into good timings, the process of death should take place at home, in a lighted environment (artificial Dias, in the vicinity of Vedic hymns) in the company of positive thinking people. In that situation, the chosen Prarabdha Karmas out of the Sanchita Karmas will be positive and the life force with positive aura will enter into the womb of parents who are positive. In this way, even if you are born to suffer, you will suffer and yet not suffer.
Note: [ The views written in the forward are my personal views and interpretations based on my literature search and knowledge acquired t after interaction with many spiritual Gurus over the last many decades]