A definition of life is important to define abiogenesis.
Another fascinating definition is death.
Clinical Death occurs when circulation and breathing stop.
Within a minute brain function stops.
And for all those that presume consciousness is a process of the brain.
Consciousness must stop by definition.
Despite modern medicine most who have a cardiac arrest die, unless they are close enough to a team who have defibrillators and know how to use them. They are brought back to life before irreparable damage is done.
There is a period in which to restore circulation for life to resume normally. Irreversible damage is done within 3-5 minutes. And very few can be brought back after that.Whilst attempts to keep some circulation going manually help extend this period, it is very low pressure and not enough to restore consciousness. Consciousness only returns after defibrillation resumes normal blood pumping. Return to measurable brain function can take time. Periods of unconsciousness can often follow ressusitation from cardiac arrest.
So so called "Near death experiences" are in clinical terms "actual death experiences"
Which is why those who can describe exact details of places , conversations and details of procedures and remote places they cannot have known or guessed are so interesting for the debate on "what is consciousness".
In this unconscious state one patient "howard" witnessed the unusual details of the ressusitation , procedures, which he cannot have known , described from a view point of the ceiling, the clothing worn by staff, and then as he floated up he described accurately a room above in the hospital off limits to anyone but staff being trained, with manikins around a central set of works tations used to train ressucitation procedures. He cannot have guessed it.
Clinically he was dead. He was clinically unconscious, whilst his experience show he was actually conscious. And his consciousness was of a remote place from his body.
The first cells to suffer irreversible damage are in the brain. It needs a lot of energy just to survive. Turns out that cells can enter a "pilot light" state. Not operating but lower energy. That is what happens during the down time, but reversibility only lasts for minutes in the brain.
Turns out The period in which can be extended by lowering body temperature dramatically, so some surgery (like cranial aneurisms) are done with the body temperature lowered dramatically. Blood is drained from the head. And just to make doubly sure, clickers are put in the patients ears with ECG monitoring any response.
One of the most famous NDE of Pam Reynolds - occured in this state.
She described with taped eyes the tools used to open her skull which she described as an electric toothbrush. turns out that is exactly what it looked like. She can never have seen it previously. Also the conversation by the vascula surgeon they could not find a sufficient blood vessel in one leg so wen to the other. She was surprised that they even needed blood vessels (actually to drain her blood, to work on the aneurism in her head)
There is not a chance in hell that her brain was active to record the conscious experience, and even if she had, she would not have been able to see what she described accurately.
This is one of hundreds of veridical NDE. That is conscious experience whose details can be validated by reference to the medics. Whilst clinically dead.
As I have said on other threads. Increasingly many neurologists and AE doctors no longer believe the hypothesis that consciousness is a product of brain chemistry. It doesnt fit the evidence. The mind controls the brain, even the deveopment of it. The brain is not the mind.
Read
Bellg "near death in ICU" as a reasonable introduction to the types of experience she has witnessed in AE
The "self does not die" Rivas - for analysis of a lot of veridical (ie verified ) experiences.
Van Lommel "conscioussness beyond life "for technical details of the science of brain process, neurologists views on consciousness, cardiac arrest and lateral studies on NDE
These are not quacks. They are real ICU , Cardiologist and neuro doctors speaking about NDE. They concluded that the hyptothesis that consciousness is a brain process is false. The evidence does not support it. . Van lommel has published his studies in the lancet several times.