Science can give the knowledge of the object being seen. In science, there is a duality, between the seer (researcher/observer) and the object being seen. The seer and the seen are independent of each other. The seer can know about the 'object been seen' but the 'object been seen' cannot know about the seer. Science's foundation is with the duality of nature. But our problems in life exist in our mind. So we need something which is independent of the mind to be able to know the mind. The problem here is, that it is only through the mind that we experience objects and know about them - terminating the mind means terminating the possibility of objects that can be known. Because all understanding comes under the realm of mind. In deep sleep, the mind is not there, therefore the mind is not conscious of the objects, hence we cannot know anything in deep sleep - there is no awareness, no time, no world - the duality of the world ceases to exist in deep sleep. Still, we say that 'we slept' when waking up. This means that there is something that has witnessed the deep sleep - then only the mind is aware that it slept, else it would look like a glitch between the time when going to sleep and when waking up. That unknown, un-named, void seer is called pure consciousness in Advaita Philosophy. That seer is just present - it cannot be seen, nor its qualities can be known. It is just there. The uniqueness of I (that is your name, your gender, your body, etc) is just false. The I that you experience is the false experience of the mind made up of 'false you' and 'pure consciousness'. Hence, because of this, you experience the duality of life when the mind is in the awake state. Letting go of the false self feels like death - but one who is able to successfully know the false self and able to drop it attains immortality in mind as birth and death are also duality. For him, death is known. If you want to know about life, you need philosophy. Real philosophy will never negate science. Philosophy and religion are different. In religion, there are some belief systems that you have to believe in - be it God, Soul, or Heaven-Hell. There might be some rituals and moral practices that you need to follow to get something - maybe admission to Heaven, etc. You can argue/question about the foundation of a religion. In philosophy, there is no belief system - it starts from 'You'. It supports arguments and questioning. The highest-known philosophy is Advaita Vedanta - or philosophy based on Non-Duality. It is based on the Self - or you. That 'unique you' experience is broken into the 'false you' and pure consciousness. And then it reveals the falseness in you which you need to break free in order to know The Truth. It will never talk about the qualities of The Truth but only the falseness in you. As only the false has qualities and The Truth just is. No qualities can be attributed to The Truth. If any quality is attributed to The Truth, it comes under the realm of mind. So if you need final fulfilment of yourself, you need to know your mental bondages and break free from it - as those bondages are just virtual and exist only in the mind - not in physical form. Advaita Vedanta will help you break free of those bondages and then you will be liberated from everything - including liberation from fear of death.