Types of views on the afterlife
There are two fundamentally different types of views on the afterlife: observation based views and faith based views.
The first type is based on some form of observation by a human or an instrument. These observations come from reincarnation research, near death experiences, out-of-body experiences, astral projection, electronic voice phenomena, mediumship, various forms of photography etcetera. They are studied by survivalism. The work of people like Bruce Moen and Robert Monroe are also of this type. Also scientific research into the afterlife is based on observation.
The second type is based on some form of faith, usually faith in the myths that are told by ancestors or faith in the truth of religious books like the Bible, the Qur'an, the Talmud, the Vedas, the Tripitaka et cetera. This article is mainly about this second type.
The afterlife in different metaphysical models
In metaphysical models, theists generally believe some sort of afterlife awaits people when they die. Atheists generally believe that there is not a life after death. Members of some generally non-theistic religions such as Buddhism, tend to believe in an afterlife like reincarnation but without reference to God.
Agnostics generally hold the position that like the existence of God, the existence of supernatural phenomena, such as souls or life after death, is unverifiable and therefore unknowable. Some philosophies (i.e. posthumanism, Humanism, and often empiricism) generally hold that there is not an afterlife.
Many religions, whether they believe in the soul’s existence in another world like Christianity, Islam and many pagan belief systems, or in reincarnation like many forms of Hinduism and Buddhism, believe that one’s status in the afterlife is a reward or punishment for their conduct during life. To the extent that the afterlife is a form of justice, it is usually restricted to humans, as animals are not held responsible for their actions.
Afterlife in modern science
Modern science, in general, either describes the universe and human beings without reference to a soul or to an afterlife, or tends to remain mute on the issue. A notable exception is a famous study conducted in 1901 by physician Duncan MacDougall, who sought to measure the weight purportedly lost by a human body when the soul departed the body upon death. MacDougall weighed dying patients in an attempt to prove that the soul was material, tangible and thus measurable. These experiments are widely considered to have had little if any scientific merit, and although MacDougall's results varied considerably from "21 grams," for some people this figure has become synonymous with the measure of a soul's mass. The title of the 2003 movie 21 Grams is a reference to MacDougall's findings.
Others, such as Francis Crick in 1994, have attempted a ‘scientific search for the soul’. Frank Tipler has argued that physics can explain immortality, though such arguments are not falsifiable and thus do not qualify as science.
Some investigations have been conducted which failed to find evidence that “out-of-body” experiences transcend the confines of the brain. For example, one hospital placed an LED marquee above its patients’ beds which displayed a hidden message that could only be read if one were looking down from above. As of 2001, no one who claimed near-death experience or out-of-body experience within that hospital had reported having seen the hidden message.
Afterlife in Ancient Egyptian Religion
The afterlife played an important role in Ancient Egyptian religion, and its belief system is one of the earliest known. When the body died, parts of its soul known as ka (body double) and the ba (personality) would go to the Kingdom of the Dead. While the soul dwelt in the Fields of Aaru, Osiris demanded work as payback for the protection he provided. Statues were placed in the tombs to serve as substitutes for the deceased.
Arriving at one's reward in afterlife was a demanding ordeal, requiring a sin-free heart and the ability to recite the spells, passwords, and formulae of the Book of the Dead. In the Hall of Two Truths, the deceased's heart was weighed against the Shu feather of truth and justice taken from the headdress of the goddess Ma'at. If the heart was lighter than the feather, they could pass on, but if it were heavier they would be devoured by the demon Ammit.
Egyptians also believed that being mummified was the only way to have an afterlife. Only if the corpse had been properly embalmed and entombed in a mastaba, could the dead live again in the Fields of Yalu and accompany the Sun on its daily ride. Due to the dangers the afterlife posed, the Book of the Dead was placed in the tomb with the body.