Arithmetic (~20,000 BC) - Counting abstract objects
The invention of arithmetic provided a way to compute abstractly about numbers of objects.

Written language (~4000 BC) - A systematic way to record knowledge
A central event in the emergence of civilization, written language provided a systematic way to record and transmit  knowledge.

Babylonian astronomy (~500 BC) - Using arithmetic to predict the heavens
The Babylonians introduced mathematical calculation as a way to find the behavior of planets and a few other systems in nature.

Pythagoras (~500 BC) - Numbers are the key to nature
The Pythagoreans promoted the idea that numbers could be used to systematically understand and compute aspects of nature, music, and the world.

Panini (~400 BC) - Finding the rules of human language
Panini created a grammar for Sanskrit, forming the basis for systematic linguistics.

Aristotle (~350 BC) - Classifying the world, and introducing logic
Aristotle tried to systematize knowledge, first by classifying objects in the world, and second by inventing the idea of logic  as a way to formalize human reasoning.

Library of Alexandria (~300 BC) - Collecting the world’s knowledge
The Library of Alexandria collected perhaps half a million scrolls, with works covering all areas of knowledge.

Archimedes (~250 BC) - Computing as a basis for technology
Archimedes used mathematics to create and understand technological devices, and may have built gear-based, mechanical astronomical calculators.

Ramon Llull (1300) - Creating knowledge by combinations
Ramon Llull promoted a scheme for systematically creating knowledge from formal combinations of ideas.

John Graunt (1662) - Inventing the idea of statistics
Graunt and others started to systematically summarize demographic and economic data using statistical ideas based on mathematics.

Gottfried Leibniz (1684) - Answering questions using computation
Leibniz promoted the idea of answering all human questions by converting them to a universal symbolic language, then  applying logic using a machine. He also tried to organize the systematic collection of knowledge to use in such a system.

Isaac Newton (1687) - Mathematics as a basis for natural science
Newton introduced the idea that mathematical rules could be used to systematically compute the behavior of systems in nature.

Carl Linnaeus (1750) - Creating a taxonomy for life
Linnaeus systematized the classification of living organisms, introducing ideas like binomial naming.

Encyclopædia Britannica etc. (1768) - Printing collected knowledge
The Encyclopædia Britannica—and the Encyclopédie of Diderot and d’Alembert—attempted to summarize all current knowledge in book form.

Charles Babbage (1830) - Printing mathematical tables by machine
Babbage constructed a mechanical computer to automate the creation of mathematical knowledge.

Melvil Dewey (1876) - Classifying the world’s knowledge
Dewey invented the Dewey Decimal System for classifying the world’s knowledge and specifying how to organize books in libraries.

Gottlob Frege (1879) - Axiomatizing knowledge through logic
Frege created a formal system and language in which mathematical and other knowledge could be represented in terms of an extended form of logic.

Oxford English Dictionary (1880s) - Collecting every word in English
With extensive information supplied by a network of volunteers, theOED was a systematic project to get complete knowledge of all the words in the English language.

Alan Turing (1936) - The concept of universal computation
Turing showed that any reasonable computation could be done by programming a fixed universal machine—and then  speculated that such a machine could emulate the brain.

Digital computers (1940s) - Automating the process of computation
The arrival of digital electronic computers provided the mechanism by which computations of all kinds could be automated with increasing efficiency.

Computational linguistics (1950s) - Algorithms for human language
Computational linguistics put the concepts of grammar into an algorithmic form that promised to automate processes of language understanding.

Computer languages (1957) - Languages for programming tasks
Fortran, COBOL, and other early computer languages defined the concept of a precise formal representation for tasks to be performed by computers.

Pop-culture computers (1950s-1960s) - Imagining intelligent machines
From the Tracy and Hepburn movie Desk Set to TV’s Batman and Star Trek to HAL in 2001: A Space Odyssey and the  robots of Isaac Asimov, the public became used to the idea that computers would eventually have human-like knowledge  and reasoning.

Artificial Intelligence (1950s-1960s) - Making computers intelligent
Artificial Intelligence defined a research program for developing computers that show general intelligence–and led to many spinoffs important for specific purposes.

Interactive computing (1970s-1980s) - Getting immediate results from computers
With the emergence of progressively cheaper computers, it became possible to do computations immediately, integrating  them as part of the everyday process of working with knowledge.

Neural networks (1980s) - Handling knowledge by emulating the brain
With precursors in the 1940s, neural networks emerged in the 1980s as a concept for storing and manipulating various types of knowledge using connections reminiscent of nerve cells.

Cyc (1984) - Creating a computable database of common sense
Cyc has been a long-running project to encode common sense facts in a computable form.

The Web (1989) - Collecting the world’s information
The web has grown to provide billions of pages of freely available information from all corners of civilization.

Google (1997) - An engine to search the web
Google and other search engines provided highly efficient capabilities to do textual searches across the whole content of the web.

Wikipedia (2001) - Self-organized encyclopedia
Volunteer contributors have assembled millions of pages of encyclopedia material, providing textual descriptions of practically all areas of human knowledge.

Web 2.0 (early 2000s) - Societally organized information
Social networking and other collective websites defined a mechanism for collectively assembling information by and about people.

A New Kind of Science (2002) - Exploring the computational universe
Stephen Wolfram explored the universe of possible simple programs, and showed that knowledge about many natural and artificial processes could be represented in terms of surprisingly simple programs.

Modern investigators indulging in inquires concerning the significance of existence, purpose of life and the meaning of the universe, will not be surprised at being exposed to a monumental ideological repository as these questions have a long history of intense philosophical and scientific speculation. These questions and answers have emerged in a variety of cultural and ideological backgrounds, resulting in their variegated engagement of the problem.

The museum of such spirited speculation shows that the approaches to the problem can be chronologically arranged in three distinct periods, corresponding to the three stages of development of human knowledge. From the fictitious to the abstract, and ultimately to positive knowledge. Theological and philosophical pursuits constitute the first two periods, and the rational, scientific method constitutes the current period.

As complex as all this may sound, but these concepts regarding life, the universe and everything, seem to be adequately expressed by regular individuals through other questions, such as Why we are here? What is the meaning of it all? and How should we act?

Theological approaches:

The theological discourse relies on a transcendental perspective and is based on religious notions of ethics, soul, afterlife and God. The religious perspectives are those which explain life in terms of an implicit purpose not defined by humans. Advantages of such an approach is finality and simplicity of the solution, transcendence of reason and strong peer support. Whereas the fatal fault in such approaches is that they fail the simplest of rational analysis.

• Christianity: Life’s purpose is to seek divine salvation through the grace of God and intercession of Christ.
• Islam: Man’s ultimate objective is to serve Allah by abiding by the Divine guidelines revealed in the Qur’an and the Tradition of the Prophet. Earthly life is merely a test, determining one’s afterlife, either in Jannat or in Jahannum.
• Hinduism: The meaning of life is tied up in the concepts of karma, samsara, and moksha. Existence is conceived as the progression of the atman across numerous lives, and its ultimate progression towards liberation from karma.
• Buddhism: The ultimate goal is liberation from suffering, according to the Four Noble Truths. This is attained in the achievement of Nirvana, or Unbinding which takes place when one realizes the emptiness of the self and everything else.

Philosophical approaches:

The philosophical pursuit relies on an anthropocentric ideals and abstractions and is based on the philosophical notions of meaning, consciousness, happiness, ethics and metaphysics. This has a clear advantage. The answers coming from this domain are straight forward. They convey meaning which we can understand directly as they answer questions which seem like the ones we would have asked, if we too were serious about the meaning of life, the universe and everything. The deficiency of such approaches is that they are abstract, hypothetical and idealist.

• Platonism: The meaning of life is in attaining the highest form of knowledge, which is the Idea of the Good, from which all good and just things derive utility and value.
• Aristotelianism: The supreme purpose of human existence involves achieving eudaemonia, meaning “happiness”, “well-being”, “flourishing”, and “excellence”.
• Cynicism: The Cynic philosophers have said that the purpose of life is rejecting conventional desires for wealth, power, health, and fame, and to be free of the possessions acquired in pursuing the conventional.
• Epicureanism: The purpose of life is in seeking modest pleasures, to attain tranquility and freedom from fear or ataraxia, via knowledge, friendship, and virtuous, temperate living.
• Stoicism: Living according to reason and virtue is to be in harmony with the universe’s divine order, entailed by one’s recognition of the universal logos, an essential value of all people. The meaning of life is freedom from suffering through apatheia, that is, being objective and having “clear judgement”. Contrary to popular perception, the stoic answer to life does not consist of indifference.
• Utilitarianism:  Doing the good that brings the greatest happiness to the greatest number of people is the ultimate purpose of human life.
• Nihilism: Life is without objective meaning, purpose, or intrinsic value.
• Existentialism: Each person creates their own purpose of life; life is only limited by oneself, one is terribly free.
• Absurdism: Man has a desire for order, meaning, and purpose in life, but the universe is indifferent and meaningless; the Absurd arises out of this conflict.

Scientific approaches:

The scientific approach is unique in the sense that it is based on the idea of objectivity, which necessarily means that it doesn’t have a perspective. Science does not inquire in the normative domain, or about how things ought to be. Instead it asks questions in the tone of how can it be. This has interesting consequences. Science and the scientific community agrees that it has no role to play in telling us what the meaning of life is, as it is not capable of that. Still the most important contributions to the inquiries about the ultimate questions have come from this domain. This is due to the fact that though science can not tell us how to ideally lead our lives, several other questions that it has answered about our origin and nature and that of the universe sets the rational standard for all intellectual inquiries. Hence science provides the context and sets the parameters for conversations on related topics. Thus the following approaches are rational ideas, based on scientific facts.

• Secular Humanism: The nature of the universe is what people discern it to be. Values and realities are determined by means of intelligent inquiry and are derived from human needs and interests as tested by experience, that is, by critical intelligence. The total personality is a function of the biological organism transacting in a social and cultural context.
  The question of the meaning of life could also be reinterpreted as “What is the meaning of my life?” Instead of becoming bogged down in cosmic or religious question about overarching purpose, this approach suggests that the question is intensely personal. There are many therapeutic responses to this question, ”Dereflection” for example, which largely translates as ceasing to endlessly reflect on the self, instead of engaging in life. On the whole, the therapeutic response is that the question of meaning of life evaporates if one is fully engaged in life. The question then morphs into more specific worries such as “What delusions am I under?” and “What is blocking my ability to enjoy things?”. Post-humanism and Transhumanism are philosophical sub-genres of secular humanism.
• Logical Positivism: The people and events in the life of a person can have meaning or importance as parts of a whole, but a discrete meaning of the life, itself, aside from those people or events, cannot be discerned. A person’s life has meaning only for himself and others as the life events resulting from his achievements, legacy, family, et cetera, but to say that life, itself, has meaning, is a misuse of language, since any note of significance, or of consequence, is relevant only in life to the living, so rendering the question erroneous. Bertrand Russell wrote that although he found that his distaste for torture was not like his distaste for broccoli, he found no satisfactory, empirical method of proving this.
• Post-modernism: Seeks to understand meaning by looking at the underlying structures that create or impose meaning, rather than the epiphenomenal appearances of meaning in the world.