That man is the product of causes that had no prevision of the end they were achieving; that his origin, his growth, his hopes and fears, his loves and his beliefs, are but the outcome of accidental collocations of atoms; that no fire, no heroism, no intensity of thought and feeling, can preserve individual life beyond the grave; that all the labors of the ages, all the devotion, all the inspiration, all the noonday brightness of human genius, are destined to extinction in the vast death of the solar system, and that the whole temple of Man’s achievement must inevitably be buried beneath the debris of a universe in ruins—all these things, if not quite beyond dispute, are yet so nearly certain that no philosophy which rejects them can hope to stand. Only within the scaffolding of these truths, only on the firm foundation of unyielding despair, can the soul’s habitation henceforth be safely built.
Bertrand Russell, A Free Man's Worship, 1903.
The question of the ultimate meaningfulness of our lives is a natural extrapolation of our reflection on proximate meaningfulness. Over the course of our lives we strive to achieve and preserve value. Even if we have no idea how our achievements will affect others in the future (after we're gone), we know that those effects will be received, however anonymously and remotely. The physically inevitable (at least according to current physics) and absolute termination of that chain of legacy-leaving (which is what the heat-death of the universe signifies), however, threatens to transmits its nullity to whatever preceded it.
Suicide is one way some despondent people demonstrate their conviction that their lives have no meaning, that the disutility of their mere biological continuance is greater than any prospective compensating utility they might enjoy. The heat-death of the universe is temporally remote enough for virtually all people to push the thought of it out of their consciousness and "get on with their lives." Evasion is just that, however, and if we frankly face the inevitable loss of all the meaning we create, we may not be able to face anything at all. Some philosophies, however, posit a repository of all value, co-existing with the physical cosmos, which would provide an alternative to dishonest evasion and to honest suicide. But ethical urgency alone cannot establish the existence of such a repository.
Earlier this year film critic Roger Ebert expressed appreciation when I used the famous Russell quotation in a comment on his blog. I deemed his appreciation an evasion of my critical point. One may judge for oneself by going to my home page, where I provide the text of our brief exchange and a link to his blog, where it first appeared.