Dennis asked:

I’m not sure if this is for you, a physicist or a priest. But here goes. Mankind is roughly 3.5 million years old but eventually (to my knowledge) the sun will die in 5 billion years. Before that all water will boil away in 1 billion years. Is that the end of human life and if so why are we here? I realize interplanetary flight is severely limited by distance and even 1 billion years is an ‘eternity’ BUT that day will come. Do you have any views? Kind regards.

Answer by Craig Skinner

Your question is one for everybody – philosophers, physicists, priests and others, alike.

You link what I think are two separate questions:

1. Is the sun’s death the end of human life?

2. Why are we here?

I will give you my views on each.

1. The end of human life

First, human life is already reduced to a single species (H. sapiens, appearing 150,000 years ago), all twenty two other Homo species having gone extinct, the last being H. neanderthalensis about 30,000 years ago. And it is unlikely that H. sapiens will split into new species here on Earth, given that we are an interbreeding global species sharing essentially the same habitat. Of course if groups of us ended up on different planets, divergent evolution could occur.

Secondly, we may go extinct long before the sun dies. It’s unclear whether our occupancy of the cognitive niche in the biosphere is stable long term. We may make such a mess of things, one way or another, as to go extinct.

Thirdly, all life on Earth will indeed die when (or before) the Earth is destroyed by changes in the sun. The only hope for our distant descendants, or for the then dominant intelligent kind, whether biological or artificial, is to find alternative accommodation. This may be easier for AI life forms who don’t need water, oxygen, food or gravity, although of course all life needs energy. One really suitable planet not too far (!) away would give us another billion years or so, and it’s quite likely that one will be found and reached in the time available. It is possible that our distant descendants, or the superintelligent AI life forms that replace us after the ‘singularity’, will have colonized the galaxy long before the sun dies.

2. Why are we here?

I take it you ask life’s meaning or purpose, rather than an account of how evolution by natural selection produced us.

My view is that we can have only the meanings and purposes we set for ourselves. And this is so whether we live for a day or a billion years.

Many think that the existence of a benevolent, omnipotent creator gives our lives meaning. But it seems to me this just moves the question up a level. For we can now ask what is the meaning or purpose of God’s life. On the Judaeo-Christian tradition, God doesn’t even enjoy a social life among equals, as humans can; indeed he doesn’t recognize other gods as equals (‘no other gods before me’ etc). The point of his life appears to be love. But this seems to me to be a good point. We humans can do likewise whether or not gods exist. The 20th Century philosopher

John Macmurray felt that Descartes set us off in the wrong direction with ‘I think therefore I am’, and that humans are essentially agents so that ‘I act therefore I am’ is a better starting point for philosophy. He goes on to say that ‘all philosophy is for the sake of action, all action for the sake of love’. If this includes love of truth, beauty and humour as well as of fellow humans, it seems a fair basis for living out the rather absurd situation we find ourselves in by existing.


Answer by Geoffrey Klempner

Even if as Craig says there is a chance that human beings could ‘colonize the galaxy’ before life on Earth is extinguished, it is considered probable that the universe itself has a sell-by date defined in terms of entropy, the so-called ‘heat death’ theory. That’s a very long way away, but adding noughts doesn’t make any essential difference to Dennis’s point. Which is that somehow, we feel that if life has any real point or value, it must go on forever.

I won’t debate this factual claim, which is a major element in religions that preach the existence of an ‘after life’. My query concerns how this could possibly solve the problem of the meaning of life. All we seem to be asking for is ‘more of the same’, without end.

That’s why more thoughtful interpretations of religious doctrine speak of the ‘eternal’ as something essentially different from the numerically infinite. My own view as an atheist is sceptical. However, supposing we were, or had the capacity to become, eternal, like God, wouldn’t that mean that we are not essentially finite beings? And, if not finite, how would one make a distinction between ourselves and the kind of being that we take God to be?

A finite being that merely ‘lives forever’ remains dependent on its creator. It continues to exist, or ceases to continue, as God decides. To exist eternally is to exist beyond any such relationship of dependency.