How long is Eternity?

Not this website, but life beyond time itself

I’m on bonus time – well past my three score years and ten. Old friends are departing this world before me. And as I attend their funerals I think about my own. As Christians we have that wonderful hope of a world beyond this one. We have the words of Jesus himself in John 3:16:

For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.

And we’re assured that eventually Jesus will return to this world and all things will be made new. The New Testament is very clear about this. We’re told that God will remake his creation and will raise his people to share in it and to rule over it, transforming them into newly embodied human beings.

As a scientist, I can’t help thinking about how this new world of eternal perfection might work.

Just as Jesus was bodily raised from the dead with his crucified body transformed into an unprecedented new type of physicality, so we too will be raised with a perfected resurrection body – no back pain, no dodgy knees, no cancer, no heart disease. As Paul writes in 1 Corinthians 15:

Listen, I tell you a mystery: We will not all sleep, but we will all be changed— in a flash, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed.

The Bible is consistently clear about this in broad outline but is short on details. As a scientist, I can’t help thinking about how this new world of eternal perfection might work.

The concept of eternity itself is particularly perplexing. Taken literally, eternity is an “infinite or unending time”. But the prospect of doing something forever, however glorious, presents problems. I can’t help but think that, eventually, I’ll get bored. There must be more to it than that. It’s here that physics provides some tantalising clues.

Time clock

Time and common sense

In our everyday experience time passes in an ordered sequence of moments. It has direction: the past precedes the future. And time appears to have a regular and predictable duration that we can measure with clocks. John Newton, the hymn writer seems to have thought that eternity would proceed along much the same course when he wrote:

When we’ve been there ten thousand years, Bright shining as the sun,
We’ve no less days to sing God’s praise Than when we’d first begun.

Until Einstein, physics saw time in the same commonsense way. Sir Isaac Newton, wrote in his Principia (1687): “Absolute true and mathematical time, of itself and by its own nature, flows equably without regard to anything external.” Time was the same for everyone everywhere. This seemed to work really well. Newton’s laws of gravity and motion brilliantly explained the movement of everything from tennis balls to planets. But by about 1900 a few nagging errors and inconsistencies had appeared as the measurement of time became more precise.

Einstein’s revolutionary idea

Einstein realised that time doesn’t “flow uniformly without reference to anything external”. Even perfectly reliable clocks don’t necessarily run at the same speed.

Einstein had realised that the universe as a whole has time as a fourth dimension

Time changes as measured by a moving observer and time changes in a gravitational field. The stronger the gravitational field the slower time passes. So much so that at the centre of a black hole time stops altogether – it ceases to exist.

Strange as this might seem, our heads are older than our feet. This is because we’re standing or sitting upright more than we’re lying down, so our feet are, on average, closer to the centre of the earth than our heads. This means that our feet are in a stronger gravitational field where time passes more slowly. The difference is very small but we now have clocks precise enough to measure it.

Einstein had realised that the universe as a whole has time as a fourth dimension. So if we could step outside the universe we’d see it as a block of both space and time in which the past, present and future are all equally real. What’s more, the laws of physics have no trouble with time running backwards. The laws of physics simply take the universe at one moment in time and predict what will happen in the future or what happened previously in the past. There’s nothing special about the present moment except that we are experiencing it right now in our minds.


Einstein’s block Universe

And to further complicate matters, “now” for me isn’t the same as “now” for you. If I look at you I always see you in the past because light takes a few nanoseconds to pass from you to me. If you were on Jupiter I’d see you two hours ago. Or, if you were on a planet going round one of the nearer stars, it could be four years ago.

So “now” isn’t the moment I see you because I always see you in what for me is the future. And as we look up at the night sky we are always seeing into the remote past. There’s no meaning to “now” except as an approximation in which we can disregard the time interval.

So, is time an illusion?

So is time itself just an illusion that enables us to make sense of our environment?

We find it hard, if not impossible, to think of time beyond our everyday experience.

Our brains use the electrical signals that come from our senses to construct a mental image of the world around us. It’s obviously a very successful strategy. We can do wonderful things with our bodies – we drive cars, read books, hug our loved ones, maybe play the piano or play cricket. But this mental image doesn’t necessarily correspond with reality.

Science tells us that the apparently solid objects around us – our tables and chairs, our computers and books – are in reality almost entirely empty space. More obviously we can observe the brain playing tricks with the electrical signals from our eyes:

In this well-known illusion, the top horizontal line appears to be longer than the bottom one. In reality, both lines are of equal length.

Einstein himself seems to have believed that time is an illusion. In a letter to the widow of a recently deceased friend he wrote:

Michele has preceded me a little in leaving this strange world. This is not important. For us who are convinced physicists, the distinction between past, present, and future is only an illusion, however persistent.

Physicists and philosophers argue about the precise nature of time. But the “block universe” picture of reality is hard to avoid. This would mean that God himself, as the creator of all things – including time – would somehow experience all things, past present and future, in one glorious reality. But we ourselves are prisoners of time. We find it hard, if not impossible, to think of time beyond our everyday experience.

Time and the afterlife: sleep or heaven?

So what does this mean for our understanding of our Christian hope?

Our journey after death might be a two-stage process.

On most Sundays at my church we recite the Nicene Creed which ends, “We look for the resurrection of the dead, and the life of the world to come.”

In the New Jerusalem, we might share to some extent God’s experience of time as a kind of continuum. Somehow all events would be equally available to be re-experienced, wrongs forgiven, and joys endlessly savoured.

But Jesus hasn’t yet returned, so it’s often suggested that our journey after death might be a two-stage process. At first, we rest in God’s presence, in a disembodied state (about which the New Testament has little to say.) Then when God renews all things all believers will be bodily raised to be with Him in the New Jerusalem.

But suppose that when we die we’re no longer bound to our worldly experience of time with its sequence of past, present and future events. The New Jerusalem is then already part of the space-time continuum and there’s no temporal barrier to us joining that great crowd of witnesses in God’s glorious presence.

This would explain why the emphasis of the New Testament isn’t on heaven as such but on God’s New Creation. I suspect that Jesus really meant it literally when he said to the dying thief:

Today you will be with me in Paradise.

Eternity isn’t a very long time; it’s all of time.

So how long is eternity? We could say, ‘As long as a piece of string.’ In other words, it’s a meaningless question.

Modern physics suggests that time is an illusion – a construction of the human mind that enables us to successfully navigate our way through this present world. Eternity isn’t a very long time; it’s all of time. We don’t really know of course, but when I die I expect to be in the glorious presence of God, maybe with a mind that experiences time in a way radically different from how we experience time in this world.

‘Blessed be the God and Father of our Lord Jesus Christ! By his great mercy he has given us a new birth into a living hope through the resurrection of Jesus Christ from the dead.’ (1 Peter 1:3-7)


Dr David Oakenfull has loved science from when he was a boy with a home laboratory.  He enjoyed a long research career in food science and nutrition and in more recent years wrote food and health article for Choice Magazine. He still enjoys cooking – but unfortunately his grandsons seem to prefer Macca’s. He is a Lay Assistant at St John’s Anglican Church, Asquith in Northern Sydney.

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