“What time is it?”

Behind this innocuous question lies a huge assumption about the world we live in. We have a concept of ‘the’ time which it is everywhere, even though we might give it a different label in another time zone. “When it’s 5 pm in Liverpool, it’s noon in New York.”

Two hundred years ago, British villages still kept local time, based on when a sundial would show noon. It was only with the coming of the railways that there was a need to have ‘the time’. In Bible days, before the invention of mechanical clocks, daylight was typically divided into 12 approximate hours. Some Bibles ‘translate’ times into our modern way of speaking but more literal translations will tell you that the Holy Spirit fell on Pentecost Sunday at ‘the third hour’ (9 am) while Our Lord was hung on the Cross at the sixth hour (noon) and breathed his last at the ninth hour (3 pm). The night was divided into four ‘watches’ which you can find listed in Mark 13.

There is a more fundamental problem with the concept of ‘the’ time. Einstein’s Theory of Relativity, as the name implies, suggests that the positions of things are relative to each other, but not fixed against any standard. This applies to positions in time, as well as in space. There is no such thing as ‘absolute speed’, only the speed of one thing moving relative to another. You could imagine unreeling two identical copies of a filmstrip showing something happening (maybe an arrow hitting its target). Hold one closer to you than the other, and by moving your head sideways to different positions, you can see the near arrow hit its target before or after the one on the far filmstrip. In the same way, Einstein showed that observers moving quickly past a scene would not always agree on which of two events in different positions happened first.

Position and speed may be relative, but changes of speed are absolute. And when an object accelerates to go on a journey and then decelerates to come back, Einstein predicted that the passage of time would slow down while the object was accelerating (in either direction). This leads to the famous twin paradox – an identical twin sent on a rocket trip at a significant fraction of the speed of light would return home younger than her earthbound sister.

While we haven’t done the experiment with twins, we have sent exquisitely accurate atomic clocks on round-the-world aeroplane excursions, and the results have always matched what Einstein predicted. Even a clock flown from London to Washington D.C. and back again will gain 32 nanoseconds over a clock which never leaves British soil.

General Relativity complicates things further, predicting that the strength of gravity also affects the speed at which a clock runs. This already has to be taken into account by SatNavs, which rely on atomic clocks mounted in satellites further from Earth’s surface than we are. Those clocks gain 45 microseconds a day over Earthbound clocks. And now that we are beginning serious exploration of the Moon, we will need to define a standard for Lunar Time – the Moon’s surface gravity there is so low that a clock will run almost 59 microseconds faster than a terrestrial clock. These numbers sound small, but when computer systems perform well over a billion calculations each second, synchronising computers on Earth with those on the Moon will be a problem!

Twice in the Hebrew Bible, we find claims that God miraculously adjusted the length of a day. Joshua 10 tells that in answer to Joshua’s prayer, sunset was delayed for a whole day while the Israelites fought a battle. II Kings 20 tells how King Hezekiah was granted the miraculous sign of the sun moving backwards, as a promise that his sickness would be healed. (There is a story which regularly circulates on the internet claiming NASA computers ‘proved’ that these two miracles took place, but this claim is at worst a hoax, and at best the result of a Christian contractor misinterpreting an in-house April Fool’s joke.) 

Now, were these miracles in which God actually changed the motion of the Earth, or were they miracles of perception in which God only touched the minds of those present? The Bible itself suggests the latter in II Chronicles 32, where foreign envoys are sent to the King to ask about the miracle which occurred ‘in the land’. We find an intriguing echo of this in the ‘Miracle of the Sun’ at Fatima in 1917, when a crowd of tens of thousands reported seeing the sun ‘dancing’ (this was documented by journalists at the time) but observers elsewhere did not.

The Bible doesn’t have a concept of ‘the time’ – only ‘the right time’. The famous passage from Ecclesiastes 3, set to music by Pete Seeger in 1959, became an unlikely hit for The Byrds, proclaiming To Everything There Is a Season, also known by its refrain Turn! Turn! Turn! Indeed, the ancient sage who wrote this Wisdom book proclaimed – depending on how you translate it – that for living, dying, gathering stones and casting them away, there is a ‘time’ or a ‘season’.

The New Testament also distinguishes the ‘passage of time’ (chronos) from the ‘appropriate time’ (kairos). We find many statements that Jesus did, or did not, do things because his hour had (or had not) come. John’s Gospel uses kairos in John 7 but otherwise uses the word ‘hour’ (hora) in a poetic way for a similar meaning (in more than half his chapters). At the start of a Eucharistic Liturgy in a Greek Church (both Orthodox and Eastern Catholic), the deacon will solemnly proclaim ‘Now is the time (kairos) for the Lord to act!’

Many people worry that if God knows in advance what we are going to do, we are not free to make choices. As an astrophysicist, I disagree. I imagine God sitting outside time, beholding the whole universe as a series of filmstrips of things happening in each place. It is because God sees what happens on your filmstrip, that God knows what you will freely do. If God should use that knowledge of the future to influence something in the past, God will do so consistently. Your free action is indeed the immediate cause of God’s knowledge.

It seems that there is nothing in the laws of physics which prevents the future affecting the past. There is even a valid solution for how to build a time machine, without the uncertainty of plunging through a black hole. The snag is that you have to assemble a row of ten almost-a-black-hole neutron stars, all spinning very fast in the same direction. Einstein’s equations then show us that a very fast spaceship, skimming close to the surfaces of these superdense stars, could fly in a path that would bring it back to where it started, but at an earlier time. The catch is that you can’t fly back to a time before you built the time machine, but otherwise it apparently works!

Is there time in heaven? Many theologians would say that there is not. Yet we profess that Our Lord and Our Lady have their bodies into heaven, and for this to be meaningful, heaven must be some kind of space – albeit not one you could fly to from ours – for these bodies to have somewhere to exist. Without time, a body is doomed to be a frozen statue. But that doesn’t mean that ‘heavenly time’ is synchronised to our experience of time; Scripture does declare that with the Lord, a thousand years can be like a day (Psalm 90, II Peter 3).

Purgatory also needs a dimension that works like time, so that a person’s purification can be ‘shortened’ in response to our prayers. Jesus hints at Purgatory in his parable (Matthew 18) of an unmerciful servant who is eventually jailed until he can ‘pay the last penny’. But who would pay your fine while you are jailed, unable to earn? The people who care about you! The fire of their love shortens your sentence, simultaneously intensifying it by accentuating your sense of unworthiness and gratitude.

Does God the Father experience the passage of time? Many scholars say no, because philosophically speaking, God cannot change (an idea affirmed in James 1). Yet many Bible passages speak of God reacting to things, feeling angry (Exodus 4, 15, 32), even changing His mind (Genesis 6, Exodus 32). Somehow, we need to distinguish God ‘in Himself’ and God ‘as he interacts with the timestream of our world’. Jesus, outside time, before taking flesh, was ‘eternally begotten’, coming timelessly from the Father. (John 1 & 5) Perhaps it is just as well that God sits outside time, since (II Peter 3) “The Lord is not slow to fulfil his promise as some count slowness, but is patient toward you.” Indeed, as it says in the very last chapter of the Bible, the Lord is coming soon!

Revd Dr Gareth Leyshon is a parish priest in the South Wales Valleys, who read physics at Oxford and completed a doctorate at Cardiff (a study of the structure of distant galaxies) before entering seminary.

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