Christian Marclay’s epic work – a clock created from film clips that tells the actual time – ought to be bleak. But time really does fly when you watch this 24-hour miracle

It’s 8.10am and I’m late for my appointment at Tate Modern. I watch the faces of passengers as the train pulls into London Bridge. It’s a Monday and the time is going too fast. One man sweats as he checks his watch. On his way to a bank heist, perhaps.

I didn’t think any of that on my train at the time, though. I revisited my journey after sinking into a white sofa and watching The Clock, Christian Marclay’s epic montage of film clips featuring clockfaces that tells the actual time. Only then, gazing at the cinema screen that’s been built at Tate Modern, did I understand that everyone on a rush-hour train is united by something magical: we’re all sharing the same instant in time.

Time as we know it is a humanising fiction that binds us together. It is community. This is the life-affirming message of The Clock and, surely, the reason why it has become such a well-loved classic of contemporary art, ever since its creation eight years ago.

When the screen says 8.23, I check my phone and find it’s telling the same time. A gaggle of clips from the 1950s and 60s signals that it’s time for the first cigarette of the day. Ashtrays full from the previous night are getting fresh ash tapped into them. Meanwhile, in a clip from the 1993 film Falling Down, Michael Douglas is in his car in a traffic jam, face tense and twitchy as he heads for a crazed rampage. And Richard Burton as a cockney gangster serves his mum breakfast in bed in a clip from – I think – the 1971 film Villain.

All these moments contain clocks – digital clocks, grandfather clocks, watches, alarm clocks or just the time on a TV newsflash – and that time is the same as the time your watch says. The Clock is a highly reliable clock. I am sure there is an art collector somewhere who owns a copy and projects it in the kitchen on a permanent loop to tell the time.

This concordance of fictional and real time has subversive consequences. When Jimmy Cagney checks the time as he nervously waits for a big jail break, and he has the same time as you, the barrier between fiction and reality is broken. There’s an instant of empathy. You and he are in the same predicament. We are all prisoners of time.

Shouldn’t that be a bleak thought? One crackling monochrome clip shows a sinister figure with a sickle. In art, the passing of time was traditionally a memento mori, a reminder of death. Hourglasses and clocks in Renaissance paintings are doom-laden symbols. The Clock, however, is not a downer at all. It’s an upper. And I use that word advisedly for the longer you watch it, the more addictive it becomes. There will be several 24-hour screenings in its Tate run, and they deserve to be packed out because time really does fly when you’re watching The Clock.

This is partly due to the pleasure its sheer ingenuity inspires. The Clock is a 21st-century answer to the elaborate mechanical clocks premodern artisans built for the town halls of central European cities. Just as those ancient clocks amaze with their sculpted wooden figures that rotate on the hour as chimes resonate on cobbled squares, so we marvel at Marclay’s technical achievement. How many hours of watching films, rewinding, freezing, isolating and grabbing brief glimpses of timepieces, went into this miracle of digital craft?

One question does arise about Marclay’s film. Entrancing as it is, does it actually say that much about time? Isn’t it a bit pre-Einsteinian in the way it portrays time as a single universal flow of moments? After all, modern physics sees time as non-linear. The idea of a single clock measuring out all our lives is a myth. After all, not all clocks tell the same time. Hours and minutes are a useful fiction, not an absolute.

In fact, The Clock reveals this in subtle and seductive ways. Its rhythm is emotional. As the moods of different scenes and sequences change, time itself seems faster or slower. You slow to the pace of a stopped train or speed to the ticking of a time bomb.

The Clock is a chronicle of cinema, a history of the modern world and a meditation on the mystery of time. It is above all a great work of art that touches the truth of being human. We fear time, but it makes us who we are. We tick to the same beat.