No-one knows what time really is. One theory holds that it is granular, like sugar. It can slip through your fingers, it can pile up. All of it is here; an accretion of buried presents.

On Bankside, brandishing my Kraftwerk ticket outside Tate Modern like Charlie Bucket at the factory gates, I’m sloshing over with continental lager – it’s Trans-Europe Express tonight, after all. A retrospective of a futuristic band in a defunct modernist megalith now repurposed to house modern art: are we looking backwards or forwards? Life is timeless. All of it is here.

Sugar, chocolate, flour; the river dissolves it all. Just there, this side of Blackfriars Bridge, stands Albion Mills, London’s first factory. James Watt’s new steam engines are driving 20 pairs of 150 horsepower millstones, grinding ten bushels of wheat per hour. ‘The most powerful machines in the world’ are taking people’s jobs. The millers riot, and soon afterwards the place burns down. 

William Blake often walks past the factory’s charred hulk, and asks whether Jerusalem was builded here. The answer, as with all of those questions, is no. That’s the point; the holy city was never built, despite the rumour, and it’s going to take fire and desire and unceasing mental fight to shift these dark, satanic mills and build it in their place. 

But the rioting millers are fighting against the current. A century downstream, London is the true heart of darkness, its black arteries stretching to the plantations and back, to the trading posts, mines and workhouses, pumping coffee and opium, clogged with tobacco and coal, cotton and sugar. Henry Tate is a great philanthropist, as only men who make such profits can be. Time is granular.

Two years into the Great War, there seems to be no end in sight. Blake’s words are set to music to provide a patriotic, morale-boosting song for the soldiers to sing on their way to an industrialised death in the Flanders mud. What has been a zealous manifesto for earthly paradise-building, becomes, on the cusp of the Empire’s decline, a retrospective yearning for an innocent Albion of ‘pleasant pastures’ and ‘mountains green’: a no-place lost in the mist off continental Europe.

The next war ends the Empire, but also presents an opportunity to forget it. The Luftwaffe pounds and pulverises Bankside into floury dust. London is on its knees, but from the rubble emerges a new founding myth; the nation is triumphant again, and still superior, but now it is also good: it can, for once, glory in the moral rectitude of its casus belli. The smoke rising from the bomb sites screens the nation from its imperial shame. The past is sugared over. In 1999 Germany’s Culture Minister calls Britain ‘the only one nation in the world that has decided to make the Second World War a sort of spiritual core of its national self, understanding and pride’.

Clement Attlee vows to ‘build a new Jerusalem’ in Labour’s 1945 election campaign. There are dissenting voices when Giles Gilbert Scott’s oil-fired power station is begun on Bankside two years later. Directly across the river from St Paul’s, the heroic symbol of the Blitz, another dark, satanic, mill is going up just next to the site of the original. Gilbert Scott has made his name designing churches and cathedrals. It is agreed that Bankside’s chimney will not reach higher than St Paul’s spire. 

After the war, Germany gets on with things, keeps itself busy. The Volkswagen Beetle, the people’s car, is the icon of the Wirtschaftswunder, the West German economic miracle of the ’50s. It is briefly sold as a ‘Victory Wagon’ upon entering the American market in 1955.

I’m watching Kraftwerk in a former Kraftwerk. They’re even the same age. Both men and machine date from 1946-7: born and brought up among the wreckage of war. As a child in Frankfurt am Main, ‘a city that had been destroyed’, percussionist Wolfgang Flür ‘enjoyed playing on the nearby bombsites’ where ‘it was possible to find all kinds of resonant objects. Of course, hideous and dangerous things also lay under the heaps of stone.’

Vergangenheitsbewältigung is the German attempt to dig up and confront some of these hideous things that lie under the surface. Kraftwerk’s first, self-titled album (1970) ends with the synthesised sounds of a bombing raid: the menacing drone of planes approaching at high altitude, the doppling effect of an air raid siren and the dreadful, rumbling detonation of a full payload. In a grim joke, the track is named after a Bach cantata, Von Himmel Hoch (‘From Heaven Above’). None of the band can remember these sounds but they are etched into the collective memory of the nation, just as they are in Britain. To synthesise this aural trauma is not only to confront it, it is to assert control over it and somehow master it by repurposing it in art. Similarly, in the ’80s, the pioneers of Detroit techno employ a sound palette haunted by the mechanical sounds of the defunct auto assembly lines that once provided their parents with livelihoods. At a late stage of the show tonight, the words ‘Detroit. Electro. Germany.’ flash across the 3D screen.

In their early Krautrock years, Ralf Hütter and Florian Schneider are using live drummers, but when Flür joins as the band’s electronic percussionist in 1973, Kraftwerk begin to discover the definitive, austere, fully synthesised sound that will go on to be so influential. It is no accident that this electronic tabula rasa comes from Germany, which needs to move on more than anywhere else. But it is wonderful to think that this new aesthetic also becomes the key influence on electronic dance music in its many forms: surely the greatest contribution to human happiness that technology has yet produced.

Trans-Europe Express (1977) marks a watershed in Kraftwerk’s career, as their first album to make use of a sequencer. The Synthanorma is a customized 32-step, 16-channel analogue machine made for the band by Matten & Wiechers, which enables drum patterns and repetitive keyboard lines to be programmed and played automatically. The responsibility of marking time, which weighs so heavily, can be signed over and entrusted to the machine. There is consolation and refuge in its repetitive reliability, but also the promise of progress. The train of history is put back on track, emerging from the tunnel and plunging into the future. Europe Endless.

For years one corner of the Tate Modern hosted The Pack, by former Luftwaffe pilot Joseph Beuys: a Volkswagen camper van towing an absurd team of toboggans, each loaded with torches, rolls of felt and lumps of animal fat. I don’t know where it has gone, or where it is going.