In his first experience of television science, back in the late 1960s, the six-year-old Johnson watched enthralled as a famous engineer sought to demonstrate the magnetic effects of induction motors.
Professor Eric Laithwaite had rigged up what looked like a conveyor belt of magnets, along which a metal tray would be propelled to illustrate the technology used in futuristic "frictionless" trains. But he had miscalculated and the tray flew off the magnets and across the studio, to roars of laughter from the audience.
Dr Johnson is hoping this image won't return to haunt him, especially in his experiments with time travel. For, in a year which marks not only the Millennium but the 200th anniversary of the Royal Institution, the theme of this year's lectures, is time itself.
Dr Johnson, now 38 and an Oxford University lecturer in theoretical physics, will examine what time is, how it is measured and how it affects us, before exploring the possibility of time travel.
Once again, demonstrations, a major feature of these lectures since they were launched 170 years ago, will be prominent.
Albert Einstein said that time slows down for objects moving at high speed. The lectures will seek to demonstrate this by sending a super-accurate atomic clock on an aeroplane to China and back, and then comparing its reading to that of a clock in the studio.
If all goes to plan, the returning clock should be a few billionths of a second "slow".
In the first lecture, Back to the Future on Boxing Day (to be broadcast on BBC2 at 11.20am), Dr Johnson will look at how our concept of time originated.
The second programme, Catching the Waves, on Monday, December 27, 11.15am, sees Dr Johnson indulging his passion for the saxophone to illustrate how sound and light waves help us keep time.
On Tuesday, The Quantum Leap, 11.40am, will grapple with quantum physics and on Wednesday, 11.50am, Living on the Edge of Chaos will explore science's ability to predict the future.
The final programme, Shaping the Future, on Thursday, 11.50am, explores "worm holes" - the possibility of time travel and whether there could be parallel universes.