NPL and the Lord Mayor of London demonstrate Einstein’s theory of general relativity in City of London’s tallest building, 22 Bishopsgate – and celebrated success tonight.

“NPL has shared the results of a time dilation demonstration – which shows that time travels faster as height increases, as predicted by Albert Einstein’s theory of general relativity. The demonstration is part of the Lord Mayor of London Alderman Professor Michael Mainelli’s mayoral theme, ‘Connect to Prosper’.

The demonstration set out to show the difference in the speed of time passing, as measured by a clock, depending on height relative to that on the ground and that time passes faster at a height than on the ground.

It involved placing a highly accurate atomic clock on the 61^st floor at 22 Bishopsgate, the tallest building in the City of London, and comparing it to a second clock located at NPL, in Teddington, south-west London, the home of time in the UK.

When the two clocks were reunited, the time on the clock that was at 22 Bishopsgate was measured to have gained an additional 100±30 nanoseconds compared to the clock that stayed at NPL, entirely in agreement with Einstein’s prediction that time does travel faster the higher up you are. This means the clock would need to spend around 1 million years on the 61^st floor at 22 Bishopsgate before we would see one second of difference between it and a clock at ground level.  

Although over the period of the demonstration, this is visible by only a tiny amount, the implications are profound. For example, this means a person would age slightly faster at the top of a tower block than someone on the ground.

The demonstration was the first in a series of showpiece exercises, which will run for the duration of the Lord Mayor’s tenure. The Experiment Series seeks to showcase innovation and invention in the City of London and promote and celebrate the many ‘knowledge miles’ within the Square Mile.

The results of the demonstration were unveiled by NPL’s CEO Dr Peter Thompson during a speech at the Horizon22 viewing platform at 22 Bishopsgate, looking out over the City of London.   

22 Bishopsgate is managed by AXA IM Alts on behalf of a consortium of international investors.

Dr Setnam Shemar, the Principal Scientist behind the demonstration said: “It was exciting to use the very tall skyscraper of 22 Bishopsgate to showcase Albert Einstein’s theory of general relativity, demonstrating how time really does travel faster the higher-up you are, although by a very tiny amount.”

Of the demonstration Dr Peter Thompson said, “The work we do at NPL is preparing us for the future – for example, smart grids, connected autonomous vehicles and time-critical 5G and 6G applications all need confidence in the timing infrastructure. Our time dilation demonstration illustrates how NPL, and our timing expertise, plays a critical role in global timekeeping and everything it underpins. I’m delighted we’ve had the opportunity to showcase our science and its impact through the Lord Mayor’s Connect to Prosper theme.”

Dr Leon Lobo, Head of the National Timing Centre (NTC) Programme said: “Many aspects of UK industry and society rely on precise time, an invisible utility. Whether it’s at home on our devices, synchronising the telecoms and energy networks, or in the finance industry where the accuracy of timestamps are unfeasibly fine: just 100 microseconds for high-frequency trading. The demonstration amplifies the critical role of NPL in managing the UK’s time, developing the next generation of quantum clocks and ensuring we have resilient time for the future.

The Lord Mayor of the City of London, Professor Michael Mainelli, said:  “British Science Week is the perfect time to present the first results from our ‘Connect To Prosper’ experiment series, which is packed with exciting experiments demonstrating the City’s inventiveness. The Square Mile is known for its financial services expertise, but our “Knowledge Miles” include science, tech, engineering and more. As this demonstration of Einstein’s theory of relativity at the City’s tallest building highlights, from the 15^th century New Learning, 16^th century Gresham College, 17^th century Royal Society, to today, our City is a timeless home of global innovation.”

Phillip Shalless, Senior Asset Manager at AXA IM Alts commented: “Since inception, we have viewed 22 Bishopsgate as being “ahead of its time” due to its pioneering approach to a new era of working. As such, it was extremely fitting to able to take part in such a cutting-edge science experiment proving the relativity of time, whilst highlighting the depth of innovation and ingenuity that has quickly become synonymous with the Square Mile itself.””

And we have had an old NPL atomic clock on the staircase all year as part of Connect To Prosper connecting with our science, engineering, and technology communities, along with a Times article on the subject.