London. Home of the world's most iconic marathon? Undoubtedly.
Cultural capital of the world? Perhaps.
Central point of Greenwich Mean Time and thus the spiritual home of time itself? Almost certainly.
But what if time as we know it doesn’t even exist?
Thanks to technology, time has never appeared more fixed, or more important.
For us runners, time can become an obsession, with splits occupying our minds “rent free” even on easy sessions.
But much like running, time has a more complex personality, one that is intentionally obscured.
"A lot of us grow up being fed this idea of time as absolute," says Chanda Prescod-Weinstein, a theoretical physicist at the University of New Hampshire.
But Prescod-Weinstein says the time we're experiencing is a social construct. Real time is actually something quite different.
And in some of the stranger corners of the Universe, space and time can stretch and slow — and sometimes even break down completely.
An authoritative sense of time is essential for an organised society and economic efficiency, so it’s no wonder time has been portrayed as rigid.
But if we are to believe leading physicists, time is far more flexible than most of us realise.
According to the general theory of relativity, space and time are tied together, and space-time can bend and curve.
As time is stretched by gravity, it slows down. And as the gravitational pull is weakened, time speeds up.
For satellites far from Earth, such as those that make up our beloved Global Positioning System (GPS), the “flowy” nature of time is problematic.
The system can only work by measuring the time difference between several satellites carrying clocks in space to the time that people measure on the ground.
In places where gravity is extremely strong, time breaks down completely.
At the edge of black holes, for example, the immense gravitational pull slows time dramatically. And upon crossing the black hole's point of no return, known as its event-horizon, space and time are said to flip.
If you're struggling to make sense of it all, you needn’t worry, as according to astrophysicist Katie Mack, time is doomed anyway.
In her bluntly titled book, “The End of Everything (Astrophysically Speaking)”, Mack argues that as the Universe enters its final phase of expansion it will become an inert cloud of energy and matter, where time has no direction or meaning at all.
In this grey nothingness, "there is no future, there's no arrow of time anymore."
So if you fail to secure that marathon PB on Sunday, you can console yourself with the fact that time is just an illusion, destined to implode.