The nature of time has been one of the great puzzles throughout human history. This has now been resolved by relativity. This shows us without question that time is a fourth dimension, essentially just like space. And the whole of the world is all there ‘already’ in a four-dimensional block. As stated by Deutsch:
Spacetime is sometimes referred to as the ‘block universe’ because within it the whole of physical reality – past present and future – is laid out once and for all, frozen in a single four-dimensional block. (1997, 268)
So here again the new physics tells us the universe is very different to how we have always understood it. It is not a three-dimensional world that is constantly changing. It is four-dimensional, and it is static and permanent.
This, of course, is why there can be no passage of time. The whole extent of time just is. Nothing moves and nothing changes. As stated in the ABC Science article:
In the block universe, time doesn’t pass (Miller, 2018)
As Deutsch states:
No accurate picture of the framework of time can be a moving or changing picture. It must be static. (1996, 264)
This of course is very strange because it means that the dynamics of the universe do not actually happen, as Deutsch goes on to describe in some detail.
The Worldline
The ‘worldline’ of an object is a basic term in modern physics. This is the four-dimensional reality of an object, threading through the four-dimensional space-time of the world. This image illustrates the worldline of an object, stretching into the future up the page.
The entire static extent of the worldline simply exists. And this is born out at the the atomic level. As the physicist Sir Roger Penrose states, the dynamics of physics do not actually happen:
… particles do not even move, being represented by ‘static’ curves drawn on space–time. (1994, 389)
So this is the great paradox. We are witnessing the passage of time, and the world changing, but none of this is actually happening in the world.
The next section is The Moving Now.