This is going to be about Einstein’s view of gravity, which while it is complex physics, I’m not going that deep into it. If you’re one of those people who get turned off by the more mathematical stuff, you don’t need to fear. And if you’re the type who already knows their physics, this is going to be frustrating due to how much is lost in the simplification. Take it as a philosophic approach to physics.
Einstein linked time to space in the concept of spacetime. This means that time is a dimension akin to the other 3, making our universe a 4 dimensional place. This in and of itself wasn’t a major shift, but it was when taken in tandem with how gravity can warp this spacetime. This makes time into a relative property, not a universal given (I actually touched on this *here*). When explaining to someone how this works, there’s a common analogy used, that of a bed sheet. A sheet is held taught in the air horizontally. A large heavy ball is placed in the middle. This distorts the sheet downwards, creating a funnel like shape. A smaller ball placed “uphill” from the larger one will descend towards it. If you toss the smaller ball around the funnel, it will rotate around the larger ball but eventually fall towards it. If friction weren’t an issue, you could fling the smaller ball at the exact right speed to orbit around the centre point. This is how gravity works. It isn’t a force per se, but a warping of space, forcing everything within our universe to “fall” towards the centre of mass.
The analogy visualizes spacetime as a 2 dimensional sheet, in reality, it’s 4 dimensional (cause of time). But we were really discussing 3 dimensions with the sheet, the two that are “within” it, and the 3rd dimension which it is warped into; the downwards direction. If spacetime is truly equivalent, then it must also be warped into a further dimension. The 5th dimension. You could call it a 4th spacial dimension but it is distinct in that it is not contained inside our universe. Gravity pushes the universe into it, but everything within our universe stays inside it. It’s merely the shape of the universe that changes.
Now, in reality this is only a metaphor. There isn’t necessarily a physical warping because there isn’t really a way the concept of ‘physical’ makes sense. Physical only applies to our experiential world, the inside of the universe. Like all of philosophy, it’s a way of conceiving of our world, which if useful, is true in some sense.
But still, 5 dimensions, kinda cool, yes?