Wouldn’t it curve and pull objects in all directions?
In: 279
I saw this video when I had the same question as you. It shows a way to visualised general relativity in 3 dimensions. https://m.youtube.com/watch?v=wrwgIjBUYVc&pp=ygUKR3Jhdml0eSAzZA%3D%3D
Yes, absolutely it does, but I defy you to find a way to intuitively represent that.
Easier to drop a dimension and show a cannonball on a rubber sheet with marbles rolling around it.
Why a sphere is drawn as a circle and not as a 3d model? Because it’s easy, pragmatic, understandable
I think many answers here are misunderstanding the underlying cognitive dissonance created by a model that depends on gravity, the very thing trying to be understood, to explain the 2D model’s function. Why do marbles roll down the depression on the 2D sheet created by the heavy object? Because of gravity? And before you give me a snarky answer, many science writers and even physicist have said, this kind of model, isn’t always useful. The better the model gets you to an understanding of gravity the worse the model becomes
The truth is, gravity is very hard to understand and all models fail in one way or another.
Tacking onto this: in these visualizations “space” is bending. But what is that? It’s a vacuum, what is bending? What is the fabric of space time?
But if something is “bent” equally in ALL directions, wouldn’t that just make it “straight”?
Short answer: yes, you got that exactly right.
The only reason to use a flat surface is that this is easier to visualize. A curved 3D space is just very hard to display in a way that people understand what is meant with it.
https://youtu.be/wrwgIjBUYVc?si=WxdExwJiqVZWm3ct addresses this problem better than I can, and comes up with a much better visualisation. Less curved sheet, more seeing the curvature of space-time as a flow.
The curvature of space-time by mass causes “straight” lines to get bent slightly out of the time dimension into a spacial one, causing objects to fall toward the mass. The acceleration in space comes with a slight slow down in how fast you’re moving through time, which is a real measured effect.
Bending a 2d plane forms a 3d shape. Similarly, bending a 3d plane, such as the one we appear to live in, forms a 4d shape.
But it’s quite a challenge to draw a 4d shape, and even more of a challenge to understand what it is you’re looking at. For now at least, 2d > 3d illustrations will have to do.
Maybe consider the opposite first… if space time shrunk in a gravitational field… the “grid” would get more dense… this would be easy to show… but it’s the opposite, space gets larger. How else would you represent this?
Latest Answers