How exactly does curved space-time describe the force of gravity?

 Today we will be talking about the Theory of Relativity and how exactly does curved space-time describe the force of gravity.

So, basically, Einstein discovered that space and time can't be separated. They are part of the same thing, and gravity is actually produced by bending and warping this "spacetime", like a heavy ball sitting on a sheet of elastic.

(for the simpler answer to the title's question look at the bottom of the page)

    Classical(or Newtonian) Physics

Time can be considered as a dimension, just like distances. In this way, our universe is four dimensional: three for space and one for time. Before Einstein came along, people thought that these dimensions were fixed: anyone who looked at something would measure the same distances, see the same things happening at the same time.

    Special Relativity

Einstein realised that this is not true. Two events that appear simultaneous to one observer may seem to happen at different times to a different observer: simultaneity is not preserved.

He came up with this idea by looking at light and realising that light always travels at the same speed, no matter how fast you are traveling. Even if you chase a photon, it always moves away from you at the same speed from your point of view.

The only way that this can be made to work is if there is a link between time and space. We can't consider them to be separate things anymore; time and space get mixed together depending on your frame of reference.

This is why physicists talk about spacetime. Just like the x, y & z directions only depend on where you put your axis so it doesn't make sense to consider e.g. the x direction separately from the y & z directions, so the time dimension cannot be considered apart from spacial dimensions since different observers put their axis in different places.

    General Relativity

Einstein then went a step further. He realised that considering time and space together as spacetime allowed him to think about gravity. Einstein imagined spacetime being bent and warped by heavy objects. This way, other objects always move on straight lines but those lines look curved to us because spacetime itself is bent.

For example, the moon looks like it's moving in a circle around the earth, but in spacetime it's actually moving in a straight line. These straight lines are called geodesics.

So, in a more simple way, gravity doesn't literally bend spacetime. What it actually does is modify the spacetime interval. So, to answer the title's question
, time does not literally "bend". A massive object modifies the proper time interval around it such that an outside observer would see objects near the mass experience less time and spacetime intervals would have their spatial components modified accordingly.     But that is a lot to say, right?     It's much easier for us to simply say that gravity is spacetime being warped.