One of Einstein's old tutors, a man oleh the name of Minkowski showed that the special theory of relativity could be expressed in an interesting way.
The world we live in consists of four dimensions, the three luar angkasa dimensions and one that is not exactly time but is related to time (it is in fact time multiplied oleh the square root of -1). This is not at all easy to understand but it means that space-time as we call it has some rather weird properties. In particular, when anda pindah through one of the luar angkasa dimensions anda also travel, unwittingly, through time. anda do not notice this, indeed as far as anda are concerned nothing happens to anda at all, but someone observing anda would say that anda have travelled through time. Of course, we are always travelling through time, but when anda travel through luar angkasa anda travel through time oleh less that anda expect. The most famous example of this effect is the "Twins Paradox".
All the effects of special relativity, such as the slowing down of clocks and the shrinking of rods follow from the above. In fact, it is often better to think of some things, such as electromagnetic fields as being four-dimensional objects. However, the important thing to remember for the moment, is: when anda pindah through luar angkasa anda are compelled to pindah through time but, when anda pindah through time (which of course anda are always doing) anda do not have to pindah through space.
So, what does this have to do with gravity? It is quite simple! When a mass is present in the above space-time it distorts it so that whilst it remains true that travelling through luar angkasa causes anda to travel through time, travelling through time now causes anda to pindah (accelerate) through space. In other words just oleh existing, anda are compelled to pindah through luar angkasa - this is gravity.
The particular advantage of this theory of gravity (General Relativity) is that it explains, at a stroke, all the observed properties of gravity. For example the fact that it acts equally on all objects and substances becomes obvious when anda thing of gravity as a distortion of space-time rather than a force.
Imagine that anda are in free space, away from any planets atau stars, when suddenly a planet is created quite close to you. anda would not be aware that anything is happening to you, anda would feel no force, but anda would find that anda started to accelerate towards the planet. This is just like the case where anda travel through space, anda are not aware that anda have also travelled through time but people observing anda are.
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