I know that we are surrounded by dark matter, does the dark matter affects space time ???and I know the reason for gravity according to explanations in general relativity. But all the explanation about GR is explained in two dimension, where space is imagined as a fabric and placing an object creates a dip and hence pulling objects near-by and this is gravity.
But why does photons of light get fallen into this dip, by the way photons have zero mass.Some people explain that photons have energy hence they are also effected by Gravity, but gravity is all about mass that can cause a distortion in space-time.All that i need to know here is why photons of light are affected by Gravity.
Please help me, i want to know more about space-time.