The spacetime fabric

The only reasonable property we mentioned about Axions is that they have a mass and when we say mass we say gravity so before going into further explanations let's take a grip on the basics.

The understanding of spacetime/gravity concept is so complicated because it's beyond the horizon of our minds, it's believed to be true because the only possible way for Einstein's theory of relativity to work is that the universe is four-dimensional!! you heard it right, as we said before the space and time are no longer independent they have to work with each other to prevent anything from travelling faster than light. In consequence, if we add one dimension to the 3d space that we know we get a 4d scale universe so to simplify the labyrinth let's consider a more straightforward approach where space and time present each one a vector so they form a 2d plan together.

If we suppose that space is just a surface of a trampoline and that we put an object in the centre, the surface will bend in the region of the mass and all other objected put in the surroundings of that curve will be attracted to this last. That works literally the same for gravity, so everything that has a mass influence the space and time in its region and the bigger the mass is the more remarkable the gravitational effect will be.

And that's not it, the spacetime curve will affect everything depending on space and time, in other words, every tangible object or everything that depends on time, more accurately everything that has speed.

Therefore, light is affected by gravity and this is the major lead that helped unravel the existence of the dark matter.