What can be time and could beings in another universe time travel with no more difficulty than climbing a mountain?

There is a fascinating scene earlier in the Interstellar movie in which Brand (Anne Hathaway) says that to five-dimensional creatures, time is like mountains and valleys. You can go forward in time like climbing a mountain. You can go backward in time like going into a valley. This phrase contains a whole new theory of perception of physics as such. It is not surprising that the director consulted with scientists when working on the movie. 

Time in physics has always been a controversial substance and was perceived as something between a philosophical understanding of reality and a real physical quantity.

What time really is, no one can say so far. They attributed the properties of the next quantum field to it, and tried to perceive it as a physical substance. They even searched for hypothetical chronons.

But among so many theories, one appeared that designated time as non-existent quantity. Under this perception, an interesting thing turns out.

Time is a measurable quantity, according to which one can estimate the lifetime of the universe or the world as such. At the same time, the world simply somehow miraculously exists forever. It is very difficult to say what eternity itself is and rather, it is very difficult to comprehend it.

Meanwhile, this approach does not cancel the theory of the emergence of the universe as a result of the big bang and other similar research. These concepts have little to do with each other. We just accept the fact that space can still be measured like this.

As a result, the past can differ from the future only by the fact that at that moment there was such a state of matter, and at another moment it changed. Here we come to the aforementioned movie phrase.

Imagine a coordinate plane. It has x and z coordinates and they exist forever, as a property of the available space. Space can be drawn in this number of dimensions. Time, according to this theory, acts as an additional coordinate plane. Its existence is simply a property of space, or another way to measure it.

When we look for the beginning or end of time with this logic, it is the same as trying to find the moment of appearance of the 3D coordinate plane. There may be a beginning, but it is definitely beyond the line of awareness of time and space itself.

According to this logic, it turns out that if there is a creature that perceives space-time not as 3 + 1 dimensions, but as a full-fledged 4 dimensions, then it will be able to move through time in the same way as we move vertically, in 3 + 1. At the same time, time travel will not be something out of hand. This will be the most common ability. The creature will just be able to go in time from point A to point B.

This approach puts everything in its place and lays it out on the shelves. If we compare time with an endless film on which a movie is recorded, everything becomes even more relevant.

Indeed, each point on the coordinate plane will correspond to some state of space. In the same way, each frame on the film corresponds to a certain point in time.

Einstein expressed the same logic but everything is complicated by the fact that then all our actions are already predestined, like a video game when communicating with NPCs. This brings us close to simulation theory. 

Well, time as such is infinite and no langoliers eat up the picture left in the past.