A Missing Film

There is a film between Inception and Interstellar that few can claim to have watched. It begins near the end of the first film and gives another perspective on the whole of the second. The story goes like this. Cobb, having observed his totem, realises that he was wrong all the way. While he was going "down" a level, he was actually going "up" one. He also learns not to brand events as dreams and reality. Not one level alone can claim any more realism than others. After this, he decides to do what he always thought he was doing: to go "down". Difference in time works the other way in that case. If one chooses wisely and goes down enough levels, one can be as close to immortality as one wants. For example, in one second spent on a level deep enough, an entire galaxy, with all its planets, civilisations and languages can be materialised, thrived and gone on some level above.

Eventually, he acquires the ability to be conscious simultaneously on all levels, without the need of medication and kicks to get in and out of them.

On one of the levels he sees a dying earth with humans unable to escape it. He decides to help them by getting one of them, named Cooper, go down a few levels and acquire some data and come back. Note that extraction was Cobb's speciality before he found he could do inception. In Cobb's trade, this data helps to bend reality at will by an expert architect. In Cooper's this is called quantum data and it helps to get humans away from their earth.

An architect in Cobb's trade bending reality on a level is equivalent to a physicist in Cooper's solving some equations. Different trades, different jargon.

Cobb selects Cooper because he has first-hand experience of what a father could endure to reunite with his children. The mission, to someone with a background in science like Cooper, looks like being led to field after field of greater gravitation. To Cobb, he is moving from level after level of greater depth. That is, towards immortality. Unnatural difference in ageing between Cooper and his daughter may be noted at this point. He has been to some deeper levels while she never left their common level.  Cooper is yet to learn that the name of "the bulk being from the fifth-dimension" is, simply, Cobb.