Abstract space is a mental map that exists within our minds and the minds of others. It is a shared conceptual reality where abstract activities - such as Software Engineering - take place.
Image graciously licensed with permission of James Sypniewski
Software Engineering is the coming together of human minds to build incredibly complex artifacts. These edifices of complexity are mostly invisible. We can see the output of a system, we see the source code and sometimes the metrics, but we cannot see the bits flowing through nor the invisible structures created by the minds of our fellow engineers. Unlike a building, we cannot instantly conceive the design by using our eyes. We first must be submerged in the source code, to build up the structure in our minds.
This is abstract space - the realm of the Software Engineer. It is what separates engineer from a programmer. In this realm, there is no wind, no heat. It is devoid of external senses; it is our inner world: visualization, thought and feelings.
The goal of abstract space, should be to turn it from something that is abstract, into something that is concerete.