You might see the space in front of any objects you're looking at
This particular space meditation has a long tradition too, and Chris Neubauer (2022) notes that there is an infinite variety of these.
The instruction to look at the space in front of objects instead at the (meditation) object has four purposes.
To de-focus, and thereby to de-personalise the meditator's view
To reduce the possibility to conceptualise and to particularise the objects
To facilitate becoming aware of the "inner space" of awareness
To slow down the left brain processing of the brain
Note: I have no idea whether what I said is Sam Harris´s true intention. But these are possible ways to explain his pointing out instruction.
1. Meditating on Space as Defocused viewing
Defocusing reduces the felt sense of "Self". Since it is actually not possible to "focus on the space" (just try!), at least not on a point in space, the effect is a more peripheral way of looking.
This is in contrast to focused looking, which can only be done using attention (as opposed to broad awareness). And, as John Churchill (2022) sais, attention is the lense of our Self.
To understand the difference between attention and awareness, read this post.
2. Less conceptualisation and particularisation
At the same time, looking at the space (or meditating on space) instead of the objects takes the attention of the objects and thereby reduces the tendency to "particularise" (ie to select specific objects from the broad field of awareness) and to "conceptualise" (ie to perceive at a higher level - e.g. to see "a chair" instead of a field of color and shape etc).
This corresponds to Chandaria's (2022) hypotheses, that trough meditation we "descend the cortical hierarchy of fabrications" to a level where the mind becomes "calm", at which point we can begin to become aware of rhe "empty" space of awareness itself. "And that is called non-dual awareness" .
Chris Neubauer in "No Self, No Problem: How Neuroscience Catches up with Buddhism" makes this point too (Neubauer 2022) in chapter "Spatial Processing".
3. Physical space as pointer to inner awareness space
"Space" is one of the few traditional metaphors that Sam Harris uses for what he usually calls condition. This is the metaphorical awareness space in which all experience occurs.
In the above instruction, he uses the term "space" to shape the way of looking at the actual space. In related meditations, he instructs to look at the air. It it the same. In both cases, space and air also stand for the inner space, the vast expanse. So, if one practices to look at the outer space or air, one also practices to perceive the inner awareness "space".
4. Slowing down the mind
As Chris Neubauer (2022) sais regarding all "space looking" exercises, of which he sais that there are an infinite variety of these:
There is something about space that slows the mind, since the mind has no way to understand it because it has no content and no container. Therefore, when we shift our awareness, the interpretive mind slows down
Shamil Chandaria. (2022, October 30). The Bayesian Brain and Meditation [Video]. YouTube. https://www.youtube.com/watch?v=Eg3cQXf4zSE
Churchill, J. (2022, 12. Dezember). The Modern Hippie Podcast - EP17: Buddhist Contemplative Psychology & Metacognitive Awareness w/ Dr. John Churchill. Google Podcasts. Abgerufen am 6. März 2023, von https://podcasts.google.com/feed/aHR0cHM6Ly9hbmNob3IuZm0vcy85NTQzNWUyOC9wb2RjYXN0L3Jzcw/episode/M2FmZDNlMTgtMjgxMC00ZTMxLTg4Y2QtOGQ3MjFhMTNlMWU5?sa=X&ved=0CAUQkfYCahgKEwi4w8Gllsf9AhUAAAAAHQAAAAAQngQ
John Churchill used to learn with Daniel P Brown
Gebel, T. (2022c). Space and no boundaries and edges. Till Gebel. Retrieved March 6, 2023, from https://www.till-gebel.com/post/sam-harris-daily-meditation-2022-09-29-space-limitless-no-boundary-no-edge
Niebauer, C. (2022). No Self, No Problem: How Neuropsychology Is Catching Up to Buddhism (The No Self Wisdom Series): Niebauer PhD PhD, Chris: 9781938289972: Amazon.com: Books. https://www.amazon.com/No-Self-Problem-Neuropsychology-Catching/dp/1938289978