Are space and time real?
According to cognitive neuroscience, our perceptual experience of reality is only a distant and convenient mapping of the physical processes causing the sensory inputs. Sound is a mapping of auditory inputs, and space is a representation of visual inputs. Space and time are “unreal” from this point of view.
Though we may not like to accept it, the foundations to our knowledge are philosophical. These foundations are assumptions in most cases. Some of the assumptions, especially the ones in physics, are not difficult to spot. Others that pertain to the nature of reality itself are far trickier to appreciate. The elusive assumptions include the existence of time and space, for instance. The realness of reality is not merely a philosophical issue; it is a subject matter of cognitive neuroscience as well. Once the issue of reality gets back to the realm of science, it becomes something that physics has to describe. Physics, in turn, is erected on the philosophical assumptions on the existence of time and space.
We can logically accept the virtual nature of time because we have no direct sensory mechanism to sense or perceive time. Despite this glaring absence, we do have a strong sense of time that plays a crucial role in every conscious decision we make in our lives. We can argue that the reason for the existence of time is our knowledge of our finite life-span. We can illustrate this argument by mapping the history of the universe to 45 years. This mapping also shows how our physics of the universe is an ambitious extrapolation from a very short span of knowledge to incredibly long time scales. Also, physics has multiple notions of time – Newton’s constant time and Einstein’s malleable time. The difference between these notions of time is indicative of its unreal nature. Time is unreal the same way as mathematics is unreal; they are both products of our intellect. And philosophically, they can be thought of as formal languages.
Unlike time, our perception of space is the end-result of our most precious sense, namely sight. For this reason, the unreal nature of space is not as obvious as that of time. If we understand the workings of our sense of sight from the perspective of neuroscience, we quickly start doubting space as well. This suspicion turns into a conviction once we look at the cases where tiny physiological defects manifest themselves as drastic disorders in visual perception. How sight creates space is analogous to how hearing creates sound. Sound is not the intrinsic property of a vibrating body, but our brain’s cognitive representation of the air pressure waves our ears sense. In fact, our whole reality is nothing but a cognitive representation. Space is our visual reality, or the cognitive representation of the light inputs to our eyes. It is no more real than sound or smell. Or time.