The cats of doing so directly in our paths, and in particular when they happen to stare full at something that seems to them to be entirely nothing. It may be odd or even frightening but in the real sense, that unwavering stare of intense observation may be a mixture of good senses, instinct, and the mind that is continuously processing the world in a way that cannot be easily observed by humans.
Increased Sensory Perception in the Work Environment

This is because a cat has more senses than us do and can hear the slightest sound, the slightest movement or the slightest changes in the light which we would not notice. Their eyes may be focused on some invisible object that their excellent hearing or eyes have caught unintentionally.
Delicacy to Huge Motions in the World

Cats are born predators, and their eyes are programmed to focus on the slightest movement, whether it is an object is a passing dust particle or a shadow passing beyond the wall. Something that does not seem to be anything to us, may seem quite significant to a cat.
Powerful instincts based on survival

Even house cats, even when well fed, still have the instincts developed through generations of survival in the wild and because of this, they are always on the lookout of everything around them. An act of looking in vacuity can be a measure of the possibility of activity or change preceding a decision on whether to take action or not.
Extraordinary Waking to the Night Vision

The eyes of cats are faster than those of humans, and cats have a better sense of low light than human beings. A slight reflection or transient change of light might draw their eyes and keep them much longer than we should suppose.
Along the Hearing Sound Beyond the Human Auditory Fork

High frequency sounds heard by the cat include distant electronics, insects or movement in the walls. By waiting and gazing about them, in order to be attentively available, they may be stealing a sound and watching in the direction of the source of a sound which we cannot hear.
Mental Processing and Concentrated Thinking

The vacant stare of a cat sometimes does not truly depict what is on the outside world but reflects the happenings in the mind. The cats may be in an attentive and deliberative state where they take in information or memories and it may seem like they are looking into a different world.
Reaction to Air Currents and Temperature Changes

Cats are also sensitive to the slightest change of air flow or temperature, and this gives a signal of movement in its surroundings. Even a slight breeze or change in atmospheric pressure can attract them and result in them gazing so hard at a particular point.
Greet Habit of Surveillance of their Property

Cats are naturally territorial creatures that tend to scan their surroundings so that they can be assured that nothing is unfamiliar to them and nothing resembles danger. At gawking into nothingness, this can easily be part of their daily routine check, to make sure that nothing has changed in their environment.
Sensation of Insects or Small Beings

Small insects can move fast and silently, and they may disappear before people notice them. A long gaze of a cat can be based on a small creature that has already disappeared before our eyes.
Curiosity Technologically Induced Reflexive Behavior

The level of curiosity is also a significant factor in the behavior of cats, as cats are driven to see and examine even the smallest anomaly. The mere touch of a button, sniffing a blind air, or seeing something can stir up that fixed concentration which we take to mean stare into emptiness.
Lapses of weary Stillness and Repose

Cats tend to strike a balance between relaxation and being ready, such that even when taking a rest , they are alert. In such situations, their distant gaze may always represent a placid but alert attitude instead of a response to something out of the ordinary.