Oh do I have a lot of information on why ghosts aren't real for youuuu.
Scientifically,
sounds emitted between 7 and 19 Hz induce psychological stress on your mind. Your conscious mind cannot perceive it, but your ears still pick it up. There are always plenty of sounds on that level at all times, but its only when its absolutely quiet that it starts to wear down on you. This is almost always why ghost stories are told in empty areas at night. Research has shown that people who hear this level of sound are very prone to fear and dread.
Its actually an evolutionary trait designed as a defense mechanism, as just about everything dangerous tends to make this sound (strong winds, earthquakes, volcanoes, ocean waves, predatory animals, etc).
Of course thats just sound.
As for
vision, sightings are almost never in DIRECT path of your eyes, but almost always on the side. Probably far off to the side, enough to make you turn your head when you see it, only to realize nothing is there. The image can take any real form or shape, and can last for much longer periods of time. Of course, if conditions are set properly it can even be in direct path of your vision as well.
Turns out, human eyes don't just pick up light. They also pick up infrasound. Strong frequency vibrations can cause your vision to smear, or forming objects out of still images, which may be too unfocused to be consciously thought of (glasses, dust, anything really).
Almost every ghost sighting now has been a result of something making vibrations. This can happen anywhere at any time with any object. Common household appliances, or even wind could cause it.
Between the sound levels and the strong frequencies, your actual psychological state is suffering from panic, though you may not actually feel it directly. If it ever comes to a point where you hear something or see a distortion, your brain will take the next appropriate step into a very commonly applied concept:
The
Rorschach test.
Our brain will almost always assign labels to everything we see, and if we cannot identify it, then we still instantly label it something. Its not something you do consciously, so its not a choice you make.
When we're stressed, or frightened, the priority of labels that can come through gets jumbled up, and we lose our reasoning and begin to instantly believe we are seeing or hearing ghosts. I believe your ghost sighting was a part of this process, and more importantly, a part of the rorschach test as a result of the loss of your cat.
Ghosts aren't real.
Ghost Hunters know everything I just said and abuse it quite well with their frequency detecting devices.