This perplexing phenomena is due to neural prostheses similar to Scratch-'n-sniff stickers, because the brain is made of science.
The olfactory nerves in the nose send information on the scent to the primary olfactory cortex of the brain. the cortex is linked to the amygdala and hippocampus of hte limbic system. The amygdala is involved in emotion. It projects fibres into the hippocampus. The hippocampus is involved in long-term memory. This is why smells evoke memories
Smell can strongly impact perception by influencing emotions, memories, and overall cognition. Certain scents can trigger specific memories or emotions, affecting the way we perceive our surroundings and experiences. Studies have shown that pleasant smells can enhance mood and overall well-being, while unpleasant smells can have the opposite effect.
All smells stimulate memories! Odor is a powerful memory trigger. Many times, just a faint scent is enough to remind you of something that happened years and years ago. Surely you can think of some specific summertime odors that remind you of something!
Certain smells that can cause nausea in individuals include strong odors such as chemicals, spoiled food, smoke, and certain perfumes. These smells can trigger a physical reaction in the body that leads to feelings of nausea.
The smells in dreams can symbolize emotions, memories, or experiences that are deeply rooted in our subconscious mind. They can trigger specific feelings or associations that may not be immediately apparent in our waking life. Paying attention to these smells in dreams can provide insight into our inner thoughts and emotions.
Perfumes are volatile, they give off invisible gasses which are made of tiny complex molecules, all different shapes. These little shapes float in the air. When these shapes go up your nose they fit into certain receptors in your nose which match the shapes, and Hey Presto! You recognise the smell! Different people prefer certain smells to others. Smells often evoke memories and the feelings associated with those memories. If the smells evoke nice memories, the perfume is appealing. But sometimes, for various reasons, some perfumes do not smell very nice. But this is all in the mind nose!
smells are hardly ever tested via exams. smells are generally not trusted.
Smells are closely linked to emotions because of the way our brains process scent information. When we smell something, our brain immediately connects it to memories, emotions, and experiences associated with that particular odor. This is due to the close proximity of our olfactory system to the brain's limbic system, which handles emotions and memories.
it means it can bring up old memories
* Yes it is possible (some do and some don't depending on why they split up.) For most people the couple have loved each other once (or thought they did) and built some fond memories together so it's highly possible your ex thinks about you off and on because sometimes certain places (even certain smells) can trigger memories that they connect you with during your relationship together.
Our sense of smell is due to specialized cells in our nose that can detect different odor molecules. These cells send signals to the brain, which then interprets them as specific smells based on past experiences and memories. This allows us to distinguish between various scents like food, flowers, or even danger signals like smoke.
Synesthesia is a condition in which the senses mix together (for example some people with Synesthesia see certain colors for certain sounds, or hear different sounds for different colors, and so on. So smells can have colors for someone with Synesthesia. There is no definite answer I can give, for three reasons. One, you did not specify which type of odor in your question. Two, I, nor anyone I know has Synesthesia. Three, the mixing of senses for people with Synesthesia is unique for every person affected, so it is impossible to give a true answer.