When something is palpable, you can touch or handle it, even though the word is often used to describe things that usually can't be handled or touched, such as emotions or sensations.
You probably won't see palpable used to describe, say, an egg or a doorknob or a motorcycle. Palpable is usually reserved for situations in which something invisible becomes so intense that it feels as though it has substance or weight. When the towers came down, the sense of sadness was so great, it was palpable.
adj capable of being perceived; especially capable of being handled or touched or felt
easily perceived by the senses or grasped by the mind
capable of being perceived by the mind or senses