I am trying to read up and understand a lot about how normal looking objects like chairs are visible to us as compared to fluorescent substances. This question says that -
"It is often said that substances, objects have color because they selectively absorb all color of sunlight except one. The wavelength that is not absorbed reaches our eyes and we perceive it as "color". This "color" phenomenon is often described as light of a certain wavelength being reflected. I think it is more appropriate to call it scattering"
So, I guess we see a blue chair as blue since it scatters/reflects light of blue wavelength. And this paper says that the main difference between fluorescence and scattering is that - "The wavelength of fluorescence emission is generally independent of the wavelength of the exciting light. In contrast, the wavelength of light scattering increases with increasing wavelength of the exciting light".
So my question is, if we increase the wavelength of light incident on a chair, will it start looking a different color/invisible, as this statement says?, whereas this would not happen for a fluorescent substance?
And apart from this (if this is correct!), is there any major difference between normal color of a object, and fluorescence? The original curiosity in my mind was that why do we use fluorescent proteins like GFP in Biology? I presume that fluorescent substances are brighter and hence easier to see, but I may be completely wrong on this.