Subject: Is there only 'Past' & 'Future' ?

We talk of "Past, Present & Future" in daily lives. Some philosophers claim there is no "Past" or "Future"-only an eternal "Now".I've never seen "The Present" quantified. There seems to be no specific "duration" or definition of "Present". Every scenario I imagine (even small scales) has its constituent parts moving sequentially from "Past" to "Future"."seeing" an object seems to encompass gathering light in the eye, through ultimate interpretation of all signals by the brain.One part of a "signal" (photon) may have "striking the retina" in its "Past", while another photon (comprising the ultimate picture), may have "striking the retina" in its "Future".(Might a photon have half of its energy ALREADY absorbed, & half of it TO BE absorbed?).It seems that only AFTER sufficient signals have completed all eye-through-brain-analysis,do we recognize or "see" the object.The tiniest processes seem to proceed from "Future" to "Past" with no discernable "Present". Is there any scientific evidence for, or definition of, a "Present" or "Now"? ( this Ques. might be directed to other catagories than just Physics.??)

Re: Is there only 'Past' & 'Future' ?