how fast an object become invisible in the eye of a human?

Answer 1

Researchers at the University of Pennsylvania School of Medicine estimate that the human retina can transmit visual input at about the same rate as an Internet connection.

Answer 2

at the beginning, I disagree with backyard Gnome. In answer on your first question: confident, theoretically the traveling merchandise could seem invisible to all observers. * the item could seem invisible to the observer gazing the item because it techniques - the quantity of blue transferring / doppler transferring of any easy reflecting (or emitted) from the item in direction of the observer could be countless -- the item is traveling on the comparable velocity because of the fact the meditated easy so all meditated wave-crests would be bunched at the same time so as that they are efficiently coincident. a limiteless doppler (blue) shift could effect in an spoke of countless meditated-easy frequency * the item could seem invisible to the observer gazing the item because it recedes into the area - any easy originating from the observer in direction of the receding merchandise could under no circumstances seize as much as the item (because it fairly is traveling on the fee of sunshine) -- as such, this easy could under no circumstances be meditated from the item - any easy emitted from the receding merchandise interior the process the observer would be infinitely crimson-shifted. there is numerous reasons for this, at the same time with the reality that a clock traveling with the item could seem to have stopped. * the item could seem invisible (greater exceedingly, infinitely small in length) to the observer gazing the item pass by employing nearby (i.e. the place the observer isn't interior the flight-process the item) - A assets of specific-relativity thought called "length Contraction" (or formally spoke of as "Lorentz Contraction" ) predicts that the size of an merchandise (interior the process its action) contracts by employing a share that relies upon on its velocity. The length of the item looks to settlement to 0 while the item is traveling on the fee of sunshine. regardless of each and all of the outcomes that i've got suggested above, the item could be causally-disconnected from the the remainder of the universe because of the effect of Time Dilation. this could efficiently render the item invisible besides.

Answer 3

by being to small for the eye to see.