Simon Peach said:
while the photon travels at light speed and a neutrino travel at just below light speed why then are photons stopped by an object and the neutrino can past through?
This is not such a silly question. The problem is your assumption that the speed of the particles is the relevant factor.
The reason that elementary particles of ordinary matter merge into atoms, molecules, dust, rocks, planets and stars is through the strong nuclear interaction that creates protons, neutrons and atomic nucleii; and, through the electromagnetic interaction that accounts for everything else. This is why there is the possibility of so-called
dark matter in the universe that interacts only gravitationally. I.e. we could theorectically observe its effect on galaxy dynamics, but it wouldn't interact and merge with itself or ordinary matter in any other way. In fact, one of the possibilities for dark matter (although perhaps not a very likely one) is lots of neutrinos.
The neutrino does not interact via the strong or electromagnetic interactions, but they do interact via the weak interaction and are produced by radio-active decay. They are not totally "dark". They are, however, very difficult to detect and their presence was calculated before any direct observations could be made. Nobel prizes have been won for neutrino detection.
In other words, neutrino interactions are so rare that they will pass through ordinary matter. Note that at the elementary level interactions are not a result of classical head-on collisions, but of probabilistic quantum interactions as described by QM and QFT.
Photons on the other hand are part of the QM theory of light and electromagnetism and do interact much more frequently with ordinary matter. Although light passes through air, water and glass (to some extent), it is absorbed through electromagnetic interactions in most solids.
