Answer:
Light is composed of particles and travels in a straight line.
Explanation:
The general consensus among scientists in Sir Isaac Newton's time in the early 1700s was that light was composed of a steady stream of particles, since it was observed that light traveled in a straight line and was able to pass through a vacuum. They argued along the lines of Sir Isaac Newton that since sound travels in waves and cannot travel though a vacuum, light must consist of something other than waves, such as particles.
Also, on reflection of light from rough surfaces, the particle theory suggests that if the surface is very rough, the particles bounce away at different angles from the surface, scattering the light as is confirmed by experimental observation.
In his 1704 book Opticks, Sir Isaac Newton stated that "Light is never known to follow crooked passages nor to bend into the shadow". This idea lent support to the particle theory, which proposes that light particles must always travel in straight lines. If the particles encounter the edge of a barrier, then they will cast a shadow because the particles not blocked by the barrier continue on in a straight line and cannot spread out behind the edge. This was observed in eclipses as well as formation of shadow of objects.
