Whether or not there is actually a 'vast amount of unseen material in the universe' is not yet known with certainty. The assertion of its existence by some theorists may be based on nothing more than half-vast science. If it does exist, that would explain some nagging questions in cosmology, but no experiment or observation has proven it yet. For purposes of discussion, it's referred to as "dark matter". The whole issue is also related to ... and the same discussion goes for ... "dark energy".
Chemical changes are considered unseen because they occur at the atomic level, changing the actual structure of the thing. This is in comparison to a physical change, which is visible.
Because of perturbations within the observed star.
The observable Universe is the part of the Universe we can see from Earth because the light from all the objects in it has had enough time to reach us. Light from outside the observable Universe has yet to reach Earth. The reason we can only see part of the Universe is because of the limited speed of light, and the expansion of the Universe, which is faster than that speed. According to Einstein, nothing in the Universe can move faster than light, but nothing stops the expansion of space from moving faster than light. This results in a large part of the Universe being completely invisible to us.
Most chemical changes happen between molecules, so they are unseen.
BeansBreamsCleansCreamsDeansDreamsGleansGreensKeensLeansMeansPeensQueensScenesTeensTweenWeansWeens
Nothing!
"Nothing" almost works except "Nothing is unseen by the naked eye." Try again.
Magnetic flux
'Unseen' is an adjective.
Unseen mysteries abound, Navigating time and space, Imagining worlds unbound, Vision of endless grace, Embracing cosmic embrace, Running through galaxies wide, Seeking the unknown's place, Exploring the universe's tide.
The Unseen One.
Unseen Hollywood - 1998 Unseen Hollywood 1-1 was released on: USA: 1998
The creature moved silently through the forest, its unseen presence sending shivers down my spine.
Unseen - website - was created in 2008.
The Unseen - novel - was created in 1990.
An Unseen Enemy was created in 1912.
Conversations with the Unseen was created in 2003.