Final answer:
If an unknown cause of red shift is discovered, it would require modifications to the current understanding of cosmology. Therefore, the most reasonable choice is: c) Cosmology would require modification.
Step-by-step explanation:
If some unknown cause of the red shift, such as light becoming tired from traveling long distances through empty space, is discovered, it would have an effect on cosmology.
Cosmology is the study of the character and evolution of the universe, and the red shift in light from distant galaxies has been taken as evidence of the expansion of space. If a new cause of red shift is identified, it would require modifications to the current understanding of cosmology to accommodate this new information.
If an unknown cause of redshift were discovered, such as light becoming tired from traveling long distances through empty space, it would likely lead to a need for modification in cosmology. The redshift of light from distant galaxies is a key observational feature that supports the current understanding of an expanding universe, as described by the Big Bang theory.
Options:
a) Cosmology would remain unchanged - This is unlikely, as a significant discovery of this nature would likely require adjustments to current cosmological models.
b) Cosmology would be invalidated - This is also unlikely, as cosmology is a broad field with many aspects, and a single discovery may not invalidate the entire field.
c) Cosmology would require modification - This is a plausible option. Discovering a new cause for redshift would likely prompt modifications to current cosmological models to incorporate this new understanding.
d) Cosmology would become obsolete - This is unlikely, as cosmology is a continually evolving field that adapts to new observations and discoveries.
Therefore, the most reasonable choice is: c) Cosmology would require modification.