My grandma believed that the Sun "revolves" or "revolved" around the Earth? [duplicate]

We all know that universal statements are always in present tense. For example,

My grandma did not believe that the Earth revolves around the Sun.

Here, though the sentence is in past tense, Earth revolves around the Sun remains in simple present tense.

But in case of a false belief that is contrary to a universal truth, does the above rule apply similarly? For example,

My grandma believed that the Sun revolves around the Earth.

Will this sentence be taken as grammatically correct? Shouldn't it be "My grandma believed that the Sun revolved around the Earth"?

Solution 1:

Yes, your sentence is grammatically correct:

My grandma believed that the sun revolves around the earth.

But I disagree that "universal truths are always in present tense". On the contrary, it is perfectly fine to say:

My grandma did not believe that the earth revolved around the sun.

preserving the proper coordination of tenses.

Solution 2:

The default position for a reported clause is for the present tense to become the past tense. Where the emphasis is on the circumstances in the reported clause continuing, the present tense may sometimes be found. However, even if the circumstances are unchanged, the past tense may still be used. It would be quite in order to write both ‘My grandma did not believe that the earth revolved around the sun’ and ‘My grandma believed that the sun revolved around the earth’.