Question

he is convinced that time travel is possible change the voice​

Answer 1

Hey mate...... here is your answer :-
He says, "Time Travel is possible."

Hope this help you mate and if helpful mark as brainliest

Answer 2

Time travel is possible’ is being convinced by him

There are two types of voices viiz Active Voice and Passive Voice.

A sentence is written in active voice when a when a subject is directly acting on the object. The structure in which the active voice is written is:

Active voice: Subject + Verb + Object

On the other hand a senesce is written in passive voice when  

When the object is acted upon by the subject. It’s structure isPassive voice: Object + Verb + Subject