Do buddhists believe that time travel will ever be possible? If yes, what would happen if someone would travel back in time to prevent other person's birth?
In general time is held to be the object of thinking.
In the earliest texts, Buddhists hold that there exist these 12 elements;

Eye &amp; Forms
Tongue &amp; Tastes
Ear &amp; Sound
Nose &amp; Aromas
Body &amp; Sensatipns
Intellect/Mind/Consciousness &amp; Ideation

They hold that is not possible to point out anything in the world that would repudiate the 12 and therefore the 12 are defined as the All or Everything in a definitive sense.
Out of these, 6 are thought of as having their respective objects.
The ideas of time and time travel are not repudiating these 12 and are included as the object of ideation.
Furthermore the 12 can be thought of as 5 classes of past, present &amp; future

Form
Consciousness
Feeling
Perception
Synthesis/Formation

Of these 4 are thought of as having an object. Form is thought of as not having an object.
The All can also be the object of thought in a collective sense and a single element, it is then thought of as the conditioned element and is thought to change as it persists rather than arising &amp; ceasing.