In order:
Theory
Fact
Hypothesis
In physics, spacetime is any mathematical model which fuses the three dimensions of space and the one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive where and when events occur differently.
Answer:
harmful effects
1. that will cause air pollution
2. that will destroy our earth
Answer:
I think it's bigger than most galaxies
