Depends on what you mean by "The Big bang". If you're talking about a seemingly spontaneous explosion of matter ~14 bya, then no, that's not science. That's like saying that the sun, or dirt, or a hurricane is science. Forming a hypothesis that all matter can be traced back to a single expansive event, then observing movement of celestial bodies, measuring those movements with redshift and seeing if that data is in-line with your hypothesis... That's science.