I'm just trying to understand the idea that our universe may be the result of a collision between two branes. According to this, what we see around us is a 3D brane floating in a higher dimentional universe? When our brane collided with another brane, it trigerred the heating and expansion that be call "big bang". So does this mean that the time dimension was not affected by the big bang, and is not expanding along with our three spacial dimensions? Is this correct?