The speed of light is the speed limit of our reality. It's a universal constant and a way to measure potential energy. The faster a particle accelerates, the more mass it has, but a particle with gravity/mass cannot reach the speed of light. If a particle with mass reaches the speed of light, it would develop infinite mass because it would take infinite energy to make it go that fast. Time would stop for whatever was traveling that fast (time dilation). It wouldn't age. It would be timeless and infinite. Thus it doesn't happen. In the case of black holes (the biggest mystery of the universe), when a star collapses and crushes mass into its tiniest, densest state, it creates a singularity, or a point of super gravity that not even light can escape. The event horizon (Schwarzschild radius) is the point where you would have to travel faster than the speed of light to escape the gravity of the singularity, and nothing moves that fast that we know of. Black holes may very well be a portal into another form of reality, but you would be ripped apart and crushed on your way in. Or would you?