Understand the idea of the Big Bang and that it is space itself that expands, not fragments flying apart through emptiness.
Not an explosion in the usual sense
How it all began
About 13.8 billion years ago, the entire universe was unimaginably hot and dense, squeezed into a tiny volume. Then it began to expand rapidly and cool. This event was named the Big Bang.
The main misunderstanding: it wasn't like a shell exploding in an empty room, with fragments flying outward through space that already exists. Space itself is expanding. There was no “center of the explosion” and no “outside.”
A good analogy is raisins in rising bread dough. As the dough puffs up, every raisin moves away from all the others. Not because they move through the dough, but because the dough between them grows. Galaxies are the raisins; space is the dough.
It follows that the expansion looks the same from any point. Whichever galaxy you look from, all the others seem to be running away from you. That doesn't mean you're at the center — there simply is no center.
And yes, the expansion continues right now, and it is even accelerating.
Lesson notes
How it all began
About 13.8 billion years ago, the entire universe was unimaginably hot and dense, squeezed into a tiny volume. Then it began to expand rapidly and cool. This event was named the Big Bang.
The main misunderstanding: it wasn't like a shell exploding in an empty room, with fragments flying outward through space that already exists. Space itself is expanding. There was no “center of the explosion” and no “outside.”
A good analogy is raisins in rising bread dough. As the dough puffs up, every raisin moves away from all the others. Not because they move through the dough, but because the dough between them grows. Galaxies are the raisins; space is the dough.
It follows that the expansion looks the same from any point. Whichever galaxy you look from, all the others seem to be running away from you. That doesn't mean you're at the center — there simply is no center.
And yes, the expansion continues right now, and it is even accelerating.