If the universe is expanding, what is it expanding into?

The concept of the universe expanding is a difficult one to grasp. It can be challenging to imagine something as vast as the universe getting bigger and bigger with time. But it's important to remember that the universe is not expanding into anything, rather it is expanding on its own.

The expansion of the universe refers to the increase in the scale of the universe with time. Scientists believe that the universe began with the Big Bang, a massive explosion that created all matter and energy in the universe. Since then, the universe has been expanding, and all matter and galaxies are moving away from each other. The universe doesn't have a center, and there's no edge to it. It is infinite and flat, and it expands uniformly in all directions.

So, the short answer to the question is that the universe is not expanding into anything. It's just getting bigger and bigger with time. The universe is expanding at an accelerating rate, which is one of the biggest mysteries in modern science. Scientists are still trying to understand why this is happening and what the ultimate fate of the universe will be.