Is it getting bigger, and if so, why?

Well, we know that there are two different meanings for "universe" - first, the

"observable universe" is everything that we've been

able to see, or observe, thus far. And second,

"The Universe" (or "the whole universe") means

everything that exists or has existed, or will exist.

More specifically, the observable universe

is the region of space visible to us from earth. And since The Universe is only about

13.8 billion years old and light takes time to travel through space, then regardless of

what direction we look, we see light that's been traveling (at most) 13.8 billion years.

So it's logical to think that the observable universe must then be 2*13.77 = 27.5 billion

light years across - but it's not. That's because over time, space has been expanding,

so the distant objects that gave off that light 13.8 billion years ago have since moved

even farther away from us. Today, those distant objects are a bit more than 46 billion light

years away. Multiply times two and you get 93 billion light years: the diameter of the

observable universe.

To give you a sense of scale, the size of the earth within the observable universe is

roughly equivalent to the size of a virus within the solar system - although that doesn't

help much because we can't really appreciate the incomprehensible smallness of a virus

nor the bewildering bigness of the solar system, either.

\ So let's just say that the observable universe

is stupendously big. But The Whole Universe, as far as we can tell, is a lot bigger - space

is most likely infinite! Or at least it doesn't have an edge, though the difference between

those is another story unto itself.

Now, what about the center of the universe? Well the

observable universe

has a center - Us! We're at the center of

the observable universe because the observable universe is just the region of space visible

from earth, and kind of like how the view from a very tall tower is a circle centered

on the tower, the piece of space we can see from here is naturally centered here. In fact,

if you want to be more precise, EACH ONE OF US is the center of our OWN observable universe.

But that doesn't mean we're at the center

of The Whole Universe, just like the tower isn't the center of the world - it's the center

of the piece of the world that it can see - up to the horizon. But just because you

can't see beyond the horizon doesn't mean there's nothing there.\

And so it is with the observable universe.

Looking up at the sky, we see light light that's at most 13.8 billion years old and

coming from stuff that's now 46 billion light years away. Anything farther is "beyond the

horizon". But each second, we see new, even older light

coming from slightly farther away (one light-second

farther, to be precise), and so our view of the cosmos is literally getting bigger all

the time - all we have to do is wait and watch as the universe ages and light from more distant

places has the time to get to us.

So here we are, sitting at the center of our observable piece of the Whole Universe.

How big is the universe? Well, the observable

universe is currently 93 billion light years across. The Whole Universe is

probably infinite.

Does the universe have an edge? The observable does (it's 46 billion light years away in

any direction), and The Whole Universe has a temporal edge (or what we call a beginning)

but almost certainly not a spatial one. Does the universe have a center? Again, the

observable universe does: YOU! The Universe as a whole? Almost certainly not.

And is the universe getting bigger? Yes - space is expanding, which makes both the observable

universe and the whole universe bigger - plus, over time, we see older and older light coming

from farther and farther away, so our observable universe gets bigger that way, too.

And that, in a nutshell, is our view from

the tower. You are the center of the universe. And so am I. And so is everyone else. And

so is no one.