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Published on Apr 6, 2018

Hi Everyone,

Today we're exploring what we mean by the Observable Universe and how large it is.

Even the smallest of amounts will help me create more and more content for YouTube and I’ll be forever grateful as you help me make my dream of becoming a full-time YouTuber a reality.
Scientists often talk about space expanding but what exactly is space expanding into?

Rather than using the term expansion, let’s use the the term stretching and say that space is stretching because that is a more accurate description.

So the question is what is space stretching into?

The first thing to consider is if this is even a valid question.

We know that space in our observable Universe continues to stretch, so the observable Universe grows larger in volume. Galaxies move away from each other and the further two galaxies are from each other the faster they move away from each other as there is more space stretching in between. The reason why galaxies themselves remain intact, is because over shorter distances the force of gravity can counteract the stretching of space.

We are woven into the fabric of this Universe and therefore does it even make sense to ask what space stretches into as we are unable to get out of the Universe to find out.

Say that the question does make sense.

So far we’ve spoken only about our Observable Universe, but let’s consider the global Universe within which our Observable Universe lives.

This global Universe could be either finite or infinite.

Say the global Universe is finite, we could be beings living on a 3D surface of a finite 4D hypersphere which we can’t detect.

To use an analogy to make that clearer, let’s take an ant sitting on the surface of a large inflating balloon. Because the ant is so small, he thinks he is on a flat surface even though we can see he’s on a 3D round surface.

Similar to that ant, we could be on a 3D surface of a finite 4D hypersphere that we can’t perceive.

If the global Universe is infinite however the stretching of the space adds to the infinite. This is similar to a number line - numbers never end, no matter how far you count. New space real estate is being created all the time and as there is nothing larger than infinity, space is not stretching into anything at all.


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