[cleanair]

Many scientific publications mention an "edge of the Universe".

Example:

Once you create a neutrino, a tiny subatomic particle, it moves at the speed of light, and it doesn't stop. It keeps going in a straight line to the edge of the universe. Straight through any stars, planets, or mountains; straight through any atoms, nuclei, or other particles that happen to lie in its path.

https://www.discovermagazine.com/the-sciences/the-unbearably-unstoppable-neutrino

The "edge of the Universe" is simply a reference to the boundary of one's perspective on his/her environment which could have been the "edge of the Earth" when people did not know yet that the Earth was round, and today it could refer to the edge of what is known about space.

By looking further, one's perspective can change. From "the edge of the Earth" to "the edge of the Universe" to "the edge of human knowledge about its environment".

[PmbPhy]

erm...Where is the "edge" of the Universe?

There is no edge to the universe. An often used analogy is a sphere whose surface the inhabitants reside in. No matter where on the surface you go you're still in the universe. The thing with this universe is that if the inhabitants take a walk in the straightest line possible they will come right back to where they came from. This is called a closed surface whose curvature is possible. Another surface is a flat plain. It's curvature is zero. Walk in a straight line and you'll never come back to where you started from. The flat universe is infinite in size.

Our universe appears to be very close, if not exactly, to being flat.

[yor_on]

Beautifully expressed Pete.

[yor_on]

This aligns perfectly with that conclusion of yours. It also say no to the Big Rip or the Big Crunch.
https://www.forbes.com/sites/startswithabang/2018/07/19/how-the-planck-satellite-changed-our-view-of-the-universe/

[Bill S]

There is no edge to the universe.

Physics, maths and, possibly, intuition tell us that this is probably so, but as far as I’m aware, there is no observational evidence.

 

An often used analogy is a sphere whose surface the inhabitants reside in. No matter where on the surface you go you're still in the universe.

Excellent analogy for a, very distinctly, curved (closed) universe.

Another surface is a flat plain. It's curvature is zero.

Could this let in the possibility of a boundary?  It seems not, because…..

The flat universe is infinite in size.

Could this be paraphrased as: “the universe is flat, therefore it is infinite?  Does one necessarily follow from the other? 

Our universe appears to be very close, if not exactly, to being flat.

So, all options are open.  I like that. 

Please, Pete, don't think I'm questioning your superior knowledge, here.  Hopefully, you know me well enough to appreciate that I have to try to get my own thoughts straight.

[hamdani yusuf]

It's curvature is zero.

How do you interpret non-zero curvature?

Our universe appears to be very close, if not exactly, to being flat.

I'll say that within some measurement uncertainty, observable universe is flat.