Recent content by Jaime Rudas

Agreed, provided it is made clear that we are referring to comoving distance rather than proper distance.

Yes, I see your point now. However, from that perspective, wouldn't it be incorrect to state, for example, that the radius of the observable universe is 46 billion light-years? I say this because a comoving observer could never observe an event occurring 40 billion light-years away. Don't...

I agree. I don't understand what you mean when you say it "is bounded." And I don't understand it because I don't see them coinciding. I don't see why the fact that they are mirror images implies that this is "the in-principle universe observable."

We certainly can observe a galaxy that is currently 20 billion light-years away. In fact, the light we see from that galaxy has a redshift of nearly 3. The observable universe is everything within the particle horizon.

The disagreement lies in the fact that @Bandersnatch seems to be linking in some way the observable universe to the event horizon, whereas I only link it to the particle horizon.

For the sake of clarity regarding terms: The particle horizon is the current distance to the farthest comoving object from which, in principle, we could be receiving a signal today. The cosmological event horizon is the current distance to the farthest comoving object that, in principle, could...

It seemed to me that in post #7, @Bandersnatch was suggesting the event horizon had some connection to the limits of the observable universe. My point is that there is no such connection.

The cosmological.

A galaxy currently located 20 billion light-years away lies beyond the event horizon but within our observable universe.

In this regard, I seem to recall that a 2-sphere is a finite but unbounded space

Actually, no. As early as the mid-18th century, Immanuel Kant and Thomas Wright proposed the "island universes" hypothesis—the idea that nebulae were, in fact, collections of stars similar to the Milky Way. This idea captivated a significant number of scientists, as illustrated by the famous...

No, it isn't. According to the Big Bang theory, the universe could be either finite or infinite.

Could you cite reliable sources that state that?

How do you know it isn't?

Yes, when I mentioned the steady-state model in the original post, I assumed, perhaps mistakenly, that it would be understood that I was referring to a homogeneous and isotropic spacetime (without torsion!) that is expanding and has a positive density constant over time. Under these conditions...