Recent content by Jaime Rudas

It is correct even for an infinite initial size.

Friedman's equations don't describe reality at t=0.

Because for calculating the particle horizon, it's not relevant to know how many times the universe has expanded since the Big Bang. What's relevant is knowing the value of the scale factor for any moment t>0.

Yes, we can't.

I will try to clarify my previous answer: the model does not include the moment t=0 because a singularity occurs there, that is, an undefined state. The fact that there is an undefined state does not imply that, in reality, neither space nor time existed at that moment. It simply means that we...

¿And?

No, the model doesn't assume that. Where did you get that from?

I agree. Thanks for clarifying.

Since the scale factor was 0.5, it has doubled; since it was 0.1, it has expanded tenfold; since it was 0.01, it has expanded 100 times; and since it was 0.00001, it has expanded 100,000 times. I really don't see your point or what it has to do with the particle horizon you keep mentioning.

I'm not sure I understand your point correctly, but it seems you might be confusing the expansion rate with the particle horizon growth rate. They are closely related concepts, but they are not the same. For example, due to expansion, since the scale factor was 0.5, distances have doubled, but...

No, that doesn't follow from what Wikipedia says. Wikipedia states that the FLRW metric is used to model the expanding universe, but it doesn't say that it can't be used to model a contracting one.

Is there really a limit to the number of ways particles can be arranged within a limited space? For example, is there a finite number of values for the distance or velocity between two particles?

No, the fact that the universe is infinite doesn't imply that a certain configuration will repeat infinitely.

From the context, it seems to me that what they're trying to confirm or refute isn't whether they are galaxies or not, but whether or not they are ULTRA-DISTANT galaxies.

Yes, because expansion, in this context, doesn't mean its size increases, but rather that the distance between objects gets ever greater, as explained in @Ibix's analogy in post #22.