Recent content by Jaime Rudas

What does "unit" mean in this context?

Is that "flat plane" two-dimensional or three-dimensional?

Wouldn't it be better to say that they do not meet condition (b) because they have a past spacetime boundary?

Yes, that's why I said "remember."

Remember that, under reasonable assumptions, the Borde-Guth-Vilenkin theorem demonstrates that inflationary cosmological models doesn't extend infinitely into the past.

Polaris? :wink:

It seems to me that, according to these two hypotheses, time was created in the Big Bang. Which makes me realize that saying that time did not exist before the Big Bang is, in fact, an oxymoron because if there was no time, there could not have been a before.

The article Where did the Big Bang happen? states: Is this really the case? Wouldn't it be more correct to say that the current consensus cosmological model is unable to describe anything that happened before, for example, the Planck time?

Where could I find some introductory text that would help me delve deeper into this?

Regarding this, I have the following question: Is it possible to embed a flat (Euclidean) two-dimensional surface in a curved, three-dimensional space?

From this, I understand that for a sphere of area ##A## around a very massive and dense star, its radius ##R## will be greater than ##\frac12 \sqrt{\frac A \pi}##. If this is correct, for the case of the sphere around the black hole, can its radius be calculated, or is it undefined?

On the other hand, the margin of error in calculating the age of the universe is on the order of hundreds of millions of years, so what happened in the first 380,000 years is irrelevant for calculating the observable universe radius.

I consider the radius of the observable universe to be, by definition, the greatest distance that anything could reach during the age of the universe propagating at speed ##c##, that is, without taking into account that, on average, the speed of light in a given non-empty medium may be less than...

I think you underestimate the enormous retrospective adaptability that these "theories" have always demonstrated.

The Gaussian curvature ##K## of the hyperboloid ##x^2+y^2-z^2=1## is ##\frac {-1}{(1+2z^2)^2}##. Thus, when ##z=0##, the curvature ##K=-1## and when ##z \neq 0## the curvature ##K## remains negative, but greater than ##-1##. It follows that the curvature of the hyperboloid is always negative...