Recent content by John Bleau

Thanks, Iced, I didn't know that. For me, that makes the question "why does the observed universe not show gamma rays from annihilation", with one hypothesis being that it's overwhelmingly matter, and another being that the vacuum between galaxies is so rarefied that there would be very few...

How do we know there's more matter than antimatter in the universe?

Thanks for your reply, DA. This suggests to me that if our universe is emerging from a white hole or falling into a black hole, then there is no reaching the singularity. It would mean that, in fact, we have been emerging from the Big Bang indefinitely. I suspect that "when the Universe...

Thanks bapowell, I consider the question still open, though it has strayed somewhat from the original post (though it's still related in a manner I was hoping to clarify). My own conception of the event horizon is similar to the speed of light in SR - we can accelerate as much as we please, the...

Apart from your first sentence, we're on the same page. Let's now take your last sentence. It will serve well to illustrate just why I'm confused. Let us now take a second traveler B, following the first traveler A toward the event horizon. Let us also say that traveler A's velocity is...

I'm wondering if the event horizon itself is observer-dependent. Say now that the observer is on Earth, which is revolving around the sun. When Earth is moving in the direction of the black hole, I doubt that makes the observer suddenly see the traveler cross the event horizon. I imagine this is...

I'm wondering if the event horizon itself is observer-dependent. Say now that the observer is on Earth, which is revolving around the sun. When Earth is moving in the direction of the black hole, I doubt that makes the observer suddenly see the traveler cross the event horizon. I imagine this is...

It is confusing, as we have two frames of reference. Note that they say: "taking an infinite time to reach it" - is that from our "at rest" point of view?

Here's the quote in Wikipedia (emphasis mine): As I interpret this, when he crosses the event horizon as we see it, there is a finite time according to his own clock. However, as he sees it, the event horizon remains in front of him.

This is not my understanding. As I understand it, for him, there is no point at which he can say he's crossing the event horizon - it's always in front of him. So from his point of view, he never actually crosses it. I would have thought that it is we who see, in finite time, the traveler...

Thanks for the replies. I remember cosmic zoom - or the series of pictures it was based on. I appreciate the answer to "two observers at rest" part of my question. I'm still curious about the other part, though, which I reproduce here: Is it reasonable for me to conceive of the Big Bang as...

Thanks both. bapowell, it seems that this gives meaning to "absolute motion." Intuitively, I would have thought that the apparent source of the CMB would have shifted slightly for the "moving" observer, making it appear as homogeneous as for the "at rest" observer. Has the "dipole anisotropy"...

Sorry about the time between my posts, life intervenes... If I understand correctly, there is disagreement and uncertainty as to how to quantify time in the very early stages of the universe (say, the Plank epoch). Re the "simplified model" marcus refers to (thanks, marcus): could someone post...

I'll be studying your answers, everyone, thanks. I'll post later in the coming week. chroot, thanks for your welcome. JB

What does "When the Universe was one minute old" mean? I understand time in terms of references such as how long the second hand takes to travel around a clock, or the definition in terms of the cesium atom, or other references such as planetary motion and heartbeats, but without such...