Pray tell me more!
It’s been a few years, and refs have disappeared. Meanwhile, Wikipedia isn’t so good on false vacuums and inflation.
However, Guth’s 1991 article Can a Man-Made Universe Be Achieved by Quantum Tunneling Without an Intial Singularity, contains the relevent point in its abstract:
10 kilograms is considerably less than all the matter currently in the universe. The rest of the matter/energy that’s around today appears as the false vacuum decays and space expands.
The biggest problem with what you said is that the Big Bang didn’t occur at a point; it occurred at every point. Every point in the Universe has an equal claim to be the center.
:rolleyes: It really is all about you, isn’t it, Chronos?
Imagine there were enough mass to pull the whole thing together again, would the balloon collapse or would all the dots collect at some point on the surface of the balloon? Or would the aggregation of the dots make the balloon collapse?
Would enough mass just concentrate all the mass and leave space empty or would space itself shrink?
This doesn’t make sense! Galaxies are moving through space. If we look at them from a relatively fixed perspective, ie Earth, are they criss-crossing the heavens in random directions, or do their paths extrapolate backwards to a fixed point?
It doesn’t sound as if you are suggesting the latter, and if that is the case, I’ll have to admit I had totally misunderstood the concept of the “Big Bang”.
Ok, I’m stuck on this. Before looking at that link, I used to believe that I had seen - on a very dark night - a tiny smudge that I took to be the Andromeda Galaxy. At least, it was where I was led to believe I should look if I wanted to see it, with binoculars. Now, if I correctly interpret this graphic, it turns out that the galaxy is considerably wider than the moon??? Can someone help me make sense of this?
If wikipedia can be believed:
According to this site, it will fill the eyepiece of most telescopes.
http://www.allaboutastro.com/M31.html
All points are receding from us at velocities directly based on their distance. If we did that extrapolation, we’d find that the big bang occurred on Earth. While possible, it is far more likely that there was just an expansion of space itself; in other words, if you performed that extrapolation from anywhere you’d get the same result and find that you were at the center.
Another way to look at it is this: the Big Bang’s “position” is just t=0, the beginning of time. If we use a telescope to observe very distant objects, we are looking back in time since the light takes so long to get here. If we look far enough away, we can be looking 14 billion years in the past, that is, we can look at the big bang. Where do we have to point our telescope to find this? Anywhere. Since everything originated with the bang, we can find t=0 everywhere in the sky as an expanding sphere, with a distance equal to the age on the universe in light years.
Footnote: we can’t actually observe the bang itself due to some highly technical properties of the early universe. But we can come extremely close - the theoretical limit is 10^-43 seconds. The closest we have come as of now is observations of the cosmic microwave background radiation with WMAP.
This is just mind boggling. There is, in the sky, an “object” that is 6 times wider than the moon, and it’s a galaxy that’s 2+ million light years away. And it’s that big! I’m totally freaked by the notion. The scale and proportion of things has suddenly been shifted for me. I gotta think about this.
I had a similar thought when read that in this thread. However, what really boggles my mind is that I’ve never noticed it. I even did a little amateur astronomy in my youth, but mostly looked at things in our solar system. You really realize how much we lose by having all these blasted lights in our cities.
To expand on this: The light we see in the CMB was emitted about 300,000 years after the Big Bang. A cosmological neutrino detector could push that back to around 200,000 years after the Bang. A gravitational wave observatory, however, could in principle look back to around 10[sup]-32[/sup] seconds after the Bang. It’d take an instrument several generations more advanced than anything we have right now, but it could be done.
What we’re going to get in the meantime is Planck, a spacebourne observatory which will look at polarization in the CMB. Said polarization may have been caused by those graviational waves. There’s an article in the May 2009 Sky&Telescope about it, but it doesn’t seem to be available on the S&T web site.
Could someone help an ignorant here finding Andromeda. My location can be dark enough at some times (We are about to enter blackout season) and I would love to see that. Can it be seen with the naked eye?.
Yes, but is BEST seen with low power binoculars generally. Run of the mill 7X by 50’s are about perfect.
Even then, its nothing spectacular. The WOW factor (as in most visual astronomy) comes more from realizing what you are looking at rather than said thing looking like something from a modern Sci Fi movie.
What part of the world do you live in? And how far away from/in how big a city are you?
I’ve just been reading the bit in the wikipedia link about the Andromeda galaxy and blue shift, and was wondering whether if someone who was observing our galaxy from within Andromeda would see a red or blue shifting galaxy?
If we are both blue shifting relative to each other, does this suggest a future cataclysmic collision? Is it possible that the Andromeda galaxy is moving towards us but because we are moving away it will never catch up to us? How would we be able to determine this?
I am in Puerto Rico, in a very small town but still some light pollution. Although as I said, summertime is blackout season so I do get plenty of opportunities to look at the sky surrounded by pure darkness.
Find Cassiopia by looking for a big W in the sky up to the north.
The W is comprised of two triangles, the sharper of the two, on the right, points almost directly at the galaxy in Andromeda. The galaxy is shown as M31 on this chart:
So for this time of year, better by dawn looking north-east, right?