I think I understand the basics of the Big Bang but after trying to explain it to someone else, I've discovered that there are many details lacking in my knowledge. So I have come here in the hopes of alleviating my ignorance... I understand that in the very early universe, all the energy in the universe was concentrated in comparatively little space, so much so that it formed an opaque plasma which is the source of the cosmic microwave background radiation. What I don't understand is why this is the very last thing we can see. Why can't we see anything past the surface of last scattering after the universe has cooled from its plasma state? Is there anything past the surface of last scattering? There must be since you'd expect photons to be emitted from the surface... ...which leads to the question of how fast the universe is expanding. How fast is the edge of the universe expanding? In a sense, I'd expect that space is expanding rather slowly since we can still see the surface of last scattering (for now!). However, if the Big Bang is the source of space-time and photons on the edge of the universe are traveling towards this edge, does that mean that space is expanding at the speed of light? This leads to yet another question: does the universe have an edge? If the geometry of the universe were elliptical then I'd understand how space can expand from a singularity. However, if it's Euclidean, then I don't understand the nature of this expansion. Does it have an edge? If it doesn't then what does it mean for the Big Bang to be the origin of space? As you can see, I'm actually quite confused by the nature of the Big Bang but I'm eager to fill out my ignorance on the subject. I have a couple more questions but I think this is a good start... Thank you!