Re on the universe: There was a Time magazine article a while ago that had the latest stuff about the universe.
According to the latest evidence, the universe is full of dark energy (different stuff than of what you, me, the earth, and stars are made up of). According to a pie graph chart in the magazine, this is the amount of matter in the universe (an estimate, of course):
Heavy elements- 0.03%
Neutrinos- 0.3%
Stars- 0.5%
Free hydrogen and helium- 4%
Dark matter- 30%
Dark energy- 65%
According to Einsteinian theory, the universe can take on one of three shapes:
A sphere (positive curvature): We are on the
surface of a sphere. Travel far enough and you will return to your original starting point. A triangle will have more than 180 degrees. Without dark energy, it will slow down, stop, and recollapse; with it, expansion will continue.
Flat: You will never return to your starting point. Triangles have pricisely 180 degrees, like in school. Without dark energy, the universe will expand forever, more and more slowly. With it, expansion gets faster. This is the shape of the universe, according to recent observations.
Negative curvature: Travelers never return, triangles have less than 180 degrees. Expansion will barely slow, even without dark energy. Until recently, most evidence favoured this shape.
Whent the big bang happened, something "blew up" from something smaller than a atom in the size of a grapefruit in {10 to the exponent of -32} of a second. Helium, deuterium, and lithium are forged in the first 3 minutes of cosmic history.
Right now, we are about 14 billion years after the big bang. This era of the universe right now, one of young stars, life, and phenomenia, has last since when the universe was a million years old. It will last until 100 trillion years from now.
The next era will range from {10 to the exponent of 14} (100 trillion years) to {10 to the exponent of 45} (10 trillion trillion trillion) years after the big bang. The universe starts expanding exponentially. Planets will detach from stars, and stars will evaporate from galaxies. Almost all stars will die in this era. Over a great deal of time, protons them selves decay.
The next era will range from {10 to the exponent of 45} to {10 to the exponent of 100} years after the big bang. The only larger objects left are balck-holes. They eventually decay into photons and radiation.
The last era will range from {10 to the exponent of 100} years to infinity. Only photons, neutrinos,electrons, and positrons remain, wandering through a universe bigger than the mind a concieve. Electrons and positrons occationaly meet and form "atoms" larger then the visible universe is today. The universe forever remains a cold, dark, and dismal place.
Earth will remain habitable for the next 2-3 billion years, after that, the Sun's brightness and intessaty will have increased so much that the water will boil off the earth. Life cannot survive.
After 5 billion years from now, the Sun will become a red giant, expanding to the size of Venus's orbit. Earth will become completely molten rock. 700 million years later, the sun will fall back down into a white dwarf, no bigger than the earth. The gas giants of our solar system will be featureless blue-green spheres. The Sun will cool to 63 degrees Kelvin. the earth will be 1 degree Kelvin, a single degree above absolute zero.
Six billion years from now, the Andromeda Galxy will collide with the Milky Way, although it is likely no stars will collide (because of the immense amount of space inbetween stars). The new galaxy will now have a gravational pull that will make the white dwarf sun have an elliptical or random orbit in the football shaped galaxy.
Hope this answers a few questions, as it took me an hour to write.
I know quite a bit about astronamy.