How did the galaxy start?

Question

i have always wondered but if any you scientists out there can tell me i would be greatfull

Answer 1

According to current cosmological theory, all the matter and energy in the universe expanded from a small region of space the size of a grape. There are 4 fundamental forces in the universe, and it is assumed at the beginning of the expansion, all the forces were united into one force. Several milliseconds after the expansion began, the forces began to separate into gravity, the "strong" and "weak" nucleur forces and the electrical/magnetic force. For millions of years, the universe continued to expand, but it was still too hot and dense for atoms to form.

Eventually the universe had expanded enough for the first matter to evolve, the element hydrogen. As the expansion continued, irregularities began to appear in the mass of hydrogen. Some regions of space became denser than others. Gravity then began to reverse the expansion in these denser regions. Eventually stars began to form and the hydrogen separated once again into subatomic particles. These began to fuse into helium.

The first stars in the universe were many times larger than our sun and fused all their hydrogen rather quickly. When this was exhausted, helium then began to be fused into carbon and then the carbon was fused into iron. As heavier elements were fused, the temperature of the star increased, expanding it into what is known as a "red giant". Ordinary solar fusion cannot create anything denser than iron, and when the star had exhausted the last of its nucleur fuel, it collapsed. The sudden decrease in size created a shock wave which destroyed the star in a violent explosion known as a "supernova". This generated enough energy to fuse iron into denser material like lead, gold and all the other elements seen in the periodic table.

This was the fate of the first generation of stars, which then "seeded" their galaxies with heavy metals. A good analogy is making soup. It starts as pure water, but successive waves of ingredients are added and a rich stock eventually forms. This is the current state of the milky way galaxy. There is still enough hydrogen left for new stars to form, but they also will contain heavy metals and this is a sure sign they are composed of material from the first stars. The fact the earth has substances like gold and uranium means our own star is a second generation star. The solar system is formed from left over material from the supernova explosions of the first stars in our galaxy.

Einstein predicted the existance of "black holes". These are regions of space so dense that their gravity is powerful enough to bend light. They are the remains of supermassive stars which collapsed and had too much material to hurl back out into space. It is theorized that the center of each galaxy in the universe contains a giant black hole around which all the other matter in the galaxy rotates.

The milky way galaxy is disc shaped with a spherical region in the center. The solar system exists along the outer rim. The nearest galaxy to ours is Andromeda, and it appears to be on a collision cource with ours. There is so much space between individual stars that it is unlikely any of them will fuse, but gravity will work to destroy the shape of both galaxies and for a time the result will be highly irregular in shape. A new galaxy will form, but nobody knows what shape it might be.

Answer 2

I think that the current thinking is that the galaxy forms before the massive black hole at the center does and starts gobbling stars and gas up. A black hole cannot form without a massive star, so how could a massive black hole exist before the galaxy that the black hole becomes the center of. There's nothing to fuel the initial super-massive black-hole without at least one star. What makes one central massive black hole "active" and another one "inactive", like the one in the center of the mIlky Way galaxy, is unknown at this time. Maybe the active ones are gobbling up dark matter.

Answer 3

Galaxy formation is an active sub-field of astronomy at the current time, and probably for the next decade or so.

After "recombination" at 400,000 years after the Big Bang, the Universe is filled with atomic hydrogen gas plus some helium, plus a lot of dark matter that is very uniform in distribution, but not totally uniform. The slightly dense regions begin to pull more material in, and become more dense. This process becomes non-linear, with very large increases in density, first on "small" scales of only 100,000 solar masses, and later on "large" galaxy-sized scales of a trillion solar masses. The gravity is dominated by dark matter, which is a cold, collisionless fluid. This pulls in the hydrogen to form first massive stars, then clusters of stars, then galaxies, then clusters of galaxies. The process comes to an end when the density in inter-cluster space drops to essentially zero, leaving the galaxies and clusters we see today.

These processes have been modelled by computer with considerable success.

Answer 4

The galaxy, ours and others are made up of the accumulation of solar systems that eventually coalesce into spiral galaxies.
The galaxies are probably an end stage in the evolution of a universe.
90% of the galaxies visible do not exist to-day.
The mechanism of their fate is very speculative,but we live in a finite universe so eventually the must go out of existence.

Answer 5

A contracting, rotating cloud of gas and dust. The centre became concentrated (the Sun) and the planets formed by accretion (clumps of matter joining together) followed by differentiation (where the heavier elements fell to the centre of the planet). Planets with a big enough gravitational pull managed to hold onto light elements e.g. gases. Periods of intense bombardment occured as clumps of matter and planets came into contact with each other.

Not very scientific I suppose but it's in laymans terms :)

Answer 6

The other people have tryed to get the 10 points by going into alot of technical information but the following website explains exactly how a galaxy is formed including our own galaxy the milky way in easy to understand steps.

http://www-thphys.physics.ox.ac.uk/users/Galactic/layman/formation.html

I hope that this answers your question.

Answer 7

Scientists have a theory that space was created by a huge blast called The Big Boom..All the gas and dust started everything, I think.

Answer 8

Well if its the latest model Ford Galaxy, you just zap the key fob, get in and push the start button. Works for me anyway.

Answer 9

Well, it depends on if you believe evolution or ceationism. If you believe in evolution, it started with a big bang. If you believe in creationism, it took 7 days for everything. Try www.answers.com and see what you get for an answer.

Answer 10

Scientists believe that it was a big bang. But christians believe it was god. Other religions probably belive that as well.