Big Bang

Big Bang

 
I don't get how two particles of dust collided to make our whole solar system...
 
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Big Bang discussion
 
10ES
I don't get how two particles of dust collided to make our whole solar system. How could two dust particles collide if there was nothing?
           
 
lucaspa
replied to: 10ES
That's not our solar system happened. Our solar system is the sun, planets, comets, asteroids.

Because of the attractive nature of gravity, yes, our solar system did begin when gravity brought particles of interstellar dust together. Now that clump exerted stronger gravity and attracted more dust, and then more, and then more and then more. Eventually (after millions of years) there would be enough matter in the volume of space that is our solar system to have the sun and everything else in the solar system.

The idea of "nothing" applies to the UNIVERSE. The data very strongly support the idea that our universe has not always existed. At some point there was no energy, no matter, no space, and no time. (Remember, space and time are inextricably intermingled as "spacetime". Also remember that energy and matter are 2 forms of the same thing: E=mc^2). The absence of matter, energy, and spacetime is called "nothing" by physicists.

So... our universe had to come into existence. That event is called the "Big Bang". At that instant spacetime and matter/energy came into existence. NOT "two particles of dust colliding". No dust, no space for the dust to be "in".

At the instant of the Big Bang spacetime was smaller than the volume of a present day atom and there was nothing but energy. Remember, energy takes up no volume. All the energy in our present day universe in a volume smaller than an atom means that the universe was infinitely "hot". As spacetime expanded, the universe cooled.

If you want to learn more, here are some places to start reading:
http://curious.astro.cornell.edu/cosmology.php#questions
http://www.astronomycafe.net/qadir/acosmexp.html
http://www.astro.ucla.edu/~wright/cosmology_faq.html#BBevidence
http://www.discover.com/science_news/newsflash/gthere.html?article=news_fish.html