Posting the link ‘cos it’s neat.
I learned something new, though. Can’t believe I’ve never thought of it. The near infinite amount of light sources in this universe (mainly stars) constantly shoot of energy in the form of photons (light). Light making it to another galaxy or terrestrial surface is like winning the photon lottery. The amount of matter compared to the amount of vast empty space is scary. Let’s assume that the universe is about 30bil light years wide in all directions, and that NASA’s estimation of the amount of mass and it’s density are right.. then that means we have
If you are willing to accept these three assumptions, then:
1.1E+57 cubic meters of matter in the universe
A cubic light year contains about 1E+48 cubic meters. So all of the matter in the universe would fit into about 1 billion cubic light years, or a cube that’s approximately 1,000 light years on each side. That means that only about 0.0000000000000000000042 percent of the universe contains any matter. The universe is a pretty empty place! Eeeeeek.
So.. to give scale.. our galaxy is @ 100,000 light years wide.. our solar system is around 1 light year, if you include the Oort cloud and all that jazz.
How does this wrap into my original point? Basically, the universe is a large room, and the matter held within it is specks of dust you see floating through the sunshine coming into the room.
Ok, so what, right?
This is where I learned something. I have never given a single thought to all the lonely photons that have been traversing our universe for billions of years, never landing or reflecting off an object. They venture into the depths of space. With all of photon-emitting sources in the universe, that makes for traffic jams of photons in certain areas where their paths inevitably cross.
Two photons of the correct energies can create matter. All different kinds. From nothing. No one, myself included, really takes the time to understand what E=mc2 means. Energy and mass are two sides of the same coin. Mass creates energy, and energy creates mass. Hence, photons/light, being a product or embodification of energy, can create matter. And anti-matter.
This may be common knowledge to a lot of people. I find it magical. I wish I got into this sooner. For some reason, my imagination pictures light reaching the end of the universe and creating this matter/anti-matter shell. Odd.