First Morning—Simple Elements
The first particles came from the collision of gamma ray photons. The collisions also fractured the rays and the photons. Whenever the colliding photons had excess energy beyond that needed to produce particles, photons of lower energy carried the excess away from the interaction region along other rays. This produced the first light. The first morning dawned almost as soon as the first evening began to produce particles.
Heat, another byproduct of the collisions, started an expansion that cooled the universe. The cooling and the fracturing of the gamma ray photons of highest energy put an end to particle production a very short time after it began. Now that we know how much energy it takes to make particles, we can understand why particle production stopped.
The End of Particle Production
It may help to compare photons to money. Let’s think of gamma-ray photons as large bills and light or heat photons as small coins. As we spend large bills to buy material possessions, we gradually accumulate change consisting of smaller bills and coins. At the end of a shopping spree we could have a huge bag of small coins. There might still be enough money in the bag to buy an expensive car, but no salesperson would want to sit down and count all the coins!
This is why there is now very little natural creation of particles from photons. Almost all the energetic photons present at the beginning of the universe are by now broken up into weak photons. Weak photons seldom come together in great numbers and therefore do not produce particles.
Heat, another byproduct of the collisions, started an expansion that cooled the universe. The cooling and the fracturing of the gamma ray photons of highest energy put an end to particle production a very short time after it began. Now that we know how much energy it takes to make particles, we can understand why particle production stopped.
The End of Particle Production
It may help to compare photons to money. Let’s think of gamma-ray photons as large bills and light or heat photons as small coins. As we spend large bills to buy material possessions, we gradually accumulate change consisting of smaller bills and coins. At the end of a shopping spree we could have a huge bag of small coins. There might still be enough money in the bag to buy an expensive car, but no salesperson would want to sit down and count all the coins!
This is why there is now very little natural creation of particles from photons. Almost all the energetic photons present at the beginning of the universe are by now broken up into weak photons. Weak photons seldom come together in great numbers and therefore do not produce particles.