by Dr. John A. Harris

Some of the Evidence for Big Bang (not eternal but very old universe) theory:

-Expansion of universe: reverse it and everything in the universe started out at one point about 13.7 billion years ago. The universe doesn't expand the way you might imagine, though.  It is common to think that the galaxies are just spreading apart into an endless space. However, it is the space itself, between the galaxies, that is expanding. It is difficult to comprehend how empty, nothing, space can expand. A good way to think about it is to take a balloon and make several dots on it with a magic marker. Now, blow it up. The balloon expands and the dots get farther and farther apart. If two dots started out one inch apart and you double the size of the balloon, the dots will now be two inches apart. But if two dots were five inches apart they are now ten inches apart. In other words, if you were a dot on the balloon and it was expanding, you would see dots that were already far away from you moving even faster away from you than dots that were close to you. In this way, the universe is like a three dimensional balloon., That's what studying the red-shift from distant galaxies showed - the farther away and object was from us, the faster it was moving away from us, The universe is growing larger at a rate of 5-10% every billion years. Cosmologists now routinely use red-shift to determine how far away objects in telescopes are.

-Speed of light: farthest distant observable object is a quasar (a young galaxy w/an active black hole at its center) (they've recently discovered that all galaxies have a giant black hole at center). They are over 12 billion light years away (so it took over 12 billion years for its light to reach us).  When you look at something through a telescope you see that object as it looked long ago (ex: 5 million light years away = 5 million years ago, 12 billion light years away = 12 billion years ago, etc., etc.).

-Colliding galaxies: If you look at a picture of two galaxies colliding, you'll see it resembles a violent car crash. The galaxies are distorted in shape and stars scatter into space. The diameter of these galaxies can be many tens of thousands of light years across, and since their speeds and the speeds of the scattered stars are far less than light speed, it is reasonable to assume this collision has been ongoing for millions of years.

-CMBR ("cosmic microwave background radiation"): this is described as the "after-glow" of the Big Bang that cosmologists theorized should exist if the universe actually did have a beginning. If the universe is over 13 billion years old like they thought, this light should have red-shifted all the way into the microwave spectrum (it's wavelength should have lengthened so much over that much time that it should be microwave radiation by now.) I would be all around us, not just in one part of the sky, because the universe is all around us. This radiation was discovered in 1964, which won a Nobel Prize, and it fit all of the characteristics cosmologists thought is would. CMBR is considered the biggest proof of a creation moment for the universe and it put the final nail in the coffin of the Steady State Theory.

     Albert Einstein started out believing in a static, eternal universe. But some of his equations suggested the universe had to be expanding.  He got around this by imagining a force he called "lambda" that repelled gravity at long distances. The static theory he believed in also bothered him (if the universe has existed forever then gravity should have collapsed everything in the universe together long ago if it had eternity to do it). He later called lambda the biggest blunder of his life, after that famous meeting with Lemaitre.

(more to come)