Cosmology 101 - Big Bang

Please visit and join to learn more. http://www.astronomy.com/asy/default.aspx

Most of the confusion about the Big Bang revolves around two different incorrect ideas. The first is that the Big Bang theory discusses the origin of the universe. The second is that the Big Bang was an explosion. Here I'll explain what the Big Bang theory really states.

Ever since 1929, astronomers have known the universe is expanding. Edwin Hubble observed that all galaxies except the closest ones to us — which are those in our local group of galaxies — are moving away. In fact, the farther away a galaxy is, the faster it is receding. This expansion isn't motion through space. It's the expansion of space itself.

So, if space is expanding, then the universe must be slightly bigger, cooler, and less dense than it was yesterday. If we extrapolate backward, then in the earlier days the universe must have been smaller, hotter, and denser than observed today. So the universe must have begun in a very hot and very compact state. It's been expanding and therefore cooling for the past 13.7 billion years. For a time after the "beginning event," the universe was so hot that atoms couldn't form.

The cosmic microwave background — called the CMB for short — also provides evidence to back up the Big Bang theory. The CMB is an amazingly uniform microwave glow that's in every direction in the sky. What could have caused a microwave background? Well, as the universe expands, its light is stretched — or redshifted.

The CMB light has been traveling through space since electrons and protons first combined into atoms some 380,000 years after the Big Bang. That light has stretched to microwave wavelengths by now. The CMB shows that a long time ago, the universe must have been smaller and denser than it is now.
Big Bang illustration
Typically when we show illustrations of the universe's history and expansion in Astronomy magazine, we show images like this one. Contrary to popular belief, the Big Bang wasn't any kind of explosion in space. The name "Big Bang" implies something along the lines of a chemical explosion — think fireworks. But the universe's beginning was really an unfolding, or creation, of matter, energy, time — and space itself. It was not an explosion in which debris flung out into a pre-existing space.

The term "Big Bang" actually refers to the moment when the universe started expanding. In fact, another common confusion is that today we can point to a spot where the Big Bang occurred. The truth is that everything in the universe — every point, every galaxy — originated from the same tiny, infinitely dense point 13.7 billion years ago. So really the Big Bang happened everywhere.

Interestingly enough, an astronomer discussing a competing theory coined the term "Big Bang." In the late 1940s Fred Hoyle was on a radio show to talk about the Steady State Model, and referred to the expanding universe model as "the big bang idea." The term stuck, and has caused plenty of confusion since. Instead of the term "Big Bang theory," a better term for the model of our universe would probably be the "expanding-universe theory."

Category:

Education

Tags:

• astronomy
• magazine
• big
• bang
• science
• cosmology
• logic
• reason

[TheCaptainLulz]

@xXComputerTechXx "god did it" is the most intelectually lazy bullshit there is. It says that you dont want to put in the effort to get an education, you just want to have it simple and stupid. Please dont post this crap on science videos, or if you do prepare to get pwned by people who understand how it really works.

[LisboaOdivelas]

@x2DiceX Where?

[carlsm95]

@tnafguy Not all atheists insult. Way to generalize...and I'm guessing all Christians are dumb backwards bigots? Because that sure seems to be the way a lot of them act. The thing we dislike is that many Christians have a limited knowledge of science and tend to make assumptions based on their ignorance. Many don't bother to do research before coming to the conclusion that something is false just because they don't want it to be true. And many atheists are tired of that.

[TheCaptainLulz]

@x2DiceX riiiiiiight. you go with that.

[x2DiceX]

@xXComputerTechXx THANK U FOR SAYING THAT.... god is real and people are to stupid to understand it.. its sad if u ask me

[x2DiceX]

@TheCaptainLulz GOD IS REAL there is to much proof

[xXComputerTechXx]

You guys are all wrong. No Offence, but the big bang was created by a powerful force which was God. If you don't believe in God, I don't stop you. But he did create Space and the Universe.

[alaric63]

This video seems to be supportive of the bankrupt series of assumptions and band-aids that has been the 'thing' for a century or so.

If so, it is about the same thing as a coward running away from a fight he cannot win and yelling back, 'I'll get you later!!, I will!!".

So, if this video is not in line with the superb and oh-so-very destructive to institution, Plasma Model or Electric Model, then I am going to have to say....

Shame on you for not backing up your words with facts.