Ask Gugel Anything About the Big Bang

[Gugel]

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What are your credentials?

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I'm not claiming to know everything and please correct me if I'm mistaken anywhere. I took some high level astronomy/cosmology courses in college and read a bit cosmology in my spare time. I'll be able to answer most questions in layman's terms.

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Please explain why a specific cosmic microwave background radiation was definitive proof that the big bang theory was correct. Just curious how Georges Lemaître could have predicted that.

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When we look at Cosmic Background Radiation, we are actually seeing a snapshot of the Universe relatively soon after the Big Bang took place (~400,000 years after). It was the moment the Universe had cooled enough so that it went from being opaque to becoming transparent. It was also the moment energy and matter became two separate things. Anyway, this Cosmic Background Radiation is really far out and receding from us fast so it's grossly distorted (redshifted) into the microwave part of the light spectrum. But if we account for the redshift, we can determine the wavelength of the light that originally left the CBR and from that, we can determine the temperature (~2800 C). 400,000 years ago, every single part of the Universe was uniformly ~2800 C (there was no empty, cold space).

[Gugel]

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- Did anything exist before the big bang?

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This is an unfair question. Did you exist in the year 1863? What did you eat for breakfast on July 23, 1863? etc. In the same way, time did not exist before the Big Bang. There is no indication that anything existed prior to the Big Bang.
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Please, tell us about the implications of String Theory on our view of the big bang, and what was before it.

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While string theory is pretty cool to think about, there just isn't any conclusive evidence to support it. But basically, it would entail lots of Universes (Big Bangs) in some kind of meta Universe that always existed and always will exist. Our own Universe is just a speck.

Here's a pretty cool movie: http://tenthdimension.com/medialinks.php

[Chunwah]

Just after the big bang were the laws of nature different than what we think of them today?

[niffe9]

Can you give some commentary on Friedmann's critical density and the upper limits of density?

[roblin]

I like to think of the universe as a point in a vector room.

This vector room has an infite number of axis and each point in this room have diffrent physical laws determind on where on each axis they are. Our universe happened to be placed in that point where the laws lead to a universe where we can observe ourself.

How wrong am I?

[Gugel]

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Just after the big bang were the laws of nature different than what we think of them today?

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There are four known forces that are responsible for the Universe as we know it: Strong Interaction, Electromagnetism, Weak Interaction, and Gravity. On a side note, the strong interaction is what holds atoms together. With the electromagnetic force, you would think protons would repel each other since they are all positively charged. When the protons are extremely close to each other, however, the strong force kicks in and binds them. It is much, much stronger than electromagnetism.

Anyway, at high enough temperatures, these forces unify. Since the Universe at some point was infinitely hot, these forces were unified. Gravity was the first to separate, followed by the strong interaction, and finally by a decoupling of the electromagnetic force and the weak interaction.

In short, the laws of physics were completely different immediately following the Big Bang. Gravity, electromagnetism, the strong force, and the weak force were the same thing.

[Noodles.]

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Just after the big bang were the laws of nature different than what we think of them today?

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There are four known forces that are responsible for the Universe as we know it: Strong Interaction, Electromagnetism, Weak Interaction, and Gravity. On a side note, the strong interaction is what holds atoms together. With the electromagnetic force, you would think protons would repel each other since they are all positively charged. When the protons are extremely close to each other, however, the strong force kicks in and binds them. It is much, much stronger than electromagnetism.

Anyway, at high enough temperatures, these forces unify. Since the Universe at some point was infinitely hot, these forces were unified. Gravity was the first to separate, followed by the strong interaction, and finally by a decoupling of the electromagnetic force and the weak interaction.

In short, the laws of physics were completely different immediately following the Big Bang. Gravity, electromagnetism, the strong force, and the weak force were the same thing.

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Source?

[Gugel]

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Just after the big bang were the laws of nature different than what we think of them today?

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There are four known forces that are responsible for the Universe as we know it: Strong Interaction, Electromagnetism, Weak Interaction, and Gravity. On a side note, the strong interaction is what holds atoms together. With the electromagnetic force, you would think protons would repel each other since they are all positively charged. When the protons are extremely close to each other, however, the strong force kicks in and binds them. It is much, much stronger than electromagnetism.

Anyway, at high enough temperatures, these forces unify. Since the Universe at some point was infinitely hot, these forces were unified. Gravity was the first to separate, followed by the strong interaction, and finally by a decoupling of the electromagnetic force and the weak interaction.

In short, the laws of physics were completely different immediately following the Big Bang. Gravity, electromagnetism, the strong force, and the weak force were the same thing.

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Source?

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The unification of electromagnetism with the weak force has been experimentally achieved on Earth (the physicists that did this got the '79 Noble prize). You can read more about it here: http://en.wikipedia.org/wiki/Electroweak_theory

There is also strong evidence suggesting a grand unified theory where the strong force will be unified with the electroweak force. It requires much more energy (10^12 more energy in fact) than uniting the electromagnetic and weak force. If three of the forces are united at high energy, it seems likely that the last force, gravity, would be united too at some even higher energy level. The unification of gravity with the rest of the three forces is suspected, but not well supported.

[m_the0ry]

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Just after the big bang were the laws of nature different than what we think of them today?

[/ QUOTE ]

There are four known forces that are responsible for the Universe as we know it: Strong Interaction, Electromagnetism, Weak Interaction, and Gravity. On a side note, the strong interaction is what holds atoms together. With the electromagnetic force, you would think protons would repel each other since they are all positively charged. When the protons are extremely close to each other, however, the strong force kicks in and binds them. It is much, much stronger than electromagnetism.

Anyway, at high enough temperatures, these forces unify. Since the Universe at some point was infinitely hot, these forces were unified. Gravity was the first to separate, followed by the strong interaction, and finally by a decoupling of the electromagnetic force and the weak interaction.

In short, the laws of physics were completely different immediately following the Big Bang. Gravity, electromagnetism, the strong force, and the weak force were the same thing.

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Source?

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see Symmetry Breaking .

[Arp220]

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What are your credentials?

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I'm not claiming to know everything and please correct me if I'm mistaken anywhere. I took some high level astronomy/cosmology courses in college and read a bit cosmology in my spare time. I'll be able to answer most questions in layman's terms.

[/ QUOTE ]

Please explain why a specific cosmic microwave background radiation was definitive proof that the big bang theory was correct. Just curious how Georges Lemaître could have predicted that.

[/ QUOTE ]

When we look at Cosmic Background Radiation, we are actually seeing a snapshot of the Universe relatively soon after the Big Bang took place (~400,000 years after). It was the moment the Universe had cooled enough so that it went from being opaque to becoming transparent. It was also the moment energy and matter became two separate things. Anyway, this Cosmic Background Radiation is really far out and receding from us fast so it's grossly distorted (redshifted) into the microwave part of the light spectrum. But if we account for the redshift, we can determine the wavelength of the light that originally left the CBR and from that, we can determine the temperature (~2800 C). 400,000 years ago, every single part of the Universe was uniformly ~2800 C (there was no empty, cold space).

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This isn't exactly right. The formation of the cosmic microwave background radiation is due to an event called 'decoupling' that occurred during the epoch of recombination, a few hundred thousand years after the Big Bang. Theres a good write up of it here:

http://en.wikipedia.org/wiki/Cosmic_...ave_background

Look in the first paragraph under 'features'.