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Big Bang. Theory and Microwave radiation

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I know the theory suggests that the universe started as a dense, and very hot point of singularity which has expanded over the years and cooled down significantly. But could someone help me understand this question stating even the most basic ideas please? Ive even tried to look st the examiners report but it isnt of my much help to me.


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Original post by jtbteddy
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I know the theory suggests that the universe started as a dense, and very hot point of singularity which has expanded over the years and cooled down significantly. But could someone help me understand this question stating even the most basic ideas please? Ive even tried to look st the examiners report but it isnt of my much help to me.


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Essentially it was very strange that some random radiation was being detected in all directions at all times of year and all at the same frequency, continuously.

The explanation must be to do with the universe itself.

Physicists predicted that the big bang would have involved a lot of radiation at very hot temperatures, which, over time, would have cooled to around 3K. And, quite marvellously, the radiation discovered by Penzas and Wilson perfectly matched with what the theory expected. So the radiation is strong proof of the theory of a rapidly expanding and super-hot-then-cooling big bang.
Reply 2
Original post by Pessimisterious
Essentially it was very strange that some random radiation was being detected in all directions at all times of year and all at the same frequency, continuously.

The explanation must be to do with the universe itself.

Physicists predicted that the big bang would have involved a lot of radiation at very hot temperatures, which, over time, would have cooled to around 3K. And, quite marvellously, the radiation discovered by Penzas and Wilson perfectly matched with what the theory expected. So the radiation is strong proof of the theory of a rapidly expanding and super-hot-then-cooling big bang.


But how did they know that the radiation they detected wasnt simply the background radiation? Like the on that comes from radon rocks?

And how did physicists know that over time it shouldve cooled down to particularly 3K?

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Original post by jtbteddy
But how did they know that the radiation they detected wasnt simply the background radiation? Like the on that comes from radon rocks?

And how did physicists know that over time it shouldve cooled down to particularly 3K?

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The reason they know the radiation wasn't from 'radon rocks' is because there are not radon rocks everywhere. If that were the case, they could just clean up the area or move the telescope to a different location and try again...

They also waited for 6 months to check their readings again, so then the earth would be on the other side of the sun, in a completely different region of space, yet when they pointed their equipment to the skies ir still detected exactly the same phenomenon. This radiation was everywhere, in every direction, and not coming from earth.

The theory predicted it would be 3K basically 'because maths'. I don't even know how they predicted it, but the simple fact is that it had been predicted, and then it was discovered, which is quite a marvellous triumph for theoretical physics really. Quite a lot of things were theorised before they were discovered, actually. It's why theoretical physicists get so smug about their capabilities, hah.

On and also, the cosmic background radiation perfectly matches the intensity spectrum of a blackbody object. Which is a fantastic sign of it being from space and being a natural phenomenon from the purest days of the universe. That may be beyond the scope of A-level physics though.

Reply 4
Original post by Pessimisterious
The reason they know the radiation wasn't from 'radon rocks' is because there are not radon rocks everywhere. If that were the case, they could just clean up the area or move the telescope to a different location and try again...

They also waited for 6 months to check their readings again, so then the earth would be on the other side of the sun, in a completely different region of space, yet when they pointed their equipment to the skies ir still detected exactly the same phenomenon. This radiation was everywhere, in every direction, and not coming from earth.

The theory predicted it would be 3K basically 'because maths'. I don't even know how they predicted it, but the simple fact is that it had been predicted, and then it was discovered, which is quite a marvellous triumph for theoretical physics really. Quite a lot of things were theorised before they were discovered, actually. It's why theoretical physicists get so smug about their capabilities, hah.

On and also, the cosmic background radiation perfectly matches the intensity spectrum of a blackbody object. Which is a fantastic sign of it being from space and being a natural phenomenon from the purest days of the universe. That may be beyond the scope of A-level physics though.



I understood everything except the last paragraph.. Since its beyond my course, i guess its alright :tongue: thankd for the detailed explanation!

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