[Bored chemist]

Sorry, you and all our scientists MUST except the observation as is.
You must agree that based on wien-law the source temp for λ peak at 2000 is 2.75K.
We can't argue about it.

No.
I could post a blue square here.
And  then I could fit it to the Wein law and it would tell me that your computer screen  is hotter than the surface of the sun.

[Bored chemist]

I have already explained that infinite Universe with infinite sources of 2.75K can easily emit BBR spectrum.

What transitions do you think are involved?

Do you understand that your claim is like saying that a green light is impossible?

[Bored chemist]

Wiens-law is very clear as it gives the source temp for each detected  λ peak.

Only for BBR. You do not seem to understand this.

[Bored chemist]

I have already explained that infinite Universe with infinite sources of 2.75K can easily emit BBR spectrum.

Liar.
You have never explained that.

[Bored chemist]

They just want to keep the BBT alive.

The properties of teh CMBR are consistent with the BBT but neither depends on the other.

[Bored chemist]

They clearly know that based on wien-Law a 2.75K temp source for the CMBR is a fatal problem for the BBT

No
It's not a problem.
The problem is your lack of understanding that a spectrum may change between emission and measurement.
Imagine that I look at a piece of red hot coal
I can get a fair measurement of its temperature from Wein's law.
Imagine I only get to see it through a piece of blue glass.
Would Wein's law still give me an idea of its temperature?

[Bored chemist]

That is a fatal mistake.

How many people did it kill?

[Bored chemist]

At this phase I fully understand the real meaning of wiens-law

You have not even learned to spell  it correctly.

[Dave Lev (OP)]

Dear BC

Please don't take it too personally.
I really appreciate your knowledge and your excellent support.

Sorry, you and all our scientists MUST except the observation as is.
You must agree that based on wien-law the source temp for λ peak at 2000 is 2.75K.
We can't argue about it.

No.
I could post a blue square here.
And  then I could fit it to the Wein law and it would tell me that your computer screen  is hotter than the surface of the sun.

I just have one question:
Let's assume that Wien was living today and he has no idea about the CMBR or the BBT.
We will show him the following observed image of the CMBR without calling it CMBR:

https://en.wikipedia.org/wiki/Cosmic_microwave_background#/media/File:Cmbr.svg

https://www.astro.ucla.edu/~wright/CMB.html

We will ask him the following:
Based on the above observed BBR spectrum, what is the expected source temperature for that spectrum?

What do you think should be his answer?

Could it be that his answer would be: 2.725K?

[Bored chemist]

He would say that if it was a thermal spectrum of a stationary object,  it was the spectrum of something at 2.725K.
But I think he would also realise it could also be the spectrum of a hotter or a colder thing that was moving away or towards him.
because he would, at least, have heard of Doppler's work.
But if you told him it was the emission spectrum of low pressure hydrogen gas at 2.725K he would laugh at you.

[Dave Lev (OP)]

He would say that if it was a thermal spectrum of a stationary object,  it was the spectrum of something at 2.725K.

Thanks
I have asked about the image of the spectrum of the CMBR.
At this phase I don't care how do we get this spectrum and if it is due to stationary object or not.
I hope that by now we all agree that based on wiens-Law the observed BBR spectrum of the CMBR means that its expected source temperature is 2.725K
Hence, based on the OBSERVED spectrum of the CMBR its expected source temperature should be 2.725K!!!
This is the meaning of real science!

The next questions would be:
How could it be that the CMBR has that kind of spectrum?
How could it be that none stationary object could have such spectrum?
And many other questions as:

Only if you are stupid enough to ignore the fact that something may have happened to the spectrum between it leaving the source and it reaching us.

But I think he would also realise it could also be the spectrum of a hotter or a colder thing that was moving away or towards him.
because he would, at least, have heard of Doppler's work.
But if you told him it was the emission spectrum of low pressure hydrogen gas at 2.725K he would laugh at you.

So, first we all have to agree that based on wiens-Law the observed BBR spectrum of the CMBR means that its expected source temperature is 2.725K and then we can decide if we wish to laugh or cray.

[Bored chemist]

At this phase I don't care how do we get this spectrum and if it is due to stationary object or not.

You might not care but it makes a difference.
If you ignore things like doppler shift you are not even trying to do science.
You are preaching.

Hence, based on the OBSERVED spectrum of the CMBR its expected source temperature should be 2.725K

Unless the source is moving or something else is happening which you refuse to consider.

[Dave Lev (OP)]

Quote from: Dave Lev on Today at 15:56:33
Hence, based on the OBSERVED spectrum of the CMBR its expected source temperature should be 2.725K

Unless the source is moving or something else is happening which you refuse to consider.

I fully agree to consider everything.
However, I hope that we can finely agree on the following:
Based on the OBSERVED spectrum of the CMBR its expected source temperature should be 2.725K, Unless the source is moving or something else is happening .
Do you agree?

[Bored chemist]

I fully agree to consider everything.

At this phase I don't care how do we get this spectrum and if it is due to stationary object or not.

Make up your mind.

However, I hope that we can finely agree on the following:
Based on the OBSERVED spectrum of the CMBR its expected source temperature should be 2.725K, Unless the source is moving or something else is happening .
Do you agree?

I have said that all along.
It's good that you agree, even if it took a while.

[Dave Lev (OP)]

However, I hope that we can finely agree on the following:
Based on the OBSERVED spectrum of the CMBR its expected source temperature should be 2.725K, Unless the source is moving or something else is happening .
Do you agree?

I have said that all along.
It's good that you agree, even if it took a while.

Thanks

Once we agree on the above let's try to verify (step by step) about something that could happen:

1. Something may have happened to the spectrum between it leaving the source and it reaching us

Only if you are stupid enough to ignore the fact that something may have happened to the spectrum between it leaving the source and it reaching us.

Can you please be more specific about that change?
Do you have an idea what was the peak of the spectrum when it is leaving the source?
Do you mean that at the source the peak was about 750 in order to meet the source of the Hydrogen recombination temp (which is 3000K)?
Can you please explain how could it keep its BBR spectrum while it change its peak so dramatically?

[Origin]

Can you please be more specific about that change?
Do you have an idea what was the peak of the spectrum when it is leaving the source?
Do you mean that at the source the peak was about 750 in order to meet the source of the Hydrogen recombination temp (which is 3000K)?
Can you please explain how could it keep its BBR spectrum while it change its peak so dramatically?

I would recommend that you reread the source you cited in your OP.  Your answers are right in your source.

[Bored chemist]

Can you please explain how could it keep its BBR spectrum while it change its peak so dramatically?

It's really very easy.
Move away from the source quickly.
Doppler shift will give you the same "shaped" spectrum but shifted to longer wavelength so it looks like it has come from a cooler source.

As has been pointed out, you cited a source which told you this.

[Dave Lev (OP)]

Can you please explain how could it keep its BBR spectrum while it change its peak so dramatically?

It's really very easy.
Move away from the source quickly.
Doppler shift will give you the same "shaped" spectrum but shifted to longer wavelength so it looks like it has come from a cooler source.

As has been pointed out, you cited a source which told you this.

Thanks
So let's agree on your above explanation.
Hence, when we observe the CMBR spectrum with λ = 2000 nm, we should know that this λ had been shifted from the value of 750 nm at its source to the current 2000 nm due to doppler shift effect.
That is very clear.
However, wiens-law tells us about the temp source assuming that it is not moving and nothing is happening:

Based on the OBSERVED spectrum of the CMBR its expected source temperature should be 2.725K, Unless the source is moving or something else is happening .

Hence, in this case, there is no meaning for the 2.725K as it doesn't represent the real temp source of CMBR spectrum (due to wiens-law).
In other words -  we shouldn't use the 2.725K as it doesn't represent the real source temp of the CMBR.

I also don't understand why do we need any sort of temperature for the Redshift calculation.
The formula for redshift is very clear:

Z = (λobserved -λrest) / λrest

I hope that we agree that:
λobserved = 2000 nm (That is what we observe today in the CMBR)
λrest = 750 (That is what we think should be the value for the CMBR reference due to the Hydrogen recombination temperature)
I have already set the calculation. however, I have used the value of λrest at 780 instead of 750 as follow:

We can claim that:
At T = 3500K,  λrest = 750 nm
The T temp of the Hydrogen recombination is 3000K.
Let's assume that its λrest is 780 nm
At T = 3000K,  λrest = 780 nm (assumption)

Based on the following CMBR data:
https://www.astro.ucla.edu/~wright/CMB.html
The peak of the CMBR is at 2 mm (or 2000nm)
Hence,
CMBR λobserved = 2000nm

Z CMBR= (λobserved -λrest) / λrest = (2000 - 780) / 780 = 1.564

So, why our scientists insist to use the temperature source in the redshift formula, while we clearly have the value of λobserved  & λrest for the CMBR?
What is wrong with this formula?

Z CMBR= (λobserved -λrest) / λrest = (2000 - 780) / 780 = 1.564
Is it too low value for you?

So, when math of real observation contradicts the theory, it's the time to twist the math?

[Bored chemist]

Once again, you have missed something important.
There is only one plausible thing in the universe which emits a black body spectrum without some sort of band or line structure superimposed on it.
And that's a hot, fairly dense hydrogen plasma.

If you do not believe that, please put forward an alternative that would emit BBR.


So we absolutely unequivocally KNOW that it started out hot.
Again, if you think there's another explanation, please let us know.

But what we see today is something that looks like a BBR spectrum from something very cold.
We absolutely know that it's not being emitted by something cold.
Again, if you think there's another explanation, please let us know.

So we absolutely know that something happened to the radiation between when it was emitted by a hot plasma and when we see it today.
Again, if you think there's another explanation, please let us know.

And so we know that it's either Doppler shifted or that space has stretched.
Again, if you think there's another explanation, please let us know.


Once you accept that, we can get on with sorting out your maths problems for you.

[Dave Lev (OP)]

Once again, you have missed something important.
There is only one plausible thing in the universe which emits a black body spectrum without some sort of band or line structure superimposed on it.
And that's a hot, fairly dense hydrogen plasma.

If you do not believe that, please put forward an alternative that would emit BBR.
So we absolutely unequivocally KNOW that it started out hot.
Again, if you think there's another explanation, please let us know

Yes, there is a simple explanation.
It is called - infinite Universe.

Please see the following explanation about the BBR:

https://en.wikipedia.org/wiki/Black_body


"A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. The name "black body" is given because it absorbs all colors of light. A black body also emits black-body radiation. "
"An approximate realization of a black surface is a hole in the wall of a large insulated enclosure (an oven, for example). Any light entering the hole is reflected or absorbed at the internal surfaces of the body and is unlikely to re-emerge, making the hole a nearly perfect absorber. When the radiation confined in such an enclosure is in thermal equilibrium, the radiation emitted from the hole will be as great as from any body at that equilibrium temperature"

Let's assume that we can set a cold gas at a Temp of 2.725K in insulated enclosure as an oven.
The light that emitted from that cold Gas is reflected from the internal surfaces of the Oven. When the radiation confined in such an enclosure is in thermal equilibrium, the internal radiation will be as great as from any body at that equilibrium temperature".
In other wards - we can get a black body radiation from cold gas that is placed in an enclosure oven.

Let's set two ovens next to each other.
Each one of them has cold gas with blackbody radiation.
If we open the wall between them, then we will get one bigger oven with the same blackbody radiation.

Now let's set unlimited number of similar ovens next to each other.
If we take out the internal walls, they all would still have a black body radiation.
The only requested limit is that the outwards wall must always be there.
However, if we could set infinite numbers of ovens that goes up to the infinity at any direction, then they all would behave as the wall is located there at the infinity.
Hence, as long as we won't be close to the open edge of the infinity, we would get the black body radiation.

Therefore, if our universe is infinite and is full with cold gas, the radiation at any location in that infinite universe would be a black body radiation.

Hence, the CMBR black body radiation in our universe PROVES that it is infinite in its size!

The infinite cold gas in a temp of 2.725K in the infinite Universe is the source for the CMBR black body radiation at the peak of λ = 2000 nm.
At any location that we will be in that infinite universe we would get the same CMBR.

So simple and clear!
The only limit is that we shouldn't be close to the edge of that infinite universe.

Therefore, based on weins-law the peak radiation of λ = 2000 nm represents a cold gas of 2.725K and that is 100% correct.
What we see is what we have!
The CMBR is due to the infinite cold gas at 2.725K in the infinite universe and not due to any sort of imagination idea that is called recombination process!