Dumb Question

If the CMB has photons being studied by scientists on earth, then shouldn't the actual present age and distance of the CMB be twice as old and twice as far than the observational data? Hence doubling the age of the universe? (Disregarding the Inflationary Hypothesis).

 

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The CMB doesn't have a distance; it permeates the universe.
But apart from that, I don't understand the question. Why twice?

 

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Hi!
Can anyone tell me what is CMB?
I do not quite know the abbreviation for the terms.

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Hi Dreamsa ...

Welcome to Sciforums.

Cosmic Microwave Background
<a href=http://www.mpa-garching.mpg.de/~banday/CMB.html><font color=red>
CMB Resources</font></a>

Take care.

 

Hi!
I see CMB=Cosmic Microwave Background.
I also have question about this:
Why is the radiation now become like the black body radiation of 2.7K, why is the temperature become so low?

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I also do not understand Fathom's question!

 

hmmm!

ARG!

 

hmmm!

Interesting. It appears my conception of what constitutes the CMB is falsified. I was under the impression that the CMB represented in some respects the edge of the universe because it was created during the early inflation period of the Big Bang. I was thinking that CMB is only being observed over the vast expanse of space as it was during it existed during its conception (at the edge of the universe). Hence my ridiculous reasoning that it is in fact twice as old as what our telescopes tell us. (Which of course makes no sense. lol). I must have thought for some strange reason that the distance deduced by measuring instruments was equal to the age somehow, so it would mean that at its' present moment its distance and age would be duplicated...blah, talk about a silly theoretical mess. In doing a small amount independent research fueled by the replies of this thread I have discovered how wrong I was. Thanks anyway. I knew there was something fundamentally wrong with what I thought CMB was.

 

Hi!
CMB are the remains of the photons of the recombination era, right?
I am also writing something about Big Bang for my assignment now, but I know too little.
Also, anyone know the answer of my previous question!

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Dreamsa,
The answer to your question is in the information provided by the link Chagur supplied.

 

I'm not sure about this, all I know is that a black body is one that will absorb all the light falling on it. It is also a perfect radiator energy. Stars can be considered to be black bodies to a good approximation. The temperature for hot objects varies due to the distance from the radiation centre of that ovject, the further away from the centre, the cooler it is according the the inverse square law. Also, since everything emits radiation which depends on the temperature of the objects, is the temperature is related to the colour of the object. The temperature reduces as the energy is radiated out into space and after millions of years, the object becomes much cooler and reaches thermal equilibrium.

Hope this helps.

 

Thanks!

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There is a specific characteristic spectrum for black bodies of different temperature. Isn't that spectrum not related to distance and only related to the temperature of the black body? I don't know.

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Distance only changes its intensity.

 

Dreamsa ...

I'm starting (admittedly I'm kind of slow) to get the impression that you're jerking
chains ... That you're far more knowledgeable than you're putting on.

Take care.

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For a star, we determine it's surface temperature according to its colour, the centre is far hotter than its surface temperature. The distance alter the temperature we measure, but we don't need it to determine the surface temperature - just look at its colour will do. Of course to determine temperature at the centre, we require other methods.

 

Still why does its wavelenght become so long now?


__________________________________________________
Chagur...
I am a physics student. Therefore the fact that I am knowledgable is just an illusion, I know little about arts.

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Because the universe has expanded since recombination time, when the universe became "transparent" to light, and the photons have been redshifted into the microwave portion of the EMR spectrum.

AFAIK

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Oh! I do not understand the part that the CMB are red-shifted!

 

When the waves moves away from the observer with the object that emits it, it creates the doppler effect and the wave front are further apart from each other. In the opposite, the blue shift where the object is moving towards us. This is the way we found out that the universe is expanding. As red shift occurs, the wavelength become longer, thus the frequency decreases. But if the distance between the object and the observer stays the same, then the wavelength don't change, but as the distance increases, the intensity decreases by the square of the distance.

 

>>Oh! I do not understand the part that the CMB are red-shifted!<<

The CMB is not red-shifted! In fact, it's invisible to the naked eye. The CMB is the very cold remnant of radiation left over from the BB and is located primarily in the microwave portion of the electromagnetic spectrum which fills the universe and can be detected everywhere we look.

Microwaves are the name given to radiation between the infra-red and radio region, with wavelengths typically in the 1mm to 10cm range. The COBE satellite, for example, was deployed to measure the diffuse infrared and microwave radiation.

 

I'm not sure about this. Even if its invicible to the naked eye, the waves can still red shift or blue shift as the source is moving as the microwave is part of the spectrum.

 

CMBR and Redshift

http://www.astr.ua.edu/keel/galaxies/cmbr.html