[Vern]

The furthest stars we know of are not visible to the human eye. The red shift is so grate they can only be seen with infra-red detectors. It may simply be the microwave radiation in the background is the furthest stars ever detected. Maybe the light is so far shifted it is no longer light.

The idea still applies, it is just at the other end of the spectrum. What was once visible light may be radio waves. And if what we suspect is true, the radio waves representing red shifted starlight would still contain the tell-tale equivalently shifted spectrum.

[techmatt]

The idea still applies, it is just at the other end of the spectrum. What was once visible light may be radio waves. And if what we suspect is true, the radio waves representing red shifted starlight would still contain the tell-tale equivalently shifted spectrum.

While it may be true the wave length would be so long an antenna the size of the moon or larger would be needed to detect the furthest stars. Therefore we may never (or at least in the precipitable future) be able to detect the furthest stars to see how big the universe really is. With in this point of time I am just keeping an open mind to all the possibilities.

I do however like to play devils advocate in any discussion to explore every theory. I think someone needs to or we may never know the truth.

[Vern]

We have equipment that can detect radiation below the visible spectrum. If the universe is ageless as we suspect that it is, much of the radiation will be below the visible spectrum. It will continue to exhibit its spectral structure however. That's how we know that the CMBR is not simply red-shifted starlight. It is black-body radiation. It is all very close to the same frequency.

[Bored chemist]

"There is only a finite amount of energy in a finite area of the universe."
That's exactly my point.
There's a finite amount of stuff in, for example, the solar system. If there are an infinite number of stars out there warming up that finite bit of stuff why isn't it infinitely hot?

I think the problem with that logic is, there is also an infinite amount of space to be warmed. Those infinite number of stars are not just warming up that finite bit of space you've mentioned. They are also warming up the rest of the infinite space we call the universe. The result is just, the 2.7 degrees Kelvin we observe................Ethos

OK you have made a good start. An infinite number of stars (each emiting a finite power) and an infinite space means that, for any finite density of stars there is a finite power density (and we know that there's a finite density of stars in our bit of the universe and one of the cop outs for Olber's paradox is that our bit of the universe is odd).

Now integrate that over the whole of time and you get an infinite total energy density which corresponds to an infinite temperature- so it should't go dark at night.
If at some time someone had set up a universe like that it might hypothetically explain the 2.7K background today. But if they had set it up an infinite time ago it would now be infinitely hot.

[Vern]

It the universe were infinitely hot, where did that infinite energy come from? We suspect that the laws of thermodynamics hold. Overall mass-energy can not increase unless there is some rule that we do not yet know about.

[techmatt]

We have equipment that can detect radiation below the visible spectrum. If the universe is ageless as we suspect that it is, much of the radiation will be below the visible spectrum. It will continue to exhibit its spectral structure however. That's how we know that the CMBR is not simply red-shifted starlight. It is black-body radiation. It is all very close to the same frequency.

The problem with the equipment that we currently have to detect the low frequency it the wave length that might be required. The lower the frequency the larger the antenna must be to detect full wave. This is a simple concept that any first year electronics major learns. Maybe the current equipment is not capable of picking up the full wave length and therefore is seems to be the black-body radiation. Ii is really just a case of sensitivity.

[Vern]

We can tune an antenna by adding inductance and capacitance, but to study single sources of energy we need to focus on the source. At the frequencies of the CMBR, we have tuned the receivers to the extent that we can determine the frequency very accurately. It is not possible that the CMBR is red-shifted starlight. It is possible that the CMBR is absorbed and re-emitted starlight. I suspect that the latter is the reality.

It would be interesting to know if the longest wavelength radio sources we observe do contain the fine structure we see in the spectrum of visible starlight. If it does not, we can forget about our speculation that the universe is infinitely old. If it does, it is just one more piece of evidence that the speculation may be real.

[Bored chemist]

It the universe were infinitely hot, where did that infinite energy come from? We suspect that the laws of thermodynamics hold. Overall mass-energy can not increase unless there is some rule that we do not yet know about.

That too is a reason why the universe can't have always been like it is (at least with the laws of physics as we know them). It would have required an infinite energy source.

The evidence is still piling up for Olber and against a perpetual universe, just as I have been saying all along.

Incidentally, there's another aproach to the problem you seem to be looking at. If the visible light has been red shifted so far to long wavelength that it's difficult to measure try looking at, for example, Xrays that have now been shifted to a more convenient region of the spectrum.
Of course, unless you can sort out Olber's paradox you will still be forced to accept that the simple answer to the original question is no.

[Vern]

Of course, unless you can sort out Olber's paradox you will still be forced to accept that the simple answer to the original question is no.

Olber's paradox has been sorted out.

I think though that Olbers paradox can be disposed of. The amount of energy per unit of spacial area doesn't increase because the same amount of energy departs as arrives. There is not an infinite amount of energy available.

You assume some sort of creation scheme when you require infinite energy to produce it. I have no problem thinking of an eternal universe that has always been much the same as it is now. Evidence to the contrary requires heavy bending of nature's rules as we know them.

Xray sources shifted into the visible range is interesting. I wonder if we would recognize that if we saw it. They will exist if our eternal scheme is the reality.

[techmatt]

Xray sources shifted into the visible range is interesting. I wonder if we would recognize that if we saw it. They will exist if our eternal scheme is the reality.

Now that is an interesting thought. Would they not appear as stars?

[Bored chemist]

Vern,
Stars burn out. If you don't have a scheme that creates them then they would all be dead by now (in an infinitely old universe).
There are still stars and so either there's something that has been making them, in violation of the law of conservation of energy, or the universe hasn't been around for ever.

As for "Olber's paradox has been sorted out."
Yes, it has; the universe isn't infinitely old so the paradox doesn't apply.
If you postulate an infinite universe then you have to answer Olber's paradox.
Please do so.

[Vern]

Stars convert matter to starlight of many frequencies. When stars burn out, they eventually end up at the centre of a galaxy where they are crunched into energy and spewed out as gamma rays and other forms of energy. The gamma-ray energy and starlight meet up in deep space and congeal into matter again.

Starlight warms space debris and this warmth is seen as the Cosmic Microwave Background Radiation.[]

If you postulate an infinite universe then you have to answer Olber's paradox.
Please do so.

Olbers Paradox; but it is not so. All of the infinite universe schemes provide a natural disposition for infinite starlight. In the Tired Light scheme, for example, light becomes mass as it is absorbed. It is then re-radiated. We observe this as the Cosmic Microwave Background.

[Vern]

Now that is an interesting thought. Would they not appear as stars?

I suspect that they would appear as stars; there should be something about their spectrum that would identify them as red-shifted Xray sources.

[Ethos]

If I may be allowed point out; The use of the word "infinity" can and has been used somewhat carelessly within this thread. When we consider an infinity of mass within the infinity of space, one must concede that the volume of space is vastly larger than the mass contained within it. As we consider this great difference in scale, the infinity of mass becomes significantly smaller by comparison. If I remember correctly, the mass density of our universe is very small, only one atom of Hydrogen available in a much larger volume of space. To assume that the infinity of mass-energy will light up an even larger infinity of space is not taking into account the difference between these two values.

 The infinity of mass in an infinite universe is not even close when we consider the volume of space within which it resides! And yes, some infinities are larger than others. Olber is wrong!