It is generally accepted that there is not enough mass in the universe to cause it to stop expanding. If true, the eventual result will be the heat-death of the universe. Under these conditions there will be no light (he said, hoping no-one screams “cite”).
The time from Big Bang to heat-death is finite. The time after heat-death is infinite.
Therefore the time during which no light will exist is infinitely larger than the time during which some light exists. To me, this implies that the “natural state” of the universe is no light.
(As I typed this another question occurred to me which could make my argument nonsense, even if it is not already so. Does time exist after the heat-death of the universe?)
I disagree with the “naturalness” of darkness, inasmuch as I think the question is answerable: everything that’s not at absolute zero gives off radiation (“light”). Nothing is at absolute zero. So, light is everywhere. If we could see in the microwave part of the spectrum, the universe would be aglow from all directions. I suppose the natural, if absurd, conclusion to that way of looking at it is that it’s never actually dark. Sounds like something you’d hear on a Pink Floyd album.
There is a [url=http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation]Cosmic Microwave Background Radiation which pervades the entire universe, everywhere. It is the “echo of the Big Bang” and even forms part of teh noise on an untuned TV screen (“Next time there’s nothing good on, you can always watch the birth of the universe” - Bill Bryson, A Short History of Everything).
If “light” is defined as electromagnetic radiation of an intensity above some arbitrary minimal threshold, nowhere is dark. If the threshold is arbitrarily raised above the threshold of the CMBR or arbitrarily limited to the visible spectrum, darkness can be said to exist.
Is this a serious question? No, there are no particles of “dark”. Is there something else you’re trying to get at? Because I don’t understand this thread.
If you’re serious then think of it in terms of hot and cold. There is no such thing as objective “cold”. There is only the lack of heat. Total lack of heat is absolute zero and total lack of light is pitch black.
Er… maybe I am just being slow today but what is the relationship between kinetic energy and a vacuum? Vacuum is the emptiness of space. Are you refering to the lack of kinetic enrgy or something? No Space=No Particles=No Relationship Between Particles=No Kinetic Energy if it was a TRUE vacuum. Am I crazy?
Inside a box that contained only a vacuum, there would still be light due to the thermal black-body radiation of the sides. The box would have to be really hot for it to be in the visible part of the spectrum, but even at lower temps it’s still photons zipping around.
Then think of it this way: when the universe reaches its final state of entropy, which may or may not be considered its “natural” state, will there be any light?
Is it a fair statement, CurtC, to say that no particle can ever be at rest because, if it were, then we would know both its position and its momentum to a certainty?
Well, I’m speaking generally of electromagnetic radiation. Some of it is visible to humans and some is not, but that is a restriction of perception, not of reality. Different eyes of different animals can discern different bands of the EM spectrum. But it’s all still there, from infrared to gamma rays.
You might say that zero point energy or the CMBR are not strictly “light” since their wavelength does not lie between 400-800 nm (to which the human eye is sensitive in air), but you could not say that there was no propagation of energy within that box.
