What Properties Might Light of Millennia Past Have that Today's Doesn't?

No, Limpy, the universe expanding could not be observed in principle. It's just an incoherent idea. Like velocity is getting brittle. These two notions do not make any sense together. It takes two entities to expand. The Universe is one and only. End of story.

The question of the thread is supremely not even wrong. For any one asking if so and so was such and such in the cosmological past naively takes for granted that he understands what he is talking about. I mean which past exactly? Imagine yourself free-falling in outer space and assume your vision is as good as that of all the best scopes combined. Let you the centre of your sphere of vision. All the farthest points on the inside of such a sphere are equidistant from you. You see them as they are equal number of billions years ago. That means they are equally in Your past. Does it mean it is one and the same time for them? If so for them it must the same present. Is that possible though? Remember any location on that sphere is separated not only from your present location but also from any other location at the same distance from you. That means some of them might be further from one another than they are from you. Think about that before pondering on the questions that are not even wrong.

What I understand is that Nuky makes another empty bigbangist assertion. What I said stands. This is called relativity of simultaneity laughably overlooked by all the "experts" in need to defend the bigbunk creation tale.

Excuse me genius, but if John stands 15 meter to the left of me and Mary stands 15 meter to the right, the distance separating John and Mary is not 15 meter. Is that too hard for you to grasp? Translate the same into cosmological distances and take into account that there could be all kinds of angles and configurations.
Otherwise, my definition of energy as a measure of motion stands. Do you have a better one? Let's hear it, Nukey.

What do you mean by in contact with each other? And how is that relevant? In contact or not they are not occupying the same location. Cosmologically they are separated in time. Are in each other's respective past, that is. And how far they are in each other's respective past may depend on the distance separating them. That was the point. The contact is not instantaneous would be another point.

Well, there is little point in pointing out what everybody and his dog agrees on anyway. The point is though that time is a strictly local measurement of distance which escapes the attention of those who persist in the belief that there could be some universal arrow of time. If that holds then the universal arrow of time is physically impossible in principle just like the whole idea of time zero and big bang creation.

Because cosmologically a particular time is a relative notion meaning a particular distance from a place to place while universally any location is as good as any other which implies that the cosmetologists might as well study your last Wednesday instead of projecting it 13.7 billion light years away from here.
Your post is lame, Inadequate. What facts you are blabbering about? Let's face it, you go round being snide and deriding theists for their silly notions but your own beliefs when examined are the same absurdity squared, cubed and squared again, Inadequate.Edited by Alfred Maddenstein, : No reason given.

Sorry, bigbangism is metaphysics so has nothing to do with any evidence. Such issues are examined on conceptual merits first and only after passing that test any evidence may become relevant. Otherwise, this whole evidence worship is modern idiocy. The feeling is that everybody is eager and ready to believe any nonsense as long as they heard that there was some evidence voted to be reliable by some reputable majority.
They say: we don't believe your proposition not because it is a clear contradiction in terms - that is fine by us- we don't believe it because we never heard there was any evidence for it. Just give us some evidence and we'll gladly join your faith.Edited by Alfred Maddenstein, : No reason given.

Well, the topic is whether light could have had different properties in the past. I examine the hidden contradiction in the question itself. It could be met with another question. Which past exactly? Light comes from every relative direction. Time is a measure of distance and distances have different directions so the assumption that it is one and the same past all light is coming from is a contradiction here.

Speak for yourself, Nuke and suit yourself. If you want to stick to linear universal calendar, you might as well do that. Then Bible, Friedman, Lemaitre and Guth will help you with the choice of magnitudes. If you don't want that, then we can discuss relativity of simultaneity. Otherwise, light coming pretty much the same from every past may strongly indicate it's constant everywhere and when.

Well, I might have used some other threads just to remind you folks that a very strong rational opposition to the currently assumed bigbangist wisdom in cosmetology does indeed exist, but the present topic has not been one of such occasions.
Here, all I did was investigate the very meaning of the question posed. What does it mean exactly - light of millennia past? Unlike the Universe which takes no plural by definition, cosmologically past should take no singular. Time and its direction is a strictly local measure relative to the local frame of reference and each of it spatial planes. Any instant of it is simultaneous with a particular relative location only, so to speak. If light is the only a constant standard of measure, then that should hold on ordinary scales too. Mary five meter to the left of you and John five meter to the right are both in your relative past. Is that exactly the same past the three of you should agree on? The cat thinks not. In that case, of course, the reciprocal delay is infinitesimal, yet the effect must exist necessarily. Negligible for all practical intents and purposes. In day to day affairs perfect simultaneity with one's neighbours is taken for granted without a second thought. Not so for the intents and purposes of physics though. The discrepancy grows as a function of distance and on the intergalactic scales lets itself be known in no uncertain terms. Thank you.

Inadequate, your attempts at defensive humour are pathetic. Go treat your snide self to another dog.

No, Coy, you don't get it. Claims for both the Bunk to have occurred and leprechauns to have existed fail on the conceptual level first and the Bunk's failure is far more dismal than that of leprechauns. That is because the leprechauns' hypothesis proposes hypothetical objects hiding pots of gold which are quite conceivable objects whereas the bang concept operates with the idea of space expanding into itself which is a more twisted proposal impossible to visualise or conceptualise in any way, shape or form. The idea could be taken on faith only and therefore any evidence suggested for its physical reality is to be treated with an expanding grain of salt.

Oh, that, Inadequate. You mean mathemagicians? Because in physics space is but an abstract relation not a substance that can expand. But in mathemagic they use the trick of multiplying zero by zero while introducing all kinds of fractions by sleight-of-hand. The fractions multiplying imitate a meaningful physical activity. They imagine all kinds of lines stretching. Vectors, tensors, lines of force and suchlike and then forget to tell the public that the lines exist only on paper. That's how it's done in a nutshell.

Sorry, Nuke, Inadequate's question was loaded with suggestion that the Big Bunk creation event of 20th century scholastics was as factual as his consuming a hot dog last Wednesday. The feline can ask loaded questions too. One of these events is impossible, which one do you think that is?