Thread: Darkness

I recently herd argument for the universe being finite as opposed to infinite, one of the points of contention for the finite was that;

If the universe was infinite then our night sky would be filled with Light, a light
akin to daylight since the innumerable lights from stars would blot out and
darkness.

In considering this argument the question which immedieatly jumped out is what is Darkness, While its true that a look into the night sky reveals darkness peppered in with the light of stars, this is not true darkness.

Our eyes can only preceive a form of darkness with even a iota sized influx of light. True darkness would have no influx of light period, and thereby be beyond the sightings of our eyes or our instruments.

If one layered his eyes with material that blocks all light, he will see nothing. his mind may attempt to lighten the flashing imagery that comes as a result of this act but in truth those fleeting images are not whats there.

Seeing nothing is not the same as seeing true darkness.

True Darkness is un perceviable to our sight which relies on light, even in a dark room our eyes may adjust to the darkness but only according to the influx of some light no matter how miniscule.

So to assume that a point of arguement for a finite universe is a lack of a completly lighted nighttime sky, is baseless since the eye cannot see true and absolute Darkness.

Darkness does not need a very fancy definition: it is the absence of light. And, yes, the eye can not see true darkness because everything would be black. Can you see in a pitch-black room?

Also, even though I am not a phycisist in any way, shape or form, I don't think that anyone said the universe was infinite. That is my assumption but I'll leave it to the more knowledgable people to confirm or deny.

Originally Posted by curious1

I recently herd argument for the universe being finite as opposed to infinite, one of the points of contention for the finite was that;

If the universe was infinite then our night sky would be filled with Light, a light
akin to daylight since the innumerable lights from stars would blot out and
darkness.

This is Olber's Paradox. He proposed it in 1823, though others had raised the issue earlier.

The paradox is resolved, in my understanding, by the finite age of the universe and the expansion of space.

Now the logic of your subsequent argument escapes me. Stating that we cannot see darkness is a tautology, since we only see light and darkness is the absence of light. But your final sentence makes no sense to me whatsoever. Can your restate it in a different way. Perhaps break it down into smaller steps.

That was what I was going to say: the universe is not infinitely old so the light from all the stars would not have reached us by now, so there would be dark spots where the far-away stars should go.

as i see it , the univers is infinite but at many finite ara like the big bang , like in ablack holl thay (the ara) are cicle at time and the light too . cuntinuying to the above

Originally Posted by Ophiolite

Originally Posted by curious1

I recently herd argument for the universe being finite as opposed to infinite, one of the points of contention for the finite was that;

If the universe was infinite then our night sky would be filled with Light, a light
akin to daylight since the innumerable lights from stars would blot out and
darkness.

This is Olber's Paradox. He proposed it in 1823, though others had raised the issue earlier.

The paradox is resolved, in my understanding, by the finite age of the universe and the expansion of space.

Right. Between the two you have red shift reducing the light intensity of distant stars and a finite observable universe.

Olber's Paradox only states that the universe must be finite in age (and undergoing expansion), it does not require that the universe be finite does it? As far as I know, Olber's Paradox can work in an infinite universe (but a finite observable universe of course)- but an infinite universe would mean very little to us, would it not? It would just mean that we can definitely never see it all as it exactly is (not that we could anyway due to the universe's accelerating expansion and the "Hubble Barrier"- I think that's what it's called).

to the best of my understanding we do live in a universe who's history and finite/infinite size is explained by the above statements.

however, considering a universe which is infinitely old and large yet having the same or a very similar concentration of matter as our own a mathematical evaluation disproving a lit up night sky can be made.

it is inherently obvious that as objects are observed to be farther and farther away their apparent size (expressed as a percent of field of vision) diminishes. this means that a disproportionate(in regards to the amount of mass involved) amount of light in our night sky comes from the small number of stars that are very close, and the farther away a group of stars is, the less each unit of mass centered in them produces light in our night sky.

this means that the farther away you look the less and less objects tend to shine, even without consideration of red shift and other factors that also reduce the amount of light reaching us. the only way that our night sky could be covered in starlight would be if there were also infinite mass in this infinite universe, and that simply isn't what we've observed.

Originally Posted by curious1

I recently herd argument for the universe being finite as opposed to infinite, one of the points of contention for the finite was that;

If the universe was infinite then our night sky would be filled with Light, a light
akin to daylight since the innumerable lights from stars would blot out and
darkness.

In considering this argument the question which immedieatly jumped out is what is Darkness, While its true that a look into the night sky reveals darkness peppered in with the light of stars, this is not true darkness.

Our eyes can only preceive a form of darkness with even a iota sized influx of light. True darkness would have no influx of light period, and thereby be beyond the sightings of our eyes or our instruments.

If one layered his eyes with material that blocks all light, he will see nothing. his mind may attempt to lighten the flashing imagery that comes as a result of this act but in truth those fleeting images are not whats there.

Seeing nothing is not the same as seeing true darkness.

True Darkness is un perceviable to our sight which relies on light, even in a dark room our eyes may adjust to the darkness but only according to the influx of some light no matter how miniscule.

So to assume that a point of arguement for a finite universe is a lack of a completly lighted nighttime sky, is baseless since the eye cannot see true and absolute Darkness.

If my understanding is correct, then due to the nature of the expanding universe and the constraints on the speed of light, only a small section of the universe is visible to us.

What is the finite age of the universe?, We cant even carbon date plain old rocks!!!

Hubbles expansion fact, does not particulary swings for a finite universe, seems like one is saying SINCE WE ARE ON A JOURNEY IT HAS TO END SOMEWHERE.

Thereby it must have an end.

The journey of expansion itself is the best evidence for the infinite of the universe if one was to calculate the distance in light years between the planets and stars in our own galaxy then factor that in into a equation that would cover said distance between objects in the whole of the universe that number would be infinite.

But we dont know or cant see all the objects in the universe, so rather light under any condition doesnt make it here or haven't as of yet, does not make the universe finite because of a lack of a lighted night sky.

No, it's "We're all on a journey, but if we trace all those separate journeys backwards, they were all in the same place about 14 billion years ago."

Originally Posted by MagiMaster

No, it's "We're all on a journey, but if we trace all those separate journeys backwards, they were all in the same place about 14 billion years ago."

So following that logic, when they were all in the same place they where not what they are now in form (suns, planets, etc etc) and the primal source was?

Back to the theroy of the Big Bang, but wait something was happening before that so.....

My point is science is to question, when we adopt parts we often make suggestions about the whole. in the finite/infinite debate no whole is know. despite our ability to know some of the parts.

Originally Posted by curious1

So following that logic, when they were all in the same place they where not what they are now in form (suns, planets, etc etc)

Right.

Originally Posted by curious1

and the primal source was?

No one knows. There are many ideas, but so far, no one's been able to find any particular evidence to support any one idea.

Originally Posted by curious1

Back to the theroy of the Big Bang, but wait something was happening before that so.....

Maybe. Again, no one really knows. I think most people suspect that something must have existed before the big bang, but we don't have any evidence for that.

Originally Posted by curious1

My point is science is to question, when we adopt parts we often make suggestions about the whole. in the finite/infinite debate no whole is know. despite our ability to know some of the parts.

Sorry, I don't really see your point. People do speculate about the whole based on what we know of the parts, but without evidence, it's all just speculation.

Sorry, I don't really see your point. People do speculate about the whole based on what we know of the parts, but without evidence, it's all just speculation.[/quote]

I concurr on the speculation, however this speculation is very easily disguised as a
discussion and debate (science forum) fact.

On this forum, most people assume that when someone asks a question, they implicitly want an answer using the best current understanding of science. All of science is a series of better approximations, so no answer will ever be definite. Trying to explain that in the middle of answering a simple question is usually counterproductive. Also, this is only an internet forum, not a peer-reviewed journal, so the standards are a bit more lax.

That said, a lot of questions have answers that are pretty well grounded in experimental evidence. If something has been measured to happen in a given situation, then no theory can ever change that.

Scientists don't really know what happened at the big bang. Ask anyone and they'll happily tell you that they're still working on it. The closest we can get with solid theory and evidence is about seconds after the big bang.