light

[Jim_Baur]

I suppose this is another easy question to answer, if one knows the answer.

How long does it take for light to dissipate?

It seems almost impossible that light from 15 billion years ago has not dissipated.

I know that the speed of light is a constant, but could it slow down?

 

[Catholic90]

I know that the speed of light is a constant, but could it slow down?

If it is a constant…it cannot slow down! Because it is a constant.

 

[GEddie]

Light does not dissipate, although it spreads out to the point where our eyes can no longer see it. You cannot see a candle flame six miles away, but it’s photons will travel on until they are absorbed by matter.

ICXC NIKA

 

[ASimon]

The Universe isn’t yet 15 billion years old.

 

[Aelred_Minor]

Light does not dissipate, although it spreads out to the point where our eyes can no longer see it. You cannot see a candle flame six miles away, but it’s photons will travel on until they are absorbed by matter.

ICXC NIKA

Which is why the star’s light doesn’t blind you.

 

[Aelred_Minor]

I suppose this is another easy question to answer, if one knows the answer.

How long does it take for light to dissipate?

It seems almost impossible that light from 15 billion years ago has not dissipated.

I know that the speed of light is a constant, but could it slow down?

Technically light could do almost anything, including slow down. It’s interesting that it doesn’t. One of those funny “laws of nature” things.

(That’s not sarcasm by the way.)

 

[Jim_Baur]

Thanks for the help!

Those laws of nature, do we know the nature of the laws of nature?

Please forgive the childlike questions, it seems to me math draws a picture of the laws, but the pictures do not tell us the nature of the laws. Is this accurate?

 

[Aelred_Minor]

Thanks for the help!

Those laws of nature, do we know the nature of the laws of nature?

Please forgive the childlike questions, it seems to me math draws a picture of the laws, but the pictures do not tell us the nature of the laws. Is this accurate?

That’s pretty much right. The “laws of nature” are just things we’ve observed actually happening the same way many times. You drop an apple many times and it travels downward each time. Eventually you come to predict that the next time you drop it it will fall down, and there is a kind of practicality in making such predictions.

But really the fact that it so far has not done so doesn’t mean the apple couldn’t fly upward or sideways or stay in place or turn into a butterfly when you let go of it. You don’t expect it to do so because you’ve never observed apples doing so in a similar situation, but that doesn’t mean it can’t happen. It’s pure superstition to think that because something has happened the same way many times there must be an inexorable law of nature by which it absolutely has to do it again.

 

[promethius]

But really the fact that it so far has not done so doesn’t mean the apple couldn’t fly upward or sideways or stay in place or turn into a butterfly when you let go of it. You don’t expect it to do so because you’ve never observed apples doing so in a similar situation, but that doesn’t mean it can’t happen. It’s pure -]superstition/-] [Theology] to think that because something has happened the same way many times there must be an inexorable law of nature by which it absolutely has to do it again.

Judeo-Christianity, mostly Catholicism, is the foundation of the idea that the universe is constructed of rational, universal laws. In other words, the only reason we have the field of science is because we theologically believe that what we observe as natural laws are rational, universal, and everlasting (meaning they do not change with time).

 

[Aelred_Minor]

Judeo-Christianity, mostly Catholicism, is the foundation of the idea that the universe is constructed of rational, universal laws. In other words, the only reason we have the field of science is because we theologically believe that what we observe as natural laws are rational, universal, and everlasting (meaning they do not change with time).

And what in theology makes us believe that?

Certainly we believe in a rational God as the source of all Creation, in certain laws of logic, and in the power of human reason. These things don’t logically lead one to conclude in the existence of inherently unalterable natural laws governing physical phenomena, though.

Indeed, at least one point of Christianity contradicts such a ridged idea of natural laws: miracles. If Jesus and Peter can walk on the water, then obviously the laws of nature are not laws at all, just interesting repetitions that have their ultimate basis the will of God, who in this case desires Peter to be able to walk on the water in this moment and to cease being able to the next moment.

 

[promethius]

And what in theology makes us believe that?

Certainly we believe in a rational God as the source of all Creation, in certain laws of logic, and in the power of human reason. These things don’t logically lead one to conclude in the existence of inherently unalterable natural laws governing physical phenomena, though.

Actually, I think Dinnish D’Souza explains this far better than I could… paraphrasing from him, it was the pre-socratics who first thought up the concept of a disenchanted universe, where Ra didn’t drive his chariot of fire across the sky once a day… but they were ultimately suppressed by Socrates and Greek Pagan theology.

As to Judeo-Christian theology, there is a reason the greek term used to describe Jesus in John 1 is logos, from which the word “logic” is derived… it is a basic precept of Christianity that rationality itself is a reflection of God’s nature. This is why Augustine exclaimed in his confessions that all creation points to and reflects the Creator. And, as Alfred North Whitehead wrote in Science and the Modern World, “Faith in the possibility of science… is an unconscious derivative of medieval theology”

It was Robert Grosseteste, a Franciscan Bishop, who first proposed that scientific knowledge be gathered through an inductive, experiment based methodology.

Indeed, at least one point of Christianity contradicts such a ridged idea of natural laws: miracles. If Jesus and Peter can walk on the water, then obviously the laws of nature are not laws at all, just interesting repetitions that have their ultimate basis the will of God, who in this case desires Peter to be able to walk on the water in this moment and to cease being able to the next moment.

Indeed, and that is because the rationality of the universe is subject to the rationality of God. God can change it’s rationality at any time to allow for Miracles. In other words, God is not bound by the laws He fashioned for His creation.

Again, Dinesh D’Souza does a far better job explaining the possibility of Miracles than I can on the fly (and I want to go home, so admittedly I’m shortchanging you):
books.google.com/books?id=vVXf2PV8pyQC&pg=PA92&lpg=PA92&dq=Dinesh+D’Souza+%22universe+is+rational%22&source=bl&ots=GEJCvj4j0B&sig=F1BF2O6kRcbviq3aU-xggHic02Q&hl=en&ei=wYfFTtnqFMji0QHxpKGYDw&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFYQ6AEwCQ#v=onepage&q=miracles&f=false

Click on the finding for page 179 and read from there. If you haven’t read his book “What’s so great about Christianity?” I strongly recommend it. Dinesh is a prodigious apologist.

 

[Aelred_Minor]

Actually, I think Dinnish D’Souza explains this far better than I could… paraphrasing from him, it was the pre-socratics who first thought up the concept of a disenchanted universe, where Ra didn’t drive his chariot of fire across the sky once a day… but they were ultimately suppressed by Socrates and Greek Pagan theology.

As to Judeo-Christian theology, there is a reason the greek term used to describe Jesus in John 1 is logos, from which the word “logic” is derived… it is a basic precept of Christianity that rationality itself is a reflection of God’s nature. This is why Augustine exclaimed in his confessions that all creation points to and reflects the Creator. And, as Alfred North Whitehead wrote in Science and the Modern World, “Faith in the possibility of science… is an unconscious derivative of medieval theology”

It was Robert Grosseteste, a Franciscan Bishop, who first proposed that scientific knowledge be gathered through an inductive, experiment based methodology.

Indeed, and that is because the rationality of the universe is subject to the rationality of God. God can change it’s rationality at any time to allow for Miracles. In other words, God is not bound by the laws He fashioned for His creation.

Again, Dinesh D’Souza does a far better job explaining the possibility of Miracles than I can on the fly (and I want to go home, so admittedly I’m shortchanging you):
books.google.com/books?id=vVXf2PV8pyQC&pg=PA92&lpg=PA92&dq=Dinesh+D’Souza+%22universe+is+rational%22&source=bl&ots=GEJCvj4j0B&sig=F1BF2O6kRcbviq3aU-xggHic02Q&hl=en&ei=wYfFTtnqFMji0QHxpKGYDw&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFYQ6AEwCQ#v=onepage&q=miracles&f=false

Click on the finding for page 179 and read from there. If you haven’t read his book “What’s so great about Christianity?” I strongly recommend it. Dinesh is a prodigious apologist.

I’ve read the book, and I think we are not as far apart in our thinking as you may think. The key thing to remember is that the “laws” of nature have a basis in a conscious choice on the part of God. Whether you speak of God setting up laws which He may occasionally choose to change or simply of God choosing to frequently repeat phenomena and occasionally make exceptions to that repetition, it means basically the same thing just with a different emphasis.

This as opposed to the superstitious attitude that just because an apple fell it had to fall, that there is something inherent about a planet as such and an apple as such that an apple would just have to move towards the planet.

Certainly there are true laws. If the apple is smaller than the planet then the planet, we can hold with firm rational dogmatism, must be larger than the apple (speaking of relative size in the same sense and at the same time). Maybe a Hindu or even a Muslim could entertain the idea of God creating an apple that is smaller than a planet that is smaller than it, but a Christian rejects the idea because we believe that even the perfect Omnipotent Being is consistently rational.

But that the apple must move towards the planet is subject to no such inherent rational law. It’s something that we observe happens consistently and can infer that God has chosen for it to do so, but to jump from that observation to drawing a mystical inherent connection between apples and falling to the earth is anything but solid reasoning.

Christianity doesn’t disenchant the earth but it insists on one, supremely rational Enchanter. The materialist version of natural laws moves this rationality from the personal Enchanter of the world to the world itself as it’s own blind inevitable enchanter, and that is superstition.

 

[promethius]

I’ve read the book, and I think we are not as far apart in our thinking as you may think. The key thing to remember is that the “laws” of nature have a basis in a conscious choice on the part of God. Whether you speak of God setting up laws which He may occasionally choose to change or simply of God choosing to frequently repeat phenomena and occasionally make exceptions to that repetition, it means basically the same thing just with a different emphasis.

This as opposed to the superstitious attitude that just because an apple fell it had to fall, that there is something inherent about a planet as such and an apple as such that an apple would just have to move towards the planet.

Certainly there are true laws. If the apple is smaller than the planet then the planet, we can hold with firm rational dogmatism, must be larger than the apple (speaking of relative size in the same sense and at the same time). Maybe a Hindu or even a Muslim could entertain the idea of God creating an apple that is smaller than a planet that is smaller than it, but a Christian rejects the idea because we believe that even the perfect Omnipotent Being is consistently rational.

But that the apple must move towards the planet is subject to no such inherent rational law. It’s something that we observe happens consistently and can infer that God has chosen for it to do so, but to jump from that observation to drawing a mystical inherent connection between apples and falling to the earth is anything but solid reasoning.

Christianity doesn’t disenchant the earth but it insists on one, supremely rational Enchanter. The materialist version of natural laws moves this rationality from the personal Enchanter of the world to the world itself as it’s own blind inevitable enchanter, and that is superstition.

hmmn… that certainly is an interesting way of viewing it, and I’d say it doesn’t contradict the balance between science and physics… but if we have an eternally rational God who mentally maintains the rational behavior of the universe at every moment, who then decides to violate that rationality to inject a miracle, don’t we run into the problem of a God who is changing his mind? (In other words, going along with Augustine’s idea that a perfect being does not ever change in the slightest… wouldn’t that make miracles problematic?)

 

[Aelred_Minor]

hmmn… that certainly is an interesting way of viewing it, and I’d say it doesn’t contradict the balance between science and physics… but if we have an eternally rational God who mentally maintains the rational behavior of the universe at every moment, who then decides to violate that rationality to inject a miracle, don’t we run into the problem of a God who is changing his mind? (In other words, going along with Augustine’s idea that a perfect being does not ever change in the slightest… wouldn’t that make miracles problematic?)

He wouldn’t be changing his mind, because from all eternity he would have willed that, for example, the water hold up Peter’s weight at this moment and then cease holding up Peter’s weight the next moment.

The repetitions we see in nature are evidence that God had decided that, for example, liquid water should ordinarily not be able to hold up the weight of a standing human. This decision and the decision to make an exception to that rule at a certain time and place would be coeternal so to speak, and so would not constitute God changing His mind.

 

[Jim_Baur]

Again, I hope you forgive my lack of comprehension and knowledge.

Again, I am here to learn. I am thinking out loud.

I find it impossible to comprehend how light from a star 15,000,000,000 years ago is still traveling to earth.

Also, the redshifts and blue shifts of the stars and galaxies perplexes me.

There seems to be a large number of blue shift stars or galaxies, even if it is a low percentage relative to the known universe.

Also, I am bewildered by the size of the universe. We have not seen the limits of it in any direction. The size is absolutely unknown.

The math therefore cannot be complete when trying to work back to a singularity, at least with my limited knowledge and comprehension.

Actually, the math is totally incomplete, in my limited comprehension.

Also, if someone reading this post might know, how many scientists have actually done the math for the Big Bang?

Also, if someone knows, if we do not know the limits of the physical universe, not to mention the immaterial parts, who can the math be correct?

Thanks!

If this is addressed, I will read it and contemplate the answers.

Thanks! Thanks! Thanks!

 

[Aelred_Minor]

Well, let’s use the analogy of a moving physical object. Light doesn’t work the same way but this is only to give another instance of how something can move in perpetuity. Newton’s first law of motion is that the velocity of a body remains constant unless the body is acted on by an external force. That includes if the velocity is zero, leading to the saying you’ve probably heard many times that an object at rest stays at rest and an object in motion stays in motion (unless acted on by an external force).

This is why moving objects have momentum and still objects have inertia. If you are pushing a car down the street it is harder to get it moving than to keep it moving, because without sufficient energy a still object will not move. But once it is moving it equally takes energy to get it to stop, which is why a baseball doesn’t drop straight down to the ground when it leaves your hand when you throw it.

We are used to moving objects eventually slowing down and stopping because on earth there is always the ground, water, or at least air that the moving object slides against, creating friction which constitutes that outside force acting to change the velocity of the object, until the object comes to rest at which point there is no friction and the velocity can remain constant. In a compete vacuum however the object would keep moving at the same speed and in the same direction forever, until it came in contact with something. Just like we can imagine a still object on earth staying at rest for ever unless something touched it.

Now, again obviously light isn’t a physical body and it works completely differently (cannot be slowed down by friction, for example- it keeps going at the same speed until the photon is absorbed somehow) but the example of momentum helps show how it’s possible for something to keep going on and on without slowing down, no matter how far the distance.

What about the dissipation of light that you mentioned earlier? Yes, light dissipates, but individual photons/rays of light keep on going until they hit something opaque. Imagine a sun with a lot of rays coming off of it. Your pupil is like a net to catch those rays in. The farther out you go, the farther apart the rays get, and so fewer rays get “caught” by your pupil. The pupil can widen a bit to catch more rays, but only a little, so the greater distance you go from the source the fewer rays are going to be caught. There is the same total amount of light (if it hasn’t touched anything) and it’s going the same speed, but the photons are spread apart over a wider area.

At some point it will be so far away that so few rays are caught by your pupil your nervous system doesn’t even register it. However, if you could bend rays that have been dispersed over a wide enough area inward so they come closer together again, you could gather the rays close enough that you could see them again. This is what telescopes do.

I don’t know if this is at all helpful. I apologize if it is not at all the level of explanation you are looking for. No time now to get into red shift and blue shift. I’d have to refresh my memory on the subject anyway. And I’ll leave the big bang and size of the universe questions to someone else.

 

[DaveBj]

Light does not dissipate, although it spreads out to the point where our eyes can no longer see it. You cannot see a candle flame six miles away, but it’s photons will travel on until they are absorbed by matter.

ICXC NIKA

Beg to differ, but light does dissipate, meaning that it weakens as it travels from its source. Both light and sound weaken in proportion to the square of the distance from the source. In other words, if you measure the intensity of a beam of light at a distance of one mile from its source and again at a distance of two miles, the intensity at two miles will be 1/4 the intensity at one mile. We can see light from galaxies 13 or so billion lightyears away, but it’s not like it is visible to the naked eye. It takes big light-bucket telescopes staring for days at a time to gather enough photons to even tell that they are there.

 

[GEddie]

Beg to differ, but light does dissipate, meaning that it weakens as it travels from its source. Both light and sound weaken in proportion to the square of the distance from the source. In other words, if you measure the intensity of a beam of light at a distance of one mile from its source and again at a distance of two miles, the intensity at two miles will be 1/4 the intensity at one mile. We can see light from galaxies 13 or so billion lightyears away, but it’s not like it is visible to the naked eye. It takes big light-bucket telescopes staring for days at a time to gather enough photons to even tell that they are there.

We may be arguing over definitions. Yes, light is attenuated as it spreads from
the source in concentric spheres, but it does not dissipate in the sense of losing energy, as sound waves or moving objects do. A photon will have the same energy reaching your optic nerve as it had at the source, but if the source is too far away, there will not be enough photons to trigger the optic nerve.

ICXC NIKA

 

[Jim_Baur]

This discussion is helpful.

Thanks for the help!

 

[buffalo]

I suppose this is another easy question to answer, if one knows the answer.

How long does it take for light to dissipate?

It seems almost impossible that light from 15 billion years ago has not dissipated.

I know that the speed of light is a constant, but could it slow down?

Interesting question indeed. What has happened to all the photons emitted by the sun in its entire history? Do they reflect off the boundaries of the universe? Do we see them again?