Alan McDougall Posted July 10, 2012 Share Posted July 10, 2012 How can we earthlings sitting out somewhere in the universe still see light from the very young universe. It makes no sense and is not as easy to answer as some might think? Link to comment Share on other sites More sharing options...
zapatos Posted July 10, 2012 Share Posted July 10, 2012 (edited) How can we earthlings sitting out somewhere in the universe still see light from the very young universe. It makes no sense and is not as easy to answer as some might think? Light we see from the early universe, say 12 billion years ago, has been travelling toward us for 12 billion years and has just now arrived. Because space has been expanding, the distance the light has had to travel has been increasing over the years. Even though the source of the light may have only been several billion light years from us when it was generated, the increase in space between us has resulted in a much greater distance for the light to travel. Edited July 10, 2012 by zapatos Link to comment Share on other sites More sharing options...
alpha2cen Posted July 10, 2012 Share Posted July 10, 2012 How can we earthlings sitting out somewhere in the universe still see light from the very young universe. It makes no sense and is not as easy to answer as some might think? From the beginning , the Universe is very large we can not imagine. Link to comment Share on other sites More sharing options...
imatfaal Posted July 10, 2012 Share Posted July 10, 2012 the Cosmic Microwave Background Radiation is the light remnant of the very early universe (380k years after Big Bang). Before the era of last scattering the entire universe was both opaque and very hot - when atoms started to form the universe started to become transparent to light; it is this last glow of the hot universe that we can now see as the CMBR. The space in between where it was emitted 13ish billion years ago and where we now pick it up on our instruments has grown massively, such that the light which was originally ultraviolet is now microwave - ie it has been red-shifted by universal expansion. the light we a currently measuring has been travelling for all of those 13ish billion years - mind boggling but true. Remember this was predicted as a necessary outcome of the big bang well before it was observed. Link to comment Share on other sites More sharing options...
Alan McDougall Posted July 16, 2012 Author Share Posted July 16, 2012 Light we see from the early universe, say 12 billion years ago, has been travelling toward us for 12 billion years and has just now arrived. Because space has been expanding, the distance the light has had to travel has been increasing over the years. Even though the source of the light may have only been several billion light years from us when it was generated, the increase in space between us has resulted in a much greater distance for the light to travel. Therefore, the expanding universe brought the light with it, as if the light were imbedded into space-time. However, how does this explain Redshift? Link to comment Share on other sites More sharing options...
michel123456 Posted July 16, 2012 Share Posted July 16, 2012 Wait a moment. The material the Earth is made of was also created in the Big Bang. So, this material has also traveled billions of Light Years. And so, what we are looking at very far away, at the edge of the observable universe, is our creation as well (and not only the birth of very distant stars & galaxies). Link to comment Share on other sites More sharing options...
Aethelwulf Posted July 16, 2012 Share Posted July 16, 2012 Wait a moment. The material the Earth is made of was also created in the Big Bang. So, this material has also traveled billions of Light Years. And so, what we are looking at very far away, at the edge of the observable universe, is our creation as well (and not only the birth of very distant stars & galaxies). What are you talking about? The material of the earth was not exactly made at big bang and has travelled billions of light years. It was created from some super-giant star which most likely went supernova, many years after big bang. Link to comment Share on other sites More sharing options...
michel123456 Posted July 16, 2012 Share Posted July 16, 2012 What are you talking about? The material of the earth was not exactly made at big bang and has travelled billions of light years. It was created from some super-giant star which most likely went supernova, many years after big bang. Oh. We are not a by-product of the BB? Link to comment Share on other sites More sharing options...
Aethelwulf Posted July 16, 2012 Share Posted July 16, 2012 Oh. We are not a by-product of the BB? Not a direct by-product, no. Yes, all energy came from the BB, but many processes happened since then and the production of planetoids. Link to comment Share on other sites More sharing options...
michel123456 Posted July 16, 2012 Share Posted July 16, 2012 Right. I should have stated "Wait a moment. The energy the Earth is made of was also created in the Big Bang. So, this energy has also traveled billions of Light Years. And so, what we are looking at very far away, at the edge of the observable universe, is our creation as well (and not only the birth of very distant stars & galaxies)." Though any material is made of some energy. Link to comment Share on other sites More sharing options...
Alan McDougall Posted July 16, 2012 Author Share Posted July 16, 2012 Right. I should have stated "Wait a moment. The energy the Earth is made of was also created in the Big Bang. So, this energy has also traveled billions of Light Years. And so, what we are looking at very far away, at the edge of the observable universe, is our creation as well (and not only the birth of very distant stars & galaxies)." Though any material is made of some energy. http://www.askamathematician.com/2012/06/q-how-can-we-see-the-early-universe-and-the-big-bang-shouldnt-the-light-have-already-passed-us/ The idea of universe exploding out of one particular place, and then all of the matter flying apart into some kind of pre-existing space, is not what is actually going on. It is just that getting art directors to be accurate in a science documentary is about as difficult as getting penguins to walk with decorum. The view of the universe that physicists work with today involves space itself expanding, as opposed to things in space flying apart. Think of the universe as an infinite rubber sheet*. The early universe was very dense, and very hot, what with things being crammed together. Hot things make lots of light, and the early universe was extremely hot everywhere, so there would have been plenty of light everywhere, shooting in every direction. If you start with light everywhere, you will continue to have it everywhere. The only thing that changes with time is how old the light you see is, and how far it has traveled. The expansion of the universe is independent of that. Imagine standing in a huge (infinite) crowd of people. If everyone yelled, “woo!” all at once, you would not hear it all at once; you would hear it forever, from progressively farther and farther away. Universe works the same way. As the universe expands (as the rubber sheet is stretched) everything cools off, and the universe becomes clear, as everything is given a chance to move apart. That same light is still around, it is still everywhere and it is still shooting in every direction. Wait a few billion years (14 or so), and you have galaxies, sweaters for dogs, hip-hop music a thoroughly modern universe. That old light will still be everywhere, shooting in every direction. Certainly, there is a little less because it is constantly running into things, but the universe is, to a reasonable approximation, empty. So most of the light is still around. The expansion of the universe does have some important effects, of course. The light that we see today as the cosmic microwave background started out as gamma rays, being radiated from the omnipresent, ultra-hot gases of the young universe, but they got stretch out, along with the space they’ve been moving through. The longer the wavelength, the lower the energy. The background energy is now so low that you can be exposed to the sky without being killed instantly. In fact, the night sky today radiates energy at the same intensity as anything chilled to about -270 °C (That is why it is cold at night! Mystery solved!). Even more exciting, the expansion means that the sources of the light we see today are now farther away than they were when the light was emitted. So, while the oldest light is only about 14 billion years old (and has traveled only 14 billion light years), the location from which it was emitted can be calculated to be about 46 billion light years away right now! Isn’t that weird? 1 Link to comment Share on other sites More sharing options...
alpha2cen Posted July 16, 2012 Share Posted July 16, 2012 (edited) Oh. We are not a by-product of the BB? Most of the elements are resultants comes from star fusion and supernova explosion. So, while the oldest light is only about 14 billion years old (and has traveled only 14 billion light years), the location from which it was emitted can be calculated to be about 46 billion light years away right now! Isn't that weird? Originally, the beginning time is not so accurate. Recently we can observe the young Universe by using deep field technology. Why the Universe is early Universe? There are no other elements except helium and hydrogen. Edited July 16, 2012 by alpha2cen Link to comment Share on other sites More sharing options...
Aethelwulf Posted July 16, 2012 Share Posted July 16, 2012 In fact... I'd argue there is no beginning of time. Not in your relativistic sense. In fact, i'd argue time was emergent... Or as I called it in my own independent research, induced, but both mean relatively the same thing. http://arxiv.org/abs/hep-th/0601234 Link to comment Share on other sites More sharing options...
zapatos Posted July 16, 2012 Share Posted July 16, 2012 Therefore, the expanding universe brought the light with it, as if the light were imbedded into space-time. So based on your post after this one, why do you say it is as if the light were embedded in space-time? It sounds as if you are saying the light is just going along for the ride as space expands, as opposed to having more space to travel through. Link to comment Share on other sites More sharing options...
Aethelwulf Posted July 16, 2012 Share Posted July 16, 2012 So based on your post after this one, why do you say it is as if the light were embedded in space-time? It sounds as if you are saying the light is just going along for the ride as space expands, as opposed to having more space to travel through. It sounds like he's been influenced by the Aether Drag Hypothesis, which is of course, not supported at all. So based on your post after this one, why do you say it is as if the light were embedded in space-time? It sounds as if you are saying the light is just going along for the ride as space expands, as opposed to having more space to travel through. There is a special case mind you where the vacuum in the observable universe is expanding faster than light... which literally drags matter and light along with it. But I doubt that is what he is talking about. Link to comment Share on other sites More sharing options...
michel123456 Posted July 16, 2012 Share Posted July 16, 2012 http://www.askamathematician.com/2012/06/q-how-can-we-see-the-early-universe-and-the-big-bang-shouldnt-the-light-have-already-passed-us/ The idea of universe exploding out of one particular place, and then all of the matter flying apart into some kind of pre-existing space, is not what is actually going on. It is just that getting art directors to be accurate in a science documentary is about as difficult as getting penguins to walk with decorum. The view of the universe that physicists work with today involves space itself expanding, as opposed to things in space flying apart. Think of the universe as an infinite rubber sheet*. The early universe was very dense, and very hot, what with things being crammed together. Hot things make lots of light, and the early universe was extremely hot everywhere, so there would have been plenty of light everywhere, shooting in every direction. If you start with light everywhere, you will continue to have it everywhere. The only thing that changes with time is how old the light you see is, and how far it has traveled. The expansion of the universe is independent of that. Imagine standing in a huge (infinite) crowd of people. If everyone yelled, “woo!” all at once, you would not hear it all at once; you would hear it forever, from progressively farther and farther away. Universe works the same way. As the universe expands (as the rubber sheet is stretched) everything cools off, and the universe becomes clear, as everything is given a chance to move apart. That same light is still around, it is still everywhere and it is still shooting in every direction. Wait a few billion years (14 or so), and you have galaxies, sweaters for dogs, hip-hop music a thoroughly modern universe. That old light will still be everywhere, shooting in every direction. Certainly, there is a little less because it is constantly running into things, but the universe is, to a reasonable approximation, empty. So most of the light is still around. The expansion of the universe does have some important effects, of course. The light that we see today as the cosmic microwave background started out as gamma rays, being radiated from the omnipresent, ultra-hot gases of the young universe, but they got stretch out, along with the space they’ve been moving through. The longer the wavelength, the lower the energy. The background energy is now so low that you can be exposed to the sky without being killed instantly. In fact, the night sky today radiates energy at the same intensity as anything chilled to about -270 °C (That is why it is cold at night! Mystery solved!). Even more exciting, the expansion means that the sources of the light we see today are now farther away than they were when the light was emitted. So, while the oldest light is only about 14 billion years old (and has traveled only 14 billion light years), the location from which it was emitted can be calculated to be about 46 billion light years away right now! Isn’t that weird? I know. The weird thing is that the BB happened everywhere, which means: the BB happened exactly here. And there. And everywhere. Link to comment Share on other sites More sharing options...
StringJunky Posted July 16, 2012 Share Posted July 16, 2012 (edited) The idea of universe exploding out of one particular place, and then all of the matter flying apart into some kind of pre-existing space, is not what is actually going on. It is just that getting art directors to be accurate in a science documentary is about as difficult as getting penguins to walk with decorum. This tickled me...could have come out of "Hitch Hiker's Guide To The Galaxy". Edited July 16, 2012 by StringJunky Link to comment Share on other sites More sharing options...
juanrga Posted July 16, 2012 Share Posted July 16, 2012 How can we earthlings sitting out somewhere in the universe still see light from the very young universe. It makes no sense and is not as easy to answer as some might think? When you look to any star in the sky, you are not seeing the star at the present time. The more far away the star the more young you see it. Why would be different for the rest of Universe? Link to comment Share on other sites More sharing options...
zapatos Posted July 16, 2012 Share Posted July 16, 2012 There is a special case mind you where the vacuum in the observable universe is expanding faster than light... which literally drags matter and light along with it. But I doubt that is what he is talking about. What is the special case called? I'd like to look it up. Link to comment Share on other sites More sharing options...
alpha2cen Posted July 18, 2012 Share Posted July 18, 2012 (edited) When you look to any star in the sky, you are not seeing the star at the present time. The more far away the star the more young you see it. Why would be different for the rest of Universe? Redshift exposure time gives no effect to calculate the distant galaxy moving? Does 10000yr redshift have no difference than 10yr redshift? Edited July 18, 2012 by alpha2cen Link to comment Share on other sites More sharing options...
alpha2cen Posted July 21, 2012 Share Posted July 21, 2012 Have we obtained that heavy atoms fraction is increased with time? At the inflation period heavy atom fraction is zero. Time: :::::::::::::::::::::Big Bang-----inflation----------------------------------------------------------->current Universe. Heavy atom fraction::::zero............zero.........?....very low....low.....small.....medium.......>increasing Do we have this kind of data? Link to comment Share on other sites More sharing options...
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