Can We See Our Past? - Milky Way & Hubble Telescope

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In summary, the Milky Way is about 13.5 billion years old and the Hubble deep field observation could see galaxies which existed only a billion years after the Big Bang. However, the Hubble telescope cannot see the Milky Way when it was only 0.8 billion years old since the light from that time has now propagated billions of light years out into space and is no longer observable. The universe is possibly infinite and the observable universe is constantly expanding, making it difficult to accurately measure the size of the universe at different points in time.
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Viopia
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The Milky Way is about 13.5 billion years old. The Hubble deep field observation could see galaxies which existed only a billion years after the Big Bang. If the Hubble telescope was pointed in the right direction, could it see the Milky Way when it was only 0.8 billion years old?
Participants: ibix
 
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  • #2
Viopia said:
The Milky Way is about 13.5 billion years old. The Hubble deep field observation could see galaxies which existed only a billion years after the Big Bang. If the Hubble telescope was pointed in the right direction, could it see the Milky Way when it was only 0.8 billion years old?
Participants: ibix

Not directly. We can see other parts of the Milky Way only up to thousands of years ago.
 
  • #3
Viopia said:
The Milky Way is about 13.5 billion years old. The Hubble deep field observation could see galaxies which existed only a billion years after the Big Bang. If the Hubble telescope was pointed in the right direction, could it see the Milky Way when it was only 0.8 billion years old?
Participants: ibix

No. The light that left the Milky Way billions of years ago has now propagated billions of light years out into space and is no longer observable by us.
 
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  • #4
I can see why the previous posts gave the answers they did. Put my question another way. Was the "young" 0.8 billion year old Milky Way one the galaxies which existed only a billion years after the Big Bang? If so, why is the Milky way different from the other galaxies which the Hubble deep field telescope can see which existed only a billion years after the Big Bang?
 
  • #5
Viopia said:
I can see why the previous posts gave the answers they did. Put my question another way. Was the "young" 0.8 billion year old Milky Way one the galaxies which existed only a billion years after the Big Bang? If so, why is the Milky way different from the other galaxies which the Hubble deep field telescope can see which existed only a billion years after the Big Bang?

It's closer. The Sun, for example, is only 8 minutes away. The light from the Sun any older that than is traveling away from us; not towards our telescopes.
 
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  • #6
This must mean that the Hubble deep field observation cannot see all of the galaxies which existed only a billion years after the Big Bang. There must have been many, many more galaxies than the huge amount observed in a very small region of the sky. Would this vast amount of early universes be more than the current estimate of Universes which exist now?
 
  • #7
Viopia said:
This must mean that the Hubble deep field observation cannot see all of the galaxies which existed only a billion years after the Big Bang. There must have been many, many more galaxies than the huge amount observed in a very small region of the sky. Would this vast amount of early universes be more than the current estimate of Universes which exist now?

A lot will have happened in our observable universe that we will never see. In order to see something 13 billion years old, it must have been about 13 billion light years away at that time. A galaxy closer than that can only be seen from a more recent time. 10 billion years, 5 billion years, 2 million years (in the case of the Andromeda galaxy) and 8 minutes (in the case of the Sun). You can only look back in time by looking a long distance away as well.
 
  • #8
Yes, I can see what you mean. We are actually at the centre of the Universe, just like everything else is. I'm not trying to be argumentative, but I've had a confusing thought. If we look out in all directions we can see galaxies 12.7 billion light years out in any direction we look. It's as thought they are imprinted on the inside of a sphere with a radius of 12.7 billion light years, and we are at the centre of the sphere. This seems to indicate that the Universe was at least 25.4 billion light years in diameter only a billion years after the Big Bang. I thought that the Universe was much smaller than this only a million years after the Big Bang. I promise not to ask you any further questions if you can please explain to me why this is not so.
 
  • #9
Viopia said:
Yes, I can see what you mean. We are actually at the centre of the Universe, just like everything else is. I'm not trying to be argumentative, but I've had a confusing thought. If we look out in all directions we can see galaxies 12.7 billion light years out in any direction we look. It's as thought they are imprinted on the inside of a sphere with a radius of 12.7 billion light years, and we are at the centre of the sphere. This seems to indicate that the Universe was at least 25.4 billion light years in diameter only a billion years after the Big Bang. I thought that the Universe was much smaller than this only a million years after the Big Bang. I promise not to ask you any further questions if you can please explain to me why this is not so.

The universe is possibly infinite, we only know about the observable universe.

One complicating factor is that the universe is expanding. This means that if something is, say, 5 billion light years away today, it will take longer than 5 billion years for the light to reach us, as space is expanding while the light is traveling towards us.
 
  • #10
Thank you for explaining that. Einstein's light speed speed limit is not compromised because space is expanding rather than the velocity of light being less than c. At least we can set a limit to the size of the Universe. The diameter of the "sphere" I was talking about can only be uncreased to a maximum of 13.7 billion light years. This is because the only thing that happened 13.7 billion years ago was the Big Bang. Nothing existed before 13.7 billion years ago and so there would be nothing to see.
 
  • #12
Viopia said:
I can see why the previous posts gave the answers they did. Put my question another way. Was the "young" 0.8 billion year old Milky Way one the galaxies which existed only a billion years after the Big Bang? If so, why is the Milky way different from the other galaxies which the Hubble deep field telescope can see which existed only a billion years after the Big Bang?

I don't understand your question. Yes, there was a young Milky Way which existed 0.8 billion years after the Big Bang. We believe it is a typical galaxy, so if we had a snapshot of it from that time, it would look similar to the galaxies seen in the Hubble deep field. Why do you think it is different? Your question seems to me like asking why an adult looks different from a class full of children.
 
  • #13
PeroK said:
A lot will have happened in our observable universe that we will never see.

If the universe is infinite in extent, then looking far enough out I'd expect we could observe light from galaxies similar to our own all the way to as soon after the surface of last scattering such galaxies formed - is that not correct?

It makes sense to me that events which occurred outside our light cone we can never observe (I think this is what you are saying).
 
  • #14
phyzguy said:
I don't understand your question. Yes, there was a young Milky Way which existed 0.8 billion years after the Big Bang. We believe it is a typical galaxy, so if we had a snapshot of it from that time, it would look similar to the galaxies seen in the Hubble deep field. Why do you think it is different? Your question seems to me like asking why an adult looks different from a class full of children.
PeroK understands my question. If you ask PeroK he will explain my question to you. Basically it seems that whatever direction we look we can only ever see past events. The further we look in light years, the younger the Universe appears to us because it has taken so long for the light to reach us. We can now see galaxies which appear to us as though they are only a billion years after the Big Bang. If we look up, these young galaxies are 12.7 billion light years away from us. If we look in the opposite direction, these galaxies also look as though they are 12.7 billion light years away us. This means that the distance between the the two observations is 25.4 billion light years. This seems a rather large distance when the Universe was only one billion years old. This is the only bit of my question I don't yet understand, but I will give it a lot of thought.
 
  • #15
Viopia said:
PeroK understands my question. If you ask PeroK he will explain my question to you. Basically it seems that whatever direction we look we can only ever see past events. The further we look in light years, the younger the Universe appears to us because it has taken so long for the light to reach us. We can now see galaxies which appear to us as though they are only a billion years after the Big Bang. If we look up, these young galaxies are 12.7 billion light years away from us. If we look in the opposite direction, these galaxies also look as though they are 12.7 billion light years away us. This means that the distance between the the two observations is 25.4 billion light years. This seems a rather large distance when the Universe was only one billion years old. This is the only bit of my question I don't yet understand, but I will give it a lot of thought.

There was a period of rapid inflation in the Big Bang Theory:

https://en.wikipedia.org/wiki/Inflation_(cosmology)

However, if the universe is infinite, then it has always been infinite; and hence was infinite as far back towards the big bang as you go.
 
  • #16
Viopia said:
At least we can set a limit to the size of the Universe.

Making more wordy what PeroK says in post 15 -

There is a limit to the size of the observable universe. Its hard for me to visualize an infinite-in-extent universe going from very very dense to less dense. The size of our present day observable universe was about that of a softball pre-inflation, according to some popular science characterizations I have read and you can find if you google. Softball or grain of sand or 1km sphere is not the main point - the main point being to picture the softball size early universe as a small piece of similar really dense stuff that is infinite in extent, all of which expands / inflates. Today we are limited observing that blown-up primordial softball, but its still surrounded by an infinite expanse of similarly blown up stuff, if the universe is infinite in extent.

If the cosmic background radiation were ever to suddenly cease, I think (I may be wrong) that would indicate that the universe is not infinite in extent, or at least that not all of it expanded like our neighborhood appears to have.
 
  • #17
What puzzles me in this debate: where do we suppose that our Galaxy is in relation to where the Big Bang happened = is the BB where the centre is and are all galaxies moving away from that centre? Hence is a younger Galaxy closer to that (virtual) centre. Because if this is true, it makes a difference in which direction you observe the cosmos. Not all galaxies move away from the observer (we) at the same speed; some are moving away from the centre in the direction that we we do, some at the other side of the (virtual) centre, opposite of ours at double speed; maybe my perception of the big bang as a the creation of a big sphere is wrong. I don’t know.
 
  • #18
RobertoV said:
What puzzles me in this debate: where do we suppose that our Galaxy is in relation to where the Big Bang happened = is the BB where the centre is and are all galaxies moving away from that centre? Hence is a younger Galaxy closer to that (virtual) centre. Because if this is true, it makes a difference in which direction you observe the cosmos. Not all galaxies move away from the observer (we) at the same speed; some are moving away from the centre in the direction that we we do, some at the other side of the (virtual) centre, opposite of ours at double speed; maybe my perception of the big bang as a the creation of a big sphere is wrong. I don’t know.

The big bang was a fast expansion of all space. It had no centre. It happened everywhere. There are many threads on here about it.
 
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  • #19
Viopia said:
PeroK understands my question. If you ask PeroK he will explain my question to you. Basically it seems that whatever direction we look we can only ever see past events. The further we look in light years, the younger the Universe appears to us because it has taken so long for the light to reach us. We can now see galaxies which appear to us as though they are only a billion years after the Big Bang. If we look up, these young galaxies are 12.7 billion light years away from us. If we look in the opposite direction, these galaxies also look as though they are 12.7 billion light years away us. This means that the distance between the the two observations is 25.4 billion light years. This seems a rather large distance when the Universe was only one billion years old. This is the only bit of my question I don't yet understand, but I will give it a lot of thought.

Note that a period of rapid expansion like inflation is not needed to understand your issue. It is simply a consequence of the fact that the universe is expanding. As you said, we see young galaxies in all directions whose light has taken 12.7 billion years to reach us. These galaxies have a redshift z of about 6. But the universe is expanding, and this is characterized by a scale factor, usually denoted by a. We take a=1 today, and we can write that a = 1/(1+z). So the scale factor of the universe 12.7 billion years ago when that light was emitted was only 1/7. So the universe was only 1/7 as big at that time. So those galaxies were much closer to us (and to each other) when the light was emitted. If you want to calculate how much closer they were, we have to agree on what distance measure you want to use, because there are numerous ways to define distance in an expanding universe.
 
  • #20
Viopia said:
We are actually at the centre of the Universe, just like everything else is.
not quite ... We are at the centre of our observable universe. You move a billion lightyears in "xxx" direction and you are now at the centre of your
observable universe from that point.
The universe has no centre.
 
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  • #21
phyzguy said:
Note that a period of rapid expansion like inflation is not needed to understand your issue. It is simply a consequence of the fact that the universe is expanding. As you said, we see young galaxies in all directions whose light has taken 12.7 billion years to reach us. These galaxies have a redshift z of about 6. But the universe is expanding, and this is characterized by a scale factor, usually denoted by a. We take a=1 today, and we can write that a = 1/(1+z). So the scale factor of the universe 12.7 billion years ago when that light was emitted was only 1/7. So the universe was only 1/7 as big at that time. So those galaxies were much closer to us (and to each other) when the light was emitted. If you want to calculate how much closer they were, we have to agree on what distance measure you want to use, because there are numerous ways to define distance in an expanding universe.

Am I right in my understanding that we can consider our observation point as a stand still (centre-like), given that all galaxies are moving away from us. And that the relative distance from our observation point to stars in our own Galaxy are not influenced by the expansion?
 
  • #22
RobertoV said:
Am I right in my understanding that we can consider our observation point as a stand still (centre-like), given that all galaxies are moving away from us. And that the relative distance from our observation point to stars in our own Galaxy are not influenced by the expansion?

Essentially, yes. There is the concept of cosmological "comoving" coordinates, which describe how everything on a large scale is swept along by the Hubble flow - i.e. everything is moving apart through expansion. But, on a smaller scale - up to superclusters of galaxies! - things can have additiional motion relative to each other and relative to the Hubble flow. The Earth orbiting the Sun, the Sun orbiting the galactic centre, the Milky Way and Andromeda galaxies on collision course etc.

You have two factors, therefore, in terms of how we observe the Cosmos from Earth. This might be interesting:

https://en.wikipedia.org/wiki/Local_Group
 
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  • #23
phyzguy said:
Note that a period of rapid expansion like inflation is not needed to understand your issue. It is simply a consequence of the fact that the universe is expanding. As you said, we see young galaxies in all directions whose light has taken 12.7 billion years to reach us. These galaxies have a redshift z of about 6. But the universe is expanding, and this is characterized by a scale factor, usually denoted by a. We take a=1 today, and we can write that a = 1/(1+z). So the scale factor of the universe 12.7 billion years ago when that light was emitted was only 1/7. So the universe was only 1/7 as big at that time. So those galaxies were much closer to us (and to each other) when the light was emitted. If you want to calculate how much closer they were, we have to agree on what distance measure you want to use, because there are numerous ways to define distance in an expanding universe.
 
  • #24
I can't understand why we need a scale factor. Hubble discovered that the further away galaxies are, the faster they seem to be retreating from us. The red shift is because the photon energy of the light is diminished because of the velocity of moving apart and is expressed by the broadening of the wavelength. It is because of the link between distance and speed that we know there was a Big Bang. The red shift is not always a measure of distance. For example, Andromeda is 2.5 million light years away from us, but the light is blue shifted because of it's movement towards us. Also, the velocity of light is always the same whether or not it is blue, or red shifted. If light has taken 12.7 billion years to reach us from distant galaxies, then surely they must be 12.7 billion light years away from us. If the scale factor relates to empty space, but not to the matter within that space, I can't see how it has any meaning. I have read about inflation and this also makes little sense to me. It appears that there is far more for me to understand about the expansion of space. I just hope that "scale factors" and "inflation" are not just mathematical artifacts to try and explain things which no one understands.
 
  • #25
Viopia said:
I can't understand why we need a scale factor. Hubble discovered that the further away galaxies are, the faster they seem to be retreating from us. The red shift is because the photon energy of the light is diminished because of the velocity of moving apart and is expressed by the broadening of the wavelength. It is because of the link between distance and speed that we know there was a Big Bang. The red shift is not always a measure of distance. For example, Andromeda is 2.5 million light years away from us, but the light is blue shifted because of it's movement towards us. Also, the velocity of light is always the same whether or not it is blue, or red shifted. If light has taken 12.7 billion years to reach us from distant galaxies, then surely they must be 12.7 billion light years away from us. If the scale factor relates to empty space, but not to the matter within that space, I can't see how it has any meaning. I have read about inflation and this also makes little sense to me. It appears that there is far more for me to understand about the expansion of space. I just hope that "scale factors" and "inflation" are not just mathematical artifacts to try and explain things which no one understands.

You need to do some reading on basic cosmology. We see galaxies moving away uniformly in all directions. A fundamental assumption of cosmology is that the universe is homogeneous and isotropic. This means we do not occupy a privileged position, that any observer anywhere in the universe will see all other galaxies moving away uniformly in all directions. This can't be explained by a static universe in which the expansion is due to the velocities of the galaxies, because then the expansion has a center and all observers don't see the same thing. The observations are explained by what is called the Friedmann–Lemaître–Robertson–Walker metric, which is what results when we apply Einstein's equations of General Relativity to the entire universe. A key part of it is there is a scale factor a(t), where all dimensions in the universe are expanding as time goes on. This is what we mean when we say "the universe is expanding." It is not a mathematical artifact, it is a fundamental fact about our universe, and it is backed up by a huge number of observations.
 
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  • #26
phyzguy said:
You need to do some reading on basic cosmology. We see galaxies moving away uniformly in all directions. A fundamental assumption of cosmology is that the universe is homogeneous and isotropic. This means we do not occupy a privileged position, that any observer anywhere in the universe will see all other galaxies moving away uniformly in all directions. This can't be explained by a static universe in which the expansion is due to the velocities of the galaxies, because then the expansion has a center and all observers don't see the same thing. The observations are explained by what is called the Friedmann–Lemaître–Robertson–Walker metric, which is what results when we apply Einstein's equations of General Relativity to the entire universe. A key part of it is there is a scale factor a(t), where all dimensions in the universe are expanding as time goes on. This is what we mean when we say "the universe is expanding." It is not a mathematical artifact, it is a fundamental fact about our universe, and it is backed up by a huge number of observations.
You are right. I only have a basic knowledge of cosmology but am trying to understand it the best way I can without resorting to complicated mathematics. When you say we see galaxies moving away "uniformly in all directions" do you mean that the gravitational force is slowing down the speed of the galaxies moving apart over time in a uniform way? The word "Uniform" means in a way that is the same in all cases and at all times. You say "This can't be explained by a static universe in which the expansion is due to the velocities of the galaxies, because then the expansion has a center and all observers don't see the same thing". I did not think that the galaxies in the Universe are static. If they were the attractive force of gravity (or the curvature of space-time if you like) would have pulled them all back together a long time ago. The "Big Bang" term suggests that there was an initial velocity to the expansion of the Universe which gravity has been reducing over time. Is this what you mean by the "scale factor". I have read the article about "FLRW" but I cannot understand the mathematics. I still think it is possible to understand a little about the Universe without a good understanding of mathematics even though a full understanding would require mathematical expertise. I have recently learned that the outermost galaxies are accelerating away from us. This makes absolutely no sense to me at all. Are the scientists absolutely sure that this acceleration actually exists? Also, does the Universe have an edge to it?
 
  • #27
@Viopia Look for a post by @phinds and read the balloon analogy insight in his signature link. There is no complicated math in it. I think you would find it helpful.

Viopia said:
we see galaxies moving away "uniformly in all directions"

Don't over-complicate it. It means (maybe among other things) that no matter what direction we look from anywhere on Earth or in orbit around earth, we see basically the same thing in terms of recession speed vs distance of observed galaxies.

Viopia said:
Are the scientists absolutely sure that this acceleration actually exists?

Yes.

Viopia said:
Also, does the Universe have an edge to it?

Not as far as any model I have read about postulates. If the universe is closed, it no more has an edge than does the surface of the earth. If it is open, then it is infinite in extent.
 
  • #28
Grinkle said:
@Viopia Look for a post by @phinds and read the balloon analogy insight in his signature link.
I agree. @Viopia you have some obvious misconceptions and the linked page (in my signature) has no math so it should help you out.
 
  • #29
Viopia said:
You are right. I only have a basic knowledge of cosmology but am trying to understand it the best way I can without resorting to complicated mathematics. When you say we see galaxies moving away "uniformly in all directions" do you mean that the gravitational force is slowing down the speed of the galaxies moving apart over time in a uniform way? The word "Uniform" means in a way that is the same in all cases and at all times. You say "This can't be explained by a static universe in which the expansion is due to the velocities of the galaxies, because then the expansion has a center and all observers don't see the same thing". I did not think that the galaxies in the Universe are static. If they were the attractive force of gravity (or the curvature of space-time if you like) would have pulled them all back together a long time ago. The "Big Bang" term suggests that there was an initial velocity to the expansion of the Universe which gravity has been reducing over time. Is this what you mean by the "scale factor". I have read the article about "FLRW" but I cannot understand the mathematics. I still think it is possible to understand a little about the Universe without a good understanding of mathematics even though a full understanding would require mathematical expertise. I have recently learned that the outermost galaxies are accelerating away from us. This makes absolutely no sense to me at all. Are the scientists absolutely sure that this acceleration actually exists? Also, does the Universe have an edge to it?

There's a good insight here:

https://www.physicsforums.com/insights/inflationary-misconceptions-basics-cosmological-horizons/

Two points, however, have to be made.

It's all right to want to try to understand things without too much mathematics, if you yourself have little mathematical knowledge. But, mathematics is the language of physics and any ideas that mathematics somehow is not a valid explanation of "reality" are misplaced.

If you have limited knowledge of a subject then it is also invalid to interpret your lack of understanding as a general problem with the theory. I, for example, can speak no Russian, but I cannot then doubt that Russians are actually speaking their own language, and start to believe that no one can speak Russian.

PF is a place to learn, but your ability to learn will be severly limited if you interpret your lack of understanding as a reason to doubt mainstream physics.
 
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  • #30
Thank you for your answers. It's nice to be able to ask a question and actually receive a reply from people who really know what they are talking about. The only part of my question remaining unanswered is the following "The "Big Bang" term suggests that there was an initial velocity to the expansion of the Universe which gravity has been reducing over time. Is this what you mean by the "scale factor"?. I take your point about my lack of knowledge. Perhaps the only way to understand physics is through mathematics if the results do not make sense in a common sense way. I think quantum physics must fall into this category. I think someone once said "shut up and calculate" or words to that effect.
 
  • #31
Viopia said:
The only part of my question remaining unanswered is the following "The "Big Bang" term suggests that there was an initial velocity to the expansion of the Universe which gravity has been reducing over time. Is this what you mean by the "scale factor"?.

No. The concept of the scale factor in cosmology is not difficult to understand. It just means that the distances between things in the universe are getting larger as time goes on, with all large scale distances being multiplied by a constant factor. One way to think of it is with the "balloon analogy" which was mentioned in an earlier post. Another way to picture it is in one dimension. Imagine a bunch of ants standing on a rubber band that is being continually stretched. The distances between the ants on the rubber band are constantly increasing. Each ant sees all the other ants moving away from it, and the further apart two ants on the rubber band are, the faster they are moving apart. But each ant is standing still on the rubber band, and is not moving with respect to the portion of the rubber band it is standing on. Also, the bodies of the ants themselves are not growing, just like local distances in the universe (the distance from the Earth to the Sun, for example) are not growing. This is the way you should think of it.
 
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  • #32
It would be possible, provided a rather large perfect reflector lay in that direction, and was several million/billion years old
 
  • #33
DeathByKugelBlitz said:
It would be possible, provided a rather large perfect reflector lay in that direction, and was several million/billion years old
This would be very difficult for an ancient civilisation to do. The mirror would also need to be very large. I was thinking that spacetime may curve light back on itself so that, if we looked in the right direction, we may see the light returning from our own milky way when it was only 0.8 billion years old. I think the Universe may need a cylindrical shape for this to happen.
 
  • #34
phyzguy said:
No. The concept of the scale factor in cosmology is not difficult to understand. It just means that the distances between things in the universe are getting larger as time goes on, with all large scale distances being multiplied by a constant factor. One way to think of it is with the "balloon analogy" which was mentioned in an earlier post. Another way to picture it is in one dimension. Imagine a bunch of ants standing on a rubber band that is being continually stretched. The distances between the ants on the rubber band are constantly increasing. Each ant sees all the other ants moving away from it, and the further apart two ants on the rubber band are, the faster they are moving apart. But each ant is standing still on the rubber band, and is not moving with respect to the portion of the rubber band it is standing on. Also, the bodies of the ants themselves are not growing, just like local distances in the universe (the distance from the Earth to the Sun, for example) are not growing. This is the way you should think of it.
Would not the Universe have to be a two dimensional spherical skin, like equally spaced dots on the surface of a balloon being inflated, for it to have a uniform isotropic expansion? Would not a three dimensional Universe be like a million or so marbles all packed as close together as they can be in a spherical shape, and then expanding in a homegeneous way to fill a much larger sphere? This would mean that, after the expansion, the marbles on the surface of the sphere would expand at the same rate, but the marbles in a line along the radius of the sphere would expand at a much smaller rate as they approach the centre of the sphere.
 
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  • #35
phyzguy said:
Note that a period of rapid expansion like inflation is not needed to understand your issue. It is simply a consequence of the fact that the universe is expanding. As you said, we see young galaxies in all directions whose light has taken 12.7 billion years to reach us. These galaxies have a redshift z of about 6. But the universe is expanding, and this is characterized by a scale factor, usually denoted by a. We take a=1 today, and we can write that a = 1/(1+z). So the scale factor of the universe 12.7 billion years ago when that light was emitted was only 1/7. So the universe was only 1/7 as big at that time. So those galaxies were much closer to us (and to each other) when the light was emitted. If you want to calculate how much closer they were, we have to agree on what distance measure you want to use, because there are numerous ways to define distance in an expanding universe.[/QUOTE
Grinkle said:
@Viopia Look for a post by @phinds and read the balloon analogy insight in his signature link. There is no complicated math in it. I think you would find it helpful.
Don't over-complicate it. It means (maybe among other things) that no matter what direction we look from anywhere on Earth or in orbit around earth, we see basically the same thing in terms of recession speed vs distance of observed galaxies.
Yes.
Not as far as any model I have read about postulates. If the universe is closed, it no more has an edge than does the surface of the earth. If it is open, then it is infinite in extent.
Do you mean from your comment that the Universe has no edge? Also I have looked up the evidence for the accelleration of the outermost galaxies and think the following may be true. When the light was emitted from the galaxies one billion years after the big bang the Universe was only 1/7 of the size it is now. The red shift would not indicate the speed of the Universe expanding one billion years ago when it eventually hits the Earth 12.7 billion years later, but would indicate the speed of the Universe expanding now because of the decreased rate of expansion due to gravity trying to pull everything back together over the intervening 12.7 billion year period. As the expansion speed has now been reduced from what it was one billion years after the big bang due to the effects of gravity, the red shift (due to velocity) would be less than it would have been 12.7 billion years ago when it hits the objects in our region of space. The amplitude of the emitted light from the galaxies one billion years after the big bang would have actually traveled a distance of 12.7 billion years to catch up with our region of space in the ever expanding Universe. This would not be affected by the difference in expansion velocities between now and one billion years ago and so the amplitude of the light would appear to be less than it should be compared to the red shift. This would mean that the the greater the distance between the galaxies, the greater would be the apparent disparity between the distance denoted by the red shift and the brightness. The result would be that the further away the galaxies are, the dimmer the light would be compared to the distance calculated by the red shift alone. The Hubble constant may appear linear if we measure very close stars from a triangular baseline of only 186 million years, but the difference in the brightness expected from type 1A supernovas would become hugely different at great cosmic distances. It's a bit like shining a light on a moving car after it has passed you when the car starts to apply its brakes. The red shift of the light from the car's perspective is not caused by the average speed of the car, but the speed it is traveling when the light actually hits it. Can you explain where I am wrong in my reasoning please.
 
<h2>1. Can the Hubble Telescope see our past?</h2><p>Yes, the Hubble Telescope is able to see objects that are very far away, which means we are seeing them as they were in the past. The light from these objects takes time to reach us, so the further away an object is, the further back in time we are seeing it.</p><h2>2. How far back in time can the Hubble Telescope see?</h2><p>The Hubble Telescope can see objects that are billions of light years away, meaning we are seeing them as they were billions of years ago. This is because light travels at a finite speed, so the further away an object is, the longer it takes for its light to reach us.</p><h2>3. Can we see our own galaxy, the Milky Way, in the past?</h2><p>Yes, we can see our own galaxy in the past. The Hubble Telescope has captured images of the Milky Way at different points in time, allowing us to see how it has changed and evolved over billions of years.</p><h2>4. How does the Hubble Telescope help us see our past?</h2><p>The Hubble Telescope is able to capture incredibly detailed images of distant objects in space. By studying these images, scientists can learn more about the history and evolution of the universe, including our own galaxy and its past.</p><h2>5. Can we see the beginning of the universe with the Hubble Telescope?</h2><p>The Hubble Telescope has captured images of the early universe, but it cannot see the actual beginning of the universe. This is because the universe was incredibly hot and dense in its early stages, making it impossible for light to travel and be captured by the telescope. However, the Hubble Telescope has provided valuable insights into the early stages of the universe's formation.</p>

1. Can the Hubble Telescope see our past?

Yes, the Hubble Telescope is able to see objects that are very far away, which means we are seeing them as they were in the past. The light from these objects takes time to reach us, so the further away an object is, the further back in time we are seeing it.

2. How far back in time can the Hubble Telescope see?

The Hubble Telescope can see objects that are billions of light years away, meaning we are seeing them as they were billions of years ago. This is because light travels at a finite speed, so the further away an object is, the longer it takes for its light to reach us.

3. Can we see our own galaxy, the Milky Way, in the past?

Yes, we can see our own galaxy in the past. The Hubble Telescope has captured images of the Milky Way at different points in time, allowing us to see how it has changed and evolved over billions of years.

4. How does the Hubble Telescope help us see our past?

The Hubble Telescope is able to capture incredibly detailed images of distant objects in space. By studying these images, scientists can learn more about the history and evolution of the universe, including our own galaxy and its past.

5. Can we see the beginning of the universe with the Hubble Telescope?

The Hubble Telescope has captured images of the early universe, but it cannot see the actual beginning of the universe. This is because the universe was incredibly hot and dense in its early stages, making it impossible for light to travel and be captured by the telescope. However, the Hubble Telescope has provided valuable insights into the early stages of the universe's formation.

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