View deep space objects

[JSM]

I see so many pictures of galaxy's millions of light years away. If they are so far away, how come the millions or billions of objects between us and those galaxy's don't block our view??? JSM

[apodman]

Nearer objects do block our view of more distant objects.

Individual stars in our galaxy might as well be point sources of light very far apart from each other, so individually they don't block much of anything.

Where there are many nearby stars stacked up in our line of sight (especially with accompanying nebulae and dust clouds), such as within and near the plane of the Milky Way, taken together they block our sight of anything behind them. We can't even see anything in our own galaxy through the central hub; the same applies to distant galaxies lying beyond in that direction.

Outside our galaxy, there are many more objects that hide distant objects behind them. M31 is as wide as three full moons, with a bright thick nucleus - it hides a lot. You can often see distant galaxies through the thin spots (between the arms, etc.) in photos of closer galaxies; there are likely more objects behind the thick spots you can't see.

At the far end of our vision, and slightly off the topic of your question, we run into Olbers' paradox: It turns out the sky at great distances is probably full of bright objects overlapping each other, but we still see mostly black sky at night because the light from the most distant stars hasn't had time to reach us yet.

[aristarchusinexile]

Is everyone aware of the website Galaxy Zoo?

[aristarchusinexile]

but we still see mostly black sky at night because the light from the most distant stars hasn't had time to reach us yet.

Spoken like a true poet, Apodman, Edgar Allan Poe being first to suggest that idea. One of Poe's passions was astronomy. From Wikipedia: "...Poe and his works influenced literature in the United States and around the world, as well as in specialized fields, such as cosmology and cryptography."

However, I just had a thought, 'what if we are seeing to the farthest stars already? What if that's all there is?' Perhaps with China building the world's largest radio telescope we will have our answer soon.

Eureka has been read in many ways, in part because Poe's sincerity in the work is questionable. It has been considered prophetically scientific, intuitively Romantic, and even calculatingly ironic.[23] Lacking scientific proof, Poe said it was not his goal to prove what he says to be true, but to convince through suggestion.[14]

Of Poe's 'Eureka' - from Wikipedia: Though modern critics have dismissed Eureka for having no scientific worth or merit,[9][30] Poe's work presages modern science with his own concept of the Big Bang.[31][32] He postulated that the universe began from a single originating particle or singularity, willed by a "Divine Volition."[1] This "primordial particle," initiated by God,[33] divides into all the particles of the universe. These particles seek one another because of their originating unity (gravity) resulting in the end of the universe as a single particle. Poe also expresses a cosmological theory that anticipated black holes and the Big Crunch theory[2] as well as the first plausible solution to Olbers' paradox.[34] Many of Poe's conclusions, however, are speculative due to his rejection of analytic logic and emphasis on intuition and inspiration.[9]

[bystander]

(from Wikipedia: "Eureka: A Prose Poem" by Edgar Allan Poe)

• ... Eureka has been read in many ways, in part because Poe's sincerity in the work is questionable
  ... Lacking scientific proof, Poe said it was not his goal to prove what he says to be true
  ... critics have dismissed Eureka for having no scientific worth or merit
  ... conclusions are speculative due to his rejection of analytic logic and emphasis on intuition and inspiration

... continuing ...

• ... Eureka is full of scientific errors
  ... critics also suggest Eureka is a sign of Poe's declining mental health
  ... Response to Eureka was overwhelmingly unfavorable

Ahh, Sputnick, this all sounds so familiar.

[astrolabe]

Hello aristarchusinexile,

'what if we are seeing to the farthest stars already? What if that's all there is?'

What if?

I'll give you a what if: What if we are seeing only the remnants of what was once an extremely well stocked and well lit universe and the 96% of the "missing" matter has moved beyond our telelcope range and the strength of the "missing" matter's gravity field is pulling the distant objects faster (due to their proximity to it) than nearer objects; resulting in the illusion of expansion attributed to Dark Energy? WHEW! There's a mouthful.

[aristarchusinexile]

Hello aristarchusinexile,

'what if we are seeing to the farthest stars already? What if that's all there is?'

What if?

I'll give you a what if: What if we are seeing only the remnants of what was once an extremely well stocked and well lit universe and the 96% of the "missing" matter has moved beyond our telelcope range and the strength of the "missing" matter's gravity field is pulling the distant objects faster (due to their proximity to it) than nearer objects; resulting in the illusion of expansion attributed to Dark Energy? WHEW! There's a mouthful.

Wow, Astro! You have expanded my concept of expansive. I expect the answer in two years at the most. The instruments being built today are stupendous.

[aristarchusinexile]

(from Wikipedia: "Eureka: A Prose Poem" by Edgar Allan Poe)

• ... Eureka has been read in many ways, in part because Poe's sincerity in the work is questionable
  ... Lacking scientific proof, Poe said it was not his goal to prove what he says to be true
  ... critics have dismissed Eureka for having no scientific worth or merit
  ... conclusions are speculative due to his rejection of analytic logic and emphasis on intuition and inspiration

... continuing ...

• ... Eureka is full of scientific errors
  ... critics also suggest Eureka is a sign of Poe's declining mental health
  ... Response to Eureka was overwhelmingly unfavorable

Ahh, Sputnick, this all sounds so familiar.

" ... In fact, the expanding Universe is often considered a consequence of General Relativity, while it could be also conceived in terms of newtonian physics, as shown mathematically only after the Relativity theory, and after Hubble showed in a clear way that the Universe was expanding. Before Einstein and Hubble, no one rejected the dogma of a static Universe, with one exception: Edgar Allan Poe. "
I wish I could find my post . . 'Edington .. Sir Arthur Charles Edington? Is that the name? He who said Poe's work showed no sign of mental deterioration.
Poe (was the first to propose) first proposed in a scientific paper which he read at an astronomical gathering the solution to Olbers Paradox. Poe proposed the singularity, Black Holes, etc. I do not agree with Poe as I propose uncountable singularities. A thread for this type of discussion, examining scientific discoveries by non-professionals, or by professionals who were made to appear unprofessional (Michael Faraday for instance) should be available. Please, Dear Nereid, I ask thee for this most wonderful of opportunities.

[aristarchusinexile]

To avoid any further OT discussion here I make this my last post on Poe unless a topic can be opened regarding unconventionality in science.

Having quoted so freely from the work of Sir Arthur Eddington, Plumian Professor of Astronomy, at Cambridge University, I felt it proper to submit this analysis of Eureka to him, in order that I might not misinterpret his views. He was good enough to reply as follows:

1940 Sept 29

I am returning your typescript separately, as I think a letter is less likely to be delayed.

First, I raise no objections to any of your quotations from my writings. Opinions will naturally differ as to how far the resemblance between the ideas I am attempting to express and those of Poe to which the quotations are considered relevant should be stressed rather than the differences; but, whilst not always convinced of the appropriateness, I am not averse to their being used in your argument.

Secondly, I think you make out clearly that ``Eureka" is not a work of dotage or disordered mind. It is, I think, the work of a man trying to reconcile the science of his time with the more philosophical and spiritual cravings of the mind. Poe, besides being fairly well-informed in science and mathematics, seems to have had the mind of a mathematician, and consequently was not to be put off with vague phrases; and made a creditable attempt to introduce precision of thought.

The correspondence between some of his ideas and modern views is interesting; but, as bearing on his intellectual powers, one must view it with some detachment. Any one of independent mind , -a rebel against conventionally accepted views- is likely to hit the marks sometimes. This is particularly the case when it is a case of philosophical and spiritual intuition versus scientific progress. The idea of ``unity in diversity and diversity in unity" is now becoming actually realised in scientific theory; but until science had reached a certain stage of development it was no more helpful to science than the doctrine of the Trinity which contains the same idea. I expect many believed that this must be an ultimate truth, but science must be left gradually to find it by its own pedestrian progress.

I should say then that regarded as an attempt to put forward a new physical theory, Eureka would rightly be regarded as a crank-theory by scientists of the time. (The trouble with cranks is usually, not that they are not far-seeing, but that they have no appreciation of the immediate obstacles in the road.) Poe's more definite suggestions (in the contemporary state of science) were not unintelligent but amateurish. But as a ``poem" on the significance of things as partially revealed in the state of science of the time, I think it showed a fine penetration.

Yours sincerely,

A.S. Eddington

If you should wish to quote any of these remarks, by all means do so.

Arthur H. Quinn, author of the best and most authoritative biography about Poe, asked Sir Arthur Eddington an opinion about Eureka:

[Chris Peterson]

I'll give you a what if: What if we are seeing only the remnants of what was once an extremely well stocked and well lit universe and the 96% of the "missing" matter has moved beyond our telelcope range and the strength of the "missing" matter's gravity field is pulling the distant objects faster (due to their proximity to it) than nearer objects; resulting in the illusion of expansion attributed to Dark Energy? WHEW! There's a mouthful.

I think the flaw here is the assumption that the edge of the visible universe is closer to the early stuff than it is to us. Fundamental to the idea of an expanding universe is that everything is pulling away from everything else. The consequence of that is that any point in the Universe- whether or not it lies in our visible sphere- sees itself at its own center. There is no preferential location or direction (allowing for some recently discovered- and very slight- hint of asymmetry), so no place feels a greater gravitational attraction in one direction over another. The Big Bang doesn't describe something like a shell of matter moving outwards from some 3D point, after all.

[neufer]

I think the flaw here is the assumption that the edge of the visible universe is closer to the early stuff than it is to us. Fundamental to the idea of an expanding universe is that everything is pulling away from everything else. The consequence of that is that any point in the Universe- whether or not it lies in our visible sphere- sees itself at its own center. There is no preferential location or direction (allowing for some recently discovered- and very slight- hint of asymmetry), so no place feels a greater gravitational attraction in one direction over another. The Big Bang doesn't describe something like a shell of matter moving outwards from some 3D point, after all.

I find this confusing, Chris.

While there is NO "edge of our universe" there is certainly an "edge of our visible universe"

The "edge of our visible universe" is a two dimensional plasma sheet that existed some 13.4 billion years ago.

http://antwrp.gsfc.nasa.gov/apod/ap050925.html

There are certainly many other spots in our current, past & future universe that observe our own sun's alpha particles, protons & electrons as a part of their own "WMAP" 2D "edge of the visible universe" (... for many more our past is on the far side of their "WMAP" 2D edges).

But whether it is us or them being observed in a 379,000 year old plasma state;
the "edge of anyone's visible universe" is (, was and will be) certainly much closer in time to the Big Bang.

[Chris Peterson]

I find this confusing, Chris.

Well, to be sure, it is a difficult thing to write about!

While there is NO "edge of our universe" there is certainly an "edge of our visible universe"

Yes. I don't think I said anything to suggest otherwise, but if so, that wasn't my intent.

The "edge of our visible universe" is a two dimensional plasma sheet that existed some 13.4 billion years ago.

I don't think that's quite correct. From our position, it appears as a plasma "sheet", but there is no plasma sphere just sitting out there around us. That is an artifact of perception. No matter where you are located in the Universe, including well outside our observable spherical volume, you would see the same shell surrounding you. It isn't like there is some superdense material on the other side of that "sheet" that is pulling it outwards. The standard cosmological model presumes that the Universe looks generally the same from anywhere (obviously, different regions are seen, but the structure should be similar).

[bystander]

I find this confusing, Chris.

I, too, find it confusing.

There are certainly many other spots in our current, past & future universe that observe our own sun's alpha particles, protons & electrons as a part of their own "WMAP" 2D "edge of the visible universe" (... for many more our past is on the far side of their "WMAP" 2D edges).

One thing I do know, good ol' Sol is way too young to be at the edge of anyone's visible universe. I don't know what the estimated age of the Milky Way is, but I doubt that it is close to 13.4 billion years old. While we may be visible to our local super cluster, we're far from living on the edge.

[Chris Peterson]

One thing I do know, good ol' Sol is way too young to be at the edge of anyone's visible universe. I don't know what the estimated age of the Milky Way is, but I doubt that it is close to 13.4 billion years old. While we may be visible to our local super cluster, we're far from living on the edge.

Presumably, no matter where you are in the Universe, you see out about 47 billion light years, to the "edge" defined by the formation of the Universe 13.7 billion years ago. And presumably, no matter where you are in the Universe, that spherical volume only represents a tiny fraction of the entire Universe. Because Sol is much younger than the Universe, it can't be at the visible edge as seen from anywhere, but it is outside the visible universe for most of the Universe.

If you know a way to make that difficult concept less confusing, I'm all ears!

[bystander]

I'm all ears!

So what are you, Ferengi?

[astrolabe]

Hello All,

Thank you for your input on an extremely interesting and thought-expanding subject. Chris, you were correct to point out the flaw- saw it myself and had to laugh at my kneejerk (emphasis on "jerk") reaction to aristarchusinexile's "what if" post". Good one ari! Great fun indeed.

I was considering yours', bystander, and our Sun IS young to be sure, but I thought the age of our Galaxy, however, to be quite old. It would mean that someone "out there" maybe would see the Milky Way when our Sun was in a star-forming region similar to the ones we see when viewing those other "Island Universes"?

When sailing, knowing that wind is the result of our atmosphere's attempt to gain equilibrium, one wonders if the sailboat is going along because of wind pushing against the sail or because the negative pressure behind the sail that is pulling it. The attempt at equilibrium on a small scale with the sail caught in the middle. I'm sure there is a correct physics answer for this. So in the Universe, is it push or pull. I think Chris hit the nail on the head when he said that it is "an artifact of perspective". Greatphrase which we all would do well to remember. That little phrase could get a lot of use by me and perhaps others in this Forum as (at least to me) it is so precise in describing a sticking point where some arguments go around full circle sometimes with no apparent resolution.

I thank you for that one, Chris.

[neufer]

There are certainly many other spots in our current, past & future universe that observe our own sun's alpha particles, protons & electrons as a part of their own "WMAP" 2D "edge of the visible universe" (... for many more our past is on the far side of their "WMAP" 2D edges).

One thing I do know, good ol' Sol is way too young to be at the edge of anyone's visible universe. I don't know what the estimated age of the Milky Way is, but I doubt that it is close to 13.4 billion years old. While we may be visible to our local super cluster, we're far from living on the edge.

I didn't say that they observed Sol, itself,.... just our own sun's alpha particles, protons & electrons localized somewhere in the primordial plasma.

[neufer]

One thing I do know, good ol' Sol is way too young to be at the edge of anyone's visible universe. I don't know what the estimated age of the Milky Way is, but I doubt that it is close to 13.4 billion years old. While we may be visible to our local super cluster, we're far from living on the edge.

Presumably, no matter where you are in the Universe, you see out about 47 billion light years, to the "edge" defined by the formation of the Universe 13.7 billion years ago.

My son lives off in San Jose, California, but I don't see him 2,000 miles away simply because I saw him off at the local airport.

We see out about 13.4 billion light years to a primordial plasma that may well be ~ 47 billion light years away by now but we don't see 47 billion light years. And there are probably beings ~ 47 billion light years away who developed out of small pieces of that primordial plasma who now observe the primordial plasma that we ourselves have developed from but they only see an ancient plasma ~ 13.4 billion light years away.

If we could see each other then we could both see ~ 47 billion light years ...but we can't!

[Chris Peterson]

We see out about 13.4 billion light years to a primordial plasma that may well be ~ 47 billion light years away by now but we don't see 47 billion light years.

I don't know what that means. The observable universe is about 47 billion light years in radius. To me, that means the farthest things we can see are about that many light years away.

[neufer]

We see out about 13.4 billion light years to a primordial plasma that may well be ~ 47 billion light years away by now but we don't see 47 billion light years.

I don't know what that means. The observable universe is about 47 billion light years in radius. To me, that means the farthest things we can see are about that many light years away.

Perhaps it is simply an issue of semantics:

1) What do you mean by "observable universe"

2) What do you mean by "is."

To my mine the "observable universe" exists entirely on the "surface"
of an imaginary light cone interior to the figure shown here:

http://antwrp.gsfc.nasa.gov/apod/ap060323.html

No part of the "observable universe" lies either out side of
or within the "surface" of this imaginary light cone.

[Chris Peterson]

1) What do you mean by "observable universe"

The observable universe is that part of the Universe that we can see (at least potentially), because we are causally connected to it. Roughly, that means because there has been time for light from it to reach us.

2) What do you mean by "is."

I'm pretty sure I just mean the third person singular of "to be".

To my mine the "observable universe" exists entirely on the "surface"
of an imaginary light cone interior to the figure shown here:

http://antwrp.gsfc.nasa.gov/apod/ap060323.html

No part of the "observable universe" lies either out side of
or within the "surface" of this imaginary light cone.

I've never liked that image, because I have problems projecting it into the 4D model it is an analogy for. I think, although I'm not certain, that the way this diagram is projecting the Universe into three dimensions places time on the horizontal axis, and then compresses three dimensions of space into the orthogonal axes (so that the disk on the end of the cone needs to be recognized as a sphere in reality). The radius of the Universe at the end of the cone (now) is very, very large- probably trillions of light years or larger, and possibly even infinite. The smaller cone representing the history of our observable universe is 93 billion light years in diameter at the end, meaning that the most distant things we can see, close to the time of the BB, are 47 billion light years away from us. The Universe of "now" in this diagram isn't a cone, but is the disc at the far right; the observable universe is a smaller disc within this. The only directions we can see are along the axes of the end disc; the horizontal (time) axis isn't spatial.

[neufer]

1) What do you mean by "observable universe"

The observable universe is that part of the Universe that we can see (at least potentially), because we are causally connected to it. Roughly, that means because there has been time for light from it to reach us.

Right; however, I believe that most people (myself included) would define
the OBSERVABLE universe as that part of the Universe that we see RIGHT NOW!

So this is basically a semantics difference!

To my mine the "observable universe" exists entirely on the "surface"
of an imaginary light cone interior to the figure shown here:

http://antwrp.gsfc.nasa.gov/apod/ap060323.html

No part of the "observable universe" lies either out side of
or within the "surface" of this imaginary light cone.

I've never liked that image, because I have problems projecting it into the 4D model it is an analogy for. I think, although I'm not certain, that the way this diagram is projecting the Universe into three dimensions places time on the horizontal axis, and then compresses three dimensions of space into the orthogonal axes (so that the disk on the end of the cone needs to be recognized as a sphere in reality).

And the "observable universe" [by MY definition] exists entirely on the space/time "surface"
of an imaginary light cone interior to the figure.

The apex of this cone is at the WMAP satellite position
while the base of this cone would lie on a circular patch
centered within the primordial plasma projection to the left
with the actual 2D WMAP represented by 1D circle of the cone's base.

Past WMAP maps are smaller interior 1D circles and
future WMAP maps are 1D larger exterior circles
on the primordial plasma plane.

The radius of the Universe at the end of the cone (now) is very, very large- probably trillions of light years or larger, and possibly even infinite. The smaller cone representing the history of our observable universe is 93 billion light years in diameter at the end, meaning that the most distant things we can see, close to the time of the BB, are 47 billion light years away from us. The Universe of "now" in this diagram isn't a cone, but is the disc at the far right; the observable universe is a smaller disc within this. The only directions we can see are along the axes of the end disc; the horizontal (time) axis isn't spatial.

Well, I agree: "The Universe of "now" in this diagram isn't a cone, but is the disc at the far right."

However, I believe that the most reasonable definition of :
"The OBSERVABLE Universe of "now" in this diagram is precisely
the space/time cone that I describe above.

[aristarchusinexile]

Most of the images of stellar explosions I've seen show relatively mirrorlike images on either side of a pinch. I will adopt the concensus view for a briefest moment here, that being the universe beginning in an explosion of a singularity. It seems if the universe really began that way, and if the explosion follows the observed pattern, there should be a mirror universe on the other side of a pinch. Of course you all know I don't believe Big Bang for even the briefest moment, so my thought here is just a mental exercise, something to do in a spare moment.

[neufer]

Most of the images of stellar explosions I've seen show relatively mirrorlike images on either side of a pinch. I will adopt the concensus view for a briefest moment here, that being the universe beginning in an explosion of a singularity. It seems if the universe really began that way, and if the explosion follows the observed pattern, there should be a mirror universe on the other side of a pinch. Of course you all know I don't believe Big Bang for even the briefest moment, so my thought here is just a mental exercise, something to do in a spare moment.

------------------------------------------------------------------------
Jerry: Now, the ending is kind of an option. I use the swirl. I like the swirl.
. I'm comfortable with the swirl. I feel the swirl is a great capper.
. [ Harry ] uses the [Z-]pinch, which I find a little presumptuous.
.
George: Is it a clockwise swirl?
.
Jerry: I prefer clockwise, but it's not written in stone.
------------------------------------

[aristarchusinexile]

Hello All,

Thank you for your input on an extremely interesting and thought-expanding subject. Chris, you were correct to point out the flaw- saw it myself and had to laugh at my kneejerk (emphasis on "jerk") reaction to aristarchusinexile's "what if" post". Good one ari! Great fun indeed.

I meant no attempt at humour, Astro. I consider it as great a possibility as any other idea presented in cosmology,
and in fact I believe within two years we will see the outer limit of the universe.

When sailing, knowing that wind is the result of our atmosphere's attempt to gain equilibrium, one wonders if the sailboat is going along because of wind pushing against the sail or because the negative pressure behind the sail that is pulling it.

According to all I have read on sailing it is the negative pressure on the downwind side of the sail which is propelling the sailboat.

The attempt at equilibrium on a small scale with the sail caught in the middle. I'm sure there is a correct physics answer for this. So in the Universe, is it push or pull.

There is a theory (although I hate to use that word because of the limitations placed on words in this forum) and this theory is not my own, but has been around since I began reading as a boy, that expansion is caused by a "Great Attractor" (NOT the local great attractor) but the Great Attractor outside the universe. I agree with this theory, and think the attractor accounts for the increasing speed of expansion the farther out the galaxies are. I believe the Attractor to be water.

I think Chris hit the nail on the head when he said that it is "an artifact of perspective". Greatphrase which we all would do well to remember. That little phrase could get a lot of use by me and perhaps others in this Forum as (at least to me) it is so precise in describing a sticking point where some arguments go around full circle sometimes with no apparent resolution. I thank you for that one, Chris.

Artifact - from Wikipedia: Artifact (archaeology), any object made or modified by a human culture, and later recovered by an archaeological endeavor
Artifact (error), an error or misrepresentation introduced by a technique and/or technology
Visual artefact, unintended graphics-related errors or noise caused by software or hardware bugs.
Artifact (medical imaging), misrepresentations of tissue structures seen in medical images
Artifact (observational), any perceived distortion or other data error caused by the instrument of observation
Artifact (software development), one of many kinds of tangible byproduct produced during the development of software
Compression artifact, data compression artifact in computer science, resulting from lossy data compression
Cultural artifact, a human-made object which gives information about the culture of its creator and users
Document artifact, an instantiation of a document.

So .. on to the meaning of instantiation .. and after a brief pause we have: "Instantiation principle - the idea that if properties exist, the essence that "has" the properties must necessarily exist
Universal instantiation and existential instantiation, two rules of logical inference
A substitution instance is a formula of mathematical logic that can be produced by substituting certain strings of symbols for others in formulas."