Observing objects that are Billions of Light Years Away

[davidwisor]

I have a question that's bothered me for a long time. Every so often you'll see news about something that Hubble saw that is Billions of Light Years Away. You'll often see stories about a much younger universe. But in that much younger universe, weren't objects much closer to each other than they are now? So, if that is true, wouldn't something that's viewed as 8 billion light years away have been much closer 8 billion years ago? And so if that object was only 6 billion light years away then, wouldn't it's light have past earth 2 billion years ago?

 

[kmarinas86]

<font color="yellow">I have a question that's bothered me for a long time. Every so often you'll see news about something that Hubble saw that is Billions of Light Years Away. You'll often see stories about a much younger universe. But in that much younger universe, weren't objects much closer to each other than they are now?</font><br /><br />According to theory, yes.<br /><br /><font color="yellow">So, if that is true, wouldn't something that's viewed as 8 billion light years away have been much closer 8 billion years ago? And so if that object was only 6 billion light years away then, wouldn't it's light have past earth 2 billion years ago?</font><br /><br />Yes.<br /><br />It's important that you know about how distance is determined, and that there are different kinds of "distances" that cosmologists use.<br /><br />http://www.anzwers.org/free/universe/redshift.html<br /><br /><font color="yellow">There are four different distance scales commonly found in cosmology:<br /><br />(1) Luminosity Distance - DL <br />In an expanding universe, distant galaxies are much dimmer than you would normally expect because the photons of light become stretched and spread out over a wide area. This is why enormous telescopes are required to see very distant galaxies. The most distant galaxies visible with the Hubble Space Telescope are so dim that they appear as if they are about 350 billion light years away even though they are much closer. <br /><br />Luminosity Distance is not a realistic distance scale but it is useful for determining how faint very distant galaxies appear to us. <br /><br />(2) Angular Diameter Distance - DA <br />In an expanding universe, we see the galaxies near the edge of the visible universe when they were very young nearly 14 billion years ago because it has taken the light nearly 14 billion years to reach us. However, the galaxies were not only young but they were also at</font>

 

[hayagreeva]

Time Phase relation must come to a KNOT. or JUNCTION.<br />How do you explain<br />vidyardhi Nanduri<br />Cosmology Vedas

 

[yevaud]

Pardon me, but that is not really an answer or question in a scientific sense. If you wish to discuss such things, please begin a seperate thread in "Phenomena."<br /><br />Thank you. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[rfoshaug]

Does this mean that we can not observe objects that appear farther away than about 7 billion lightyears?<br /><br />If it's about 14 billion years since Big Bang, and these objects move at close to light speed, we should see them at 7 billion ly distance. Since that light was emitted 7 billion years ago from the position they had then, they have continued to move away at almost light speed and now, 7 billion years later, their real position is at 14 billion ly away from us while the old light we see is still from where they were at 7 billion years ago. The light they emit at their present positions won't reach us for another 14 billion years, and by then their distance will again be twice as long as that we can observe...<br /><br />Is this correct? Do the very most distant object appear to be about 7 billion light years away? <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>I have a question that's bothered me for a long time. Every so often you'll see news about something that Hubble saw that is Billions of Light Years Away. You'll often see stories about a much younger universe. But in that much younger universe, weren't objects much closer to each other than they are now?<p><hr /></p></p></blockquote><br /><br />Yes. In fact, the most distant light visible in the sky is the Cosmic Microwave Background. The universe was a lot smaller when that light was emitted. (It's not visible light, BTW. It's lower frequencies than those visible to the human eye. In fact, it's radio waves. When you tune your radio to a frequency where there is no transmitting station, you hear static, right? What you're hearing is actually the cosmic microwave background. There is radio being emitted on those frequencies; it just doesn't have a pattern.)<br /><br />One weird thing about astronomy is that the further away you look, the longer ago you are seeing. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[robnissen]

"Does this mean that we can not observe objects that appear farther away than about 7 billion lightyears?"<br /><br />No. We can view objects that are over 13 billion light years away. Those objects were 13 billion light years away 13 billion years ago, those objects are now at least 26 billion light years away, but actually quite a bit more because inflation is still going on.<br /><br />You might ask how something could be 13 billion light years away within a short time after the big bang, the answer to that is that in the instant after the big bang the universe inflated (i.e. space was created between matter) to make the universe many, many times larger than 13 billion light years. I have seen estimates that the universe inflated to 2 to the 50th power light years immediately after the big bang. This is all very mind blowing, but the big bang, immediately followed by massive inflation is the best model we currently have.<br />

 

[7lives]

"No. We can view objects that are over 13 billion light years away. Those objects were 13 billion light years away 13 billion years ago, those objects are now at least 26 billion light years away, but actually quite a bit more because inflation is still going on. "<br /><br />I am sorry but that is incorrect. Light years is not only a time measure , but it is also a distance measure. and you are confusing the two. The 13 billion light years away is a distance measure. It is how far - the distance - light has traveled in 13 billion years. The object is only 13 billion light year distant. Multiply 186,000 miles by how many seconds are in 13 billion years and you can figure out how many miles away that object is. Also it can't be 26 billion light years away now because the Universe is only 15 billion years old. If it is now 26 billion light years away that object would have traveled almost twice the speed of light since the Big Bang. And according to Einstein, that is impossible!<br /><br /><br />"I have seen estimates that the universe inflated to 2 to the 50th power light years immediately after the big bang. ". <br /><br />Another misunderstanding. Yes the Universe expanded at a tremendous rate in that early inflationary period. But the trouble is it did in a very small fraction of a second. It went from the size of an atom to size of a basketball in that fraction of a second. And this inflationary period happenned at several instances after the Big Bang, not in an instance.<br />

 

[robnissen]

"Also it can't be 26 billion light years away now because the Universe is only 15 billion years old. If it is now 26 billion light years away that object would have traveled almost twice the speed of light since the Big Bang. . . . It went from the size of an atom to size of a basketball in that fraction of a second. "<br /><br />You are flat wrong because inflation did not expand the universe to the size of a basketball, it did (and still is) expanding the universe trillions of light years across. Now, if inflation only expanded the universe to the size of a basketball, you would be right because then no galaxy could be more than about 13.5 billion light years away (the big bang was about 13.5 not 15 billion years ago.) But you are wrong because the fact is that immediately after inflation the universe was trillions of light years across (relativity was not violated because no particles moved faster than c, rather space between particles was created -- I have no idea how that is possible). Among galaxises that were in our neck of the universe, i.e. 13 billion light years away from us, an instant after the big bang, we are just now seeing light from those galaxies, but those galaxies have continued to move away from us at close to light speed for the last 13 billion years, such that they are now about 26 billion light years away.

 

[dragon04]

<font color="yellow">If it is now 26 billion light years away that object would have traveled almost twice the speed of light since the Big Bang.</font><br /><br />Let's go Newtonian for a minute:<br /><br />Bowling ball A and bowling ball B are touching. Both are accelerated away from one another at any velocity you wish. For simplicity sake, they're moving away from one another on a straight line at 1 km/h.<br /><br />At the end of that hour, they are 2km apart. KNowing their velocity, that means they are 2 hours apart from one another in an hour's time.<br /><br />Thus, in an expanding, accelerating universe, any object we see at 13 billion LY has to be farther away due to the intervening time between when the object emitted that light we see, and when we see that light.<br /><br />The only possible way that I could conceive that this would not be the case would be if every one of these mega distant objects we see are visible due to gravitational lensing. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[yevaud]

I don't even think Lensing would change anything. After all, the distance would still remain the same, and C would still remain the same. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[dragon04]

You're absolutely right. I have it backwards. If anything, lensing would imply that the objects were even farther away. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[7lives]

No you are wrong. The original inflation theory is as I indicated previously. <br /><br />Yes in the INITIAL inflationary period SPACE DID expand at that tremendous rate (faster than the speed of light) and the Universe was no bigger than a basketball at the end of that inflationary period. Space and the Universe then expanded at a "normal" rate at the Hubble constant, which is much smaller than the speed of light. . Recently they have found that the Universe or space itself has entered into a second inflation phase. It has not been in an inflationary period for 13.5 billion years (or as most scientists believe the last 15 billion years); as you seem to suggest. These are not my beliefs. These are scientific facts.<br /><br />If in fact the inflation that you seem talk about happenned then the Universe is much younger than the 13.5 billion years. The faster it expands the younger the universe. There is a inverse relationship. Which can't be. The oldest dated stars are in the 13.5 billion years old range. Therefore, the universe is older than 13.5 billion years old. <br /><br />

 

[robnissen]

No, you are still wrong. Although I think I know why you are wrong. The original inflation theory did have a lower limit where at 10 to -30 seconds the universe was not huge (the range was from 10 centimeters to about the size of the Milky Way). But that was the lower limit, more recent studies have put the initial inflation MUCH larger than that. The most thorough discussion I have seen on inflation is the Jan. 2006 Scientific American that discusses this much higher limit. I tried to get a link, but they make you buy the article. But here is an article by a professor at North Carolina State that is putting the inflation estimate at 10 to the 10 millionth power, which is an unbelievably large number (which does indeed make the universe trillions and trillions of light years across).<br /><br />http://www.ncsu.edu/felder-public/kenny/papers/cosmo.html<br /><br /> "during inflation the universe expanded, i.e. all distances increased, by a factor of over ten to the ten million. . . . By comparison, the total number of elementary particles in the observable universe is much less than ten to the hundred. "<br /><br />BTW, most cosmologists put the age of the universe at 13.8 billion years. The oldest stars are thought to be 14 billion years, but that is plus/minus 500 million years which does not conlict with a universe age of 13.8 billion years.<br /><br />BTW, if indeed the universe only inflated to the size of a basketball, and is 15 billion years old, how could we see anything further away than 7.5 billion years, when we have seen quasers at over 12 billion light years away.<br /><br /><br />