point of no return

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kabtn05

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Hi. In this article: <br /><br />http://www.space.com/scienceastronomy/universe_end_011212.html <br /><br />Robert Roy Britt (and Abraham Loeb) says:<br /><br />"The point of no return for these galaxies is called an event horizon, a concept more commonly used to describe the hypothesized sphere around a black hole beyond which nothing, not even light, can escape. <br /><br />Matter falling into a black hole, according to theory, should also leave a final image for the outside world to see.<br /><br />Loeb calls this final image near a black hole "a frozen image," analogous to the suspected eventual image that we will have of distant galaxies in the universe."<br /><br />My question is -- Are we really, and I mean r-e-a-l-l-y sure, that what we see now isn't a frozen image?
 
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newtonian

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kabtn05 - Thank you for that link. I often refer to Loeb's model without linking to it.<br /><br />What would such a frozen image look like?<br /><br />And why would it fade away, and how fast would it fade away?<br /><br />The problem is that we have difficulty perceiving the present rate of expansion by observing galaxies as they were billions of years ago.<br /><br />We need to observe the effect of dark energy, aka vacuum energy, aka the cosmological constant, locally and at present.<br /><br />Some have theorized that the slowing of the space probes is caused by this cosmological constant, though this is coungerintuitive since it seems to be slowing not speeding up the expansion.<br /><br />However, it is quite possible that Loeb is correct and that galaxies we now observe over 6 billion light years away may already be beyond our visibility horizon, i.e. expanding away from us FTL ( = faster than light).<br /><br />If so, in the future we may need dark energy telescopes to view these galaxies.<br /><br />Meanwhile, we may also already be expanding into another universe - but we don't see the effects yet.<br /><br />Or, perhaps, acceleration of expansion is just such an effect!<br />
 
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newtonian

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eburacum45- Thank you for that concise and insightful post.<br /><br />Of course, the red shift would approach infinity.<br /><br />Now, when approaching that infinite limit, wouldn't the theory of relativity have the change slow down - close to being frozen so to speak?<br /><br />And while the red shifted light would not be visible, it would be detectable electromagnetic radiation, correct?<br /><br />So, how about an answer to the original question: have we seen a nearly infinite red shifted galaxy, and also nearly frozen?<br />
 
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Saiph

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Well, the images we see at the edge wouldn't be frozen, but very very slow (cause if they were frozen the infinite redshift kicks in).<br /><br />We have a huge time delay due to light getting to us, to tell if the time is slowed for them, we have to observe changes in them.<br /><br />We see quite a few changes, supernovae and such.<br /><br />Quasars (basically the most distant single objects we know of) vary on timescales from hours to months, so they aren't really frozen either. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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the_masked_squiggy

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Interesting question, but as Saiph also said, we see enough change around us to exclude a static image. In fact, it's extremely dynamic. Not only supernovae and quasars, but just about anything we observe--variable stars, galactic rotation, everything. So just because we look up at night and see the exact same thing as we did for as long as we can remember, and have a very good idea of where things are, doesn't mean it's not changing on a grand scale. Just most of it isn't enough to notice with the naked eye--planetary transitions and variables that get really bright excluded.
 
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the_masked_squiggy

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Wouldn't these near-infinitely redshifted galaxies be extremely difficult to detect? I mean, how do you detect a near-infinitely long wavelength? Think not just down into subsonic levels, but perhaps a wave with a period as long as our galaxy. How would we even detect the vibration?
 
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kabtn05

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Wow. I'm humbled by the replies. Thank you. I have a lot to think about. You don't have to reply to this, but I was just wondering if Loeb's model is in any way related to something I heard in school about the possibility that the universe at some point may fold in on itself, and that what we see really far away is actually us, at a different time. Anyway, I was just wondering. Thank You.
 
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nexium

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Radio telescopes such as Aricibo, can look at wave lengths up to about one kilometer (about 300,000 Hertz) but the gain is low and the direction only approximate. Mostly we look at less than one meter wave lengths.<br /> It has been theorized that interesting things happen at million and billion kilometer wave lengths. Perhaps we will have antennas in solar orbit with dimentions in the millions of kilometers in a century or so. Neil
 
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