Most Distant Galaxy - What's wrong with this statement?
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Most Distant Galaxy - What's wrong with this statement?
 
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From the BBC at
http://www.bbc.co.uk/news/science-environment-24637890 (today)
Because it takes light so long to travel from the outer edge of the Universe to us, the galaxy appears as it was 13.1 billion years ago (its distance from Earth of 30 billion light-years is because the Universe is expanding). Robert C ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
Re: Most Distant Galaxy - What's wrong with this statement?
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On Thu, Oct 24, 2013 at 01:15:53PM -0600, Robert J. Cordingley wrote:
> From the BBC at > http://www.bbc.co.uk/news/science-environment-24637890 (today) > > /Because it takes light so long to travel from the outer edge of the > Universe to us, the galaxy appears as it was 13.1 billion years ago > (its distance from Earth of 30 billion light-years is because the > Universe is expanding)./ > > Robert C It implicitly assumes a universal "now" at which the galaxy is located 30 billion light years away. Such a "now" is actually not meaningful, according to relativity. Of course the universe was only 13.1 billion light years away when the photons departed it that we're seeing now. -- ---------------------------------------------------------------------------- Prof Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Professor of Mathematics [hidden email] University of New South Wales http://www.hpcoders.com.au ---------------------------------------------------------------------------- ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
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In reply to this post by Robert J. Cordingley
> From the BBC at http://www.bbc.co.uk/news/science-environment-24637890
> (today) > > /Because it takes light so long to travel from the outer edge of the > Universe to us, the galaxy appears as it was 13.1 billion years ago (its > distance from Earth of 30 billion light-years is because the Universe is > expanding)./ I don't see much wrong with it (though I don't know if it's a true statement). "Galaxy X was 13.1 billion light-years from here-and-now, along a light-like geodesic, when it emitted the radiation we are presently detecting. The present location of Galaxy X (assuming the truth of present physical theories, etc.) is, partly because the Universe has been expanding, 30 billion light-years from here-and-now, in the sense that (with the same disclaimer) radiation we are presently emitting will be detectable at Galaxy X in 30 billion years." Does my attempt at paraphrase go beyond, or not as far as, the original? If not, what's wrong with the paraphrase? Lee Rudolph ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
Re: Most Distant Galaxy - What's wrong with this statement?
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(30-13.1) / 13.1 = 1.29 light-years / year. -- rec -- On Thu, Oct 24, 2013 at 3:25 PM, <[hidden email]> wrote: > /Because it takes light so long to travel from the outer edge of the ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
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And so? Matter/energy can't move faster than 1 light year per year, but the expansion of the
universe isn't making any matter/energy move in its local frame, it's just putting more space- time between the local frames of various different bits of matter/energy. I mean, consider the size and state of the universe in the immediate aftermath of the Big Bang. Whole lotta space appearing, stuff all over the place getting separated from other stuff at supraluminal velocities without contradiction. Not so? (I don't even play an astrophysicist on TV, but I roomed with one for two years of college, and later dated another [long since moved to Los Alamos to do goodness knows what besides marrying a lawyer, but probably not astrophysics; maybe fusion?]. So I'm just talking. But it sounds good to me.) > (30-13.1) / 13.1 = 1.29 light-years / year. > > -- rec -- > > > On Thu, Oct 24, 2013 at 3:25 PM, <[hidden email]> wrote: > > > > From the BBC at http://www.bbc.co.uk/news/science-environment-24637890 > > > (today) > > > > > > /Because it takes light so long to travel from the outer edge of the > > > Universe to us, the galaxy appears as it was 13.1 billion years ago (its > > > distance from Earth of 30 billion light-years is because the Universe is > > > expanding)./ > > > > I don't see much wrong with it (though I don't know if it's a true > > statement). > > "Galaxy X was 13.1 billion light-years from here-and-now, along a > > light-like > > geodesic, when it emitted the radiation we are presently detecting. The > > present > > location of Galaxy X (assuming the truth of present physical theories, > > etc.) is, > > partly because the Universe has been expanding, 30 billion light-years from > > here-and-now, in the sense that (with the same disclaimer) radiation we are > > presently emitting will be detectable at Galaxy X in 30 billion years." > > Does > > my attempt at paraphrase go beyond, or not as far as, the original? If > > not, > > what's wrong with the paraphrase? > > > > Lee Rudolph > > > > > > ============================================================ > > FRIAM Applied Complexity Group listserv > > Meets Fridays 9a-11:30 at cafe at St. John's College > > to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com > > > ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
Re: Most Distant Galaxy - What's wrong with this statement?
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Where is "the outer edge of the Universe" and what sort of observation would locate something there? All that the original report in Nature established was redshift (7.51), age (700 Myr after the Big Bang), and a surprising rate of star formation (330 solar masses / year).
-- rec --
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Re: Most Distant Galaxy - What's wrong with this statement?
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Regardless of the poetic 'outer edges' is it possible what might be
meant is in the context of a hyperspherical universe where the
radius is time and is 13.5 by? The center being when the big bang
occurred. Then the furthest object would be diametrically opposite
and hypercircumferentially at 13.5*pi bly or 42.4 bly away? So in
the 'now' being at 30bly away is chicken feed.
Robert C. On 10/24/13 9:20 PM, Roger Critchlow
wrote:
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Re: Most Distant Galaxy - What's wrong with this statement?
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http://en.wikipedia.org/wiki/Metric_expansion_of_space: "Because of the changing rate of expansion, it is also possible for a distance to exceed the value calculated by multiplying the speed of light by the age of the universe. These details are a frequent source of confusion among amateurs and even professional physicists."
-- rec -- On Thu, Oct 24, 2013 at 10:08 PM, Robert J. Cordingley <[hidden email]> wrote:
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Re: Most Distant Galaxy - What's wrong with this statement?
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Administrator
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Just to check: the expansion of the early universe does not take part in this issue, right? It occurred both very early and before the release of photons (around 300My after big bang?). But it did massively change the "size" of the universe.
-- Owen
On Thu, Oct 24, 2013 at 10:12 PM, Roger Critchlow <[hidden email]> wrote:
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Re: Most Distant Galaxy - What's wrong with this statement?
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In reply to this post by Roger Critchlow-2
So it sounds like during the expansion phase a lightyear was still a
lightyear but growing bigger? If you were there how would you
tell? My platinum standard meter bar is now a longer but still
standard meter bar? Has time dilated as well? If so what does the
age of 13.5by mean? In what dimensions could you measure these
changes? [Confusion may be an understatement.]
Robert C On 10/24/13 10:12 PM, Roger Critchlow
wrote:
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Re: Most Distant Galaxy - What's wrong with this statement?
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In the spirit of "will it blend?" and
"how much is a buttload?" I have to ask, what is the speed of
light in "furlongs per fortnight?"
- Steve So it sounds like during the expansion phase a lightyear was still a lightyear but growing bigger? If you were there how would you tell? My platinum standard meter bar is now a longer but still standard meter bar? Has time dilated as well? If so what does the age of 13.5by mean? In what dimensions could you measure these changes? [Confusion may be an understatement.] ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
Re: Most Distant Galaxy - What's wrong with this statement?
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1,799,884,800,000 f/f give or take, in a vacuum.
Robert C On 10/25/13 11:37 AM, Steve Smith
wrote:
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Re: Most Distant Galaxy - What's wrong with this statement?
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Which leads to this interesting tidbit: "A garden snail has a top speed of about 78 furlongs per fortnight." On Oct 25, 2013, at 12:02 PM, "Robert J. Cordingley" <[hidden email]> wrote:
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Re: Most Distant Galaxy - What's wrong with this statement?
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In reply to this post by Robert J. Cordingley
1,799,884,800,000 f/f give or take, in a vacuum.Terran fortnight, Martian or registered with Betelgeuse 5? And in *some STATES!* apparently there is in use an archaic measure for the furlong which varies by .000002 % which I suppose is within your precision and the "give or take"... I'm guessing the furlong is still 10 chains, 220 yards but their chains or yards vary? The wear on the end of the "chains" could account for more error than that, not to mention manufacturing variation! "The nice thing about standards is that we have so many to choose from" - Andy Tanenbaum, creator of Minix. Andy is also known for: "Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway." But I think it needs to be updated to Minivan or 9 passenger SUV.
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Re: Most Distant Galaxy - What's wrong with this statement?
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In reply to this post by Joshua Thorp
Josh -
More (of my version of) blending (a violent metaphor for the technical non-sequitor?): Speaking of Firkin Furlongs per Fortnight ... the garden snail also seems to weigh in at about 20-30 grams or .0006 firkin/snail... which suggests that if converted entirely to energy, said snail is worth very roughly ~2.0 E21 Firkin-Furlong^2/Fortnight^2. Since a good way to convert mass entirely to energy is via a matter-antimatter interaction, take one anti-matter garden snail and one normal-matter garden-snail put them together (aka ticking the snail's tail). We have: `4.0 F*(Furls/Fort)^2 total energy... So what is the theoretical maximum specific impulse of a snail-powered rocket engine in Fortnights? (spoiler answer: ~600 fortnights..) On our next installment, "who wins the race, the antimatter tortoise or the antimatter snail"? And which one tastes better in garlic butter? ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
Re: Most Distant Galaxy - What's wrong with this statement?
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In reply to this post by Steve Smith
Meanwhile, I still want to know what space-time was expanding
relative to!
Robert C On 10/25/13 12:21 PM, Steve Smith
wrote:
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Re: Most Distant Galaxy - What's wrong with this statement?
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Robert -
Meanwhile, I still want to know what space-time was expanding relative to!<semi-serious> Relative to the concept of a constant (geodesic) distance metric (in Furlongs of course) calibrated the Speed of light (in F/F of course)? Distance == Time for Light to Travel / C . </semi-serious> At what time (in femto-fortnights) after the big bang was our universe roughly one buttload in volume? Hint: conversion factor is roughly 7.56*10E-06 cubic furlongs/buttload. Challenge: What is the value of Pi in a spherical metric space (assuming the universe expanded from a point in the shape of a spheroid)? Referring back to an earlier thread: Just because I don't do math doesn't mean I can't do arithmetic! - Steve Robert C ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com |
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