Comments on: Across the Universe, the stars cry out

By: TheHowler

TheHowler — Thu, 23 Dec 2010 13:23:45 +0000

@51 Doug; the light we’re seeing now left that galaxy 11 billion years ago. Your right that its redshift, say z=2.5 (which gives 11billion years light travel time: http://www.astro.ucla.edu/~wright/CosmoCalc.html)
puts it at some current ‘luminosity distance’ from the Milky Way 67.509 billion light years.
There is (amazingly) no contradiction with far flung regions of the Universe being carried away from each other by expansion “faster” than the speed of light. This doesn’t violate any physics … it’s just the way it is.

By: Captn Tommy

Captn Tommy — Mon, 20 Dec 2010 15:19:20 +0000

1. Since those Galaxies are at least 2 Sagons away, all those new stars are being created every yesterday.

2. Are all those galaxies actually that crunched together? Or… are we looking through a Sagon or so of depth(like suspended motes in a murky sea)?

Merry Christmas to All… Irregardless

Captn Tommy

By: Joseph G

Joseph G — Sun, 19 Dec 2010 20:22:19 +0000

@51 Doug: That’s a tricky question, for two reasons – first, space itself is continually expanding, to an extent that it’s possible for two objects to be receding from each other at a relative speed of greater than the speed of light while still receiving light from each other (that is, old light). And second, it’s commonly thought that there was a period of rapid inflation shortly after the big bang (see “cosmic inflation“)
Annnnd that’s about all I know. I know enough to know I can’t explain it, but other people can

By: Doug

Doug — Sun, 19 Dec 2010 06:36:15 +0000

OK, maybe a stupid question, but if the big bang was 13.7 billion years ago and this galaxy existed 11 billion years ago, would the photons of light from that galaxy at that time have reached the milky way 2.7 billion years after the big bang? How many light years could a galaxy be from the milky way 2.7 billion years after the big bang? Unless the expansion was faster than the speed of light how could we only be these 11 billion year old photons now?

By: Father Tyme

Father Tyme — Sun, 19 Dec 2010 03:59:39 +0000

We have to remember that we are looking at galaxies that were in that part of the sky 11 billion years ago. Chances are they aren’t actually where they appear now, having moved a few feet! LOL!
And even sadder, they may not even exist “right now, our time.”
Life adn civilizations that may have flourished4, 5, 6 billion years ago may be of a distant past while new life is beginning, that we will never know.
Feeling rather small and quite insignificant right now.

By: Joseph G

Joseph G — Sat, 18 Dec 2010 21:25:07 +0000

@#48 forrest: As long as we’re making predictions, I predict that at some point, telescopes will resolve an enormously distant gray grid, overlaid with a flashing “Loading…” sign

By: forrest noble

forrest noble — Sat, 18 Dec 2010 21:07:20 +0000

Phil,

I think possibly even a bigger wonder may start to be realized after the next round of space telescopes. At which time I fully expect that in reality there will be no observable limit to the number of galaxies out there and the distances involved, in deference to the present BB model. Don’t think the universe is infinite but the only limits to the extent of observation will be those of technology.

If this is found to be valid then the scope of future observations will only be limited by the imagination. This has been, and will continue to be my prediction.

By: Gary Ansorge

Gary Ansorge — Sat, 18 Dec 2010 18:55:49 +0000

37. Regner Trampedach

Of course, that simulation was only for aggregate asteroids. It would be totally useless for an iron rock.

On the other hand, such a solid core (iron) asteroid would be ideal to hollow out and use as a space colony.

Gary 7

By: Oli

Oli — Sat, 18 Dec 2010 18:54:18 +0000

@45. Ross: they are in the past, but for us they are sort of present as well. When astronomers say “there” they mean at that point in space and time, so an astronomer’s “there” = a layman’s “there” and “then” combined.

By: Ross

Ross — Sat, 18 Dec 2010 17:49:09 +0000

When we talk about things like this, are we to talk about them in the past or present tense? What I mean is presumably these events are long over what with the 11 billion year travel time of the light but to us we are still seeing it and will continue to for a looooooooooooooooong time no doubt so which is the correct tense?

By: Pareidolius

Pareidolius — Sat, 18 Dec 2010 10:08:55 +0000

Actually, it’s those images of infinite vastness that uplift me and give me perspective and the will to keep fighting the good fight. That we are self-aware star-stuff means that each and every one of us has won a lottery with odds so unimaginable that it makes picking seven numbers seem like a piece of cake. We are some kinda lucky monkeys, regardless of our circumstances.

By: Joseph G

Joseph G — Sat, 18 Dec 2010 02:24:29 +0000

It’s ok, stars. Everything’s gonna be fine. Shhhh. You’ve got millions of good years ahead of you yet. Hush, I won’t tell anyone. There there.

By: Jess Tauber

Jess Tauber — Sat, 18 Dec 2010 00:22:14 +0000

Phil is part Wormhole Alien/Bajoran Prophet on his mother’s side- he sometimes has a bit of a problem with temporal matters.

By: Brian Too

Brian Too — Sat, 18 Dec 2010 00:03:33 +0000

Is there any indication that the Milky Way might have had an highly active star forming period in it’s past? Similar to these galaxies? In other words, could the Milky Way have been a ULIRG long ago?

By: Chip

Chip — Fri, 17 Dec 2010 22:50:30 +0000

@Tom K –
It is a fairly common misnomer that the surface brightness of a distant galaxy would be exactly the same from all locations if you were much closer to it. In other words small faint gray fuzzy objects in a telescope would become large faint gray fuzzy objects to the human eye if seen up close. It is generally true if all conditions were exactly the same at all times but they are not. These objects, though at staggering distances, are so gigantic and richly detailed compared to the tiny Earthly scale that there would actually be specific coordinates and locations wherein a hypothetical observer would see considerably more detail including those colors the human eye could perceive from glowing gasses. Areas that were faint would remain faint though more detailed but other areas that were faint would brighten up due to the close proximity of stars and gas clouds not seen from Earth.

The reverse could also occur with nebulae within our galaxy. A beautiful faint nebula illuminated by nearby stars would be discernible to the human eye when viewed from a hypothetical approaching starship but as the starship enters the enormous nebula it would all but disappear except for pockets of denser gas further away within it, due to the relative size differences of the ship and the nebula. Some nebulae are quite brightly illuminated by stars within and would display clearly seen details and areas of brightness whereas others would likely remain faint near or far.

By: Buzz Parsec

Buzz Parsec — Fri, 17 Dec 2010 22:36:52 +0000

Bigby @2,

In astronomy, we’re *ALWAYS* looking “then” as well as “there”, even when we are looking at the moon (1.3 seconds ago) or the Sun (8 minutes ago), or Alpha Centauri (September or October, 2006) or at these galaxies 11 billion years ago. When astronomers say “there”, they mean “at that point in space and time.” So, yes, Phil means “if you were there 11 billion years ago”, but it’s implied and redundant to say that every time.

(This should be a Bad Astronomy FAQ, if it isn’t already.)

If you were here (i.e. in the Milky Way Galaxy) 11 billion years ago, it would probably look pretty similar.

By: CB

CB — Fri, 17 Dec 2010 21:56:27 +0000

@ Bear

What’s glowing red and green?

Nothing? This image was taken by an infrared telescope, so it’s necessarily a false-color image. I couldn’t find any obvious information about what wavelengths were given what colors in the image on the linked website, so I can’t tell you more.

By: Regner Trampedach

Regner Trampedach — Fri, 17 Dec 2010 20:46:17 +0000

Gary 7 @ 6 (which is different from 7 of 9…)
Anwho, the rubble-pile asteroid that was blasted by a nuke in their simulation, was 500 m across, similar to Itokawa, which looks positively dinky in Emily Lakdawalla’s “asteroid comparison chart” (search those terms on this blog to find the picture). Against most of those chunks (rubble piles) our nukes would still have little effect. On the upside, of the closest encounters since 1932 (from IAUs Minor Planet Center) only 2% were by rocks larger than 500m in diameter, and those were all pretty wide encounters – more than 62 Earth radii from the surface of our home = outside the Moon’s orbit (Caveat: a 500m long doggy-bone, i.e., Itokawa, has a lot less mass than a 500m diameter round rock). This nuke simulation is not particularely surprising news, but it is somewhat reassuring. The small rocks are presumably the ones we will have the least warning of.
Cheers, Regner

By: Ron1

Ron1 — Fri, 17 Dec 2010 20:46:08 +0000

@33 J.B. and @35 Leon … Nothing beyond our galaxy will appear to exist.

All the billions of galaxies outside our own galaxy will disappear – they will still exist, but will not be visible to us. To intelligent lifeforms of our galaxy, we will appear alone in the void – the universe will be our galaxy – the prevailing human ‘view’ from a few hundred years ago.

By: Leon

Leon — Fri, 17 Dec 2010 20:39:00 +0000

I just had an interesting thought. If there were a star in one of those galaxies that evolved sentient life and a technological civilization (I know, probably unlikely, given there would have been very little more than hydrogen and helium back that early in the universe), and they had those kinds of vistas to look at, they’d be long gone by now. Also, their astronomers might have marveled that, with everything moving apart, beings in the distant future–like us for instance–would live in a much less interesting universe (they would say, since the future wouldn’t afford such spectacular views and everything would be so much further apart).

By: Matt B.

Matt B. — Fri, 17 Dec 2010 20:08:12 +0000

When we receive light from something 11 billion light-years away, that light must be less than 11 billion years old, because some of the intervening distance that we perceive now didn’t yet exist (due to the expansion of the universe) when the light would have passed through it. Hence the fact that the edge of the visible universe is 42 billion light-years away (according to #7) even though the the Big Bang was only 13.7 billion years ago. It’s mind-blowing.

By: J.B

J.B — Fri, 17 Dec 2010 18:46:38 +0000

“…imagine being surrounded by the Orion Nebula everywhere you look. Wow.”

Another thing that fascinates me is: if intelligent lifeforms were to develop in those galaxies, how exactly would they form their view of the universe? Would the assumption of mediocrity prevail, such that they’d think the whole Universe was one great, big cloud of luminous dust? How long would it take them to figure out a balanced view of the Universe? And of course this line of thought leads to: is our own view of the Universe similarly hampered in some way, and is there something else beyond what we can see? Silly and ultimately pointless lines of thought, I know, but its just one of those things you think when you’re lying in bed and getting all philosophical and stuff.

By: Ron1

Ron1 — Fri, 17 Dec 2010 18:35:13 +0000

For a good video overview of a lot of these concepts, see ‘A Universe From Nothing’ by Lawrence Krauss, AAI 2009 on YouTube.

http://www.youtube.com/watch?v=7ImvlS8PLIo

Dr Krauss is Professor of Physics, Foundation Professor of the School of Earth and Space Exploration and Director of the Origins Project at the Arizona State University

By: Stan9fos

Stan9fos — Fri, 17 Dec 2010 18:28:54 +0000

… Best Song Ever … I’m just sayin’.

By: John EB Good

John EB Good — Fri, 17 Dec 2010 18:25:37 +0000

@28 uudale: Thank you. But being myself a layman, I can’t do it in any other fashion!

I personally thank all the brilliant physicists that are able to get to the point in their books without using a single equation. It’s the only way, as Richard Feynman would have put it, they’ll convince me they know their stuff in and out and in reverse.