Talk:Starlight problem/Archive1

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Omphalos

Icewedge, what have you done? I can't even follow the logic of the edits, let alone what is there now... mind if I try to merge what we had with what you've added from AIG? While I copyedit... human^{be in} 21:10, 19 September 2007 (EDT)

Just a stupid question

But does no one (in the creationists circle, that is) wonder why god would go to the bother to create "Billions and Billions" of stars... if the only exist to provide "us" with pretty lights at night??????????????--WaitingforGodot 17:42, 24 July 2008 (EDT)

YOU QUESTION GODS PLAN. Obviously he wanted Eve to be able to see at night when she was making Adam a sammich. -- Gen. S.T. Shrink ^{That's what she said.} 17:43, 24 July 2008 (EDT)

They also gave her material for questions to pester him with while he was trying to enjoy the game and a few brewskis. ħuman 17:55, 24 July 2008 (EDT)

*insert innapropriate fellatio joke here* -- Gen. S.T. Shrink ^{That's what she said.} 17:57, 24 July 2008 (EDT)

Metric expansion of space

Hello everyone (fabulous wiki you got here... I like it) I believe that the editors of the article may have fallen into a common trap regarding distances, the speed of light and the age of the universe. It doesn't affect the gist of the article so don't worry, you don't have to change your beliefs! (Though as rationalists, you wouldn't mind if you did have to anyway.)

The problem is that one of the furthest objects from earth that can be seen currently is 28 billion light years away. The light that reaches us now from this object (incidentally, a pulsar) has taken 12 billion years to do so. The reason for this seemingly contradictive occurance is that 12 billion years ago, the pulsar was 4 billion light years away from earth, but instead of taking only 4 billion years to reach us, the distance between us and the pulsar (and hence the distance between us and the light on its journey) has increased over time. So the photons have travelled 'against the flow' of the space they are in, if you see my point. For a nice diagram of this, see the ever-wonderful Wikipedia (http://en.wikipedia.org/wiki/Image:Embedded_LambdaCDM_geometry.png#Mathematical_details).

This is called the metric expansion of space, and is the reason for the Doppler effect, and the basis of the Big Bang theory (extrapolating back in time to a point where everything was a lot closer together). So it is helpful to think of the big bang as a stretch rather than an explosion - the galaxies themselves aren't moving relative to eachother (much), instead the space between them just got bigger. 86.153.222.16 11:51, 12 September 2008 (EDT)

I make no great claim to any expertise here, but isn't the speed of light supposed to be invariable between any two points regardless of their velocities? I had understood that what changes was its frequency - the Doppler effect. So, if light from an object 4 billion light years away started out now it would reach us in four billion years time. However if there were a significant difference in the velocities of the star and ourselves it would be red shifted if the star was moving away or blue shifted if it was moving towards us. I accept that the position of the star itself would be vastly different from where it was when the photons started out. Or am I way off? --Bob^{bing up} 12:13, 12 September 2008 (EDT)

I am not an expert either, merely an inquisitive undergraduate student! Yes, all that you say is right, except that "light from an object 4 billion light years away started out now it would reach us in four billion years time" is wrong. Its hard to explain, except to refer to the often-used 'balloon model' of the universe - imagine the earth and the pulsar as points on its surface. Obviously these points get further apart as the balloon expands, but what is a little harder to imagine is what would happen to another point that is moving between these two fixed points. The moving point has to travel a lot further than the original distance between the two fixed points, as the balloon is expanding while the moving point is travelling. But it also has to travel less far than the final distance between the two points, as by the time the balloon has expanded to its final size, the moving point has already travelled most of the way. I'm sorry if I'm not the best explainer - I've seen digging at Wikipedia and found this more rigorous explanation by someone else: http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2008_March_16#Speed_in_space.28not_the_drug.29 . 86.153.222.16 12:36, 12 September 2008 (EDT)

This is a good point. It's easy to confuse Doppler redshift vs. cosmological redshift (which is ultimately what I think this discussion is about), but I don't immediately see a way to work it into this particular article without explaining it to such an extent that it dilutes the main point.--Bayes 15:14, 12 September 2008 (EDT)

The one thing that I was thinking could be done, to ensure accuracy with the minimum of explanation, would be to correct the following sentence, with a reference to provide explanation if people want it: "Because light travels at a finite speed, only stars within 6,000 - 10,000 light years of earth should be visible in the creationist model of history. This is not the case though, since radiation from stars over 13 billion light years away have been detected[1], which would seem to put the lower limit on the age of the universe near 13 billion years."

What I'd suggest is this: "Because light travels at a finite speed, only stars within a few tens of thousands of light years from earth should be visible in the creationist model of history. This is not the case though, since quasars over 28 billion light years away have been detected, which, allowing for the metric expansion of space, puts the lower limit on the age of the universe near 13 billion years." Unfortunately I do not know how to accurately extrapolate the creationist age of the universe to a maximum radius (I don't know anyone that would bother to try), but it would be roughly the same ratio as the 13 billion years/28 billion light years for the universe studied by those of us who have a grip on reality - so 6000-10000 years gives a radius limit of a few tens of thousands of light years. What do you reckon? 86.153.222.16 15:51, 12 September 2008 (EDT)

I think the best solution would be to refer to the issue somewhere within the article and link to a comprehensive explanation from there. (Adding a line along the lines of "in reality it's not quite that simple as is explained here". And if somebody has got the smarts to write a RationalWiki article that would be great, as I find it a bit of a mind twister.--Bob^{bing up} 16:21, 12 September 2008 (EDT)

That's kind of what I suggest as all that's changed is a few words, but the comprehensive explanation is contained in a wikipedia article rather than on RW. I think that's fine, as this wiki is primarily concerned with refuting anti-science, and regularly links to more detailed wikipedia articles. 86.153.222.16 17:47, 12 September 2008 (EDT)

Actually, as a general rule we don't link to WP and prefer to explain things ourselves and go to primary sources. This is in part because our objectives differ to those of WP, and in part because we don't really want to be a WP "add on".--Bob^{bing up} 10:22, 14 September 2008 (EDT)

Really? There are lots of RW articles that link to WP, & it's a shortcut in the wiki coding we use - eg. [[wp:Wikipedia]] rather than having to do a full external link. RationalWiki:Project Whitewash/What is a RationalWiki article says:

"Most of the contributors at RationalWiki enjoy Wikipedia, and we encourage people to use it for research, fun, or anything else that requires more encyclopedic and neutral articles. We cannot and do not want to compete with Wikipedia. We are attempting to create something that is different but hopefully complementary to Wikipedia."

Doesn't that rather contradict what you just said? weaseLOId~ 10:40, 14 September 2008 (EDT)

Amusing by BON

"It is also impossible for the speed of light to change for quite a different reason. Because, under the metric system, the speed of light is always set as a constant of 299 792 458 m/s, and a meter has, since 1983, been defined as the distance travelled by light in vacuum in 1⁄299,792,458 of a second, it is actually, by definition, impossible for the speed of light to change. If, somehow, light ever did begin travelling at a different speed, it would not alter the velocity of light, but would instead change the length of a meter. Although this sort of pendantic dickering is, in and of itself, not useful, it does provide a handy way of spotting fools who don't know what they're talking about. Anyone who talks about changes in the speed of light without at least mentioning the definitional problems with such a statement clearly has little to no idea what they're talking about."

While amusing, I don't think the conclusion is very strong. But if people think it should go back in the article, please feel free to argumentify, mobify, set up voting bars, consult the Goat, and forget what we were talking about... ħuman 23:58, 14 September 2009 (UTC)

The comment is far from a pedantic bit of dickering. In fact, it shows a fundamental misunderstanding of physics that pervades the entire "variable speed of light" idea. In physics, the only constants whose change would have an effect on actual physics are dimensionless constants, like the fine structure constant or the ratio of electron to proton mass. Dimensioned constants like the speed of light are merely conversion factors (in the case of SOL, between time and length). While in earlier days the SOL was not defined in the invariant way it now is, instead being considered as measured (hence the misunderstanding), now understood that any change in the measured speed of light under the old metric system (where the meter was defined by a physical bar in Paris, France) would actually have been due to some change in dimensionless constants that change the length of the physical bar relative to the meter's SI definition. The unfortunate thing for enthusiasts of the "changing speed of light" idea is that we have direct evidence that the constants that would affect the measuremnt have not changed for hundreds of millions and even billions of years. Of course, this will have no affect on these folks, because they think the Earth is only 6000 years old.

In my opinion as a professional astrophysicist, the explanation that has been deleted from the article (apparently) is the correct one; everything else flows from it. It should be restored.

Conservapedia's Version

I think it would be prudent to mention in the article that Conservapedia has an article called "Starlight Problem," but it says that the starlight problem actually disproves that the Earth is over 10,000 years old. Here's how they pulled this off:

"

The starlight problem, or starlight travel-time problem concerns the placement of stars at distances so far from Earth that starlight could not traverse that distance, at its current velocity, in less than the age of the universe. Yet the light has reached Earth anyway. This raises a question under any creation-based theory, including the Big Bang theory: how did this starlight reach Earth so quickly? There is no conflict with the description in Genesis, which says, 'let there be light, and there was light." It doesn't say, "let there be light, and there was darkness that light later reached.'"

I think that this should be mentioned in the main page.

=[ Beckenor ]= (talk) 01:38, 17 July 2011 (UTC)

What's a "Conservapedia"? P-Foster_{The Grateful Dead were neither grateful nor dead. Discuss.} 01:41, 17 July 2011 (UTC)

Hi Beckenor. We don't usually quote CP in mainspace as it's not really a relevant or influential source and it's not even taken seriously even by its target audience. Having said that I can't really understand the point being made. It it a badly-expressed form of the Omphalos hypothesis?--Bob^{Spring is sprung!} 06:34, 17 July 2011 (UTC)

Geocentricity vs Parallax

(moved from the article) If a) the whole Universe is circling around the Earth, including the Sun, we are not moving through the sky as the Sun appears to hide variously Virgo or Pisces and we are therefore not seeing Alpha Centauri or the other ones from two different places, and b) Alpha Centauri and the other ones is not linked to the Sun either, THEN parallax does not prove very long distances, thus no starlight from stars as they were 10,000,000,000 years ago. What is the age of starlight from them if placed just outside Van Oort's Belt? ^{— Unsigned, by: 129.102.254.253 / talk / contribs}

If the Earth was stationary there wouldn't be any parallax. The fact that there is parallax shows the Earth isn't stationary so this whole idea can be dismissed. rpeh •T•C•E• 16:03, 12 November 2012 (UTC)

Here are a few gifs from Wikimedia Commons that should display the concept nicely:

No movement = no parallax. We see parallax, therefore there is movement and therefore creationists are really just being silly. ^{d hominem} 18:02, 12 November 2012 (UTC)

There's no "Van Oort's Belt". There's the Oort cloud on the outskirts of the Solar System (and he was Jan, not Van) and the Van Allen radiation belt around the Earth.--ZooGuard (talk) 18:11, 12 November 2012 (UTC)

What problem?

God creates the heaven and the earth in Genesis 1:1, but the first day isn't until Genesis 1:5. If quasars pre-date the seven days of creation, that wouldn't contradict anything in Genesis. PeterKa (talk) 04:38, 10 January 2014 (UTC)

An odd compromise. However, since our own galaxy is >100,000 light years across, even that alone poses a problem. We should have a "visible" universe that barely reaches outside our local group of stars. ^moral 13:24, 10 January 2014 (UTC)

I can't actually claim credit my "compromise". It's called "gap creationism" or "the gap theory". It was presented in the Scofield Bible, and it is probably the most commonly held form of creationism. The article should at least mention it. PeterKa (talk) 05:13, 12 January 2014 (UTC)

Please give us a link so we can mention it. Proxima Centauri (talk) 15:42, 7 April 2014 (UTC)

I found something,

1. Why the Gap Theory Won't Work
2. What is the Gap Theory? This is from the about.com website, isn't peer reviewed and needs to be checked with other sources.
3. The Gap Theory This is from Atheism Wiki but I didn't write it.
4. Fellow Atheists: Thoughts on the Gap Theory? Proxima Centauri (talk) 16:41, 7 April 2014 (UTC)

The proverbial snail

If the speed of light decays exponentially, how long before snails are FTL creatures? 82.44.143.26 (talk) 15:04, 7 April 2014 (UTC)