Talk:Miller-Urey experiment

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Could anybody elaborate on more advanced experiments please? Including the molecules produced in the experiment

-- HJH

Why doesn't the Miller Page say something about the fact that He and Urey only produced 13 of the 21 basic amino acids? Or that nobody has since done any better (to my knowledge at least).

Here are a couple of Links that confirm what I just said.

The Facts of Life

Have all 20 acids been created in a Lab

One of Miller's Web Page Articles

Did Life Begin in an RNA World

13 of the 21 amino acids

RSB

It already said that "some" of the amino acids of life were created in the experiment, which implies "not all", but I'll add the specific number now that you mention it. I should point out that the earthage.org site appears to be a creationist website, and as such using it as a sole reference for anything other than creationsm-specific articles is unlikely to stick. Bryan 19:02, 8 May 2005 (UTC)

Contents

[edit] Urey-Miller or Miller-Urey

Isn't this usually called a Urey-Miller experiment?

I've always known at as the Urey-Miller experiment. But tastes change and modern usage seems to be to give Miller's contribution more of the emphasis it deserves by reordering the names as Miller-Urey.
However, either way, we should be consistent within the article. So I will now update the name ordering throughout. -- Solipsist 08:43, 20 Mar 2005 (UTC)

Another interesting point about this experiment: it makes it plausible that life could originate on Jupiter (since Jupiter's atmosphere is vaguely similar to what they used in the experiment). But it suggests that life could not have originated on Earth (if you do the experiment with gas mixtures similar to postulated early Earth atmospheres (or more recent ones) nothing interesting happens).

Actually, I think that all of the various experiments have liquid water in common, and that's not something that's readily available on Jupiter. Uranus and Neptune, on the other hand, could actually have layers of liquid water within them. If such layers exist, then they could have a volume on the order of the entire Earth. That's an amazing volume for an ecosystem to inhabit, though at this point it's sheer speculation.
Even if interesting biomolecules weren't easily formed in Earth's early atmosphere, life could still have originated on Earth if those biomolecules were formed elsewhere (eg on comets) and were then imported to Earth along with the rest of the cometary material. I believe this is considered one of the more plausible scenarios currently.

Thanks you, Bryan, for the elaboration. I added subtitles. --HJH

no problem, my pleasure. :)

Why no talk about the problems with his work as proof? There are many arguments and flaws with his work. The amino acids were "collected" in a special chamber, to avoid being destroyed by the electricity. This just discredits his work. It cannot function as prove. Does anyone else see this? User:172.212.158.123

I see that it seems to claim it 'proved' life can be made from a 'primordial soup', without talking about the problems. I'm no scientist, but I've read of numerous critiques of the experiment. In short, User: 172.212.158.123: I agree.Ben davison 20:11, 24 September 2005 (UTC)

Could the agenda driven creationists stay away and leave the encyclopedias to the rational people.

Maybe you should tell us how there were no problems then, if that's what you think. What about the fact that the experiment was engineered by people, when there were no people around to do so when it supposedly actually happened, severely denting the chances. Or that it (I have heard) only produced one-handed molecules, when life needs both handedness? Or that the early atmosphere supposed by Miller and Urey is now thought not to have been correct? And I suppose we have an agenda, but you don't? How very short-sighted of you. Please sign your comments, also.

This article might do well to take note of this:

"Unbiased writing does not present only the most popular view; it does not assert the most popular view is correct after presenting all views; it does not assert that some sort of intermediate view among the different views is the correct one. Presenting all points of view says, more or less, that p-ists believe that p, and q-ists believe that q, and that's where the debate stands at present. Ideally, presenting all points of view also gives a great deal of background on who believes that p and q and why, and which view is more popular (being careful not to associate popularity with correctness)." Ben davison 16:10, 25 October 2005 (UTC)

Life doesn't need "both handedness". All living organisms today use only left-handed amino acids. - 68.33.120.32 19:26, 25 October 2005 (UTC)

Sorry, I was trying to remember what I had read about it. I knew there was something about the handedness thing, though:

"In all living systems the building blocks of the DNA and RNA exist exclusively in the right-handed form, while the amino acids in virtually all proteins in living systems, with very rare exception, occur only in the left-handed form.

The dilemma for materialists is that all "spark and soup-like" experiments produce a mixture of 50% left (levo) and 50% right-handed (dextro) products. Such a mixture of dextro and levo amino acids is called a "racemic mixture." Unfortunately, such mixtures are completely useless for the spontaneous generation of life."

Complex molecules such as DNA and proteins are built by adding one building block at a time onto an ever-growing chain. In a "primordial soup" made up of equal proportions of right and left-handed building blocks, there is an equal probability at each step of adding either a right or left-handed building block. Consequently, it is a mathematical absurdity to propose that only right-handed nucleotides would be added time after time without a single left-handed one being added to a growing DNA molecule. Sooner or later an incorrect, left-handed nucleotide will be added. The same goes for proteins. Every time another amino acid is added to the growing chain of amino acids the chances are virtually certain that both right and left-handed amino acids will be added." [1]

It is not a mathematical impossibility (I assume that's what you meant by the relatively ill-defined word "absurdity"), any more than it's mathematically impossible to, for example, randomly pick a finite number of all white billiard balls out of a bag that contains equal, but much larger than the number picked, numbers of black and white balls. It may not be a particularly large chance, but it's most definitely not zero. Now, keeping this in mind, take another look at the timescales we're dealing with (The article suggests 100 million years - that's 1 followed by EIGHT zeros. Convert that to seconds and you're looking at 3.1 x 10^14 - FOURTEEN orders of magnitude!), and then consider the sheer number of randomly reacting molecules across across the entire surface of the planet in even a single second out of those 100 million years, if in fluid or gaseous form constantly being moved about by diffusion, convection, etc - is the emergence of such a level of complexity out of their interaction REALLY mathematically impossible? Just very unlikely? Perhaps even quite likely? How about if we include every other planet in the universe in the equation, which is yet another colossal number - is it mathematically impossible then that finitely complex arrangements of chemicals, capable of self-copying and surviving for a finite time greater than the time taken to self-copy in their respective environment, would arise anywhere at all?

Ben davison 21:53, 25 October 2005 (UTC)

This criticism of the Urey-Miller experiment appear to be assuming that the experiment is being held to "prove" more than it was actually intended to prove. The Urey-Miller experiment isn't supposed to be some grand demonstration of abiogenesis that starts with sterile water on day one and ends one week later with "thus we refute God! Haha!". Instead, it merely attempts to show that the spontaneous formation of basic building blocks of life is plausible under conditions similar to what might have existed early in the solar system's history. Many of the various remaining details are the subject of other theories and speculations, it's not necessary to nail each and every one right here. For example, I recall reading some recent work that showed that circularly polarized UV light could preferentially destroy left- or right-handed amino acids, depending on whether it was polarized clockwise or counterclockwise, and since space has a good deal of circularly polarized light it could have resulted in a non-racemic mixture in the early solar system. This isn't directly related to the Urey-Miller results, though, so it's not necessary to go into great detail about it here.
To summarize, all that Miller and Urey were trying to show with this experiment was that the early Earth could have been rich in complex organic molecules produced by abiotic means. Getting from there to the first living organism is a separate issue that doesn't need to be thoroughly addressed in this article, there are others with broader focus to cover that. Bryan 01:18, 26 October 2005 (UTC)
interesting, the above enantio-enrichement in space has been observed in the analysis of the murchison meteorite, which solves one of the creationist arguing points Xcomradex 04:09, 26 May 2006 (UTC)

[edit] New Diagram

I like the new diagram that has been added to the article however, it incorrectly shows H2 being evaporated from the water bath when it should be H2O which is evaporating and cycling through the system...just like the water cycle on earth does. Could someone change it?--Deglr6328 06:44, 6 November 2005 (UTC)

[edit] New Photograph

I have uploaded a high-res photo: http://en.wikipedia.org/wiki/Image:Miller-urey.jpg Don't know how to encorporate it into the Wiki page, though ... Anyone care to swap it for the current one?

since its the same exact image except better quality I just cropped the version you uploaded and reuploaded it over the older one here using the same name. --Deglr6328 05:07, 19 September 2006 (UTC)

[edit] Number of amino acids

The following article - the original article indicates that only 2 amino acids were identified, though others may well have been in the mixture in very small amounts. Miller 1953 paperhttp://www.issol.org/miller/miller1953.pdf. Why would the number 13 of 21 be used in this discussion?

I think the 13 of 21 quote was added based on information from a site critical of abiogenesis theories, so it probably got assumed that this was a safe minimum to mention. See the links at the top of the talk page. Sfnhltb 16:21, 20 March 2006 (UTC)
all amino acids have been created with different atmospheres and UV, lightning and heat

[edit] Formatting: Earth's early atmosphere-section

This may have been brought up before, but the section on Earth's early atmosphere is oddly formatted. The second and third paragraph are direct quotes from a website[2] (which is not clearly indicated).

I'm not even sure why these paragraphes are quoted from another source, instead of being rewritten for this article. -- Ec5618 22:40, 22 August 2006 (UTC)

[edit] Recent related studies: Trainer material

This section says, "See also the work of Melissa Trainer an astrobiologist who in 2004 demonstrated empirically that life could have formed on Earth through the interaction of methane, carbon dioxide and ultraviolet light (sunlight)." The Trainer work I found had nothing to do with the direct formation of life or BIOmolecules. It had to do with the formation of organic haze, aerosols and clathrates. While this may be relevant to the early earth atmosphere and that of other objects in our solar system (Mars, Titan), there is nothing that I could find in Trainer's work that "demonstrated empirically that life could have formed ...". In fact, the conclusion of the cited paper is: "After life arose, the haze may thus have provided food for biota." Note: AFTER life arose (by other means; they cite Miller), organic haze MIGHT have been food.

The work is a lot of physical chemistry but not biochemistry or biology. You might as well add every physical chemistry paper about atmospheric ozone, UV penetration, greenhouse effects or lightning to the Miller-Urey article. Trainer's own web page describes her research interests as "Planetary atmospheres; Mars methane chemistry; heterogenous chemistry" and there is nothing directly related to astrobiology, certainly not as directly related as the Miller-Urey and many other experiments.

Furthermore, all of the Trainer papers I found were multi-author works. The cited work is by: Trainer MG, Pavlov AA, Curtis DB, McKay CP, Worsnop DR, Delia AE, Toohey DW, Toon OB, Tolbert MA. (Tolbert is corresponding author; Toon is a senior aerosol researcher; McKay is a senior NASA scientist with many papers on astrobiology and the origin of life; Trainer was a grad student; most of the others have many more publications than Trainer and specialize in mass spec or physics or other areas.) To assign exclusive credit to Trainer is a serious breach of scientific ethics ("theft of credit").

As written, the results of the cited paper are grossly overstated -- make that misstated -- ("demonstrated empirically that life ...") and barely relevant to the Miller-Urey results. On this basis, I think that reference to the Trainer material should be deleted.AdderUser 14:38, 27 October 2006 (UTC)

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