Talk:Earth Similarity Index/Archive 1

Habitability or not ?
Citation: "ESI is not a measure of habitability, ..."

but the article is in category "Planetary habitability" and "Search for extraterrestrial intelligence". --Mahgü (✉) 22:01, 9 February 2014 (UTC)

Higher than Venus or Mars
"The following planets have been determined to have higher ESI than Venus or Mars:" No they haven't. The table goes down to 0.53. The top of the article says Venus 0.78, Mars 0.64 or 0.70. Even above says Venus 0.44, Mars 0.70 – and I don't think "higher ESI than Venus or Mars" means "either higher than Venus, or if not, then higher than Mars" because that could be simplified to just "higher than Venus". Should we qualify the "determined" statement, or shorten the table? It's a contradiction if we don't do either one. Art LaPella (talk) 22:12, 31 July 2014 (UTC)

Kepler-452b
as today, the NASA official Kepler web site does not report the mass of the planet http://kepler.nasa.gov/Mission/discoveries/ so while the planet radius is know with good approximation, the density is unknown. Many speculating web site report values from 5 EM to <1. So the ESI index for 452b reported in the article is completely arbitrary, remove it from an enciclopedia--Efa (talk) 19:52, 24 July 2015 (UTC)


 * I have implemented the ESI value for Kepler-452b that was provided by PHL. I also moved it (Kepler-452b) below Kepler-62e again to match PHL. If there are any more issues than let me know and I will look over the data. Davidbuddy9 (talk) 15:56, 27 July 2015 (UTC)

What is going on with the table?
Just as a note hypopsychroplanet and hyperthermoplanet could have Extremophiles living on them! Thats why they were originally labled  instead of   and Mercury is considered Non-Habitable. Davidbuddy9 (talk) 16:17, 31 August 2015 (UTC)

Clarification of Key to table
The key for the table in the Planets with relativiely high ESI section lists possible values for the pClass but doesn't include megaterran, the entry for #8, K2-3d. Where does it fall in the range? WesT (talk) 23:54, 16 December 2015 (UTC)

Venus ??
How on Earth (excuse the pun) did it go from 0.44 to 0.78 ?? --EvenGreenerFish (talk) 06:05, 29 June 2013 (UTC)
 * The value for Venus is wrong here (second-ranked is Mars not Venus). See example calculation in de:Earth Similarity Index or data_solar_ESI.txt referenced in Earth Similarity Index (ESI). The values in HEC: Data of Potential Habitable Worlds are calculated different. --Mahgue (talk) 18:28, 8 February 2014 (UTC)
 * The docs.google.com documents seem to be all broken. A copy of the table can be found in slide 7. It is written in German, but for the table this should not matter. --Mahgü (✉) 16:59, 16 February 2014 (UTC)

Venus is listed as having different values on different Wikipedia pages. All the pages are backed by contradictory citations. I tried to add a note about the dispute to the actual page so that people wouldn't think the number here is authoritative, but that edit got reverted. A request for an expert was added to this page in 2014. That request has yet to be answered, so please someone add a note that the number is disputed. I apparently lack the standing to even note this contradiction. AristosM (talk) 18:42, 1 January 2016 (UTC)

NEVER MIND. I just discovered that another user did actually verify the numbers and set them right! :-) AristosM (talk) 18:45, 1 January 2016 (UTC)

Improvements to the article
Remove original research and self-published sources is extremely important for articles about fringe proposals, which this idea is. We need to contextualize it ''properly.

Thus, this version, which I think does an admirable job describing this topic. We can add more sources as we may.

05:33, 3 April 2016 (UTC)


 * If you looked at many of your AfD's that you opened up or even read your talk page, people are reminding you that you don't understand what WP:OR is. According to you all sources need to be peer reviewed. Unfortunately all of your TfD's don't make sense that you made Earlier this month you do not need to have peer reviewed papers to justify what shades of red to green it should be for numbers ranging from 0 to 1. And no this version is not admirable its either a stub or a start much smaller than the previes version, and Ironically you pulled the equation how to calculate it! And then you go around looking for templates complaining that the ESI is purely Original research WOW. April Fools happened 2 days ago ok it's over get over it. PS. here you stated that it was "vetted by experts" where is the peer reviewed paper please? Or else thats WP:OR! Davidbuddy9  Talk 05:46, 3 April 2016 (UTC)
 * David, I understand WP:OR perfectly well. We are not in the business of promulgating information that is sourced to a single self-published website. That's not how Wikipedia works. Please read WP:ONUS. The ONUS IS ON YOU to show the peer reviewed paper that actually cites this. NOT THE sole paper published in an obscure journal by the self-same author of the website, any paper citing it. That's what you need to establish the prominence of the information so that you can include it. jps (talk) 05:48, 3 April 2016 (UTC)


 * This is how I like to handle situations when I am in your position.


 * 1) Revert to the edit that was used before the controversy started.


 * 2) Open up an RFC on the WP:AST talk page for community input.


 * yes that is OR but it works and as a community we reached agreements for example WP:AIAO to handle Artists impressions of :::Astronomical objects. Everyone views the rules differently so we need to find a balanced approach of what the entire community thinks, :::not just you or I. Until something can be reached we shall follow the defacto approach that was used before which was clearly not in :::your understanding of WP:OR. So whats holding you back go make an RfC on WP:AST's talk page about this PHL/HEC = Original :::research. Until then I'm going to fight for how things were done before (well until I get pissed off enough that I make my own RfC). Davidbuddy9  Talk 05:56, 3 April 2016 (UTC)

You are in no position to make demands. Your current argument is that you as a community agreed to violate a fundamental policy of Wikipedia. Since there are no peer-reviewed citations of this idex as a calculation, there can be no coverage of it at Wikipedia. Artists conceptions are totally separate matters. jps (talk) 05:58, 3 April 2016 (UTC)
 * PS. ONUS states " Consensus may determine that certain information does not improve an article" Which further reinforces my idea of opening up an RFC to determine whether or not we PHL/HEC is OR or not. Davidbuddy9  Talk 06:00, 3 April 2016 (UTC)
 * Opening an RfC is fine with me. Just realize that according to WP:RfC you must word it neutrally. This means that you have to explain that what you are arguing for is that these specific calculations that you want to include which have never been published in a serious first-rate academic journal in astrophysics and a means of calculating an index which has never been cited in any serious WP:MAINSTREAM literature. If you think you're up for the task of explaining why your calculations and interest in this WP:FRINGE material should be included, by all means start an RfC. jps (talk) 06:04, 3 April 2016 (UTC)
 * There is a noticeboard to help determine whether a source is considered reliable, have you considered taking the matter there? LjL (talk) 20:58, 3 April 2016 (UTC)
 * The point is pretty secure. Since it is self-published the onus is on those wanting to include the source to show that it is noticed by third party sources. I don't think there is an argument that can be made against that. jps (talk) 21:48, 3 April 2016 (UTC)
 * My initial argument, which I made elsewhere, is that I don't necessarily agree it's self-published in the first place. You claimed that it is based on the assumption that "the person" maintaining that "web page" is the only one with control over it. However, that web page (the Habitable Exoplanets Catalog) is hosted on the official website of an academic institution, which could easily be construed as a publisher of work, and unless they explicitly disclaim the content of their own website, it seems reasonable to assume that they do have editorial control over it. Editorial control is often the key point that is brought up on Wikipedia in discussing whether something is to be considered self-published. Just not having a DOI or ISBN isn't what makes the difference. LjL (talk) 21:52, 3 April 2016 (UTC)
 * Nope. That's not how it works. Academic websites are not under any editorial control whatsoever. They only represent the opinions of the person who puts up the website. jps (talk) 23:54, 3 April 2016 (UTC)
 * That's not quite true. It depends on who is hosting the academic's web-site.  In my real-life, I have a web-site which is hosted by my University.  This is vetted/edited by the University Press Office. DrChrissy (talk) 15:09, 4 April 2016 (UTC)

The presumption is that unless there is a statement to the contrary all websites that are personally hosted (and not part of the university's main site) are WP:SELFPUB. It may be that certain universities have different policies, but I'm sure, for example, you could produce that policy from your university if we needed to verify that such was the case for your personal website. I am certain that the University Press Office of UPRA does not vet/edit this particular website, and would challenge anyone to produce proof to the contrary. Per WP:ONUS, we should treat this page as WP:SELFPUB until shown otherwise. jps (talk) 16:11, 4 April 2016 (UTC)

Lead section
It seems the lead section, which must be a summary of the article (WP:LEAD), is longer than the article itself. Please review. Thank you. BatteryIncluded (talk) 15:42, 4 April 2016 (UTC)
 * Yep. This is a problem. I'm not sure that we need sections yet, but this article is still very much a work in progress. jps (talk) 16:03, 4 April 2016 (UTC)
 * I tried to fix this. See what you think! jps (talk) 16:19, 4 April 2016 (UTC)
 * Thank you. BatteryIncluded (talk) 19:07, 4 April 2016 (UTC)

ESI is not the same as PLANET HABITABILITY INDEX
Someone has gone substituted PHI figures in for the ESIs in the tables. The two are completely different measures.--EvenGreenerFish (talk) 01:32, 28 September 2014 (UTC)


 * If relevant, perhaps someone can add a sentence on the difference between ESI and Planetary Habitability Index?  They are different. By the way, Planetary Habitability Index eventually redirects to Circumstellar habitable zone.  Thanks, BatteryIncluded (talk) 18:54, 4 April 2016 (UTC)


 * I don't think a "Planetary Habitability Index" exists in quite the same way. There are selection criteria that might be of interest, but the much ballyhooed index here appears to have been slightly de-emphasized as of publication in ApJ: . jps (talk) 19:45, 4 April 2016 (UTC)

"Vetted by experts" isn't a rationale
I'm not getting into the edit war and undoing this, but I will point out that its edit summary rationale is starkly unsatisfactory. It is claimed that the current version must be accepted as vetted by experts, but the self-appointed expert in question is themselves who made the edit. Even if you really are an WP:EXPERT, that does not grant you any privileges in resolving conflicts in their favor: in a content dispute between a (supposed) expert and a non-expert, it is not permissible for the expert to "pull rank" and declare victory. Wikipedia policies and guidelines must be respected by experts and non-experts alike, so if your WP:BOLD mass-removal of content from this article is challenged, you should follow the same WP:BRD process that everyone else has to, and you should be the one taking it to the talk page at that point, not ask others to while reverting back. LjL (talk) 20:57, 3 April 2016 (UTC)
 * I don't see any coherent challenges to the new article. If you have a specific argument you'd like to make on why self-published website should be used as a sole source for certain sections, please go ahead and make it! jps (talk) 21:49, 3 April 2016 (UTC)
 * I do not think it's necessarily self-published: see what I posted in the section above. In any case, justifications for reverts are also important, and your claim that because you're an expert, it should be taken to the talk page by the other party, instead of you following the WP:BRD cycle was incorrect, so I pointed it out. LjL (talk) 21:55, 3 April 2016 (UTC)
 * I question your WP:COMPETENCE when it comes to source evaluation, in that case. You need to understand how content is published. This is a personal website. Nothing more. jps (talk) 23:55, 3 April 2016 (UTC)
 * And this is Wikipedia, where you don't slap on editors' face the fact that you're an WP:EXPERT and where WP:COMPETENCE is required about being able to edit the encyclopedia, not about your specific field of study (and where if you actually check what it says at the top of WP:COMPETENCE, it's not considered nice to put it the way you just have). You have been aggressively removing material from this and various other articles in spite of several opinions against it, and you should stop thinking you can single-handedly decide your version is proper because "you are an expert" and an academic website is not a reliable source, without having discussed it properly on the WP:RSN or other proper venues. You're also clearly edit warring at this point. LjL (talk) 00:53, 4 April 2016 (UTC)

If you are not improving the encyclopedia, you need to step aside. I'm sorry that people's opinions are that bad sourcing and violations of Wikipedia's policies of WP:NOR, WP:RS, and WP:V should be ignored in favor of including your favorite self-published webpages and unpublished manuscripts, but consensus does not trump best practices. jps (talk) 00:56, 4 April 2016 (UTC)
 * Slapping labels on who is an expert and who is not is just going to further discourage editors to improve and expand articles because we can't use a measurement to stack planets against each other on the page all about the unit. Should we be able to have tables showing the ESI in action on the page all about the ESI(duh!)? But I mean Really, vetted by experts is such a terrible and discriminatory rationale because it assumes that the other editor is not an expert. What happened to Wikipedia's slogan "the free encyclopedia that anyone can edit]]?? Davidbuddy9  Talk 02:27, 7 April 2016 (UTC)
 * The best people to write articles are those who are experts in the subject. I am not discounting that you might be an expert in the subject (are you?) but it looks to me that you aren't because you keep insisting that ESI is a measurement when it is just an arbitrarily calculated index that isn't consistently used by those who study exoplanets. jps (talk) 13:02, 7 April 2016 (UTC)

ESI values mentioned in the press
There are a lot of press articles with ESI values mentioned. I think this can serve as a means to notability for the topic. Can people who have seen press mentions of the ESI (I know that NOVA was mentioned as one place) start to list them here. To be clear, this article is more about science popularization, and so mainstream science press articles would be useful to include.

jps (talk) 01:39, 4 April 2016 (UTC)

I guess I'll get the ball rolling:


 * Méndez TED talk
 * space.com
 * planetary.org
 * Popular Science

Here is a debunking done by another astronomer: and one done by Seth Shostak:

jps (talk) 19:03, 4 April 2016 (UTC)


 * I agree with not using ESI in other articles but this one; when the data says "Earth-like mass or size", it gets mistranslated to "Earth-like", which is horribly misleading as habitable. Besides, if the experts in exoplanetology are not using this index (ESI) in their research papers, we should not use them in Wikipedia. BatteryIncluded (talk) 02:48, 7 April 2016 (UTC)


 * Thank you! I think that's a very well thought-out position. The question is how we should best describe it on this page. jps (talk) 13:03, 7 April 2016 (UTC)

Kepler-62e consistency of ESI?
In this article we state the ESI is 0.82, but in the Kepler-62e article it is stated to be 0.83. It might just be rounding differences, but the lack of sources to these (both articles) means I can't check them and we are failing the policy of verifiability. DrChrissy (talk) 15:57, 4 April 2016 (UTC)
 * The problem is that the webpage has different values than the initial paper that was published. This is a bug that the index does not include uncertainties in its calculation. It's one of the biggest problems that people have with this index because consistent calculations are nearly impossible (and dependent a lot on assumptions). I am of the opinion that most if not all the actual index values should be removed from Wikipedia pending verification for, as you rightly point out, they often fail verification. jps (talk) 16:08, 4 April 2016 (UTC)
 * The verifiability I am talking about is enabling WP readers to verify from a source that something has been stated. DrChrissy (talk) 16:43, 4 April 2016 (UTC)
 * In many cases, even this is not possible because the webpage often changes the ESI value (and even the way it is calculated). jps (talk) 17:32, 4 April 2016 (UTC)
 * I found a secondary source - this has been edited into the article. DrChrissy (talk) 23:41, 7 April 2016 (UTC)

Formula
One of the problems with uncritically including the formula is that the formula needs to be fined-tuned to obtain the result that the 2011 Astrobiology paper demands and this tuning is too much detail to include in our article since it has not been mentioned by third-party independent sources. Typically what happens is that the ESI value is quoted in the media and then left at that, though note the problem DrChrissy identifies above! My opinion is that the formula does not add anything of value to the article because the tuning of the parameters cannot be replicated by the reader and the values used are not of any physical significance.

Basically, ESI is an attempt to use a quantitative measure where a classifier would have been more appropriate (in a data science sense). I would say that including the formula here is a bit too much WP:PROMINENCE relative to the way in which ESI has been referenced by third parties. Thus, I think we should remove the formula.

Thoughts?

jps (talk) 16:08, 4 April 2016 (UTC)


 * Earth Similarity Index is the title of the article, so it is proper to have the means by which it is/they are produced. It seems that there are at least 2 versions of ESI (Schulze-Makuch, Méndez, et al. 2011 and Chandra et al. 2015). The former has been referenced and used by others in the community. I have not investigated the usage of latter, and so have not included the latter's formula. If I were to have included Chandra 2015's formula, without doing any due diligence, then I believe Chandra's formula would meet WP:PROMINENCE criteria for removal. If both are in use by the community, however, both should be included.  ~ Tom.Reding (talk ⋅dgaf)  16:47, 4 April 2016 (UTC)
 * The problem is that the formula itself is not illustrative because the unit scaling and the precisely tuned weights are not given. It turns out, in fact, that Méndez provides yet a different set of weights for his page than is in the paper, so there are actually three different forms of the ESI. This is problematic because we cannot just list all of them. What we need to do is find out which ones are being used specifically. I find that basically the formulae themselves are not being used. People quote ESI values without bothering to calculate them (normally they just go by what Méndez's webpage says). That's why the formula probably shouldn't stay on this page. jps (talk) 17:17, 4 April 2016 (UTC)
 * Of course we should have at least one formula - an article saying it is about an index without giving the formula of how that is calculated would be a seriously lacking article. I have not seen the other versions and their weighting factors, but in principle, I suggest these are included for complete and balanced coverage.  If these are extremely detailed, then they could be mentioned in the text linked with sources or even external links. DrChrissy (talk) 17:34, 4 April 2016 (UTC)
 * The problem is that since there is no consistency in the weighting and there are at least three different ways to obtain ESI (all three of which give different numbers, incidentally), it's difficult to know how to report this accurately. Should we report just the value that has been published (from the 2011 Astrobiology paper?) should we report the one the tables on Wikipedia tend to use (from Méndez's website), or should we report the values from the recent preprint that's on the arxiv? And why? At some point we have to acknowledge that the arbitrary nature of the index and they way it has been used uncritically in the media has resulted in a situation where a calculation is meaningless. What is more meaningful is where the ESI has actually been declared in, for example, popular science articles (where the formula is NEVER given so it's very difficult to know which version was used to calculate the claimed index value). jps (talk) 17:38, 4 April 2016 (UTC)

Also, it's important to understand that Astrobiology as a journal is not exactly a top-notch journal. The quality of papers published in it are variable and this particular paper is one of the poorer ones. jps (talk) 17:40, 4 April 2016 (UTC)
 * There are similar problems in biology. Calculations of e.g. the total number of insects, are rarely given, only the number.  This might be a case of "verifiability, not truth".  I hate to be saying this because as a scientist, I totally disagree with it - as I suspect you might However, it is WP policy. DrChrissy (talk) 17:47, 4 April 2016 (UTC)
 * There may be similar problems in biology, but the biggest issue here is that we have what essentially amounts to a WP:FRINGE claim in astronomy (that this index is meaningful and worth calculating in this fashion). The fact that there are three ways to calculate it which contradict each other and no validation means that we should simply report that the index exists rather than taking sides as to how to calculate it. We also cannot present all possible ways to calculate it since the website, for example, is subject to change. Therefore, it seems reasonable to refer to the places that the index is calculated but not reproduce the formula here. That's the easiest way to guard against failed verification that will crop up if we report actual values, for example. jps (talk) 17:50, 4 April 2016 (UTC)
 * I think the formula has a prominent place in this article, as long as we indicate it is ambiguous. Removing it is akin to removing the Drake equation from the Drake equation article.  Cheers, BatteryIncluded (talk) 02:54, 7 April 2016 (UTC)
 * The problem as I see it is that unlike the Drake Equation, the weights that are proposed for ESI are necessarily tuned and since there is only one example to which to tune them (Earth), many of the exact choices for which combination of weights to use is arbitrary. I think a qualitative description of how the formula works is therefore more advisable than any pretense that this is a consistent calculation. After all, the formula as written would help no one actually calculate anything whereas with the Drake Equation, the calculation is as simple as substituting in estimated values. jps (talk) 13:06, 7 April 2016 (UTC)

My god, but that's an awful source. For our purposes, it certainly identifiees the formula and declares what weights it requires, but it is by far and away the worst paper I've read in a long time. The journal itself is so obscure as to make me wonder whether it really exists. I see that its wikipedia article was started by someone who claims connection with the journal editor. jps (talk) 03:50, 8 April 2016 (UTC)
 * Seems to me that if you simply gave the formula in the article and then condensed this discussion into the article by saying "Note that the weights and parameters of this formula can be tuned and may result in different values", perhaps in a footnote linked to the formula, you'd have solved the entire issue. It seems otherwise completely absurd to have an article about a formula without giving the formula, and jps may argue that this index and its formula are ill-advised until everyone's computers are rotting in the post-nuclear winter, but that won't make that self-evident absurdity go away... LjL (talk) 14:59, 7 April 2016 (UTC)
 * If you cannot actually use the formula for doing anything because the weights keep changing, what's the point of including it? jps (talk) 18:48, 7 April 2016 (UTC)
 * Well, clearly existing ESIs have been calculated from something. We should include that something, since this is the article about that something. If you think these calculated numbers are suboptimal due to the weights keeping changing, then find a reliable source making that particular criticism, and include the criticism into the article. LjL (talk) 23:30, 7 April 2016 (UTC)
 * I have recently included a secondary source quoting the formula. I agree with the need for RS to be provided about criticisms. DrChrissy (talk) 23:34, 7 April 2016 (UTC)
 * Does that source call it specifically Méndez's formula? Because if it doesn't and just claims it is the generally valid ESI formula, then we shouldn't say it's Méndez's. LjL (talk) 23:39, 7 April 2016 (UTC)
 * Yes, I see what you are saying. The article says The Earth Similarity Index (ESI) was developed in the Habitability Lab of the University of Puerto Rico at Arecibo [2]. It is defined as DrChrissy (talk) 23:46, 7 April 2016 (UTC)
 * Edited accordingly. DrChrissy (talk) 23:50, 7 April 2016 (UTC)
 * I am getting totally fed up with your attacks on my editing. You are now publicly accusing me of fabricating a source.  I invite you to strike that accusation against me.  I am seriously wondering about your competence to edit here. DrChrissy (talk) 15:46, 8 April 2016 (UTC)
 * I believe the consensus on the nascency, yet legitimacy, of ESI in the proper context has been established on this talk page and on the various AfDs (though they have not yet closed); many more for than against (ignoring the potentially-sockpuppeted votes). Advances were taken to constrain the wording around its use to address its potentially-mischaracterized usage. If cannot control themselves and deliberately takes actions against established consensus (due to their obviously-strong opinions on the topic), then a topic ban, at the least, would seem appropriate.   ~ Tom.Reding (talk ⋅dgaf)  17:15, 8 April 2016 (UTC)
 * Yes, I had been having similar thoughts myself, based on the increasing disruption to this talk page and the article. DrChrissy (talk) 17:41, 8 April 2016 (UTC)
 * DrChrissy, it is abundantly clear that you WP:WIKISTALKed me here. If you'd like to start a discussion of my behavior, be aware that you are likely to be WP:BOOMERANGed for WP:STICKy issues. I would recommend, Tom, looking into DrChrissy's promotion of pseudoscience on other pages in Wikipedia and look at the topic bans that DrChrissy is subject to and ask yourself whether this is an account on the up-and-up. jps (talk) 17:46, 8 April 2016 (UTC)

Clarification
A colleague pointed me to this discussion and after reading this and other talk sections I can confirm that I’m having a personal attack by user I9Q79oL78KiL0QTFHgyc. This user is actively misrepresenting the work of the Planetary Habitability Laboratory (PHL) to others and blaming only me for its content. I was given the identity of user I9Q79oL78KiL0QTFHgyc but I don’t know him or his motivation. The work of the PHL is based and reviewed by the experts on planetary habitability (shown here), which includes astronomers, planetary scientists, and biologists with a long track of publication in this field. We also get the input from the wide exoplanet community and work with the data and people from the NASA Exoplanet Archive and the The Extrasolar Planet Encyclopaedia. I did notice that there are some issues regarding the representation of our work in Wikipedia pages so I’m open to questions by the creators and editors of the pages to improve them. – Abel Méndez Axmendez (talk) 15:20, 8 April 2016 (UTC)
 * Abel, welcome to Wikipedia. Are you aware of the guidelines around conflict of interest.  If not, I suggest you read WP:COI.  I am not writing this to warn you off, but to help you avoid making mistakes which could end up with other people attacking you. DrChrissy (talk) 15:31, 8 April 2016 (UTC)
 * I'm new here and not familiar with the procedures. I will be quiet and anyone can contact me via email with any question. Thanks. Axmendez (talk) 15:55, 8 April 2016 (UTC)
 * Thank you for joining Wikipedia and being open to questions (albeit under unpleasant circumstances). It is great to have a subject matter expect here to help clarify any issues and/or misunderstandings! If and/or when you feel comfortable replying to questions publicly, it's usually in your best interests to do so, since it would have a much larger and more permanent impact than via email, and will most likely save time.  ~ Tom.Reding (talk ⋅dgaf)  16:26, 8 April 2016 (UTC)
 * Yes, I agree with Tom. I think there are enough friendly faces here and I think we would all appreciate a public discussion here on this Talk page.  By the way, please understand that if you reply to any emails, the recipient will then know your email address.  You might not want this to happen.  You can set up another email address and use this only for wikipedia if you want to keep your other email address private. DrChrissy (talk) 17:13, 8 April 2016 (UTC)

Hi User:Axmendez and welcome to Wikipedia! I hope you don't think I am personally attacking you. It seems to me that the ESI has been used mostly in reference to work with which you have been involved and the only place ESI values are curated is at your webpage. Is that correct? I note that there are some questions as to why there hasn't been any work published in ApJ, MNRAS, or A&A for example. Can you speak to that? Finally, I'm interested in what exact validation the ESI has undergone. The claim is that planets with an ESI ~ 0.8 are close to Earth-like. Why was that threshold chosen? I cannot find a reference for it. Cheers! jps (talk) 17:44, 8 April 2016 (UTC)
 * Axmendez - please do not feel any need whatsoever to answer why you have not published in those journals. As a well-published scientist myself, I know there can be many reasons why we choose to publish or not publish in certain Journals.  I think you should also remember that this talk page is intended to discuss what should and should not be included in the article.  Whilst the answers to the above questions would be interesting, I'm wondering whether the questions should have even been asked. DrChrissy (talk) 18:00, 8 April 2016 (UTC)
 * I think it's relevant enough. He doesn't need to answer of course, but Wikipedia does value both peer review and editorial control of publishing venues (without necessarily requiring either, per WP:RS et al), so the answers to these questions could in fact be of interest to us. LjL (talk) 18:10, 8 April 2016 (UTC)
 * Yes, it is a very pertinent question. If this is supposed to be a genuinely scientific topic, it is quite reasonable to ask why it has a single source that is not peer reviewed, if that is indeed the case. Guy (Help!) 21:26, 8 April 2016 (UTC)
 * To be clear, there is a 2011 paper published in Astrobiology that is peer reviewed that is used as a source in this article, but the numbers provided in that paper differ from the numbers used at Wikipedia and reported at the website being cited. There are also a few other papers that have been found by various Wikipedians that reference ESIs in various ways, but none of them seem to do so consistently and the ones in higher impact journals seem to criticize it implicitly. jps (talk) 21:40, 8 April 2016 (UTC)
 * Why not provide the sources for this criticism and edit them into the article? DrChrissy (talk) 21:51, 8 April 2016 (UTC)
 * It's already in the article. jps (talk) 22:06, 8 April 2016 (UTC)
 * You stated above that The claim is that planets with an ESI ~ 0.8 are close to Earth-like. Where is that claim in the article? Please remember the Talk page is to discuss content in the article. DrChrissy (talk) 18:08, 8 April 2016 (UTC)
 * "The ESI is designed so a planet with a high ESI (values in the range from 0.8 and 1.0) corresponds to one that is of terrestrial rocky composition." jps (talk) 18:14, 8 April 2016 (UTC)
 * I would not interpret "terrestrial rocky composition" to mean "earth-like". DrChrissy (talk) 18:39, 8 April 2016 (UTC)
 * That's what "terrestrial" means. jps (talk) 20:12, 8 April 2016 (UTC)
 * I agree with DRCrissy in this one. That is how the media makes their circuses. Terrestrial means a rocky planet, with silica composition. Translating that to "Earth-like" again implies habitable. BatteryIncluded (talk) 20:18, 8 April 2016 (UTC)
 * Except the only planet in the solar system with ESI > 0.8 is Earth. If it means any rocky planet with silica composition, surely Mercury, Venus, and Mars would have ESIs in that range too, right? jps (talk) 20:32, 8 April 2016 (UTC)
 * The point is that in addition of their maths, their proposed terminology (Earth-like) is misleading. Are we done yet? BatteryIncluded (talk) 20:41, 8 April 2016 (UTC)

I'm not sure I understand what you're saying. I believe that the intention of the index is for planets with an ESI > 0.8 to be considered "most similar" to Earth. I could be wrong in that, but it seems reasonable considering the evidence I've outlined. What I don't know is why 0.8 was chosen as the threshold for this demarcation. That's my main question. jps (talk) 20:57, 8 April 2016 (UTC)
 * So you were against ESI before you were in favor. OK. BatteryIncluded (talk) 02:30, 9 April 2016 (UTC)
 * What? jps (talk) 04:30, 9 April 2016 (UTC)

Thanks all for the welcome to Wikipedia. I know this is complex but interesting topic and I’m impressed with the hard work you put into these pages. I should put a FAQ from these and other questions at some point in the future. Here are some long answers.

What’s the source of ESI numbers?

We maintain Earth Similarity Values (ESI) values in our Habitable Exoplanets Catalog (HEC) for the general science community. The ESI values we use in our catalog are only based on the stellar flux and mass or radius of the planet. Thus they are based on observed values and uniform between the exoplanet data. As we stated in our paper, the ESI is an open metric where the user evaluates their desired parameters. The ESI described in the paper is better as an indirect measure of habitability but it requires more information from the planet (i.e. mass, radius, and surface temperature). We did a prof of concept in the paper using these parameters, which are available for Solar System objects but were modeled for exoplanets. No matter what parameters and formulation you use to define your ESI the common denominator is that as those selected parameters get closer to terrestrial values the ESI value should get closer to one. ESI values calculated with different parameters are not necessarily compatible between them. Other papers propose different formulations or parameters for the ESI and that is perfectly fine.

A common misconception is that ESI values are absolute, but they are relative values between 0 and 1. Therefore, it is more important the ordering of the planets than the actual ESI value or formula to calculate it. As an example of a similar confusion is the definition of the habitable zone (HZ). There are many mathematical formulations of the HZ with a wide variation of limits. This might be interpreted as contradictory but each HZ is defined for certain conditions (e.g. planet similar to Earth, desert planets, H2-dominated atmospheres, etc.) and complement, not replace, each other.

Another misconception is that the ESI pretends to answer the habitability of a planet with a single number. The ESI is an indirect measure of habitability, which means that it only considers a set of those parameters necessary for life, but not all. As a measure of Earth-likeness the term seems to imply ‘all likeness’ with Earth, specially for the general public, but this is a technical term. As we know, all similarities measures are based on a finite set of parameters to be compared, and are only applicable to those parameters. The question we are all seeking is: Are planets with high ESI (i.e. planets with size and stellar flux closer to Earth values) are really habitable? We don’t know yet the answer to this. Many other factors detrimental to life (e.g. lack of water, excessive star radiation, lack of tectonics) could be so common that Earth might be more especial than previously thought. Scientists describe planets with a bunch of numbers (e.g. mass, radius, orbital parameters, composition, etc.), likewise the potential habitability of worlds is described by many numbers (e.g. equilibrium temp, ESI, location in the HZ, star type, etc.).

Most of the cited ESI numbers by the media come from our catalog but others come from the paper, hence the confusion. As long as they are based on the same cited source is fine. The ESI calculation in our catalog is very stable and most changes come from updates to the actual parameters of the planets or the stars. It is up to the editors of this article to include any ESI mathematical formulation. If you include ours (as the first one) just add references to other alternatives (some links below).

Any publications in astronomical journals?

We prefer to publish in astrobiology journals because that is our intended target, a community with astronomers, planetary scientists, and biologists. The creation of habitability metrics is a multidisciplinary task and we want others, specially biologists (i.e. the actual experts on habitability), to contribute more to this effort. On 2012 I co-organized a session on habitability metrics in the NASA AbSciCon 2012 to stimulate more participation outside the astronomy community in this emerging field. Nevertheless, the ESI is cited by the astronomy community (e.g. González et al., 2014; Armstrong et al., 2015; Mia & Kushvah, 2016) and inspired others to create similar or complementary metrics (e.g. Barnes et al., 2015; Chandra et al., 2015; Saha et. al, 2015; Bora at al., 2016). Our Habitable Exoplanets Catalog (HEC) is also cited (e.g. Niedzielski et al., 2014; Wittenmyer et al., 2014; Duncan et al., 2015; Armstrong et al., 2015; Ludwig et al., 2016). All these recent citations include papers from ApJ, MNRAS, and A&A among others.

Why Earth-like planets have an ESI > 0.8?

Earth-like planets are those of terrestrial composition with a temperate atmosphere. This is the definition we used on our 2011 paper to define Earth-like planets. We used an ESI based on radius, density, escape velocity, and surface temperature (i.e. radius, mass, and surface temp are necessary) to put this definition into numbers. The ESI scale was adjusted (via the weight exponents in the formulation) for objects to match this definition for ESI > 0.8. More specifically, if the planets are too small to hold an atmosphere, or too big and hold a hydrogen atmosphere, or not dense enough to be rocky, or with a surface temp outside the complex life limits (0° to 50°C), then they will have an ESI value below 0.8. In other words, a set of some conditions that we all agree are necessary for planets similar to Earth were put into a fuzzy logic number. This is why I call this the scale the “easy scale” because it is a straightforward application of techniques mostly used on biology, chemistry, and computer science to interpret large datasets (e.g. cluster analysis). A way to validate/interpret any ESI scale is by comparing its application with Solar System objects as we did in our paper. Technically, the ESI can be interpreted as a measure of Earth-likeness, or an indirect measure of habitability, or a clustering algorithm given some specific planetary properties. So the 0.8 ESI value comes from the paper formulation but it does not apply to the ESI we use in our catalog since there we use other (observed) parameters (i.e. stellar flux and mass or radius). A threshold value is not a necessary requirement of an ESI formulation.

It is important to note that our catalog uses the widely accepted work of Kopparapu et al., 2014 to identify its sample of potentially habitable worlds and we work together with them on maintaining this sample. The ESI is only used to sort this sample by stellar flux and radius or mass closer to Earth value (i.e. ESI=1), not selecting planets. This seems to be a common misconception in pages such as this. Other metrics that we study also appear in the text and tables of the Wikipedia pages (e.g. SPH, HZD, HZC, HZA) but I recommend to delete them because they are modeled values for comparison purposes. If you want to list the planets tables I recommend to use the simple format of our catalog. I also recommend deleting tables on the Kepler candidates, this here, which are regularly updated by the Kepler Team and are only valuable for scientists selecting targets for validation.

Axmendez (talk) 16:14, 10 April 2016 (UTC)


 * Thanks for posting this response. I have a few follow-up questions, if you may indulge me:
 * You say "if the planets are too small to hold an atmosphere, or too big and hold a hydrogen atmosphere, or not dense enough to be rocky, or with a surface temp outside the complex life limits (0° to 50°C), then they will have an ESI value below 0.8." But I don't understand this because (a) surface temperature can definitely be above 50°C with Earth radius and Earth-like stellar irradiation, and (b) how can we rule out low-density planets from having Earth-like radius and irradiation, and therefore high ESI?
 * You say "it is a straightforward application of techniques mostly used on biology, chemistry, and computer science to interpret large datasets (e.g. cluster analysis)" Does the original ESI paper do any kind of cluster analysis? If so, what kind?
 * When you say "indirect measure of habitability" what do you mean by that? "Indirect measures" tend to refer to proxies for other measurements, but it is unclear to me how an index that is designed by you and your collaborators is a proxy at all and what it's supposed to be a proxy for exactly. Clarity on what you mean by calling ESI a "measurement" (it looks to me to be a way of combining other measurements) and "indirect" would be appreciated.
 * The ESI value compares three (more likely two — even the original paper uses a mass-radius relation for exoplanet examples) observable parameters with Earth: mass, (and/or) radius, stellar radiation. As such, this value is (at most) a basic target selection tool for weeding out planets that are similar to Earth in these limited categories. This can be used for follow-up regarding habitability, but it is not a measure of habitability: that is, a value with an ESI of 0.9 and one with an ESI of 0.7 are not necessarily ordered correctly for their habitability, due to the myriad of other factors involved. Would you agree?
 * Related to this, you say that the ordering property of the ESI is more important than the actual value. Fair enough, but it does not seem to me that the ESI has consistent ordering in the sense that for different weights you have used there have been different orders of various conditional ESIs. In that sense, it does not seem fair to say that a planet with a higher ESI than another is always more Earth-like since this order can be adjusted according to the different weighting schema chosen. Maybe you mean to say that the ESI is your best guess as to a ranking system, but I think it's clear that it could be a situation where a planet with a lower ESI could have life while one with a higher one might not. In that sense it doesn't seem to me that the actual order is all that relevant except to say it is the opinion of those people who have invented the ESI that this is the order. Would you agree?
 * The original 0.8 value comes from the use of surface temperature which is not available for exoplanets, so is it fair to try to include any mention of this threshold with regards to exoplanets on Wikipedia? (I'm thinking of pages that are in particular about specific exoplanets that have been discovered for which your website provides what I surmise to be *estimated* values of the ESI.)
 * You say, It is important to note that our catalog uses the widely accepted work of Kopparapu et al., 2014 to identify its sample of potentially habitable worlds and we work together with them on maintaining this sample." I think you mean that you are only using the ESI after the planet has been identified as in the HZ as defined by Kopparapu et al., 2014. I don't see any evidence that you actually collaborate with the Kopparapu group directly. Is that correct?
 * Thanks again for your response to our concerns here, and I hope you are feeling welcome!
 * jps (talk) 14:22, 20 April 2016 (UTC)

How ESI is calculated
The "Formulation" section explains fully how ESI is calculated by combining a set of values $$x_i$$ using weightings $$w_i$$. But it doesn't specify what any of these values or weightings are. So the reader has no understanding of what the index actually is – making all statements about its value for particular planets worthless. Maproom (talk) 06:09, 15 April 2016 (UTC)
 * Suggested weightings are given here. Perhaps we need to include these in the article? DrChrissy (talk) 16:13, 15 April 2016 (UTC)
 * I think we need to look for people who are independent of Méndez to comment on what weightings are before we include them. jps (talk) 13:45, 28 April 2016 (UTC)

Venus "true color"
The first image on the page showing Mercury, Venus, Earth, and Mars purports to show the planets in "true color". This is a false color radar map of Venus taken by Magellan in the 90s. E.g., https://en.wikipedia.org/wiki/Venus#/media/File:Venus_globe.jpg — Preceding unsigned comment added by 130.132.173.38 (talk) 20:53, 28 April 2016 (UTC)
 * Thanks! Fixed. jps (talk) 22:28, 28 April 2016 (UTC)

ESI for Mars
In the figure at the top of the article, the ESI for Mars is given as 0.797, supported by reference 1. In the text, the ESI for Mars is given as 0.70, supported by reference 8. I suggest this inconsistency should be resolved. EdChem (talk) 16:42, 28 April 2016 (UTC)
 * There is no resolution as there is no agreed upon way to calculate ESI. jps (talk) 16:55, 28 April 2016 (UTC)
 * Does this edit clarify matters at all? This is not very easy to discuss in Wikipedia without engaging in original research. jps (talk) 18:35, 28 April 2016 (UTC)
 * I think it looks silly for two different values to be quoted in one article. However, if there are no reliable discussions of such inconsistencies then as you say policy prevents any comment.  As a scientist, the lack of a reliable discussion of how to determine the unique ESI of a planet / exoplanet demonstrates to me that ESI is either very new or very marginal in its scientific significance.  EdChem (talk) 13:27, 29 April 2016 (UTC)
 * Without specific knowledge, I would imagine the difference is due to the use of different weightings. Other estimates, such as Heritability, also use weighted means.  Both Mars values are verifiable.  Perhaps we should include a sentence early in the article, "Due to the use of different weightings used in the calculation of the ESI, values for single planets may differ slightly"...or words to that effect. DrChrissy (talk) 14:11, 29 April 2016 (UTC)
 * Yeah, I think that might be it. However, when I tried to reproduce the numbers using the weightings that were mentioned in either source, I couldn't, so it might also be due to a difference in which particular temperature, for example, is used or it could be due to an error in the calculation of one of the sources. Since we don't have any sources which explain this, it's a bit difficult for me to know how Wikipedia should handle it. jps (talk) 14:28, 29 April 2016 (UTC)
 * I don't think we have to try to handle this - we are editors here, not scientists. It's absolutely fine to discuss your OR here on the Talk page, but unfortunately, we can not use that as the basis of content for the main article. I have said this before and I really hate saying it again, but on WP verifiability trumps the truth. DrChrissy (talk) 15:34, 29 April 2016 (UTC)

I'm in agreement on this point. Seems to me that the Wikipedia article will just have to reflect the fact that there are two different sourced ESI values for Mars and there isn't much we can do about it. jps (talk) 16:38, 29 April 2016 (UTC)

The formula is broken anyway
Experienced Wikipedians will dismiss this comment as "Original Research".

The formula given in the Formulation section seems so badly designed that it's worthless. Suppose someone finds a planet with a score of 0 for one of the $$x_i$$ values (these aren't listed in the article, so I can't provide a plausible example – rotational velocity, maybe?). Then that value's contribution to the index will be 0, and as these are multiplied together after applying the weightings, the ESI will be 0, regardless of all the other $$x_i$$ values. Maproom (talk) 06:22, 15 April 2016 (UTC)
 * Isn't that exactly what it is supposed to tell us? If a planet has a rotational value=0, this means it is so extremely dis-similar to Earth that the formula calculates this as 0 (zero). DrChrissy (talk) 16:11, 15 April 2016 (UTC)
 * That is not what I would expect a useful index to tell me. For instance, if a planet had rotational value=0 (like Mercury), and that value was among those scored, it would have an ESI of 0, however similar it was to Earth in other respects. Maproom (talk) 17:56, 15 April 2016 (UTC)
 * Maybe that is what the formulators wanted... DrChrissy (talk) 18:32, 15 April 2016 (UTC)


 * Well, Mercury takes 58.6 Earth days to revolve and it is not locked in 1:1 orbital resonance, so its (angular) rotational velocity != 0, and Earth takes 1 day to revolve. Expressing those values as days/rotation and putting them into the formula gives rotation's contribution as 0.14, 0.03, and 6e-9 for the smallest weight (mean radius, 0.57), weight=1, and the largest weight (surface temperature, 5.58), respectively, assuming rotation was the only property (n=1), and assuming the weight that rotation was assigned falls within that range. With 4 other properties (n=5), rotation's contribution can span from 0.68 to 0.51 to 0.02, respectively, making the same assumptions. I would further assume that rotation period would not be assigned as high a weight as surface temperature, which is an outlier among the other weights listed on the website; the others averaging 0.78.


 * It is up the author and/or those using & determining ESI and weights to also determine the best reference units to use for each property; i.e. perhaps (days/rotation)/(days/revolution) is better, or 1/365.25 for Earth, 58.65/87.97 for Mercury, and 1 for anything in 1:1 orbital resonance. Given those values, the 1:1 resonance object has revolution contributions to ESI of 0.55, 0.35, and 0.003 for the 3 weights I used above, respectively, and n=5. In modeling terms, this gives a great deal of wiggle-room for the modelers while only requiring them to modify 1 term (weight), precisely what is intended when modeling (starting from the simplest approximation). When we have more data, 2nd and 3rd order terms (variables) can be added. For now, this is a 1st order approximation.  ~ Tom.Reding (talk ⋅dgaf)  19:51, 15 April 2016 (UTC)
 * I don't think anyone has ever used ESI to model anything. jps (talk) 13:51, 28 April 2016 (UTC)
 * Irrelevant; ESI is a model of Earth similarity.  ~ Tom.Reding (talk ⋅dgaf)  14:10, 28 April 2016 (UTC)
 * Indexes are not models. jps (talk) 16:55, 28 April 2016 (UTC)


 * Zeroes aren't an issue. Quantum mechanics prohibits a temperature of exactly zero. Anything below schwarzschild radius collapses in a black hole. Density and escape velocity can't be zero unless mass is zero, and that is a planet that doesn't exist. Grin.


 * That said, this shouldn't get general usage in the encyclopedia unless it gets more mainstream acceptance. The weightings are completely arbitrary, the factors are somewhat arbitrary (I could easily tweak it to similarly reasonable versions), the result is a weak measure of anything, and the values plugged for exoplanets are often wild guesses. The outside world needs to decide if this is a relevant useful value. Alsee (talk) 15:05, 19 April 2016 (UTC)
 * Totally in agreement at this point. I think it is important that we look for the places where the outside world has commented on this index for consideration as to what ought to be included in this page. Ideas sourced solely to the webpage, for example, probably should be omitted. Emphasis should be placed on the fact that the ESI has been used by the media and amateurs far more than in professional publications, and where it has been used in professional publications it is either handled in an off-handed way, critiqued by the authors, or in venues that are not top-notch. jps (talk) 13:42, 28 April 2016 (UTC)
 * Why not add a "Controversy" section where all these concerns can be edited-in with their RS. DrChrissy (talk) 15:18, 28 April 2016 (UTC)
 * This seems like the most amicable solution that would satisfy both sides of the discussion.  ~ Tom.Reding (talk ⋅dgaf)  15:34, 28 April 2016 (UTC)

I have no problem adding a controversy section (there are sources that can be used listed above). However, this is not a "solution" to the problems mentioned here. jps (talk) 17:08, 28 April 2016 (UTC)
 * A controversy section would be a good place to summarize the discussions here (in an encyclopedic way), would it not?  ~ Tom.Reding (talk ⋅dgaf)  15:24, 29 April 2016 (UTC)
 * The controversies that are sourced above can be reflected in the article, but 's quite legitimate concerns cannot find their way into the article without a source that backs them up. jps (talk) 16:40, 29 April 2016 (UTC)
 * I've addressed their concerns in my response to them.  ~ Tom.Reding (talk ⋅dgaf)  17:29, 29 April 2016 (UTC)
 * Sorry, I meant . jps (talk) 22:22, 29 April 2016 (UTC)
 * If Alsee's concerns have no RS, they can not be introduced into the article. DrChrissy (talk) 22:35, 29 April 2016 (UTC)
 * That was basically my point. jps (talk) 22:38, 29 April 2016 (UTC)
 * So what is the point? I'm sure any editor that is passionate about their subject becomes frustrated at some point because they cannot find an RS to support something they want to say.  It's the nature of being an editor on here, DrChrissy (talk) 22:43, 29 April 2016 (UTC)

If you reread the discussion you'll hopefully see that I was saying that having a controversy section is fine, but it is not a "solution" to the problems outlined. jps (talk) 22:58, 29 April 2016 (UTC)
 * I did read that and you are correct. There is no solution to the problem you perceive.  So where do we go from here? DrChrissy (talk) 23:34, 29 April 2016 (UTC)
 * I think trying to find how sources other than PHL have dealt with ESI is the best we can do. jps (talk) 00:37, 30 April 2016 (UTC)