Talk:Escape velocity

Article title: "Escape Velocity" vs. "Escape Speed"

There have been several mentions on this talk page that the term "escape velocity" is a misnomer, as it's actually a speed and not a velocity. The reason given previously for keeping the title of the article as "Escape Velocity" is that "escape velocity" is the more commonly used term in most circles, and WP:COMMONNAME tells us that we should use the most recognizable title. However I contend that this is an improper usage of the WP:COMMONNAME policy, as it also says:

"Ambiguous or inaccurate names for the article subject, as determined in reliable sources, are often avoided even though they may be more frequently used by reliable sources. [...] When there are multiple names for a subject, all of them fairly common, and the most common has problems, it is perfectly reasonable to choose one of the others."

"Escape velocity" is outright wrong, and as such I don't believe that WP:COMMONNAME is in any way telling us that we have to continue to use an incorrect title. While "escape speed" may not be quite as common as "escape velocity", it is still an often-used term in many resources, and it's quite easy for the average person to understand what is meant. I highly doubt that anyone would be confused by an article titled "Escape Speed", even if that person were accustomed to the concept being called "escape velocity". I nominate that the title of the page and all references in it to "escape velocity" be changed to "escape speed", and a sentence added in the introduction that mentions the confusion in other sources. KingSupernova (talk) 06:39, 7 February 2018 (UTC)

The literature seems to strongly disagree:

Google	Scholar	Books	Web
"escape velocity"	37,900	93,000	505,000
"escape speed"	6,900	12,600	144,000

Wikipedia is here to reflect the literature. - DVdm (talk) 06:56, 7 February 2018 (UTC)

DVdm I don't mean to be rude, but I think you need to read my post again. KingSupernova (talk) 19:13, 8 February 2018 (UTC)

And you mine - DVdm (talk) 19:27, 8 February 2018 (UTC)

Well if you refuse to make any sort of intelligent statement and instead stick with vague insults and implications, then I doubt we're going to have any sort of reasonable discourse. If you care to compose an actual response or refutation to my original statement, I will happily read though it. KingSupernova (talk) 05:26, 9 February 2018 (UTC)

If it is true that,"When there are multiple names for a subject, all of them fairly common, and the most common has problems, it is perfectly reasonable to choose one of the others.", then, since your own figures show that "escape speed" is fairly common (used in about 10% to 20% of all cases, including those in non-physics publications), it seems to me that it logically follows that you should be agreeing with KingSupernova's conclusion. The data you provide in fact supports KingSupernova's position, surely? Arctic Gazelle (talk) 00:35, 2 September 2021 (UTC)

I find KingSupernova's argument convincing and would support a move to "Escape Speed" with a redirection from "Escape Velocity". —Ka-Ping Yee (talk) 05:39, 13 November 2021 (UTC)

Given what the literature says, I think that KingSupernova's argument is irrelevant. Wikipedia is still here to reflect the literature. - DVdm (talk) 10:22, 13 November 2021 (UTC)

Otoh, I agree with your edit, apart from this little tweak, that is. - DVdm (talk) 13:24, 13 November 2021 (UTC)

Update, see #Moved against literature consensus. - DVdm (talk) 12:19, 29 December 2023 (UTC)

Black hole

Black holes are objects from General Relativity, and the fact that their escape velocity at the event horizon is c is merely a coincidence. Light can't escape from it, but it's not because of the escape velocity. See the History section of [Black holes]: "Modern relativity factually dispels Michell's (this) notion of a light ray shooting directly from the surface of a supermassive star, being slowed down by the star's gravity, stopping, and then free-falling back to the star's surface."

I thought about plainly deleting that, but we might want to delete the link to black holes altogether. Opinions? LucasFehlau (talk) 11:43, 30 May 2018 (UTC)

This has since been cleaned up. -- Beland (talk) 09:03, 26 January 2024 (UTC)

Multiple bodies section

It would be nice to get some references in this section so that readers interested in the derivation of this expression, and how the assumptions play into this result, have some leads.

207.38.134.235 (talk) 22:19, 16 January 2021 (UTC)

Yes, that would be nice. And necessary. I have tagged the section for sources. I will remove it per wp:NOR in a month or so. Thanks for having noticed. - DVdm (talk) 22:32, 16 January 2021 (UTC)

A month has gone by. I have removed the unsourced section. - DVdm (talk) 14:45, 16 February 2021 (UTC)

The section should be restored as this formula trivially follows from the previous section, namely the hyperbolic excess speed formula. Moreover, the next section uses the currently deleted formula for the system escape speed column. One can find full derivation from scratch in Italian, Russian, and Ukranian Wikipedias. The formula can also be found in Hendel, A. Z. Solar escape. The only difference is using the escape speed for the second body instead of the orbital speed; however, it is well-known and mentioned in this English article that they are proportional with the coefficient ${\sqrt {2}}$. Anton Lapounov (talk) 19:26, 8 December 2021 (UTC)

Possible correction about first manmade object to reach escape velocity

"Luna 1, launched in 1959, was the first man-made object to attain escape velocity from Earth (see below table)." Sputnik was 2 years earlier, why is this not listed? The source number 5 seems to not make such a claim as the image caption does. HolmKønøman (talk) 22:26, 5 May 2022 (UTC)

@HolmKønøman: Sputnik never achieved escape velocity. It only ever orbited Earth before burning up in the atmosphere. I added a link to List of solar system probes for verification. -- Beland (talk) 09:21, 26 January 2024 (UTC)

Comparison to Economic Order Quantity Formula

Has anyone ever been to the economic order quantity Wikipedia article and noticed how that formula is remarkably similar to the Escape Velocity formula? Would it be justified to add that observation into the article or not?

Theboombody (talk) 22:20, 24 May 2022 (UTC)

I don't think so; they have nothing to do with each other, and the fact they both use the denominator in a square root is a coincidence. -- Beland (talk) 09:05, 26 January 2024 (UTC)

Surface gravity units

In the lede:
For example, the escape speed from Earth's surface is about 11.186 km/s (40,270 km/h; 25,020 mph; 36,700 ft/s) and the surface gravity is 9.8 m/s (35 km/h; 22 mph; 32 ft/s).
The units of gravity are those of acceleration (m.s^-2), but those given in this sentence are velocity. Or am I missing something? Wocky (talk) 23:32, 26 September 2022 (UTC)

Good catch; that's since been fixed to m/s². -- Beland (talk) 09:24, 26 January 2024 (UTC)

Physics

Q:How much velocity is needed to go out the range of gravitational field and who we named it? 103.200.197.234 (talk) 10:11, 13 February 2023 (UTC)

Moved against literature consensus

User KingSupernova (talk · contribs) moved the article from Escape velocity to Escape speed with an edit summary "Perform requested move, see talk page: Moving to a more accurate title". As far as I can see, their own request dates from November 2021, and there was no consensus for it. Moreover, the literature seems to favour the original name even more than two years ago:

Google	Scholar	Books	Web
"escape velocity"	56,200	196,000	4,720,000
"escape speed"	9,810	16,200	263,000

I strongly propose to move it back to the original consensus version. - DVdm (talk) 11:55, 29 December 2023 (UTC)

Even without taking into account the wider usage of the term escape velocity above, something like this should have been properly requested and not based on a discussion from two years ago because it's clearly uncontroversial. That being said, I wouldn't be opposed to the change because escape velocity is indeed a misnomer. Sgubaldo (talk) 13:30, 30 December 2023 (UTC)

Some textbooks below:

Escape velocity:

Muncaster - A level textbook, 1993 (this one is in the article already).

Classical Dynamics of Particles and Systems - an older textbook, Chapter 5.

Escape speed:

My copy of Young and Freedman says escape speed (14th Global Edition, Chapter 13, p. 430) - I don't have a pdf to share for this.

Gregory's Classical Mechanics uses escape speed in a couple of examples (Pp. 77–78 & & 143–144) - the Google Books link might not be of much help but if someone else has a copy they should be able to corroborate.

Both:

Carrol and Oslie's An Introduction to Modern Astrophysics (the international edition) uses escape velocity (p. 639, 695, 696, 713, 796) and escape speed (p. 45, 47, 794, 886).

Sgubaldo (talk) 14:40, 30 December 2023 (UTC)

This one is both simple and complex.

Simple, as it was very inappropriate to make a move two years after a brief discussion with no obvious consensus.

Complex, as while it is true that "escape velocity" is the more common term, pedantically it can be considered as less accurate. Velocity is a vector, whereas speed is a scalar. The appropriate term to use is kind-off a scalar, since so long as the velocity does not lead to a collision only the scalar value matters.

Hence it therefore a range of vectors, not just a simple scalar -- directions that collide must be excluded.

Since neither term is 100% rigorous, and pedantic considerations should not enter into the choice of a name, we should use the most common term. Therefore I vote Revert back to Escape velocity. Ldm1954 (talk) 15:16, 30 December 2023 (UTC)

@Ldm1954 Did you read the Talk:Escape_speed#Article_title:_"Escape_Velocity"_vs._"Escape_Speed" topic? It was 3 for move vs one loud against move. Rather than inappropriate it seems to me that this move was done with careful deliberation. Johnjbarton (talk) 15:46, 30 December 2023 (UTC)

@Johnjbarton, three to one is not a big consensus, particularly since the discussion is two years old. I would have liked to see this much more widely discussed, with input from users with fairly extensive experience (such as you) first. Hopefully a few more will chime in including a few with higher level admin privileges. Ldm1954 (talk) 15:58, 30 December 2023 (UTC)

Perhaps, but the move was less a crime against wikipedia and more a minor excess of enthusiasm. Johnjbarton (talk) 16:12, 30 December 2023 (UTC)

Ok so it looks like consensus is 4 to 2, but not 3 to 1 ;-) Johnjbarton (talk) 23:55, 30 December 2023 (UTC)

@Johnjbarton: well, wp:CONSENSUS is not really about voting. The thing here is that there was a lack of consensus to make a change, and per wp:NOCONSENSUS, "When discussions of proposals to add, modify, or remove material in articles end without consensus, the common result is to retain the version of the article as it was prior to the proposal or bold edit." Cheers and a happy year-ending! - DVdm (talk) 00:43, 31 December 2023 (UTC)

@DVdm Sorry, that makes no sense. The previous discussion and this one are very similar. The previous discussion was as much a "consensus" as this one. The only real difference I see is that you agree with this outcome and not the other one. I have no problem with the outcome, but I disagree with the negative characterization of the move. There is no value in dumping on the other editor who was doing something they thought was right, with a good edit summary, and preceding Talk discussion. Seemed very on the up and up to me. Johnjbarton (talk) 01:30, 31 December 2023 (UTC)

Leave the rename. Both terms are used in the sources, so everyone should realize this is not a big deal either way. I pick "speed": this is a physics page and the physics favors "speed". The internet vote is not a determining factor: we don't generally let the internet vote on physics. Johnjbarton (talk) 16:17, 30 December 2023 (UTC)

• Revert move. "Escape velocity" is the overwhelming COMMONNAME. The "velocity is a vector" stuff is mostly for physics education, so you can get high-school students to understand that e.g. constant motion in a circle is acceleration, but it's an arbitrary assignment of the Latinate word to the vector quantity; in real physics it's perfectly fine to use the word "velocity" for a scalar. --Trovatore (talk) 17:41, 30 December 2023 (UTC)
• Revert move and put it back to "escape velocity", the actual term that people actually use. Wikipedia is not a vehicle for imposing pedantry. XOR'easter (talk) 22:42, 30 December 2023 (UTC)

Note: I have restored the original common name per WP:RMUM and WP:COMMONNAME ([1]) and the version before the undiscussed change ([2]). Thanks all for your input. - DVdm (talk) 23:11, 30 December 2023 (UTC)

Requested move 11 January 2024

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: Not moved. Early close due to unanimous opposition and a rather inaccurate nomination statement. (non-admin closure) SnowFire (talk) 16:33, 14 January 2024 (UTC)

---

Escape velocity → Escape speed – The previous discussion on this subject ended with a 3:1 consensus in favor of moving. The only dissenter was user DVdm, who ignored the argument in favor of the move and voted against it without providing justification. I performed the move, and DVdm reverted the move, again without providing any reasoning for this behavior. The page move is clearly correct as per WP:COMMONNAME's stated policy of avoiding inaccurate article titles in cases where there exists a literature consensus that the most frequently used name is inaccurate. I believe user DMdm has acted inappropriately by reverting a page move despite clear support for the move in Wikipedia policy *and* a consensus in favor of the move among editors. Additionally, DVdm's consistent refusal to provide a justification for their opposition to the page move is a violation of Wikipedia's norms around reaching consensus through good faith discussion. I propose that the move to Escape speed is performed as per the reasons presented in Talk:Escape_speed#Article_title:_"Escape_Velocity"_vs._"Escape_Speed", and if necessary moderator action is taken to prevent further vandalism from user DVdm. KingSupernova (talk) 06:57, 11 January 2024 (UTC)

•  Comment: Acting 2+ years later on a poorly-attended discussion (that was actually started 5 years ago and only attracted more comments after several years, and claiming "that's consensus now and it's vandalism for someone to require a current discussion with status-quo pending that" is troubling in at least three ways. It's completely reasonable to have a fresh RM discussion. But an occasional comment or two scattered over several years is not a real discussion that can be claimed as "consensus". And it's not correct to demand that the apparently-ignored old discussion is the default...too much stale-discussion and involved-editor activity here. I'm saying that all as admin, since oyu have requested admin assistance. DMacks (talk) 07:43, 11 January 2024 (UTC)

Note: WikiProject Spaceflight has been notified of this discussion. Vanderwaalforces (talk) 08:11, 11 January 2024 (UTC)

Note: WikiProject Physics has been notified of this discussion. Vanderwaalforces (talk) 08:15, 11 January 2024 (UTC)

Note: WikiProject Astronomy has been notified of this discussion. Vanderwaalforces (talk) 08:16, 11 January 2024 (UTC)

• Oppose: Current count of relevant terms in the literature (and, less importantly on the web)

Google	Scholar	Books	Web
"escape velocity"	56,900	158,000	4,310,000
"escape speed"	9,830	16,300	299,000

Per wp:COMMONNAME, this always has been a no-brainer.

In the preceding section I don't see that it "ended with a 3:1 consensus in favor of moving". As far I can see, the wp:CONSENSUS policy is not about counting, "nor is it the result of a vote", but it clearly ended with a consensus in favor of Revert move to Escape speed. Also per wp:NOCONSENSUS ("When discussions of proposals to add, modify, or remove material in articles end without consensus, the common result is to retain the version of the article as it was prior to the proposal or bold edit."): there never was a consensus for the move to Escape speed to begin with.

And I think that a phrase like "...moderator action is taken to prevent further vandalism from user DVdm." can be taken as a personal attack. - DVdm (talk) 08:38, 11 January 2024 (UTC)

• I will quickly note that I'm noticing that many Google Scholar results for "Escape Velocity" are not about physics, but use it as a metaphor (for for example social sciences). If we want to follow the literature, we should look at appropriate publications. Sources like JPL would be relevant, as well as perhaps styleguides of technical journals. I'm having a hard time Googling for this, however. ~Maplestrip/Mable (chat) 09:04, 11 January 2024 (UTC)

Even when I explicitly add "gravity" to my Google Scholar search, the top results still discuss family therapy, a digital search algorithm, and the battle on aging. Maybe also helpful to keep in mind that a specific escape speed could be an escape velocity: in the physical world, all speed is velocity. This might affect sources too, but we are not writing about a specific escape velocity here. ~Maplestrip/Mable (chat) 09:07, 11 January 2024 (UTC)

Indeed, if there is a speed, there is a velocity. If there is an escape speed and you take direction into account, then there is an escape velocity. But even then, there is nothing wrong with saying that some velocity has a certain value: every reader (and certainly every physicist and engineer) will know that you actually mean that the velocity's magnitude has that particular value. - DVdm (talk) 09:14, 11 January 2024 (UTC)

In theoretical physics, the distinction is helpful. If we can remove the assumption that escape speed depends on direction, that would be great. I'd like to see an actual literature review here though, rather than merely a numbers game. But genuinely, I don't really know how to access the right sources for such a thing... ~Maplestrip/Mable (chat) 09:42, 11 January 2024 (UTC)

But the article already removes any assumption that escape speed depends on direction. It says: "it is more accurately described as a speed than a velocity because it is independent of direction", which is why I agreed on 13 November 2021 with that earlier edit. - DVdm (talk) 09:47, 11 January 2024 (UTC)

• Oppose move – I realized what makes sense: actually looking through the sources used in the current article. I could access a majority of them, and only one [3] of them uses "escape speed" rather than "escape velocity." All the others I can access use "velocity" throughout. If these are the sources we consider appropriate for this subject, we should follow their lead. ~Maplestrip/Mable (chat) 09:49, 11 January 2024 (UTC)

Comment This request is troubling in a few way: there was no previous requested move, rather a small forgotten discussion a few years before a move, wp:consensus is not a vote; the rational for this move is wp:or as it goes against literature; and immediately accusing another editor of vandalism for reverting an undiscussed move is disruptive. At the very least wp:AGF—blindlynx 16:03, 11 January 2024 (UTC)

• Oppose move Unless it can be shown that there is a significant movement in the relevant physical science literature to change the common term, Wikipedia should stick with Escape Velocity. As noted in a comment further up the page from Ldm1954, neither term is quite correct, so there's not a completely obvious choice, I don't think. - Parejkoj (talk) 16:55, 11 January 2024 (UTC)
• Oppose move per WP:COMMONNAME PianoDan (talk) 19:23, 11 January 2024 (UTC)
• Oppose move per COMMONNAME. Note in passing, not strictly on-topic here: Because of the history of English, it very often has two words for the same thing, one deriving from Latin and/or French, and one coming from the language's Germanic "genetic" roots ("genetic" in this sense having nothing to do with DNA).
  In this case, "velocity" and "speed" are simply the Latinate and Germanic words, respectively, for the same thing. Latin velox simply means "fast", not "fast in a particular direction".
  Now, for purposes of physics education, it's convenient to have different words for the vector quantity and its magnitude, specifically because students would otherwise be likely to confuse them. In actual science, this confusion is much less likely, and therefore the arbitrary choice of the Latinate word for the vector and the Germanic one for its magnitude is much less important and less strictly observed. --Trovatore (talk) 20:33, 11 January 2024 (UTC)
• Oppose as velocity is the most common word used for this. Graeme Bartlett (talk) 20:47, 11 January 2024 (UTC)
• Oppose per my earlier remark that Wikipedia is not a platform for advancing pedantry. Without evidence of, as Parejkoj put it above, a significant movement in the relevant physical science literature to change the common term, "velocity" is fine. XOR'easter (talk) 17:30, 13 January 2024 (UTC)
• Oppose I don't see any evidence for "common name" favouring the proposed title. Azuredivay (talk) 19:26, 13 January 2024 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Link to Parabolic trajectory article?

This article might be improved by an early link to Parabolic trajectory, which covers the celestial mechanics fairly well. Is it appropriate to do that in the lede section? (sdsds - talk) 00:30, 1 February 2024 (UTC)

Oh there it was, with the target parabola rather than parabolic trajectory. (— 𝐬𝐝𝐒𝐝𝐬 — - talk) 09:44, 27 February 2024 (UTC)

Frame of reference

Currently the article uses speed (and velocity) without mention of a particular frame of reference. There's the implicit assumption the primary body is fixed and all the motion pertains to the secondary body (with mass m << M). The article would be improved either by making that explicit, or by discussing the relative velocity of the two bodies. The second alternative has much less practical application, and is well covered in the Two-body problem article. (— 𝐬𝐝𝐒𝐝𝐬 — - talk) 10:10, 27 February 2024 (UTC)