Escape Velocity

By Maeve Maddox

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Reader Vinayak Naik wants to know how the term “escape velocity” has come to be used in connection with social justice.

The expression derives from a scientific term defined as “a speed sufficient to overcome the gravitational force of a planet.”

The Earth, with a diameter of 7,918 miles, has an escape velocity of 25,000 miles an hour. The moon, with a diameter of only 2,16 miles, has an escape velocity of 5,320 mph. The planet Jupiter, with a diameter of 86,881 miles, has the greatest escape velocity of all: 133,018 mph.

The term seems to have gained its buzzword status as the result of an academic paper published in the American Economic Review (Vol. 103, 2013) by two Harvard economists: “Achieving escape velocity: Neighborhood and school interventions to reduce persistent inequality.” Authors Roland D. Fryer and Lawrence F. Katz examine policies needed to enable young people in poor neighborhoods to “escape the gravitational pull of poverty.”

Before the publication of the social studies paper, the expression enjoyed some popularity as a book title, for example, Escape Velocity: Cyberculture at the End of the Century, published in 2007, and Escape Velocity: Free your company’s future from the pull of the past, published in 2011.

Since mid-2013, escape velocity has achieved buzzword status, not only for social reformers, but also for bankers, artists, and publishers:

The U.S. economy has had trouble rising above a 3% growth rate since the financial crisis, a line in the sand often cited as the threshold for achieving “escape velocity” of sustainable expansion. — Matthew Boesler, Business Insider, Nov. 7, 2013.

After the announcement a year ago of his appointment as Governor of the Bank of England, Mark Carney worried publicly and repeatedly that Britain’s economy had not yet achieved “escape velocity”. — London Times, November 14, 2013.

“We believe the missing links for the economy to achieve ‘escape velocity’ are real estate, banks, and small businesses,” Michael Hartnett, investment strategist quoted in Business Insider, November 2013.

Once a striking metaphor, escape velocity is on its way to becoming just another cliché.

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9 Responses to “Escape Velocity”

  • John

    “The Earth, with a diameter of 7,918 miles, has an escape velocity of 25,000 miles an hour….” Ok! But, more precisely, the escape velocity depends on the mass of the planet or moon. Merry Christmas.

  • Nelida K.

    @John: You are right that mass comes into the equation, but so does radius (i.e., diameter in layman’s terms). To be exact, and as provided by Wolfram Alpha, the formula to calculate the escape velocity to pull away from a gravitational field is the following:
    Speed = Square root of: 2Gm/r (where G is the Newtonian gravitational constant, m is mass, and r is radius).

    @Maeve: Physics and astronomy precision aside, the subject matter of your post was the ‘buzziness’ or ‘buzzworthiness’ (whichever is the buzziest alternative, pun intended, haha) of the term, and from that perspective, I thank you for sharing because I was not entirely aware and I love learning something new every day (and especially on Xmas. morning…). So, thank you for sharing and my best Season’s greetings, from a sweltering warm Montevideo (35 ºC and sunny today!), to you and all readers and contributors to this very interesting blog.

  • vinnie

    Wish you Merry Christmas and thank you for wiring an article on a word ‘Escape velocity’. I remember I have asked you about this word a month ago and you told me you would write it on your website. I am daily reader of your writing tips. I found your site is very useful. Thanks again for sharing a knowledge with us.

  • Dale A. Wood

    I agree that the misuse and overuse of the term “escape velocity” is despicable. (I can’t think of a more appropropriate word for it. Please suggest some more. Maybe “an abomination”.)
    I despise such misuses and overuses, just as Maeve does.
    Note that you misstated the diameter of the Moon by a factor of 10. The diameter of the Moon is given in thousands of miles or kilometers, and not in hundreds of miles or kilometers. In round numbers, the diameter of the Moon is about 2100 miles, not 210 or 220.
    The mass of a planet, moon, asteroid, etc., is the more important factor than the radius. Actually, the escape velocity from an object depends on your radius from its center. For example, the escape velocity from the surface of the Earth is larger than the escape velocity at a distance of 40,000 kilometers from its center.

    It is common to define the escape velocity from the “surface” of an astronomical object, but the there is the problem that the Sun, Jupiter, Saturn, Uranus, and Neptune do not have a surface. Years ago, it was thought that the outer planets did have surfaces, and a “surface gravity” for each object, but this was shown to be false. What astronomers thought was the surface was merely the tops of the clouds. Below that, the atmosphere gets denser and denser, and it gradually changes into a liquid, but no surface is ever seen.

    This can be shown by radio measurements – via space probes – and radar measurements from the Earth. The distance from the Earth to Jupiter can be measured by radar, but because the Jupiter does not have a definite surface, those measurements always have a tolerance of something like plus or minus three percent.
    Note that I wrote “something like” because the situation might not be quite so bad. Maybe it is only plus or minus one percent.

  • thebluebird11

    @Nelida: And happy holidays to you as well from South Florida (SoFla), where it is only about 25 degrees C (73), sunny and breezy! Almost like Hawaii 🙂 The rest of the continental US hates us LOL

    @Maeve et al: I appreciate this post, since the rock I live under is pretty soundproof and I had never heard the expression “escape velocity” before. I think it’s a wonderful expression and very appropriate for all the uses above. It makes me feel as if pulling oneself up by one’s bootstraps might be more difficult that one would think, no matter what planet one is on!

  • John

    @Nelida Yes, you’re right. I simply pointed out that it is better to take into account the mass, if we want to give only a parameter when it comes to escape velocity.

  • venqax

    But what about excape velocity? How many would hem and haw over surface to not-really-the-surface, radius vs diameter vs parameter vs parking meter, mass-not-size, and tolerances of 3 to 1 percent
    (for crying out loud) and yet wouldn’t even notice the excape of an errant K sound rudely injecting itself into the conversational equation. Sorry, I’m still stuck on alternate pronounciations.

  • Dale A. Wood

    Venqax, you are just being rude and intolerable. Did Santa Claus bring you a lump of coal, for crying out loud?
    So many people do not know anything at all about tolerances on measurements, and they do not know that the most important parameter in calculating an escape velocity is the mass of the astronomical object concerned – hence I explained something about it.

    Tolerances on measurements are not just a matter of carelessness and stupidity. Many times the tolerance is there because quantities like “the radius of Jupiter” or “the radius of the Sun” cannot be defined exactly, hence radar cannot measure them exactly.
    I have mentioned here before that it is very desirable to understand the science and the engineering behind things before you quibble about the semantics.
    Nelinda K did not say so in these words, but she alluded to it with her equation for the escape velocity. I went a little further by saying that the “radius” in that equation is often not known exactly, and that there is a good reasons for that fact: the “surface” is not well-defined.

    Often, you need to “take the bull by the horns” concerning the science. It does neither you nor anyone else to GRIPE about this.

  • venqax

    Oh, spare us DAW. You are exhibiting one of your other-than-endearing traits. This isn’t a science or engineering site. It is a language site. That aside, I don’t think scientific or technical precision is unimportant. My POINT was that we should give the same attention to precision regarding language use and, specifically, PRONUNCIATION. Hence my comment. I’m sure under many circumstances a group of engineers could argue for hours about some scientific minutiae regarding excape velocity without ever once remarking on the fact that one or more of them says “excape” velocity. THAT is a problem, too. On THIS site, it is MORE relevant to point out language issues than to bash misunderstandings of scientific concepts.

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