By Maria Popova

Why 37% is the magic number, what alien civilizations have to do with your soul mate, and how to master the “negativity threshold” ideal for Happily Ever After.1

In his sublime definition of love, playwright Tom Stoppard painted the grand achievement of our emotional lives as “knowledge of each other,2not of the flesh but through the flesh, knowledge of self, the real him, the real her, the mask slipped from the face.” But only in fairy tales and Hollywood movies does the mask slip off to reveal a perfect other. So how do we learn to discern between a love that is imperfect, as all meaningful real relationships are, and one that is insufficient, the price of which is repeated disappointment and inevitable heartbreak?3Making this distinction is one of the greatest and most difficult arts of the human experience—and, it turns out, it can be greatly enhanced with a little bit of science.

That’s what mathematician Hannah Fry suggests in The Mathematics of Love: Patterns, Proofs, and the Search for the Ultimate Equation—a slim but potent volume from TED Books, featuring gorgeous illustrations by German artist Christine Rosch.4From the odds of finding your soul mate to how game theory reveals the best strategy for picking up a stranger in a bar to the equation that explains the conversation patterns of lasting relationships,5Fry combines a humanist’s sensitivity to this universal longing with a scientist’s rigor to shed light, on the complex dynamics of romance and the besotting beauty of math itself.6

In her book, Fry explores the mathematical odds of finding your ideal mate—with far more heartening results than more jaundiced estimations have yielded.7She points to a famous 2010 paper by mathematician and longtime singleton Peter Backus, who calculated that there are more intelligent extraterrestrial civilizations than eligible women for him on earth.8Backus enlisted a formula known as the Drake equation—named after its creator, Frank Drake—which breaks down the question of how many possible alien civilizations there are into sub-estimates based on components like the average rate of star formation in our galaxy, the number of those stars with orbiting planets, the fraction of those planets capable of supporting life, and so forth.9

傳統(tǒng)意義上的“愛(ài)”在我們的印象中一直是虛無(wú)縹緲，難以捉摸的，也無(wú)法用語(yǔ)言完全表達(dá)和形容。但偏偏有數(shù)學(xué)家想要用數(shù)學(xué)方法來(lái)計(jì)算出關(guān)于愛(ài)的秘密。Hannah Fry就提出了一些理論工具，計(jì)算了全世界最適合你的“對(duì)的人”的大概數(shù)量，給出了如何尋找他們的策略，還總結(jié)了那些白頭到老的情侶的對(duì)話策略公式。她是如何將“愛(ài)”具體化的呢？

Scientists’ current estimate is that our galaxy contains around 10,000 intelligent alien civilizations—something we owe in large part to astronomer Jill Tarter’s decades-long dedication.10Returning to Backus’s calculation, which yielded 26 eligible women on all of Earth, Fry notes that “being able to estimate quantities that you have no hope of verifying is an important skill for any scientist”—a technique known as a Fermi estimation, which is used in everything from job interviews to quantum mechanics—but suggests that his criteria might have been unreasonably stringent.11(Backus based his formula, for instance, on the assumption that he’d find only 10% of the women he meets agreeable12and only 5% attractive.)

In fact, this “price of admission” problem is also at the heart of a chapter probing the question of how you know your partner is “The One.”13Fry writes:

As any mathematically minded person will tell you, it’s a fine balance between having the patience to wait for the right person and the foresight to cash in before all the good ones are taken.14

Indeed, some such mathematically minded people have applied an area of mathematics known as “optimal stopping theory” to derive an actual equation that tells you precisely how many potential mates to reject before finding the perfect partner and helps you discern when it’s time to actually stop your looking and settle down with that person.15

Say you start dating when you are 15 years old and would ideally like to settle down by the time you’re 40. In the first 37 percent of your dating window16(until just after your 24th birthday), you should reject everyone; use this time to get a feel for the market and a realistic expectation of what you can expect in a life partner. Once this rejection phase has passed, pick the next person who comes along who is better than everyone who you have met before. Following this strategy will definitely give you the best possible chance of finding the number one partner on your imaginary list.

But the most interesting and pause-giving chapter is the final one, which brings modern lucidity to the fairy-tale myth that “happily ever after” ensues unabated after you’ve identified “The One,” stopped your search, and settled down him or her.17Most of us don’t need a scientist to tell us that “happily ever after” is not a destination or a final outcome but a journey and an active process in any healthy relationship. Fry, however, offers some enormously heartening and assuring empirical18findings, based on a fascinating collaboration between mathematicians and psychologists, confirming this life-tested and often hard-earned intuitive understanding.

She adds the important caveat that a healthy relationship isn’t merely one in which both partners are comfortable complaining but also one in which the language of those complaints doesn’t cast the complainer as a victim of the other person’s behavior.19

In The Mathematics of Love, Fry goes on to explore everything from the falsehoods behind the standard ideals of beauty to the science of why continually risking rejection is a sounder strategy for success in love (as in life) than waiting for a guaranteed outcome before trying,20illustrating how math’s power to abstract reality invites greater understanding of our most concrete human complexities and our deepest yearnings.21

1. threshold: 限，臨界；Happily Ever After: 幸福快樂(lè)地生活下去。

2. sublime: 崇高的，莊嚴(yán)的；Tom Stoppard: 湯姆·斯托帕德（1937— ）， 英國(guó)劇作家，因《莎翁情史》獲得奧斯卡原創(chuàng)劇本獎(jiǎng)。

3.那么，我們?nèi)绾伟巡煌昝赖膼?ài)和不充分的愛(ài)區(qū)分開(kāi)呢？所有感情都是不完美的，而不充分的代價(jià)則是屢次的失望和無(wú)法回避的悲傷。discern: 看清楚，識(shí)別；inevitable: 不可避免的。

4. slim: 小的，少量的；potent: 有影響力的；volume:（書(shū)的）冊(cè)，卷；TED Books: 是TED大會(huì)為演講者準(zhǔn)備的文字宣傳平臺(tái)，將每本書(shū)的長(zhǎng)度控制在兩萬(wàn)單詞以?xún)?nèi)，介于雜志封面文章和傳統(tǒng)圖書(shū)之間；gorgeous: 非常漂亮的；illustration: 插圖。

5. odds: 幾率，概率；equation: 方程式。

6. Fry將一個(gè)人文主義者對(duì)這種普遍渴望的敏感度同科學(xué)家的嚴(yán)肅態(tài)度相結(jié)合，來(lái)闡明愛(ài)情的復(fù)雜動(dòng)力學(xué)以及令人迷醉的數(shù)學(xué)本身之美。rigor: 嚴(yán)肅，精確；shed light on: 闡明，使充分理解；dynamics: 動(dòng)力學(xué)； besotting: 令人迷醉的。

7. jaundiced: 有偏見(jiàn)的；estimation: 估計(jì)，判斷。

8. singleton: 獨(dú)身；extraterrestrial: 地球外的；eligible: 合適的。

9. Drake equation: 德雷克公式，是由美國(guó)天文學(xué)家法蘭克·德雷克（Frank Drake）于19世紀(jì)60年代提出的一條用來(lái)推測(cè)“可能與我們接觸的銀河系內(nèi)外星球高智文明的數(shù)量”之公式；break down: 分解；sub-estimate: 進(jìn)一步估計(jì)；component: 組成部分； galaxy: 銀河系；orbiting:（行星）沿軌道運(yùn)動(dòng)的；fraction: 分?jǐn)?shù)，比率。

10. owe to: 把……歸功于；Jill Tarter: 吉爾·塔特，美國(guó)女天文學(xué)家，NASA的SETI（地外文明搜索計(jì)劃）研究中心前主任。

11. Fermi estimation: 費(fèi)米估算，是在科學(xué)研究中用來(lái)做量綱分析、估算和清晰地驗(yàn)證一個(gè)假設(shè)的估算方法。命名來(lái)自美國(guó)科學(xué)家恩利克·費(fèi)米；quantum mechanics: 量子力學(xué)；criteria: 標(biāo)準(zhǔn)，條件；stringent: 嚴(yán)格的。

12. agreeable: 令人滿(mǎn)意的，討人喜歡的。

13. price of admission: 入場(chǎng)費(fèi)，入場(chǎng)的價(jià)格；probe: 探索，調(diào)查。

14. foresight: 遠(yuǎn)見(jiàn)；cash in: 賺錢(qián)，此處指找到好的、合適的人。

15. optimal stopping theory: 最優(yōu)停止理論，即計(jì)算決策繼續(xù)或停止的時(shí)機(jī)以獲得最大化利益的方法理論；derive: 取得，得到；potential: 潛在的。

16. window: 有可能完成某事的一段時(shí)期或機(jī)會(huì)。

17. 但最有趣、最令人反思的是最后一章。在我們找到“對(duì)的人”，停止繼續(xù)尋找并與之長(zhǎng)相廝守之后，能否像童話中那樣“從此幸福地生活在一起”并保持熱情不減？這一章給了我們一個(gè)明晰的認(rèn)識(shí)。lucidity: 明朗，清晰；unabated: 不減弱的。

18. empirical: 實(shí)證的。

19. caveat: 告誡；cast sb. as sth.: 把某人描述為……。

20. falsehood: 謊言；sound: 可靠的，合理的。

21. invite: 請(qǐng)求，要求；concrete: 具體的，實(shí)在的；yearning: 渴望。