Immortality. In movies, kings are always searching for the secret to immortality. But is immortality really a good thing? To a ten-year-old boy, one year is the same as 10% of his life. To his forty-year-old mother, one year is merely 2.5% of her life. The same year, 365 days, can feel differently to different people. If we live until we're 82, that's about 30,000 days. If this boy lives for 30,000 years, a year to him could feel like a day. And if this boy's emotions sustain through the potential boredom of living for millions of years, he might become extremely lonely and sad, knowing he has and always will outlive everyone he has ever loved. But what if everyone were immortal? Well, first off, Earth is only so big. So, where would we all live? (Grunts) "Excuse me!" "That's my face!" "Stop it!" "Pardon me." "Tight in here!" Do you remember what you did last year or when you were five? How much of your past have you forgotten? If you have trouble remembering what you did when you were five, how will you remember what happened if you were alive a thousand years ago? A million years ago? We don't remember every single detail of our past because our brains have a limited capacity and we replace useless memories, like middle school locker combinations, with relevant information. If this immortal boy finds a companion to fall in love with once every hundred years, he would have ten thousand girlfriends in a million years. And how many of those ten thousand girls' names will he be able to remember? This changes what a meaningful relationship means, doesn't it? Another tricky thing about immortality: Human beings have not always looked the same. This can be explained by Darwin's theory of evolution. For instance, if women find taller men more attractive, then more tall men would mate and have children, putting more tall genes in the gene pool. That means, in the next generation, more children will have the genes to be taller. Repeat that process for a million years and the average height will be a lot taller than the average height today, assuming there's no natural disaster that wipes out all the tall people. Our ancestors were short, hairy apes. We still have body hair, but we don't look like apes any more. If you're the only person who is immortal, while everyone else keeps evolving, generation after generation, you will eventually look quite different than the people who surround you. "Hi, how you doing?" If one of our ancestors, apes, is still alive today, how many people will make friends with it instead of calling the Museum of Natural History? And one more physical consideration for immortality: Scars. After all, immortality doesn't automatically translate to invincibility, it just means you cannot die. But it doesn't guarantee what condition you'll be alive in. Look at your body and count how many scars you have. If you have made this many permanent scars within your life, imagine how much damage you would have if you were one thousand years old! Now, there are approximately 185,000 amputation-related hospital discharges every year in the U.S. These injuries are due to accidents or illnesses. Certainly the percentage is low comparing to the total population if you only live for a hundred years. However, if you've been alive for over one million years, the odds of still having all your limbs are pretty slim. What about little accessories, like your eyes, your nose, your ears, fingers or toes? What about your teeth? What are the odds of you keeping your dental health for a hundred years? A thousand years? One million years? You might end up looking like a horribly scuffed-up Mr. Potato Head with missing pieces and dentures. So, are you sure you want to live forever? Now, which superpower physics lesson will you explore next? Shifting body size and content, super speed, flight, super strength, immortality, and -- invisibility.
Keabadian. Dalam film, raja-raja selalu mencari rahasia keabadian. Tapi apa keabadian itu baik? Bagi bocah sepuluh tahun, satu tahun sama dengan 10% hidupnya. Bagi ibunya yang 40 tahun, satu tahun cuma 2,5% hidupnya. Tahun yang sama, 365 hari, bisa terasa berbeda pada orang berbeda. Jika kita hidup hingga 82 tahun, itu sekitar 30.000 hari. Jika bocah ini hidup 30.000 tahun, satu tahun terasa seperti satu hari. Dan jika emosi bocah ini bertahan melewati kemungkinan bosan karena hidup jutaan tahun, dia mungkin menjadi sangat kesepian dan sedih. Sebab dia pernah dan akan selalu hidup melebihi semua yang dia cintai. Tapi bagaimana jika semua orang abadi? Pertama-tama, besar Bumi terbatas. Jadi, di mana kita semua akan tinggal? (Mendengus) “Permisi, wajahku!” “Hentikan!” “Maafkan aku.” “Sempitnya!” Ingat yang kau lakukan tahun lalu atau saat umurmu lima tahun? Berapa banyak masa lalu yang kau lupa? Jika kau sulit mengingat kegiatanmu saat lima tahun, bagaimana kau ingat yang terjadi jika hidup seribu tahun lalu? Satu juta tahun lalu? Kita tak ingat tiap rincian masa lalu kita karena otak kita punya muatan terbatas dan kita mengganti memori tak berguna, seperti kode loker SMP, dengan informasi lebih berguna. Jika bocah abadi ini menemukan pasangan yang dicintai tiap ratusan tahun sekali, dia akan punya sepuluh ribu pacar dalam satu juta tahun. Dan berapa banyak dari sepuluh ribu nama gadis yang masih dia ingat? Hal ini mengubah makna dari hubungan berarti, bukan? Hal rumit lainnya soal keabadian: manusia tidak selalu terlihat sama. Hal ini bisa dijelaskan teori evolusi Darwin. Misalnya, jika wanita merasa pria tinggi lebih menarik, lebih banyak pria tinggi yang kawin dan punya anak, lebih banyak gen tinggi dalam lungkang gen. Artinya, di generasi selanjutnya, lebih banyak anak punya gen tubuh lebih tinggi. Ulangi itu selama satu juta tahun, dan tinggi rata-rata akan bertambah daripada tinggi rata-rata saat ini. Itu pun jika tak ada bencana alam yang memusnahkan orang tinggi. Nenek moyang kita adalah kera pendek berbulu. Kita masih punya bulu badan, tapi tidak lagi mirip kera. Jika kau satu-satunya yang abadi, sedangkan semua terus berevolusi, dari generasi ke generasi lain, kau akhirnya terlihat berbeda dari orang sekitarmu. “Hai, apa kabarmu?” Jika salah satu nenek moyang kita, kera, masih hidup, berapa banyak yang berteman dengannya daripada memanggil Museum Sejarah Alam? Dan satu lagi pertimbangan fisik untuk keabadian: luka. Bagaimanapun, keabadian tidak serta-merta diartikan kebal. Kau sekadar tak bisa mati. Keabadian tak menjamin dengan keadaan apa kau hidup. Lihatlah tubuhmu dan hitung luka yang kau punya. Jika kau memiliki banyak luka permanen selama hidupmu, bayangkan banyaknya cedera yang kau punya jika umurmu seribu tahun! Saat ini ada sekitar 185.000 kasus terkait amputasi di rumah sakit, tiap tahun di AS. Cedera ini berasal dari kecelakaan atau penyakit. Memang persentasenya rendah ketimbang total populasi bila kau cuma hidup seratus tahun. Namun, jika kau hidup lebih dari satu juta tahun. peluang semua anggota tubuhmu masih utuh itu rendah. Bagaimana soal aksesori kecil, seperti mata, hidung, telinga, jari tangan, atau jari kaki? Bagaimana dengan gigimu? Berapa peluang kau memelihara kesehatan gigi selama seratus tahun? Seribu tahun? Satu juta tahun? Kau mungkin jadi mirip Mr. Potato Head yang mengerikan dengan bagian-bagian hilang dan gigi palsu. Jadi, kau yakin mau hidup selamanya? Pelajaran kekuatan fisik super mana yang mau kau lihat selanjutnya? Perubahan bentuk dan massa tubuh, kecepatan super, terbang, tenaga super, keabadian, dan tembus pandang.