The science of symmetry - Colm Kelleher

Translator: Nufiar Saahi Reviewer: Deera Army Pramana

When you hear the word symmetry,

Ketika mendengar kata simetri,

maybe you picture a simple geometric shape

yang terbayang adalah bangun geometris sederhana

like a square or a triangle,

seperti persegi atau segitiga,

atau pola rumit pada sayap kupu-kupu.

or the complex pattern on a butterfly's wings.

Jika kau cenderung artistik,

If you are artistically inclined,

you might think of the subtle modulations of a Mozart concerto,

kau mungkin memikirkan modulasi halus pada konserto karya Mozart,

or the effortless poise of a prima ballerina.

atau sikap prima balerina yang elegan.

When used in every day life,

Dalam kehidupan sehari-hari,

kata simetri melambangkan gagasan samar

the word symmetry represents vague notions of

beauty, harmony and balance.

akan keindahan, harmoni, dan keseimbangan.

In math and science, symmetry has a different,

Di matematika dan sains,

simetri memiliki makna yang berbeda dan sangat spesifik.

and very specific, meaning.

Dalam arti teknisnya,

In this technical sense,

a symmetry is the property of an object.

simetri adalah sifat suatu objek.

Pretty much any type of object can have symmetry,

hampir semua objek bisa memiliki simetri,

dari benda nyata seperti sayap kupu-kupu,

from tangible things like butterflies,

sampai hal abstrak seperti bangun geometris.

to abstract entities like geometric shapes.

So, what does it mean for an object to be symmetric?

Jadi, apa artinya jika sebuah objek bersifat simetris?

Here's the definition:

Ini definisinya:

a symmetry is a transformation that leaves that object unchanged.

Simetri adalah transformasi yang tidak membuat objek berubah.

Okay, that sounds a bit abstract, so let's unpack it.

Nah, terdengar agak abstrak, kan. Ayo kita uraikan.

Lebih mudah jika kita melihat contoh tertentu,

It will help to look at a particular example,

like this equilateral triangle.

seperti segitiga sama sisi ini.

If we rotate our triangle through 120 degrees,

Jika kita memutarnya 120 derajat,

around an access through its center,

mengelilingi pusatnya,

we end up with a triangle that's identical to the original.

kita mendapatkan segitiga yang persis sama dengan sebelumnya.

In this case, the object is the triangle,

Di kasus ini, objeknya adalah segitiga,

and the transformation that leaves the object unchanged

dan transformasi yang membuat objek tidak berubah,

is rotation through 120 degrees.

adalah rotasi 120 derajat.

So we can say an equilateral triangle is symmetric

Jadi, kita bisa bilang bahwa segitiga sama sisi bersifat simetris

with respect to rotations of 120 degrees around its center.

dengan rotasi 120 derajat mengelilingi pusatnya.

If we rotated the triangle by, say, 90 degrees instead,

Jika kita memutarnya, misal, 90 derajat,

segitiga akan terlihat berbeda.

the rotated triangle would look different to the original.

Dengan kata lain, segitiga sama sisi tidaklah simetris

In other words, an equilateral triangle is not symmetric

with respect to rotations of 90 degrees around its center.

dengan rotasi 90 derajat terhadap pusatnya.

But why do mathematicians and scientists care about symmetries?

Tetapi, kenapa matematikawan dan ilmuwan peduli dengan simetri?

Turns out, they're essential in many fields of math and science.

Ternyata, simetri penting di bidang mereka.

Let's take a close look at one example: symmetry in biology.

Ayo kita lihat satu contohnya: simetri dalam biologi.

You might have noticed that there's a very familiar kind of symmetry

Kau mungkin menyadari ada tipe simetri familier

we haven't mentioned yet:

yang belum kami sebut:

the symmetry of the right and left sides of the human body.

simetri kanan dan kiri tubuh manusia.

The transformation that gives this symmetry is reflection

Simetri ini dibentuk oleh transformasi cerminan

by an imaginary mirror that slices vertically through the body.

oleh cermin khayal yang membelah tubuh secara vertikal.

Biologists call this bilateral symmetry.

Biolog menyebutnya simetri bilateral.

As with all symmetries found in living things,

Sama seperti semua simetri pada makhluk hidup,

it's only approximate,

yang hanya kira-kira,

ciri tubuh manusia ini tetaplah mencolok.

but still a striking feature of the human body.

We humans aren't the only bilaterally symmetric organisms.

Manusia bukan satu-satunya makhluk simetris bilateral.

Banyak hewan lain, misalnya rubah, hiu, kumbang,

Many other animals, foxes, sharks, beetles,

that butterfly we mentioned earlier,

kupu-kupu yang kami sebut tadi,

have this kind of symmetry,

memiliki simetri jenis ini,

sama seperti beberapa tumbuhan seperti anggrek.

as do some plants like orchid flowers.

Makhluk lainnya memiliki simetri jenis lain,

Other organisms have different symmetries,

yang hanya terlihat

ones that only become apparent

when you rotate the organism around its center point.

ketika kau memutarnya pada pusatnya.

It's a lot like the rotational symmetry of the triangle we watched earlier.

Hampir sama seperti simetri rotasi pada segitiga sama sisi tadi.

But when it occurs in animals,

Tetapi, ketika terjadi pada hewan,

this kind of symmetry is known as radial symmetry.

simetri ini disebut sebagai simetri radial.

Contohnya, beberapa bulu babi dan bintang laut

For instance, some sea urchins and starfish

have pentaradial or five-fold symmetry,

memiliki 5 simetri lipat atau simetri pentaradial,

that is, symmetry with respect to rotations of 72 degrees around their center.

artinya, simetri dengan rotasi 72 derajat mengelilingi pusatnya.

Simetri juga tampak pada tumbuhan,

This symmetry also appears in plants,

yang bisa kau lihat dengan memotong apel secara horizontal.

as you can see for yourself by slicing through an apple horizontally.

Some jellyfish are symmetric with respect to rotations of 90 degrees,

Beberapa ubur-ubur simetris dengan rotasi 90 derajat,

sementara anemon simetris dengan rotasi sudut berapa pun.

while sea anemones are symmetric when you rotate them at any angle.

Some corals, on the other hand, have no symmetry at all.

Beberapa koral, sebaliknya, tidak punya simetri,

They are completely asymmetric.

sama sekali asimetris.

But why do organisms exhibit these different symmetries?

Tetapi, mengapa makhluk menunjukkan tipe simetri yang berbeda?

Does body symmetry tell us anything about an animal's lifestyle?

Apakah simetri tubuh menunjukkan cara hidup hewan itu?

Coba kita lihat salah satu grup:

Let's look at one particular group:

bilaterally symmetric animals.

hewan simetris bilateral.

In this camp, we have foxes, beetles, sharks, butterflies,

Di grup ini ada rubah, kumbang, hiu, kupu-kupu,

and, of course, humans.

dan, tentunya, manusia.

The thing that unites bilaterally symmetric animals

Hal yang menyatukan hewan simetris bilateral

is that their bodies are designed around movement.

adalah tubuh yang dibuat untuk bergerak.

If you want to pick one direction and move that way,

Jika kau ingin bergerak ke satu arah,

it helps to have a front end

lebih mudah jika ada bagian depan tubuh

where you can group your sensory organs--

yang memiliki semua organ indra--

your eyes, ears and nose.

mata, telinga, dan hidung.

It helps to have your mouth there too

Lebih bagus jika ada mulut juga

karena kau mungkin akan bertemu makanan

since you're more likely to run into food

or enemies from this end.

atau musuh dari bagian ujung itu.

Pasti kau kenal betul kelompok organ ini, plus mulut,

You're probably familiar with a name for a group of organs,

plus a mouth, mounted on the front of an animal's body.

yang ada di depan tubuh hewan.

It's called a head.

Bagian itu disebut kepala.

Having a head leads naturally to the development of bilateral symmetry.

Keberadaan kepala mendorong perkembangan simetri bilateral,

And it also helps you build streamlined fins if you're a fish,

juga membantumu membangun sirip yang efisien jika kau seekor ikan,

aerodynamic wings if you're a bird,

sayap aerodinamis jika kau seekor burung,

or well coordinated legs for running if you're a fox.

atau kaki yang lincah jika seekor rubah.

But, what does this all have to do with evolution?

Tetapi, apa hubungannya ini dengan evolusi?

Turns out, biologists can use these various body symmetries

Ternyata, biolog bisa menggunakan tipe simetri tubuh ini

to figure out which animals are related to which.

untuk mencari keterkaitan di antara hewan.

For instance, we saw that starfish and sea urchins have five-fold symmetry.

Contohnya, kita melihat bintang laut dan bulu babi memiliki 5 simetri lipat.

Tetapi, lebih tepatnya simetri ini berlaku bagi bintang laut dan bulu babi dewasa.

But really what we should have said was

adult starfish and sea urchins.

In their larval stage, they're bilateral, just like us humans.

Di masa larva, mereka bilateral, seperti manusia.

For biologists, this is strong evidence

Untuk para biolog, ini adalah bukti kuat

that we're more closely related to starfish

bahwa kita lebih dekat dengan bintang laut

than we are, to say, corals,

daripada, misal, koral,

or other animals that don't exhibit bilateral symmetry

atau hewan yang tidak menunjukkan simetri bilateral

at any stage in their development.

pada masa pertumbuhannya.

One of the most fascinating and important problems in biology

Salah satu masalah yang menarik dan penting di biologi

is reconstructing the tree of life,

adalah menyusun pohon kehidupan,

discovering when and how the different branches diverged.

menemukan kapan dan bagaimana cabang yang berbeda berpisah.

Memikirkan hal sesederhana simetri tubuh

Thinking about something as simple as body symmetry

can help us dig far into our evolutionary past

bisa membantu kita menggali masa lalu evolusi kita

dan memahami kita, sebagai spesies, berasal dari mana.

and understand where we, as a species, have come from.