What is Zeno's Dichotomy Paradox? - Colm Kelleher

Što je Zenonov paradoks dihotomije? - Colm Kelleher

3,698,962 views

2013-04-15 ・ TED-Ed


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What is Zeno's Dichotomy Paradox? - Colm Kelleher

Što je Zenonov paradoks dihotomije? - Colm Kelleher

3,698,962 views ・ 2013-04-15

TED-Ed


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00:00
Translator: Andrea McDonough Reviewer: Bedirhan Cinar
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Prevoditelj: Martina Valković Recezent: Ivan Stamenković
00:15
This is Zeno of Elea,
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Ovo je Zenon iz Eleje,
00:16
an ancient Greek philosopher
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antički grčki filozof
00:18
famous for inventing a number of paradoxes,
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slavan po brojnim paradoksima koje je smislio,
00:21
arguments that seem logical,
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argumentima koji djeluju
00:22
but whose conclusion is absurd or contradictory.
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logični, no čija je konkluzija apsurdna ili kontradiktorna.
00:25
For more than 2,000 years,
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Više od 2000 godina,
00:27
Zeno's mind-bending riddles have inspired
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Zenonove zagonetke inspirirale su
00:29
mathematicians and philosophers
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matematičare i filozofe
00:31
to better understand the nature of infinity.
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da bolje razumiju prirodu beskonačnosti.
00:33
One of the best known of Zeno's problems
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Jedan od najpoznatijih Zenonovih
00:35
is called the dichotomy paradox,
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problema zove se paradoks dihotomije,
00:37
which means, "the paradox of cutting in two" in ancient Greek.
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što na starom Grčkom znači "paradoks dijeljenja na dva dijela".
00:41
It goes something like this:
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Ide otprilike ovako:
00:43
After a long day of sitting around, thinking,
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Poslije dugog dana sjedenja i razmišljanja,
00:46
Zeno decides to walk from his house to the park.
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Zenon odluči prošetati od svoje kuće od parka.
00:48
The fresh air clears his mind
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Svjež zrak razbistruje mu um
00:50
and help him think better.
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i pomaže kako bi bolje mislio.
00:51
In order to get to the park,
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Kako bi došao do parka,
00:53
he first has to get half way to the park.
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prvo mora doći na pola puta do parka.
00:55
This portion of his journey
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Ovaj dio njegovog puta
00:56
takes some finite amount of time.
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uzima neku konačnu količinu vremena.
00:58
Once he gets to the halfway point,
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Jednom kada dođe do polovice,
01:00
he needs to walk half the remaining distance.
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treba prehodati pola preostale udaljenosti.
01:02
Again, this takes a finite amount of time.
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Ponovno, ovo uzima određenu količinu vremena.
01:05
Once he gets there, he still needs to walk
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Jednom kada dođe do tamo, još treba prehodati
01:08
half the distance that's left,
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pola preostale udaljenosti,
01:09
which takes another finite amount of time.
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što opet uzima neku konačnu količinu vremena.
01:12
This happens again and again and again.
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Ovo se ponavlja ponovno i ponovno i ponovno.
01:15
You can see that we can keep going like this forever,
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Možete vidjeti da ovako možemo nastaviti u nedogled,
01:18
dividing whatever distance is left
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dijeliti preostalu udaljenost
01:19
into smaller and smaller pieces,
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na manje i manje dijelove,
01:21
each of which takes some finite time to traverse.
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za prijelaz svakog od kojih je potrebno neko konačno vrijeme.
01:25
So, how long does it take Zeno to get to the park?
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Pa, koliko dugo treba Zenonu da dođe do parka?
01:27
Well, to find out, you need to add the times
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Kako bi to saznali, trebate zbrojiti vremena
01:30
of each of the pieces of the journey.
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svih dijelova putovanja.
01:32
The problem is, there are infinitely many of these finite-sized pieces.
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Problem je to što postoji beskonačno mnogo tih konačno velikih dijelova.
01:36
So, shouldn't the total time be infinity?
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Stoga, nebi li ukupno vrijeme trebalo biti beskonačnost?
01:39
This argument, by the way, is completely general.
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Ovaj argument je, usput rečeno, posve opći.
01:42
It says that traveling from any location to any other location
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Kaže da bi putovanje od jedne do druge lokacije
01:45
should take an infinite amount of time.
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trebalo trajati beskonačno dugo.
01:47
In other words, it says that all motion is impossible.
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Drugim riječima, kaže da je svako kretanje nemoguće.
01:51
This conclusion is clearly absurd,
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Ovakva konkluzija je očito apsurdna,
01:52
but where is the flaw in the logic?
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no gdje je pogreška u logici?
01:54
To resolve the paradox,
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Kako bi ga riješili,
01:55
it helps to turn the story into a math problem.
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paradoks možemo pretvoriti u matematički problem.
01:58
Let's supposed that Zeno's house is one mile from the park
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Pretpostavimo da je Zenonova kuća udaljena milju od parka
02:01
and that Zeno walks at one mile per hour.
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i da Zenon hoda brzinom od jedne milje na sat.
02:04
Common sense tells us that the time for the journey
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Zdravi razum kaže nam da bi potrebno vrijeme
02:06
should be one hour.
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trebalo biti sat vremena.
02:08
But, let's look at things from Zeno's point of view
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No, pogledajmo stvari s Zenonove točke gledišta
02:10
and divide up the journey into pieces.
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i podijelimo putovanje na dijelove.
02:13
The first half of the journey takes half an hour,
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Prva polovica putovanja traje pola sata,
02:15
the next part takes quarter of an hour,
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sljedeći dio traje četvrt sata,
02:17
the third part takes an eighth of an hour,
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a treći dio traje osminu sata,
02:20
and so on.
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02:20
Summing up all these times,
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i tako dalje.
Zbrajajući sve ovo vrijeme,
02:22
we get a series that looks like this.
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dobivamo niz koji izgleda ovako.
02:24
"Now", Zeno might say,
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Zenon bi mogao reći,
02:25
"since there are infinitely many of terms
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"s obzirom da imamo beskonačno mnogo uvjeta"
02:27
on the right side of the equation,
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na desnoj strani jednadžbe,
02:29
and each individual term is finite,
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a svaki individualni uvjet je konačan,
02:31
the sum should equal infinity, right?"
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zbroj bi trebao biti jednak beskonačnosti, zar ne?"
02:34
This is the problem with Zeno's argument.
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Ovo je problem sa Zenonovim argumentom.
02:36
As mathematicians have since realized,
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Kao što su matematičari od tada shvatili,
02:38
it is possible to add up infinitely many finite-sized terms
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moguće je zbrojiti beskonačno mnogo konačnih uvjeta
02:42
and still get a finite answer.
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i ipak dobiti konačni odgovor.
02:44
"How?" you ask.
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"Kako?", pitate.
02:45
Well, let's think of it this way.
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Pa, razmislimo o tome ovako.
02:47
Let's start with a square that has area of one meter.
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Počnimo s kvadratom površine jednog metra.
02:50
Now let's chop the square in half,
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Sada prerežimo kvadrat napola,
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and then chop the remaining half in half,
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a onda preostalu polovicu prerežimo napola,
02:54
and so on.
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i tako dalje.
02:56
While we're doing this,
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Dok ovo radimo,
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let's keep track of the areas of the pieces.
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vodimo računa o površinama dijelova.
03:00
The first slice makes two parts,
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Prvo rezanje stvara dva dijela,
03:02
each with an area of one-half
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svaki površine pola metra.
03:04
The next slice divides one of those halves in half,
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Sljedeće rezanje dijeli jednu od te dvije polovice
03:06
and so on.
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napola, i tako dalje.
03:07
But, no matter how many times we slice up the boxes,
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No, bez obzira na to koliko puta prerežemo kvadrate,
03:10
the total area is still the sum of the areas of all the pieces.
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ukupna površina je i dalje zbroj površina svih dijelova.
03:14
Now you can see why we choose this particular way
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Sada možemo vidjeti zašto smo izabrali baš ovaj način
03:17
of cutting up the square.
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dijeljenja kvadrata.
03:18
We've obtained the same infinite series
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Dobili smo isti beskonačni niz
03:20
as we had for the time of Zeno's journey.
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kao što smo imali kod vremena Zenonovog putovanja.
03:23
As we construct more and more blue pieces,
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Kako konsturiramo sve više plavih dijelova,
03:25
to use the math jargon,
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matematičkim žargonom rečeno,
03:27
as we take the limit as n tends to infinity,
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kako uzimamo granicu jer n teži beskonačnosti,
03:30
the entire square becomes covered with blue.
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cijeli kvadrat postaje pokriven plavim.
03:33
But the area of the square is just one unit,
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No površina kvadrata je samo jedna jedinica,
03:35
and so the infinite sum must equal one.
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i tako beskonačni zbroj mora biti jednak jedan.
03:38
Going back to Zeno's journey,
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Sada možemo vidjeti
03:39
we can now see how how the paradox is resolved.
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kako je paradoks Zenonovog putovanja razriješen.
03:42
Not only does the infinite series sum to a finite answer,
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Ne samo da beskonačni niz daje konačni zbroj,
03:45
but that finite answer is the same one
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već je taj konačni zbroj isti onaj
03:47
that common sense tells us is true.
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za kojeg nam zdravi razum kaže da je točan odgovor.
03:50
Zeno's journey takes one hour.
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Zenonov put traje jedan sat.
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