The Student Room Group

Your favourite Paradox

Scroll to see replies

On opposite day... is it actually opposite day or not?

:colonhash:
Original post by ANIGAV
Unfortunately, we aren't talking about stars having an infinite distance. We do not know if the universe is infinite or finite so I am not really sure why you think that current physics understanding is correct..


Well we are? The whole point of the paradox is assuming that if the universe is infinite a contradiction can be derived. But if the assumption causes the contradiction to be invalid then so is the paradox.


Furthermore current physics understanding is the best understanding we have; otherwise it wouldn't be our current understanding, and the understanding I was referring to was of the thermodynamics quoted.
Reply 22
Original post by ANIGAV
Let's all try to share abit of knowledge so that we can all grow. What is your favourite paradox? it can be anything from maths to physics to philosophy itself.

Also please try to give a very brief explanation of the paradox if you understand it.

I start;


Video: http://youtu.be/aH2fpmxMV4Q

Correct me or any other user if the explanation of the paradox is wrong.


Everything I say is a lie.
Reply 23
Original post by ANIGAV
19th or 21st century, the youtube video is 2010..do you need any more clues?


Ok, you're obviously either trolling or an idiot, be quiet

Original post by Guru Jason
Fair enough, maybe the real life analogy was not such a good idea. :tongue: Still though, no matter how many 9's you have past the decimal point, there will be one more 01 if subtracted from 1. . .I think


I know what you mean, it's tough to get your head around. I'll see if I can explain it a little better, we'll call the number of 9s n and d the difference

n = 1 => d = 0.1 = (1/10)^1
n = 2 => d = 0.01 = (1/10)^2
n = 3 => d = 0.001 = (1/10)^3

etc.....

so if we have an infinite number of 9s, which is what recurring means (and that's the most important thing to remember, it doesn't mean a lot, it means an infinite amount) then we have

d = (1/10)^infinity = 0

Mathematicians would probably get a bit angry with me writing that, should really have used limit notation but I'm not sure what your mathematical background is.

So yeah, is d = 0 then 0.9999..... (with an infinite number of 9s) = 1
Original post by Guru Jason
Hence why I believe it's a paradox. :biggrin:


I don't really think I've helped by saying 0000...1 because it causes to think of it incorrectly; you shouldn't think of it as simply 'adding 9s on' infinite times.

0.9 recurring as a definition = 1

To deny its complete certainty you would also be denying that 0.1 recurring = 1/9 or that 0.3 recurring is 1/3

There are various explanations - one example:

let x = 0.9 recurring
then 10x = 9.9 recurring

then 9x = 10x - x = 9

so x = 1
Reply 25
Original post by Mr Ben
Ok, you're obviously either trolling or an idiot, be quiet

I know what you mean, it's tough to get your head around. I'll see if I can explain it a little better, we'll call the number of 9s n and d the difference

n = 1 => d = 0.1 = (1/10)^1
n = 2 => d = 0.01 = (1/10)^2
n = 3 => d = 0.001 = (1/10)^3

etc.....

so if we have an infinite number of 9s, which is what recurring means (and that's the most important thing to remember, it doesn't mean a lot, it means an infinite amount) then we have

d = (1/10)^infinity = 0

Mathematicians would probably get a bit angry with me writing that, should really have used limit notation but I'm not sure what your mathematical background is.

So yeah, is d = 0 then 0.9999..... (with an infinite number of 9s) = 1


The video was presented by an assistant professor of Physics & Astronomy in 2010, need more clues?
Original post by Mr Ben

I know what you mean, it's tough to get your head around. I'll see if I can explain it a little better, we'll call the number of 9s n and d the difference

n = 1 => d = 0.1 = (1/10)^1
n = 2 => d = 0.01 = (1/10)^2
n = 3 => d = 0.001 = (1/10)^3

etc.....

so if we have an infinite number of 9s, which is what recurring means (and that's the most important thing to remember, it doesn't mean a lot, it means an infinite amount) then we have

d = (1/10)^infinity = 0

Mathematicians would probably get a bit angry with me writing that, should really have used limit notation but I'm not sure what your mathematical background is.

So yeah, is d = 0 then 0.9999..... (with an infinite number of 9s) = 1


Did A level but your explanation is pretty clear. It does makes sense. It's not be a paradox then it seems.
Original post by hassi94
I don't really think I've helped by saying 0000...1 because it causes to think of it incorrectly; you shouldn't think of it as simply 'adding 9s on' infinite times.

0.9 recurring as a definition = 1

To deny its complete certainty you would also be denying that 0.1 recurring = 1/9 or that 0.3 recurring is 1/3

There are various explanations - one example:

let x = 0.9 recurring
then 10x = 9.9 recurring

then 9x = 10x - x = 9

so x = 1


This is the way I learnt it at college, but thought it must be a paradox, however the way Mr Ben explained it makes sense now.
Reply 28
Original post by Guru Jason
Did A level but your explanation is pretty clear. It does makes sense. It's not be a paradox then it seems.


Glad it was fairly clear :smile: infinities are some of my favorite things to play around with in maths, they can be sooooo beautiful a times. I'm not usually too good at explaining things though, so I'm glad I managed this time.
Reply 29
(1) I love that one!

(2) Yeah, that one does work...
I thought it was if i was crossing a road, and i crossed halfway, and then half the distance i just crossed, again etc..., would i ever reach the other side...?
Reply 30
Is that the achilles and the tortoise paradox?
Reply 31
Is 2 really a paradox? It has an answer: you will never reach the destination...
Reply 32
Original post by 117r
Is 2 really a paradox? It has an answer: you will never reach the destination...


Well, technically no, but its fun to think about! xD
what happens when a unstoppable force comes into contact with an immovable object?
Everyone must know about the grandfather paradox. I love that one!

It's like this: Just say you could go back in time and kill your grandfather (also works perfectly well for father too actually). If your grandfather dies, then obv you werent born.....MEANING you couldn't have gone back in time to kill your grandfather, MEANING your grandfather actually isnt dead, MEANING you do exist and can go back in time to kill him....and so on!
Reply 35
Original post by Ilyas
what happens when a unstoppable force comes into contact with an immovable object?


All matter of being is unleashed and the world as we know it ends! Hehe! =D
Original post by 117r
Is 2 really a paradox? It has an answer: you will never reach the destination...


Surely it depends on what the destination. If your crossing the road with a finite distance then, it will take a long long while but you would eventually get there wouldn't you?
Original post by Quexx
(1) I love that one!

(2) Yeah, that one does work...
I thought it was if i was crossing a road, and i crossed halfway, and then half the distance i just crossed, again etc..., would i ever reach the other side...?


(2) Yes, you would. But you might get run over before reaching the other side :biggrin:
Reply 38
Original post by SimplyEccentric
(2) Yes, you would. But you might get run over before reaching the other side :biggrin:


Hahaha! And, no you wouldn't. Because if you kept going half the distance you previously went and the first distance across the road you went was halfway or less then you would never make it to the other side, you would always be (1/2)^n times the width of the road, away from the side. (Where n is the number of steps)
Reply 39
Liar paradox. :cool:

Quick Reply

Latest