The Paradox of Infinity

  • Thread starter RuroumiKenshin
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  • #101
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Originally posted by MajinVegeta
But how do you explain the Doppler effect? It's used as evidence to prove the universe is expanding.
I believe that the Universe is expanding. My previous post just refines ones view of what it means to "expand", according to Relativity.
 
  • #102
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clearing misunderstandings

"This is what drag, and others, keep saying, but I disagree. If someone speaks of the spacial dimensions themselves as expanding, then it doesn't follow that just some things could be getting farther apart, but all things should be getting farther apart. And if all things are getting farther apart, then this has to be happening throughout the entirety of space. Of course, there is not "entirety of space" in an infinite universe, which is why I don't think that everything can get farther away from everything else, in an infinite universe. Thus, the spacial dimensions cannot expand, in an infinite universe, IMCO (in my current opinion)".

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"Everyone, listen to my new good buddy, sage!

Sage, I agree entirely with you here. In fact, I have been trying to make the same point for some time now".- MENTAT.
no wonder you agree with me mentat.they were originally posted by you!they are quotes!thanks for calling me buddy,and THANK YOU for explaining to me how the universe could indeed have expanded faster than light during inflationary phase.you are my buddy too you know!:smile: let me state clearly what my views are:
1) mentat asked how could our universe expand as it is infinite
2) drag said a infinite universe can indeed expand.
3) i said the universe we study is NOT infinite.it CANNOT BE as it began at a big bang a finite time ago(10 billion?18 billion?estimates vary)but if an entity began expanding from a point a finite time ago at no later stage can it be infinite.it's common sense.
4) since universe we know is finite it can expand.CASE CLOSED.

majin vegeta you said models of an infinite universe made more sense.can you tell us briefly what these models are?thanks
 
  • #103
drag
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Greetings !
Originally posted by sage
2) drag said an infinite universe can indeed expand.
3) I said the universe we study is NOT infinite.
Correction.
drag said that the point of the Universe
being finite/infinite is irrelevant here as
the thread deals with the possible paradox
of an expanding given infinite Universe. :wink:
Originally posted by sage
it CANNOT BE as it began at a big bang a finite
time ago(10 billion?18 billion?estimates vary)but
if an entity began expanding from a point a finite
time ago at no later stage can it be infinite.
it's common sense.
Had I been a sadistic human being I'd ask
you to precisely formalize the connection.
And even if you succeeded in this task I would
then ask you to prove that the type of "common
sense" you used is indeed absolute and
must "make sense".
I guess you should be glad I'm not a sadistic
human being...

Peace and long life.
 
  • #104
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Originally posted by drag
Had I been a sadistic human being I'd ask
you to precisely formalize the connection.
What do you mean, sage made it pretty obvious: If something starts out finite, it will never reach infinity. This just has to do with the basic definition of infinity, which means "going on forever".

On the off chance that you still don't understand it, think of how long it would take a finite entity to reach infinity. Answer: forever. Since forever hasn't passed yet (and never will), the universe would never reach infinity.

And even if you succeeded in this task I would
then ask you to prove that the type of "common
sense" you used is indeed absolute and
must "make sense".
I'd say that it's not just "common" sense, it's definitive, and strikes at the very meaning of the words being used ("finite"; "infinite"; "expansion"; etc...).
 
  • #105
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Originally posted by sage
"This is what drag, and others, keep saying, but I disagree. If someone speaks of the spacial dimensions themselves as expanding, then it doesn't follow that just some things could be getting farther apart, but all things should be getting farther apart. And if all things are getting farther apart, then this has to be happening throughout the entirety of space. Of course, there is not "entirety of space" in an infinite universe, which is why I don't think that everything can get farther away from everything else, in an infinite universe. Thus, the spacial dimensions cannot expand, in an infinite universe, IMCO (in my current opinion)".

--------------------------------------------------------------------------------



"Everyone, listen to my new good buddy, sage!

Sage, I agree entirely with you here. In fact, I have been trying to make the same point for some time now".- MENTAT.
no wonder you agree with me mentat.they were originally posted by you!they are quotes!
It sounded like my style, when I first read them. I just assumed you had come really close.

thanks for calling me buddy,and THANK YOU for explaining to me how the universe could indeed have expanded faster than light during inflationary phase.you are my buddy too you know!:smile:
Well, good. And you're welcome.
 
  • #106
drag
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Originally posted by Mentat
What do you mean, sage made it pretty obvious: If
something starts out finite, it will never reach
infinity. This just has to do with the basic
definition of infinity, which means "going on forever".
Maybe it just became infinite - like an on/off
switch - no expansion (a word that discribes
the derivative of the ratio between the volume
and the time) involved.
 
  • #108
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2


Originally posted by drag
Maybe it just became infinite - like an on/off
switch - no expansion (a word that discribes
the derivative of the ratio between the volume
and the time) involved.
No, because that means that there was a time when it was not infinite. If there was a time when it wasn't infinite, it can never become infinite.
 
  • #109
drag
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Originally posted by Mentat
If there was a time when it wasn't infinite,
it can never become infinite.
Why ?
(I was trying to avoid being sadistic, but
it just didn't work out that way... )
 
  • #110
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2
I've seen this before, and it is a perfectly acceptable cosmological model, but doesn't answer the question of how the spacial dimensions themselves can expand, if the universe is already infinite. You see what I mean? While the model proposed in your link could be true, I wasn't questioning it, I was questioning the model of a universe (by which I mean the whole universe) that was small and became infinite.
 
  • #111
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Originally posted by drag
Why ?
(I was trying to avoid being sadistic, but
it just didn't work out that way... )
'

I don't like repeating myself...

Originally Posted by Me
On the off chance that you still don't understand it, think of how long it would take a finite entity to reach infinity. Answer: forever. Since forever hasn't passed yet (and never will), the universe would never reach infinity.
 
  • #112
drag
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Originally posted by Mentat
I don't like repeating myself...
Can't say I like it either, so I won't...
I'll let you do all the work - go 7 messages
back (including this one). :wink:
 
  • #113
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2


Originally posted by drag
Can't say I like it either, so I won't...
I'll let you do all the work - go 7 messages
back (including this one). :wink:
Nothing is instantaneous, according to Relativity, so your on/off example is flawed from the start. Then you have the matter of the Universe's having been finite at some point in time. This also does not allow the Universe to (at any point, short of forever) reach infinite size.
 
  • #114
drag
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Originally posted by Mentat
Nothing is instantaneous, according to Relativity
The BB itself doesn't make sense according to
Relativity, so ? :wink:
Like I said, this thread was dealing with the
hypothetical case of an infinite Universe and
the related possible paradox, not with the
scientific indication or possibility of the
Universe's nature.

Live long and prosper.
 
  • #115
110
0
Originally posted by MajinVegeta
What is infinity? How can something infinite expand? Once and for all, how can we conclude that the universe is infinite?
.
look at the third question that majin asked.so drag let us leave the decision of what this thread is dealing with to him.not that i am saying that the universe could not be infinite.read on.
but before that lets clarify whether a finite quantity can expand to become an infinite one.consider the set of all positive integers.it's infinite.now consider the set{1}.it is a finite subset of the above infinite set with no. of elements being one.now say add other positive integers serially one after another in ascending order such that the set increases by n integers per second with n being finite.so when will the set become infinite?NEVER.or not until infinite time has elapsed.i can give more examples but the fact is iff the universe was finite at the time of the big bang it cannot be infinite today.this applies well to our observable universe which was just a point at the time of the bang.indeed hazzy's site gives it's actual radius.so what's the point?
now let us talk about the total universe.that's a red herring.you can't see it, observe it and there is no hope of observing it in future.what's the use thinking of something we can't even verify.but i must say the approach of physicists is rather pragmatic.they feel we live in an unbiased sample of the universe and whatever is true for the part we can see is true in general.research shows that our part is most probably flat.a flat surface extends to infinity.so they conclude the entire universe is a flat surface extending to infinity.if so by our previous conclusions it follows the universe as a whole must be infinite at the beggining of the big bang.since it has been expanding since(vide the idea that anything that holds here holds everywhere). so we come to the original question-can a infinite entity get bigger?
seen a thin rubber sheet?strech it-it elongates does it not?now assume a rubber sheet of the same material extending to infinity say along its length.mark 2 points on it by a sketch pen.now strech holding the sheet at these two points.surely the sheet will elongate(i.e. the dist. between the points increase)otherwise we will have to conclude that rubber has suddenly become as rigid as stone just because it extends to infinity.absurd is'nt it.verdict-infinite entities can expand and there is no logical fallacy in assuming that the universe, infinite at the time of the bang is expanding ever since.
i must say that any assumptions about the entire universe is purely hypothetical and will change constantly as more advanced theories come into being to explain newer facts about the observable universe which we are only beggining to probe in detail.anyway drag what does a switch has to do with the universe.enlighten me will you?
 
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  • #116
drag
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Greetings !
Originally posted by sage
look at the third question that majin asked.so drag let us leave the decision of what this thread is dealing with to him.
To her...:wink:
Originally posted by sage
but before that lets clarify whether a finite quantity can expand to become an infinite one.consider the set of all positive integers.it's infinite.now consider the set{1}.it is a finite subset of the above infinite set with no. of elements being one.now say add other positive integers serially one after another in ascending order such that the set increases by n integers per second with n being finite.so when will the set become infinite?NEVER.or not until infinite time has elapsed.i can give more examples but the fact is iff the universe was finite at the time of the big bang it cannot be infinite today.this applies well to our observable universe which was just a point at the time of the bang.
Did you also remember to tell the Universe
it must follow mathematical logic ? :wink:
Originally posted by sage
anyway drag what does a switch has to do with
the universe.enlighten me will you?
I was just giving an example to Mentat how one
state can change into another (a light switch is
a good example - light/no light).

Live long and prosper.
 
  • #117
LogicalAtheist
Drag - You're a female? How old are you?
 
  • #118
drag
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Originally posted by LogicalAtheist
Drag - You're a female? How old are you?
NO ! NO ! NO !
Oh, sorry ! I meant - no, I'm not. :wink:
MajinVegeta is, and I believe she said she's 13.

Live long and prosper.
 
  • #119
LogicalAtheist
Oh ok, I thought you were corrected someone calling YOU male.

Majin, hmm 13, hmmm. Darn.
 
  • #120
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0
Philosophy of Nature. Time and Space

Here is a contribution to this issue of infinity.

http://csf.colorado.edu/psn/marx/Archive/1877-AD/p1.htm#c5" [Broken]
 
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  • #121
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2


Originally posted by drag
The BB itself doesn't make sense according to
Relativity, so ? :wink:
Not true. There are many models of the expansion of the Universe, that are perfectly compatible with GR.
 
  • #122
3,762
2


Originally posted by drag
Did you also remember to tell the Universe
it must follow mathematical logic ? :wink:
This is one of the assumptions that Science has already made (and everything in Theoretical Physics must conform to the assumptions of Science, obviously).

I was just giving an example to Mentat how one
state can change into another (a light switch is
a good example - light/no light).
It's a good enough example, but irrelevant as a description of the Universe's expansion - as I've already shown.
 
  • #123
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2
Originally posted by LogicalAtheist
Oh ok, I thought you were corrected someone calling YOU male.

Majin, hmm 13, hmmm. Darn.
You know, souding this deperate is not exactly a good strategy... Oh well. :wink:
 
  • #124
drag
Science Advisor
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Greetings !
Originally posted by Mentat
Not true. There are many models of the expansion
of the Universe, that are perfectly compatible with GR.
What does the "expansion of the Universe" have
to do with the BB ?!

Anyway, I have to point out (and you do
know, I hope, that I'm a person who ussualy
tends to mind his manners :wink: ) that you're
BSing me. Really !
I'm telling you that the Universe could just
become infinite as a hypothetical assumption,
a potentially usefull one for this hypothetical
thread btw, and you're shoving some current
scientific theories in my face saying "no, it's
impossible !". Is science complete ? Do we care
about science in this unscientific hypothetical
debate ?
I'm a very patient person, but it certainly seems
to me that you keep arguing just for the sake
of arguing, tell me it isn't so ! :frown:
Originally posted by Mentat
This is one of the assumptions that Science has
already made (and everything in Theoretical Physics
must conform to the assumptions of Science, obviously).
Science makes no assumptions. Math is a language
and science uses it to discribe the Universe
(not with perfect success btw, whatever perfect
success might mean) if and when it works
better than other availible languages.
Originally posted by Mentat
It's a good enough example, but irrelevant as
a description of the Universe's expansion - as
I've already shown.
No. The Universe's expansion is irrelevant to
this example because this example has nothing
to do with expansion.

Don't answer this if you feel you have to,
answer it if you feel you can make a relevant
point, please. :wink:
Thanks !

Live long and prosper.
 
  • #125
3,762
2


Originally posted by drag
Anyway, I have to point out (and you do
know, I hope, that I'm a person who ussualy
tends to mind his manners :wink: ) that you're
BSing me. Really !
I'm telling you that the Universe could just
become infinite as a hypothetical assumption,
a potentially usefull one for this hypothetical
thread btw, and you're shoving some current
scientific theories in my face saying "no, it's
impossible !".
That's not all I'm doing. I'm also reasoning with you on the nature of infinity. You continue to side-step my arguments, and it's rather frustrating to have to keep repeating them.

I'm a very patient person, but it certainly seems
to me that you keep arguing just for the sake
of arguing, tell me it isn't so ! :frown:
It's not. I do feel I have an obligation to defend my position, but if you would prove me wrong (which you don't seem to want to do, given your obvious side-stepping tendencies), I would give up that position.

Science makes no assumptions.
That is dead wrong. Science makes plenty of assumptions. For example: it assumes that there is an objective Universe, even thought this cannot be proven or falsified. This is just one example, but it should serve to prove that Science makes assumptions.

No. The Universe's expansion is irrelevant to
this example because this example has nothing
to do with expansion.
Yes it does. If something was smaller, and then was bigger, it got from smaller to bigger. If it did so, then it expanded, because "expansion" means "getting bigger".

Don't answer this if you feel you have to,
answer it if you feel you can make a relevant
point, please. :wink:
Thanks !
I like to believe that all of my points have been relevant, but, even if they haven't been, they have all had merit (as have all of yours), and should thus be considered directly, instead of being side-stepped.
 

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