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Author Topic: Is infinity what you get when youu place to plan mirrors parallel to each other?  (Read 9283 times)

Offline The Scientist

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Or is there a limit? Please share your views with us. Thanks!

Sorry everyone. There are too many typing errors I made  [xx(] The question goes:

Is infinity what you get when you place two plane mirrors parallel to each other?
« Last Edit: 28/12/2010 07:41:04 by The Scientist »


 

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Offline Foolosophy

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Or is there a limit? Please share your views with us. Thanks!

us??

You mean you are not really THE SCIENTIST? There are more of you??

You may have to consider calling yourself "WE SCIENTISTS"

Can you or your committee rephrase your question in order to make it a little clearer?

I am not certain as to what the real nature of your question is

Thanks for your help
 

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Offline The Scientist

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Or is there a limit? Please share your views with us. Thanks!

us??

You mean you are not really THE SCIENTIST? There are more of you??

You may have to consider calling yourself "WE SCIENTISTS"

Can you or your committee rephrase your question in order to make it a little clearer?

I am not certain as to what the real nature of your question is

Thanks for your help

Hi there Foolosophy, there is only one of myself. The reason why I use 'us' is so that we can all share knowledge with one another instead of using the word 'me'. Thanks for letting me know about the question. Typo errors, my mistake.
 

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Offline Foolosophy

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Hi there Foolosophy, there is only one of myself. The reason why I use 'us' is so that we can all share knowledge with one another instead of using the word 'me'. Thanks for letting me know about the question. Typo errors, my mistake.
[/quote]

I can't dissagree with that sentiment.

So are you really "THE" Scientist or just "A" Scientist?

Are WE really in the presence of cosmic emminence?

« Last Edit: 28/12/2010 09:43:21 by Foolosophy »
 

Offline MysteryGuitarMan

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Hi all

I believe I understand what The Scientist is trying to say. 2 mirrors which are parallel to each other, will give you and image formed that is replicas of the two mirrors, so you'll see many identical mirrors. Hope it helps!

MGM
 

Offline Foolosophy

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Hi all

I believe I understand what The Scientist is trying to say. 2 mirrors which are parallel to each other, will give you and image formed that is replicas of the two mirrors, so you'll see many identical mirrors. Hope it helps!

MGM

I think you may well be right

Well done

Thanks for your assistance on this critical issue

Best wishes

Foolosophy
 

Offline Magnus W

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If the mirrors are perfect i would say yes, but since mirrors are never perfect you will not get an infinite amount of reflections.
 

Offline Foolosophy

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If the mirrors are perfect i would say yes, but since mirrors are never perfect you will not get an infinite amount of reflections.

are you saying that something happens to the photons that are bouncing between the imperfect mirrors?

is there a mathematical or physical barrier that prevents an infinite number of reflections from being generated? (even if it's a theoretical barrier?)   
 

Offline Bill S

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I think the reality here is that you (one, anyone, a person etc. for the benefit of nit-pickers)could never actually know.  It might be safe to say that the number of images could be infinite, in theory, but in reality, the only way to know would be to count them, which would not be possible if infinity was involved.
 

Offline yor_on

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hmmm :)

Ah yes, ignoring the discussion entirely (as usual:), doing my (as usual:) eloquent monologue I must say that I agree..

With what you might wonder?

Well, with myself naturally :)

If we assume perfectly reflecting mirrors, and no energy/momentum loss for that photon as it 'bounces'? Infinity ahoy, here I come :) So, let us assume that we are 'propagating' beside it, being 'still' relative it, will 'it' still represent a infinity to us?
==

And if you think it does, what would differ that 'infinity' from the first example.
« Last Edit: 28/12/2010 16:11:22 by yor_on »
 

Offline Bill S

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Quote from: yor on
will 'it' still represent a infinity to us?

How would you know if it was infinite?

Have you been at the booze?  ;D
 

Offline yor_on

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Sad to say, no :)

If you happen to have a dram, send it :)

The first example assuming perfectly reflecting mirrors and no momentum energy loss, as well as no 'outside influences' naturally, I think should be able to 'tick' forever. And that should be a 'infinity' to me at least.

In the second idea you have all kind of possibilities though, depending on where you stand looking at it, well, as I see it:)
==

Ah, that would be the idea. "stand looking at the idea" I mean :)
« Last Edit: 28/12/2010 17:02:49 by yor_on »
 

Offline QuantumClue

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No it will not project to infinity - the reason why is that light cannot be projected off a mirror into infinity - eventually the mirror absorbs the photon energy.
 

Offline Bill S

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Quote from: QC
light cannot be projected off a mirror into infinity - eventually the mirror absorbs the photon energy.

True, but also because the initial reflection is a finite action, as are subsequent reflections, and nothing finite can become infinite.
 

Offline QuantumClue

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Offline Bill S

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Quantum Clue; after witnessing a recent exchange in another thread, I have to ask if you mind that I abbreviate your name to"QC" in the quotes?

Yor_on; I would happily send you a dram, but my ancient lap-top is not up to such extravagant feats.  [:-'(]
 

Offline QuantumClue

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No, of course not, I don't mind at all. :)
 

Offline yor_on

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The durations of the reflections are all possible to define as finite, I agree. but their interaction with those perfect mirrors have no limit. And where you can't find a limit I would say you have a good contender for 'infinity' :)
==

Ah, i knew there was a limit to E-mails..
Da*n
 

Offline Bill S

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Quote from: yor_on
And where you can't find a limit I would say you have a good contender for 'infinity' :)

You know from elsewhere that I will not be able to let that pass without comment. :P

You might have a good contender for a mathematical infinity; in reality, unbounded might be OK, but infinity is a different thing altogether.
 

Offline yor_on

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consider renormalizations.
why do we need them?

Heh ::))
 

Offline yor_on

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But I agree, I've never felt that I've got 'infinity' spiked down, once and for all. I still get hiccups thinking of smaller and larger infinities. Like, can I put a larger infinity inside a smaller? After all, they're both infinities, are they not? And if I did, would it still be the smaller infinity?

And now somebody gonna prove it to me too, right :)
 

Offline QuantumClue

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Renormalization was created because scientists did not like running into infinities. Some scientists - notably Dirac believed renormalization was an ugly feature of quantum mechanics, and was never quite satisfied by it.
 

Offline JP

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Quote from: yor_on
And where you can't find a limit I would say you have a good contender for 'infinity' :)

You know from elsewhere that I will not be able to let that pass without comment. :P

You might have a good contender for a mathematical infinity; in reality, unbounded might be OK, but infinity is a different thing altogether.

I agree with Bill S.  It takes a finite time for the light to bounce from one mirror to the other.  It only takes a few nanoseconds for light to travel between mirrors that are ~ 1 meter apart.  That's fast, so that you would get something near a billion bounces between those two mirrors in 1 second, but it's not infinite.  Even if you set these mirrors up in the early universe and timed the bouncing, it would still not be infinite.  Multiplying 1 billion bounces times the age of the universe in seconds, I get roughly 1026 bounces in the age of the entire universe.  That's certainly a huge number, but it's not infinite.  In practice, all you're really doing here is using the bounces to time the age of the universe, so if the universe's age isn't infinite, this won't form infinite images.

The concept is quite nice, though.  Light travels so fast that hundreds of images seem to appear instantly to our eyes, and they appear to be continuing to infinity, so this experiment gets across the idea of infinity, but it's important to realize that nothing is becoming infinite in this experiment in reality.
 

Offline The Scientist

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If the mirrors are perfect i would say yes, but since mirrors are never perfect you will not get an infinite amount of reflections.

so how many reflections will the mirrors get in general?
 

Offline JP

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If the mirrors are perfect i would say yes, but since mirrors are never perfect you will not get an infinite amount of reflections.

so how many reflections will the mirrors get in general?

That depends on the properties of the mirror.  Mirrors have a property called reflectivity, denoted by R, which tells you the amount of incident light that gets reflected.  If the amount of light hitting a mirror is denoted by I, then the amount reflected is RI.  After n bounces, amount of light left is Rn times the incident light. 

I don't know if that's all confusing or not, but what it means is that you can calculate how much light is left after a bunch of bounces if you know how good the mirror is at reflecting light.  Two mirrors with 90% reflectivity (which is really good for a household mirror) would lose over 99% of the original light after 44 bounces.  If you had an incredibly well engineered mirror for a technical application which reflects 99.9% of the light, it would take 4603 bounces to lose 99% of the light.
 

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