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Author Topic:   0.99999~ = 1 ?
Straggler
Member (Idle past 94 days)
Posts: 10333
From: London England
Joined: 09-30-2006


Message 70 of 237 (543477)
01-18-2010 1:31 PM
Reply to: Message 67 by Dr Jack
01-18-2010 10:01 AM


Re: 0 and Infinitesimally Small - Something and Nothing
The difference isn't infinitesimally small, it's 0.
Indeed. It approaches 1 and is 1 at the limit. No disagreement there.
Strag writes:
Except that it still seems like 0.999R should be infinitesimally less than 1. Which I suppose it is. If by infinitesimally small we mean tending to 0.
0.9999999~ is the limit of 0 + 9/10 + 9/100 + 9/1000 + 9/10000 + ....
The limit. And the limit of that series is 1, not something infinitesimally different from one.
Isn't that what I said? That at the limit the difference between 1 and 0.999R is 0.
Strag writes:
Which brings us to distinguishing between 0 and something that is infinitesimally small. Which brings us to distinguishing between something and nothing. Which is where I think the whole intuition things takes over and gets things wrong.
I am not arguing with your maths here. I am trying to explain why it still feels intuitively wrong.

This message is a reply to:
 Message 67 by Dr Jack, posted 01-18-2010 10:01 AM Dr Jack has replied

Replies to this message:
 Message 72 by Dr Jack, posted 01-18-2010 1:49 PM Straggler has replied

  
Straggler
Member (Idle past 94 days)
Posts: 10333
From: London England
Joined: 09-30-2006


Message 71 of 237 (543478)
01-18-2010 1:33 PM


Headbanging Lunacy
In my time at EvC there have been some truly head banging conversations. Ones that have gone down in forum folklore as examples of brazen lunacy. One about the center of the surface of a sphere springs to mind. As does one by Buz about a non-bending steel bar in curved space-time.
At this point I feel that this one might be on the verge of going down in history as the Straggler says 1 doesn’t equal 1 thread.

  
Straggler
Member (Idle past 94 days)
Posts: 10333
From: London England
Joined: 09-30-2006


Message 73 of 237 (543550)
01-19-2010 5:20 AM
Reply to: Message 72 by Dr Jack
01-18-2010 1:49 PM


Re: 0 and Infinitesimally Small - Something and Nothing
Oh, sure, it feels intuitively wrong, no doubt. But as in higher level physics, intuition is a shoddy guide to higher maths.
Which is exactly why I am not disagreeing with you?

This message is a reply to:
 Message 72 by Dr Jack, posted 01-18-2010 1:49 PM Dr Jack has replied

Replies to this message:
 Message 75 by Dr Jack, posted 01-19-2010 10:01 AM Straggler has not replied

  
Straggler
Member (Idle past 94 days)
Posts: 10333
From: London England
Joined: 09-30-2006


Message 79 of 237 (543604)
01-19-2010 3:02 PM
Reply to: Message 77 by Dr Jack
01-19-2010 2:51 PM


Re: Asymtotes
0.999999~ is the asymptote, not the value approaching it.
I think you have hit the nail on the head here. And IGIT has to be commended for asking the right question.
Even if we think of 0.999R as the infinitie series 9/10 + 9/100 + 9/1000 + 9/10000 + ...... as is the correct way to think of this then I think in our heads we intuitively do the conceptual equivalent of plotting y as the sum of the series and x as the number of terms in the series. In which case y never actually equals 1.
But as you say 0.999R isn't the sum of the series as such. It is the asymptotic value.
It all makes more sense to me expressed like that anyway.

This message is a reply to:
 Message 77 by Dr Jack, posted 01-19-2010 2:51 PM Dr Jack has not replied

  
Straggler
Member (Idle past 94 days)
Posts: 10333
From: London England
Joined: 09-30-2006


Message 165 of 237 (544421)
01-26-2010 8:17 AM
Reply to: Message 157 by RAZD
01-25-2010 6:29 PM


Re: ~ to the 10th power?
It might be interesting to see how people think which explanations are the ones that best convince them -- Huntard and Straggler and any other lurkers who had trouble with this issue.
Well I was convinced of the wrongness of my initial intuitive assertion pretty much straight away. Just looking at what others had written and thinking about it a bit convinced me of that on a rational level. I just didn't like it. It didn't feel right. I pursued the matter to A) Try and explain why I thought intuition and fact were so at odds B) To find a way of reconciling the two in my own head.
I think I achieved both (to my own satisfaction anyway) by thinking of this in terms of an infinite series and asymptotes. As per Message 79
Straggler thinking to himself out loud writes:
Even if we think of 0.999R as the infinitie series 9/10 + 9/100 + 9/1000 + 9/10000 + ...... as is the correct way to think of this then I think in our heads we intuitively do the conceptual equivalent of plotting y as the sum of the series and x as the number of terms in the series. In which case y never actually equals 1.
But as you say 0.999R isn't the sum of the series as such. It is the asymptotic value.
It all makes more sense to me expressed like that anyway.
All of which Mr Jack had been saying to me in so many words anyway. It was just this particular approach/phraseology that made the penny drop in my own intuitive head.

This message is a reply to:
 Message 157 by RAZD, posted 01-25-2010 6:29 PM RAZD has seen this message but not replied

  
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