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Irrational Space

  1. May 31, 2012 #1
    It seems like human understanding of space can be no clearer than our understanding of time. I still don't understand time. On the one hand it is a discrete interval; but it is also continuous and infinite. All our science is based on an understanding of this time concept and its constructions.
    Is there a solid understanding of time out there? What is it?
    Much like PI is an irrational number (perhaps because it represents the relationship between the continuous length of a circle and the discrete length of its diameter) so it seems that time may also be irrational in our minds. If so, how could space-time be any different? Why don't scientists spend more time explaining time? And why is the art of science in its attempt to describe the world we live in defined as being "time-invariant"?
  2. jcsd
  3. May 31, 2012 #2


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    What is the difference between distance and time? Both are measurements using some sort of measurement device. One is called a clock, the other could be any number of things. Distance, like time, is also continuous and infinite. (to our knowledge) In my opinion time is no more complicated than distance is.

    Edit: We also just had a big thread on time get locked a little while back, so be warned this is a very touchy subject. The thread is here: https://www.physicsforums.com/showthread.php?t=587235
  4. May 31, 2012 #3
    Yes, I agree. And that was my point really - that space could not be less complicated than time.
  5. May 31, 2012 #4
    by the way - thanks. I checked out the thread that you suggested, and certainly don't want to restart a heated debate that goes nowhere. I withdraw my original comments and label them as "not at all useful" (until such time as someone comes up with a shocking and useful new theory - and then I can say, "see - I knew it"!)
  6. May 31, 2012 #5
    If Albert Einstein proved anything it was that time was not the simple and obvious concept everyone thought it was. He spent a great deal of his time explaining time. There is a great deal of material on this subject available. Check it out if you want to know more.
  7. May 31, 2012 #6


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    A good book on this topic is Brian Greene's "Fabric of the Cosmos". It explains our ideas of space/time and reality in a way that appeals to the layman. I was especially intrigued by the chapter on time, where it is mentioned that although we tend to think of time akin to a flowing river (based on our stream of experiences from past to present to future), in reality it is like a huge frozen ocean, an arena where all events of the past,present and future are embedded and it is our own human experience that moves from one point to the other in this block of ice.
  8. May 31, 2012 #7
    Er...what? You keep using words like "discrete" and "continuous" and "irrational", but you seem to be operating under some very non-standard definitions (you're certainly not using them the same way mathematicians use them). Pi, like almost all real numbers, cannot be expression as a ratio of integers; there is no grand philosophical significance to this fact. And what would it mean, exactly, for space-time to be "irrational"?
  9. May 31, 2012 #8
    The word i used was interval, I think. Never used the word integer. I don't have answers about what irrational space means - it's just my layman's term to convey a lack of clarity on the subject.
  10. Jun 1, 2012 #9
    You drew a distinction between "discrete" and "continuous":

    Discrete is more usually used to describe for example the number of atoms in a molecule in the sense that each atom is a discrete entity hence it is associated with integers. Diameter and circumference are both real numbers so it is not clear what distinction you are drawing. Time intervals as far as we know are also continuous, no different to lengths in space.
  11. Jun 1, 2012 #10
    Yes, you are right. My distinctions are not very clear, and it does seem that time and distance are very similar, both conceptually irrational and real. Space-time therefore is also so is it not?
  12. Jun 1, 2012 #11
    Perhaps I am just saying stuff that everbody knows, but expressing it very inefficiently.
  13. Jun 1, 2012 #12
    The problem here is that you're equivocating the bajeezus out of the word "irrational". You start out talking about "the irrationals", which are an uncountable subset of the reals that cannot be expressed as a ratio of integers, and you start talking about "the universe" being irrational. You seem to be trying to link the two, but it's not clear what this is supposed to mean.

    Time is a coordinate system. Distance is a metric. There is no need to attach any sort of grand, philosophical significance to either of them.
  14. Jun 1, 2012 #13
    I respectfully disagree about the need to attach significance to the concepts of time and space. Certainly not all people need to do so, but some certainly should.
  15. Jun 2, 2012 #14


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    I'm not sure this is correct. I believe time is included in the metric of General Relativity and that a coordinate system includes time and space both.
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