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Do time and space exist within the universe?

  1. Oct 30, 2006 #1
    Or is it the other way around? Either way, how do we know this? (I read somewhere that Einstein taught that they existed within the universe, but how he came up with this idea, that's the question.)
     
  2. jcsd
  3. Oct 30, 2006 #2

    pervect

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    [edit]
    At first glance, this question appears to be entirely philospohical - as are most questions about "existence". (The only exception that comes to mind is "existence proofs" in mathematics, which are mathematical rather than philosphical).

    If the original poster has some particular question in mind that can be reduced to physics (reducing the question to the outcome of some specific thought experiment would be one way of acheiving this), the thread probably belongs here. But if the original poster is entirely interested in philosophy, this thread probably belongs in the philosophy forum.
     
    Last edited: Oct 30, 2006
  4. Oct 30, 2006 #3
    you should go to the NASA. :biggrin:
     
  5. Nov 2, 2006 #4
    I can only say that, in physics, with "universe" we mean not only matter, energy and bodies of various kind, but space and time as well.
    However, according to Einstein's General Relativity theory, it comes out that the very matter and energy, in a certain way, create space and time, because some properties of space and time are determined by the mass and the energy which are present there.
    Is this related to what you wanted to ask?
     
  6. Oct 16, 2009 #5
    I have similar questions.
    How can I design an experiment which tests for 1 m of space?
    How can I design an experiment which tests for 1 s of time?
    How would I implement controls for these experiments?
     
  7. Oct 16, 2009 #6

    Dale

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    Use a rod or ruler.
    Use a clock
    Compare your rod and clock to existing standards.
     
  8. Oct 16, 2009 #7
    Is that not calibration?
     
  9. Oct 17, 2009 #8

    Dale

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    Yes, you control measurement errors by properly calibrating your measuring instrument to existing standards.
     
  10. Oct 17, 2009 #9
    The existing standards are subjective are they not?
    When I measure a standard m length of space (for example in a vacuum) what am I actually measuring?
     
  11. Oct 17, 2009 #10

    Dale

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  12. Oct 17, 2009 #11
    It is not.
    Thank you Dale.
     
  13. Jun 28, 2010 #12
    Long time...
    I suppose your answer was directed at Pete81t, but your statement is interesting to me because it reverberates with my *intuition* about space and time, as being emergent and dependent, rather than fundamental and absolute universal physical properties; contrary to the Newtonian model.
    Granted, my view of the subject is philosophical, for this I feel I must apologize. Whatever happened to thinking about physics anyway? During the early 1900's physicists did a lot of thinking and debating as well as experimentation in combination with mathematics. Recently it seems, thinking has been outmoded in the field of physical study; I've often heard the phrase "do the math and you'll get the right answer". This may be true within the scope of standard quantification, however a standard (normalized value) does not always correlate absolutely with experimental data (i.e. electron charge value). Does this not mean that any calculation incorporating a standard value is biased?

    Last winter I performed a very basic calculation based on given values for quarks and found that just over 1% of the mass-energy of a proton was accounted for. Interestingly, I found that total proton mass-energy was approximate to the sum of quarks2.7.
    I took this to mean that the space in which a proton resides is created by the interaction of quarks over time.

    So, do point particle interactions produce the emergent phenomenon of space?
     
  14. Jun 29, 2010 #13

    Ich

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    In reality, it's (Number of goals scored by Germany at the World Cup so far)3.1
    It means that a proton is round.

    :rolleyes:

    What I wanted to convey:
    If you do the math, be sure you know what you're doing. That's the kind of thinking required in physics, 100 years ago and now.
     
  15. Jun 29, 2010 #14

    Chronos

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    Time without space is like knowledge without ignorance.
     
  16. Jun 29, 2010 #15
    Hi Ich,
    I suppose you are poking fun. Fair enough. I am not a physicist or mathematician, so am able to do only the simplest calculations. Please could you help me to understand how can I account for the majority of proton mass-energy?
     
  17. Jun 29, 2010 #16
    I am trying not to be ignorant; my knowledge is limited ; )
     
  18. Jun 29, 2010 #17
    I think it would be fair to say that the Universe is spacetime, within which such oddities as mass act to warp it. In a more general sense, isn't a universe simply a region in which physical constants (aka the laws of physics) are uniform? In that sense, there is no "within" a universe, because that implies a 3D body you can leave.
     
  19. Jun 29, 2010 #18
    I was under the (possibly erroneous) impression that spacetime is a model Universe. Also that aspects of the model change relative to dynamic points of observation. The impression I have is that the manner in which one experiences time is changeable and dependent on the rate at which one interacts with space, relative to some other point of space interaction.

    I would agree that spacetime is a useful idea, but am having great difficulty in placing it as the (or a) physical universal foundation. Spacetime seems somewhat analogous to the grid of longitudinal and latitudinal lines we paint on a globe in order to navigate more easily.
     
  20. Jun 29, 2010 #19

    Dale

    Staff: Mentor

    Whatever happened to actually learning about a subject before thinking that you knew enough to make reasonable critiques? The pace of scientific debate and thought has increased dramatically since the 1900's, particularly with the advent of improved communications. To make this comment shows an enormous ignorance about the field and history.
     
  21. Jun 29, 2010 #20
    You can't separate spacetime in GR... that's why its called "spacetime" or 3+1 dimensions. The Stress Energy Tensor should make that clear.
     
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