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Time and physicality of dimensions

  1. Jul 9, 2011 #1
    Is it correct to say that the three space dimensions are no more physically (as in materially) real than the time dimension, but that only the mass that exists in the dimensions are real in a material sense?
    I have a suspicion that why som people insist that time (and spacetime) does not exist, not even as a dimension, is that a ruler can measure something tangible (mass), like the length, width and height of an ice cube, while a clock measures something not directly tangible (a process), like how long it takes for the ice cube to melt.
  2. jcsd
  3. Jul 9, 2011 #2


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    Three dimensions of space, one dimension of time, along with matter having mass and energy without mass are valid ways of understanding the world around us, and us, too, for that matter.

    Next time you go to buy a big screen TV and borrow money to pay for it and lug it home and get your electric bill to watch it, you'll find out just how real they all are.
  4. Jul 10, 2011 #3
    If you always drove at 60 mph along an interstate going from Cininnati to Cleveland, you could put time marks along the side of the road and keep track of your progress with time measurements. That's basically what you are doing when you move along the 4th spatial dimension at speed c and make time readings. A mechanical clock just marks off time points along the world line (extended along the 4th dimension). That doesn't make the world line "time" any more than the time marks along the interstate makes the interstate "time." A typical world line might extend for 10^13 miles along the 4th dimension.
  5. Jul 10, 2011 #4


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    This would depend completely on the definition of the words "real" and "material." If you don't provide your definition of those words, then we can't have a meaningful discussion.
  6. Jul 10, 2011 #5


    Staff: Mentor

    Generally only matter will be anything "in a material sense." After all, "matter" is the root word of "material."

    Mass is not matter, mass is a property of matter, like charge.
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