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Why can we see space, but not time?

  1. Aug 23, 2013 #1
    If space and time are really related, why is it that we can see space, but we can't see time?
     
  2. jcsd
  3. Aug 23, 2013 #2

    ZapperZ

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    How are you able to see space?

    Zz.
     
  4. Aug 23, 2013 #3
    I can see space right now. The space between me and my computer. I can see myself move through space, though not through time. I have to look at a clock to see my movement through time. Are space and time really related?
     
  5. Aug 23, 2013 #4

    Dale

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    We don't see either space or time, we see light.
     
  6. Aug 23, 2013 #5

    ZapperZ

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    Actually, you don't see space. You see the object! And you do you know why you think you are seeing a 'distance'? Because (i) you have depth perception because of your two eyes and (ii) the light from the object reaches your eyes AT DIFFERENT TIMES! In other words, your sense of distance actually depends on some time differences! So if we apply your "logic" of seeing space, I could also argue that you're seeing time as well!

    Zz.
     
  7. Aug 23, 2013 #6
    By not being able to see time, I assume what you mean is that you can't see into the 4th dimension, even though you can see in the 3 spatial dimensions. This is because you are inherently a 3 dimensional being, and suffer from the physical limitation that you cannot see into your own fourth dimension. You can however see partially into the 4th dimension of other reference frames and objects that are moving relative to yourself.
     
  8. Aug 23, 2013 #7
    You have to be precise asking these kinds of questions, and define what you mean when you say you can "see" space. Your eyes are able to gauge distance because of parallax - the image each eye sees is slightly different, depending on how far away something is. You measure distance, or percieve it, by measuring the parallax.

    With time, you don't have a sensory organ specifically devoted to sensing time, at least not one you're so consious of as with your vision. However, you can feel the passage of time, you know that what you did this morning happened several hours ago, and that you went to sleep before you woke up.

    You can "see" time by watching a clock, or water dripping, or anything which occurs in some regular way, but your eyes aren't directly meant to measure it.
     
  9. Aug 24, 2013 #8
    mmmmmm....I don't think we do see light !!! we see what light shines on.
    I look at a candle and I see the flame because of light. I look from the side but I cannot see 'the light' from the candle pass me. If we could see light the space in front of me would be covered with criss cross lines of light !!! Like a spider web or a mesh of some kind.
     
  10. Aug 24, 2013 #9
    I dont think so. Light is the only thing we can see. Light is what enters the eye. Of course you cannot see the light crossing in front of you... It has not entered your eye.
     
  11. Aug 24, 2013 #10

    A.T.

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    The eyes see light.
    The brain sees space.
     
  12. Aug 24, 2013 #11

    Dale

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    The function of the human eye is well studied. We see light.
     
  13. Aug 24, 2013 #12

    Dale

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    That is a reasonable point. The brain "sees" time every bit as much as it "sees" space.
     
  14. Aug 24, 2013 #13

    A.T.

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    And the brain doesn't need eyes to see space. People born blind grasp 3D space just fine.
     
  15. Aug 24, 2013 #14
    You have not given my quote as it was stated !!!!
     
  16. Aug 24, 2013 #15

    Dale

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    I quoted you exactly. Your quote, as it was stated, was wrong.

    Our eyes see light, not objects, not space, not time.
     
  17. Aug 24, 2013 #16
    Not really. Well, not for most of us. There are some people though who have no more vision than to tell the difference between light and dark. Those people only see light. They have only light perception.

    http://en.wikipedia.org/wiki/Blindness

     
  18. Aug 24, 2013 #17

    Drakkith

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    I don't know what you're getting at. The eye detects one thing and one thing only. Light. The brain then interprets the signals sent by the eye to form an image that you "see".
     
  19. Aug 24, 2013 #18

    Dale

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    Another excellent point (you are on a roll A.T.!)
     
  20. Aug 24, 2013 #19
    What about shapes? The eye detects shapes. Shapes aren't light though. Though people with very severe visual impairment can't see shapes, only light.
     
  21. Aug 24, 2013 #20

    Drakkith

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    The eye does not detect shapes. It detects the presence of light. Based on the pattern of signals your brain puts together the image, including the shape of things.
     
  22. Aug 24, 2013 #21
    The eye can only sense photons that happen to enter the iris. It can detect the number of photons, (Brightness) some info about their frequency (Color) and also direction relative to the eye itself. (Shapes)

    From there, the brain invents ideas such as "Space" and "Time" to develop a model of what it thinks is going on around you. Other senses like sound and touch can contribute to and extend this model. But you don't really "see" space; it might be better to say that you infer it.
     
  23. Aug 24, 2013 #22
    Because although they are related, they are not the same thing. You may as well ask "if thunder and lightning are really related, why is it that we can see lightning, but we can't see thunder?"
     
  24. Aug 24, 2013 #23

    phinds

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    Nice analogy !
     
  25. Aug 25, 2013 #24

    A.T.

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    The question remains why the concept of time seems different than the concept of space. Is it because they are objectively physically different, or because the way the brain works? Maybe it is because the thought process itself inherently requires the passage of time, and state changes over time.
     
  26. Aug 25, 2013 #25

    ZapperZ

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    But a priori, why should they be the same?

    I wonder if an alternate universe, if these two concepts appear the same, someone's going to ask why they are not different?

    Zz.
     
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