Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Let's talk about time

  1. Aug 1, 2004 #1
    what is time
  2. jcsd
  3. Aug 1, 2004 #2
    Time is what you read on a clock.
  4. Aug 1, 2004 #3
    This is a pretty shallow definition.
  5. Aug 1, 2004 #4
    Time is that part of the universe that is infinite.

    Post Big Bang, time is that part of the universe that is bound up with space such that space can go in motion.

    Space can only be still, except for time, as space goes in motion through time.
  6. Aug 1, 2004 #5
    to Prom

    You mean the body clock , atomic clock etc are simple ??????
  7. Aug 1, 2004 #6
    Not at all. Nor did I say that these are simple.

    What I said, and what I contend, is that to consider time only in the context of what a clock measures is a pretty shallow concept of time.

    While all bears are animals, it does not follow that all animals are bears.

    While all clocks measure time, it does not follow that all time is what clocks measure.
  8. Aug 1, 2004 #7
    I believe we have no knowledge of time but through clocks -- but they come in a variety of form , a clock is something which changes with time , it is the change we recognize -- maybe your just restricting your definition.
  9. Aug 2, 2004 #8
    The more fundamental the concept the more difficult it is even to explain.
    The concept is associated with "change". Time can be considered as that quantity against which we "measure" change.
  10. Aug 2, 2004 #9
    How nice. That is the same thing that I just said about you.

    Your belief is valid. However, I suggest that you investigate the theory of relativity. This will provide you with a greater context for time.

    Are you suggesting that time only exists as a man-made construct, such that we can only identify it through the use of clocks. When relativity speaks of space-time, do you believe that the time part of space time is no more than what a clock measures?

    I am sorry. Of course, that is what you have been saying. I recommend that you lessen the restriction on your definition. You will find that time now has much more meaning that your limited concept.
  11. Aug 2, 2004 #10
    I will not argue with this statement, except to suggest that it is somewhat limiting.

    Are you suggesting that time only exists as a function of our ability to use it for measuring purposes?
  12. Aug 2, 2004 #11
    Question is....

    Question was.....What is Time?

    Time is that part of the universe??? What is it mean to be part of the universe? What isn't part of the universe? hmm.....

    Space can go in motion?? Space can go in motion relative to what?? or What is space?? What is it mean to be bounded?

    Well, I must agree not with this type of verbal poetic argument of time. I prefer the previous post saying that time is what you read on the clock. At least it gives you the way to "measure" time.
  13. Aug 2, 2004 #12
    Time is a tool(like a ruler) used to measure something intangible. Infinitely divisible in itself unless looked at by quantium mechanics. Time has significant relationship to motion which is not quite understood. One cannot measure time without motion.
  14. Aug 2, 2004 #13
    I heard that time moves the solid 3 dimensions/cube.
  15. Aug 2, 2004 #14
    From a physical, biological or psychic viewpoint?

    Time is associated to Universe expansion, increase in entropy and aging.
  16. Aug 2, 2004 #15
    As someone said earlier ... the more fundamental the concept, the more difficult to explain.

    A similarly difficult question is 'What is space?'. Particularly, 'what is one dimension of space?'

    I think that you have to use the 'restricted' language of mathematics to attempt to describe time, space etc. in such a way that the description can be tested by experimenters.

    All else is philosophy.
  17. Aug 2, 2004 #16
  18. Aug 7, 2004 #17


    User Avatar
    Staff Emeritus
    Science Advisor

    It's a very good definition, if one is interested in science. While you don't absolutely HAVE to measure something to make predictions about it, it's usually very difficult to get very far without doing measurements. Talk about time that doesn't involve actual measuments tends to drift off into philosophy, unfortunately, rather than science. The problem with this is that philosophical issues can be debated endlessly, and tend to become disconnected from the physical world. So, all in all, "time is what you measure with a clock" is a great definition for science. IMO, anway.
  19. Aug 7, 2004 #18

    One of the endless debates which goes on is the meaning of time in this context. Some people would like to replace the clock with a concept of 'absolute time' and 'absolute space' because measurements seem to indicate wierd things are at work such as 'dilation and 'contraction' and in the 4 space of STR we must look at 'the interval' as the 'distance' between events.
    But you will notice that try as they might they still refer to clocks even if it's 'dimension' is orthogonal to 3 space.
    The definition is not restrictive , indeed the bears mentioned are excellent reminders of the 'hibernation clock' and those who would like to avoid the physical there is the 'mental clock' , so I stick by my definition and for those who find it 'shallow' then your welcome to swim in deeper waters.
  20. Aug 7, 2004 #19
    Personally, I would not agree that any definition that contains the pronoun you could possibly qualify as a great definition, but that is just me.

    Time is what interacts with space to form space-time, the fundamental building block of the universe. I consider that any definition of time that ignore space completely, and that ignores the impact on space of time, is quite shallow. To instead contend that time is no more than what a clock measures minimizes most of the value of understanding time, in my opinion. I accept this definition as having value from a social point of view, so that we can know when to celebrate each other's birthday and such, but not from the view of modern science. The frame of reference of a clock is basically completely irrelevant, in my opinion, to the main value of understanding how the space of an object in space-time interacts with its time.

    Please feel free to use whatever definition you wish. There is certainly no requirement that we agree. Feel free to consider this to be a complete definition if you wish. I do not, however.
  21. Aug 7, 2004 #20
    Do you consider that a clock provides us with absolute time?

    On the basis of your definitoin, I get the impression that you do.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook