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Does time exist?

  1. Nov 21, 2009 #1
    Hey, I just want to be open about the fact that I have already tried to discuss this in the General Physics Forum, but it was dismissed as more of a philosophical issue, so hopefully this section of the Forum will be more open to the discussion.

    Having had a glance through some of the other threads in here, it certainly is not a new idea or notion, but it is one I am trying to get a better understanding of, or at least hear a logically coherent refutation of the issue as I perceive it.

    I didn't post this in any of the other threads that appeared relevant to the issue as this query appeared to be more basic, and I did not want to derail any of the threads.

    I must apologise in advance, as it is more than likely my own understanding that will be developed by, hopefully, drawing on the undoubtedly vast knowledge base in this forum. I doubt I will be providing any mind-blowing insight for anyone, but hopefully you guys won't mind too much indulging a lay person, with an inquisitive mind.

    To get to the crux of the issue as I have so far discussed, I am of the opinion that time is not a measurable force/entity/law of nature, but rather a system of measurement akin to the metric system. More pointedly, that time does not actually exist, but is rather the subjective rationalisation of mankind, based on the misinterpretation of naturally occuring phenomena.

    One point that seems to be made in support of the existence of time, as a real force of nature, is time dilation, and the experimental results that verify its validity.

    The issue I have with this is that time dilation is based on a self-contained set of assumptions that, upon investigation, appear to be fallacious.

    The basic assumptions appear to be:
    1. That time exists
    2. That a clock measures time

    Now the issue that I have is with the assumption that a clock measures the force that is known as time. The example I am most familiar with is the atomic clock, where the microwave emissions of changing electrons are noted as the measurement of the force of time. This however, as far as I can see is a non sequitor. To say that the microwave emissions of changing electrons is a measurement of the force known as time, does not follow logically, and is merely an arbitrary interpretation.

    I would greatly appreciate any feedback on this inquiry.
  2. jcsd
  3. Nov 21, 2009 #2
    I think you've been misled... time is not a force. A force is defined as something that causes a change in motion F=ma F=mg etc. etc.
    Another misled assumption is that clocks are measuring what time is. They aren't measuring 'time' in the way you think. They measure or portray what a second is or a minute or an hour. Other methods of measuring time could be different sizes of pendulums swinging or the moon cycle or the stars.

    I wouldn't even consider the fact that time exists as an assumption anyways. Why would you say that time is an assumption? Can you show any other way?
  4. Nov 22, 2009 #3

    apologies, I am having difficulty in classifying time, or trying to pin down what it actually is, or how it is treated in physics.

    what is leading me to this questioning, is the way in which time appears to be dealt with in physics - this could just be a fundamental misunderstanding - but time appears to be given very real qualities, in its bundling together with space, in spacetime. It appears that it is purported to exist as either some external entity/law of nature/etc., however it is labelled it appears that it is treated as a real "thing", that exists, as opposed to a concept that was created in the human mind. This appears to be true in the sense that it is said that gravity can exert influence over time, that time itself can potentially be manipulated.
  5. Nov 22, 2009 #4
    Time does have very real qualities you keep saying 'physical qualities' time is not a spatial dimension it is a temporal dimension. Time is basically what allows motion to take place so if we notice a baseballs movement it occurs in stages the progress of these stages is what we call time... how small you measure these stages or how large is irrelevant. Time also has an apparent direction based on entropy.
  6. Nov 22, 2009 #5


    Staff: Mentor

    How is this different from any other physics concept? In other words, is your concern that time is somehow given a different treatment from other physics concepts and you think it should be treated the same, or is your concern that time is not treated differently from other scientific concepts and you think it should be treated differently? Why are you singling out time as opposed to say voltage?
  7. Nov 22, 2009 #6


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    You do seem to be confused about the nature of modelling here. We are pretty sure something time-like exists about reality. Things change, things move. So then we invent a way to measure change and movement. One way is to treat time as a space-like dimension. This has all sorts of well-known issues - space allows motion in both directions but time seems to move forward only. So other models of change are talked about. But treating time as a space-like dimension has proved very powerful in a general way - indeed, a general relativistic way.

    So science would not assume time exists. Science has found certain models of change, motion and development to be effective.
  8. Nov 22, 2009 #7
    "Time (and space) are conventions,not experiential realities. What one observes as the passage of time or past time objects/events can only be verified when some change occurs. The only sense of time as actually existing is as the casual sum of changes which is experienced in the 'now'. Thus one may have a memory of past event or object such as ones youth but what one does not have a direct experience of time but only the various signs of ageing, which amounts to a variety of changes. Any physical qualities that one tries to give to time as a reality amounts to some observed change. If there was not any change in something, or relational change between things then there would be not any way to measure time at all. As some changes are regular it possible to make a standard measure known as time. For instance the motion of celestial bodies or the decay of atomic particles. These kinds of changes are regular under 'normal' conditions but when the conditions are altered (under higher energy conditions for instance) then the regularity of change ceases. All that is definitely verifiable comes down to the experience of change which under certain conditions is regular and can be shown to follow certain laws whilst those conditions hold. Time as a conventional reality depends completely on this."

    Is this right?
  9. Nov 22, 2009 #8


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    From the cognitive neuroscience point of view, awareness is anticipatory. Or what philosophers might call intentional. So we don't even naturally experience the now. We are oriented towards what is coming next (based on accumulated prior experience).

    We can make attempts to catch the "now" - focus on some fleeting event. But it takes about a third of a second to achieve such a state of attention (about something that has already happened, like the flash of a light). And we have to suppress awareness of events to either side of that instant.

    So our experiencing of time is quite complicated. And remembering itself is just anticipation - rousing an expectation of "what it would have been like to be back at that place".
  10. Nov 22, 2009 #9


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    Time exists simply because there is an entity called time which we associate with our concept of reality. It is actually quite absurd to doubt that time exists in this sense. Also, the concept of time is implemented in our very language. We even use it unconsciously.
  11. Nov 22, 2009 #10
    yes that accords with my experience - there is an intentional aspect of the cognition of change is always present in any experience. But I dont think that it is even possible to a have a direct experience of the 'now' aside from this intentional aspect which as you say is anticipatory based on previous experiences of change.This has important implications for how we relate to the 'changiness' of phenomena - especially to do with how shape our experience through that intentional function.
  12. Nov 22, 2009 #11
    How does the time-energy uncertainity come in here? Is time analogues to position and energy analogues to momentum like the quantum uncertainty principle? Is measuring position in quantum mechanics like measuring time in general relativity? What is the time of quantum mechanics?
  13. Nov 23, 2009 #12
    Time is the measurement of change. There is change, therefore time exists. So we can say it is independent of observation.
  14. Nov 23, 2009 #13
    It's 3:05 am. I go to work in 12 hours. I just hope time is correct so that I am not late.
  15. Nov 23, 2009 #14
    Yes, when modeling the evolution of a system over time, you can point an arbitrary time co-ordinate and describe the state. However, time is a constant forward moving flow, the point is more so a useful abstraction then an absolute physical reality.
  16. Nov 23, 2009 #15
    Time does not exist in our head. Concepts of time does. Time is a dimension of our universe, and as such, does exist outside of our minds. If it was just an idea in our head, then why can't we move backwards in time? Why can we only remember the past, and not the future? If its not real, then what separates cause from effect?
    Just as we measure gravity in man-made terms, we measure time in man-made terms. Gravity and time are real, and have a relationship. If time was not real, then how can it be effected by gravity? You can look at gravitational time dilation, and space-time.
  17. Nov 23, 2009 #16


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    The two could be seen as reflections of particle vs waves descriptions. So there is the uncertainty of particles in terms of the locations and motions or kinetic energy of point-like objects. And then the uncertainty related to a wavelength view where the more narrow the temporal window of obervation, the more uncertain becomes the number of cycles contained within that temporal expanse.

    QM occurs in time - the wavefunction evolves in time. And is also collapsed at some point in time.

    Where things get really interesting though is the experimental evidence for retrocausality - quantum eraser, hopefully Cramer's planned new experiment, etc. So QM, if taken seriously, must change our conception of time as a simple "motion" from a past to a future "location".

    Time could be treated as an extrinsic dimension in the Newtonian model, and an intrinsic dimension in GR, but another kind of model would be demanded as a result of accepting retrocausality.
  18. Nov 23, 2009 #17
    thanks apeiron. I was worried that would be a really stupid question.
  19. Nov 24, 2009 #18


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    Everything "exists in our heads" if I must speak your language. Time is a structure in which our minds interpret perceptions. The thing-in-itself have no spatial or temporal properties. Time does not "exist" independent of the mind. The temporal construct is however necessary for human experience, and thus it is naturally firmly implemented in our language.
  20. Nov 24, 2009 #19
    Time is a measurement of change, so it certainly exists outside of our minds. To say that everything exists in our heads is just baloney, yes it is true to some extent, but you have to remember that things exist without observation.

    The rules that describe nature seem to be mathematical. This is not a result of the fact that observation is the judge, and it is not a characteristic necessity of science that it be mathematical. Nature in short, is mathematical.
    - The laws are not the observations
  21. Nov 24, 2009 #20


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    Is it baloney? Yes, time is incorporated in the meaning of change, and we can indeed measure it with respect to the concept of quantity. How does this imply in any way that it "exists" outside our minds? You say things exist without observation. Does it really make sense to say that? It is actually the very act of observing a thing that makes it senseful to talk about its existence.

    Yes, nature is mathematical, but for diametrically different reasons than what you might think. Mathematics is twisted and formed to apply to nature, thus nature is "mathematical" in the same sense as mathematics is "natural".

    The natural laws are deliberately over-simplified principles to aid our understanding of natural processes. Natural laws in general does (deliberately) not take the overall complexity of natural processes in account, but captures the essential parts which we can make use of.
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