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The physics of the "present"

This is a discussion on The physics of the "present" within the General Discussions forums, part of the Community Boards category; I don't mean the state of physics in modern times, but the physical nature of what we call the "present". ...

  1. #1
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    The physics of the "present"

    I don't mean the state of physics in modern times, but the physical nature
    of what we call the "present".

    Does the "present" have a physical reality outside of conscious perception?
    If no one existed to experience time and the present, would the present have
    any physical meaning?

    It seems to me that without our knowledge or perception of the present, there
    would be nothing to determine it. On the other hand, if everyone suddenly
    disappeared, it's hard to imagine that it still wouldn't be May 19 2012. But
    that would mean that there's something special about May 19 2012. That
    with or without us, there is some kind of physical pointer to this point in time.
    And I can't imagine the nature of such a pointer.

    So possibly time is a continuum, existing all at once, with no physical distinction
    between any one point in time and another, as far as one being the "present".
    It would only be our perception of that point in time as being "present". And that
    would have been the individual perception for each person throughout history.

    Or possibly there is no time continuum; there is only the "present", a single "point
    in time" which undergoes constant change. We perceive the change as "past,
    present and future".

    There is of course, the physical quantity of time that shows up in so many physics
    equations. The occurance of that term seems independant of "past, present, future"
    except for the direction (sign) of the term.

    So basically, my question, is there a formal physical definition of "the present"?

  2. #2
    Registered User manasij7479's Avatar
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    AFAIK, no.
    Consider an observer at 'present' looking at earth from 65 million light years away.
    Does that mean that the earth still has dinosaurs at 'present'?

    It is our consciousness (which itself does not have a definition, I think) that perceives 'present'.
    Just as any other coordinate frame, the 'origin', 0 of a time line could be called 'present', but that is easily transformed.
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    It does seem that consciousness is involved. Once you remove our own perceptions,
    several aspects of time (as we experience it) disappear along with it. The rate and
    flow of time is competely subjective, with the rate of our own neural activity as the
    reference. The length of a day still has meaning insofar as it is one revolution of the
    earth, but there is nothing we can say of it beyond that.

    We need a model of time that also explains the conscious perception of time, even
    if consciousness itself isn't explained.
    There is is one model that I find highly unlikely, the model of a vast number of universes,
    each one representing a single step in time. Somehow, things progress through these
    individual configurations of matter, and this progression is called time. One big problem
    with this is that there would have to be some kind of cosmic temporal pointer that identified
    one of these universes as being the present one. It's very hard to imagine how consciousness
    could even be possible in such a world of discrete static universes, and even if consciousness
    could exist, what is pointing to our "present" state of consciousness?

    More likely, I think, is a single universe which undergoes continual change. In such a world it is
    always "now". But what differentiates this particular configuration of matter from any others
    that preceded it? Or any others that may follow? The configuration of our neurons determine
    our perception of "now" as they are part of the material configuration of the universe. It's not
    hard to imagine why we are aware of this point in time, as we are a material part of it. But why
    aren't people in 1942 also concurrently aware of their present? Or are they?
    Just as our "current" configuration of matter exists, so must every previous configuration have
    existed, and every future configuration will exist.

    Is every conscious being's perception throughout history equally valid then? Is there a "present"
    that is only relative?

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    I disagree that consciousness or perception is involved in the definition of the "present".

    I would define the "present" as the total (aggregated) state of existence at the current point in time.

    Existence is not the same as observability, observing something is not the same as perceiving it.
    Right 98% of the time, and don't care about the other 3%.

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    Registered User whiteflags's Avatar
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    Time is just a human invention with human utility. If we need a model that explains the conscious perception of time, what would we use that model for? We can already objectively measure time. You can measure how much time passed between you and other objects in the universe.

    More importantly this may not even be a physics question, I'm thinking it's a psychological or even a philosophical question, depending on the kind of answer you want.
    Last edited by whiteflags; 05-20-2012 at 03:31 AM.

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    Registered User manasij7479's Avatar
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    Quote Originally Posted by grumpy View Post
    Existence is not the same as observability, observing something is not the same as perceiving it.
    That is not correct... as far as my little understanding of Quantum physics and Relativity leads me to believe.
    Last edited by manasij7479; 05-20-2012 at 07:42 AM.
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    2.The fast and unsteady suddenly falls asleep while running !



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    Quote Originally Posted by grumpy View Post
    I disagree that consciousness or perception is involved in the definition of the "present".
    I didn't mean that consciousness or perception was involved in the physical reality of the "present".

    Quote Originally Posted by grumpy View Post
    Existence is not the same as observability, observing something is not the same as perceiving

    it.
    I agree, although perception can have high degree of correlation to physical reality. Life would be impossible
    or very brief otherwise. I think the question here is, just how correlated is time perception to the physical?

    Quote Originally Posted by whiteflags View Post
    Time is just a human invention with human utility. If we need a model that explains the conscious

    perception of time, what would we use that model for? We can already objectively measure time. You can measure how much time

    passed between you and other objects in the universe.

    More importantly this may not even be a physics question, I'm thinking it's a psychological or even a philosophical question,

    depending on the kind of answer you want.
    Yes, a model of time perception would be psychological or philosophical.
    I would look for a model of time perception so that the perception could possibly be separated from the physical
    reality. It is the physical nature I'm interested in.

  8. #8
    Unregistered User Yarin's Avatar
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    It's futile at best to try to understand the mechanics of what allows there to be a "past", "present", & "future", I think, considering we exist completely within it & are completely reliant on it.
    Of course, one could try to argue with that from a metaphysical PoV, but I don't even know of any such arguments.

    But really, "the present" can de defined rather easily, I think, without need for philisophical or scientific rumination.
    Simply, it is what is, without consideration of what has been or what will be. This means that the "present" has the same "value" everywhere, always, irrespective even, of the "speed" of time in different places.
    Of course though, everyone in the universe has a different observation of the present, and hence differing perceptions of it, but I imagine that's already pretty well understood.
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    Captain Crash brewbuck's Avatar
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    Given that the laws of physics are symmetrical with respect to time there should be no reason for the past to be any different than the present, but it obviously is. Thermodynamics says that as things change they tend to change into states with more disorder. That can be stated without appealing to any particular time direction. Time appears to have a consistent direction because we originated in a region of the universe with above-average degree of order and are now progressing into less-ordered states (on a medium scale -- on the small scale of humans order can increase noticeably). This is all just due to random fluctuations in entropy throughout the universe. Eventually we'll just be an undifferentiated soup with no clear direction being "forward in time" or "backward in time." Listen to Feynman's very interesting lecture on this topic.

    As far as the meaning of "now," that's just a word we made up to describe things that are immediately present in our consciousness, i.e. not memories but actual perceptions of reality. This is not actually a point -- "now" is actually a range of times and events which are all immediately pertinent -- and the radius of "now" depends on who you are, what you are doing, the details of your specific brain, etc.
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    	if (a) do { f( b); } while(1);
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  10. #10
    Master Apprentice phantomotap's Avatar
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    I'm presently eating a cookie! ^_^;

    Take that na´ve perception away and we get to dive into fun theories; would you want your guess to be flavored by physics, philosophy, religion, or how much faster my dog seems to run when he wants nums?

    I only ask because you are going to get four very different answers.

    Soma

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    Quote Originally Posted by phantomotap View Post
    I'm presently eating a cookie! ^_^;

    Take that na´ve perception away and we get to dive into fun theories; would you want your guess to be flavored by physics, philosophy,

    religion, or how much faster my dog seems to run when he wants nums?

    I only ask because you are going to get four very different answers.

    Soma
    A metaphysical explanation would be very interesting, but it's the objective, purely physical one
    that I am wondering about.

    One might ask it as, "what time is it if no one is looking?"
    And it may just be completely meaningless.

    It would seem that certain characteristics of the universe must be there even if no one were around to be
    aware of it. There is the problem though of imagining anything about them in the absence of conscious
    perception. It's by definition impossible.
    The progression rate of time is subjective and variable as we experience it. There is no basis for believing
    that time would march on at the same rate that we perceive it, in our absence, whatever that might mean
    (there's that problem of imagining it again).
    We might not be perceiving the rate of time, but creating it.

    Quote Originally Posted by brewbuck View Post
    Given that the laws of physics are symmetrical with respect to time there should be no reason for the

    past to be any different than the present, but it obviously is. Thermodynamics says that as things change they tend to change into

    states with more disorder. That can be stated without appealing to any particular time direction. Time appears to have a consistent

    direction because we originated in a region of the universe with above-average degree of order and are now progressing into

    less-ordered states (on a medium scale -- on the small scale of humans order can increase noticeably). This is all just due to random

    fluctuations in entropy throughout the universe. Eventually we'll just be an undifferentiated soup with no clear direction being "forward in

    time" or "backward in time." Listen to Feynman's very interesting lecture on this topic.

    As far as the meaning of "now," that's just a word we made up to describe things that are immediately present in our consciousness,

    i.e. not memories but actual perceptions of reality. This is not actually a point -- "now" is actually a range of times and events which are

    all immediately pertinent -- and the radius of "now" depends on who you are, what you are doing, the details of your specific brain,

    etc.
    We could expand that radius to include our entire lives, and expand the question to one about an era
    in the history of the universe instead of just a single instant. Something like the anthropic principle could
    explain why the universe happens to be in this era, or what determines the current era. It is simply this
    era because we happen to be here in this one to ask about it. There was no one around at other times.

    Is there no particular point in time in our absence? are there all points in time in our absence?

    Quote Originally Posted by Yarin View Post
    It's futile at best to try to understand the mechanics of what allows there to be a "past", "present", & "future", I

    think, considering we exist completely within it & are completely reliant on it.
    Of course, one could try to argue with that from a metaphysical PoV, but I don't even know of any such arguments.

    But really, "the present" can de defined rather easily, I think, without need for philisophical or scientific rumination.
    Simply, it is what is, without consideration of what has been or what will be. This means that the "present" has the same "value"

    everywhere, always, irrespective even, of the "speed" of time in different places.
    Of course though, everyone in the universe has a different observation of the present, and hence differing perceptions of it,

    but I imagine that's already pretty well understood.
    Indeed, we probably know more about physical time than we do about perceived time.

    Time would probably be easier to grasp if it were the independant quantity that we perceive it as. But when
    it's an inseparable part of the larger space-time, it seems it has a nature that must be different than we perceive.
    Just as space is not just an empty void that things float around in.
    Our perception of time might be closer to it's physical nature if a 3D model is correct (3 spatial with time separate).
    But if the 4D model is correct, with time as one of the 4 dimensions, then I have trouble imagining exactly what it is
    we are percieving.

  12. #12
    Registered User whiteflags's Avatar
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    The progression rate of time is subjective and variable as we experience it. There is no basis for believing
    that time would march on at the same rate that we perceive it, in our absence, whatever that might mean
    (there's that problem of imagining it again).
    I disagree with that. I think we need external cues to understand when we think we are, which is what makes our time perception either awful or really accurate. It depends on the stimulus in the environment that we are using: e.g. the ticking of clocks, which is accurate, or just sleeping eight hours and not knowing it. But objectively you have objects moving in the universe, that move even if you aren't paying attention, so they serve as an objective reference. You can measure the amount of movement and the rate of movement for time, just like how the sun moves 15 degrees an hour across the sky. So if you want to be accurate on the passage if time, you should use sources of information that don't depend on subjective observation.

    Another good point is that there will be evidence that you exist for a long time (especially if you get fossilized!) so there are ways to objectively affirm that you existed some time between the future after death and the epoch on someone's calendar.

    I did manage to find an article that supports what I'm saying, but it's not recent. It could be bunk by now.
    Last edited by whiteflags; 05-22-2012 at 02:58 AM.

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    Quote Originally Posted by whiteflags View Post
    I disagree with that. I think we need external cues to understand when we think we are, which is what makes our time perception either awful or really accurate. It depends on the stimulus in the environment that we are using: e.g. the ticking of clocks, which is accurate, or just sleeping eight hours and not knowing it. But objectively you have objects moving in the universe, that move even if you aren't paying attention, so they serve as an objective reference. You can measure the amount of movement and the rate of movement for time, just like how the sun moves 15 degrees an hour across the sky. So if you want to be accurate on the passage if time, you should use sources of information that don't depend on subjective observation.

    Another good point is that there will be evidence that you exist for a long time (especially if you get fossilized!) so there are ways to objectively affirm that you existed some time between the future after death and the epoch on someone's calendar.

    I did manage to find an article that supports what I'm saying, but it's not recent. It could be bunk by now.
    I don't completely disagree with that.
    Any number of things can serve as a clock, including our own
    mental processes. And some can use their "internal clocks" pretty
    accurately. In that sense you could say that we perceive time with
    some degree of objectivity.

    But a feeling of time flow is only that - a feeling or perception. How
    do you know which of the various perceptions we have are the "real"
    or "correct" ones? Which reflect the "real" flow rate of time?
    I could argue that the sense of flow that we have when unconscious
    is most accurate since conscious perception is absent for that interval.

    When we try to imagine time in our absence we are usually making
    two mistakes. First if are imagining anything at all we are not absent.
    And second, it is only a model we are imagining. We are still separated
    from the physical world by the interface of our senses.

    True, whatever time is doing now, it will continue to do after we are gone.
    Also true, we, and our internal clocks are real enough. But we shouldn't
    mistake the model for the real thing. When we are gone, certain things
    about time, as we perceive it, will be gone also.

  14. #14
    spurious conceit MK27's Avatar
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    What multi-disciplinary madness have I been missing?!??

    Quote Originally Posted by Newtonian curmudgeon
    I would define the "present" as the total (aggregated) state of existence at the current point in time.

    Existence is not the same as observability, observing something is not the same as perceiving it.
    I agree that the "existence of everything" is not observability, but it also does not define the present any more than a warehouse defines a box on a shelf. You need a point in space (the existence of something more specific) for your definition of present, since the "totality of everything" at a fixed point in time is a) abstract at best; b) mostly irrelevent since the speed of light localizes things.

    So, here's your answer:

    Matter is existence, existence is matter. Time is fundamental to atomic matter, but while our physics is entirely about atomic matter, I have never seen it asserted that matter is/could not be anything but atomic (in fact I think the early points in big bang theory imply very strongly that existence/matter is the foundation for atomic physics, but cannot quite be synonymous with it, there is a point in time before atomicity). So while time is a fundamental aspect of atomic matter, it perhaps is not a fundamental aspect of "matter", which is why it does not make sense to speak of the beginning or end of existence (the same way "literally nothing" is a paradoxical concept), only the beginning and end of our universe.

    The same is probably true of space (it is no more fundamental to matter than time), which makes "what is matter, beyond the atomic?" kind of an interesting question. However, I think it is fundamental to physical science that the question cannot be addressed (or, can't be addressed yet); no one asks what are the smallest sub-atomic particles "made of"; there is only one possible answer (matter) which makes it circular (it's the same question as "what is matter made of"). Or you say "quants of force", which refers to matter's relationship with itself (matter as the medium of energy). Matter is existence, existence is matter.

    The mind is a state machine that creates the holographic world of our perceptions. Like any electronic device the brain clearly involves specific frequencies (time cycles) -- we do not percieve things with infinite granularity, time-wise, which is why the color red is fully present to you instead of being some pulse. The fact that the speed of light is a constant for atomic matter is not arbitrary; we can consider frequencies as "steady" and that is what makes heterogenity in the form of matter meaningful to us and the tiny particles of which we are made. Without that fundamental measuring stick for precise and equal units, there would not be eg, the equality of two protons. 'c' is the bounds of the form of our universe (it deliniates and defines the beginning and end of it).

    Which takes us to the answer: the present is not a "point" in time, it is a duration, but it is not something we experience as a duration; it involves phenomenon that do have a beginning and an end and can be considered in greater granularity in atomic physics, but for our perception, these phenomenon are effectively simultaneous -- their beginning and end are always present to us. I'd assume this duration is on the order of milliseconds, like sound. A high pitch and a low pitch are different but they are the same in the sense that they are both singular and present all at once, although we can infer the way they take place in time via the concept of frequency. Another example: gamers may bicker about the experiential significance of 80 fps vs. 20 fps, but no natural human being will ever bicker about the experiential significance of 1000 fps vs. 1000000 fps (unless it is with reference to the perception of heat, lol).

    People have written here about the mind in relation to clocks, which is good (atomic matter is also a clock, think of c again). Now consider that a second hand has a width.

    The "duration of the present" is given to us within a correlative region of space, which is why the mind experiences space as defined by components such as shape, sound, color, etc. It's the fundamental frequency of your state machine, the carrier wave of the mind. You're atomic, inside and out.

    Everyone understand now? There is a joke in here about the "Hertz donut" but you really have to be there for that...
    Last edited by MK27; 05-30-2012 at 04:34 AM.
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    cpwiki -- our wiki on sourceforge

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    Registered User manasij7479's Avatar
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    I have never seen it asserted that matter is/could not be anything but atomic
    Maybe I'm missing your point, but matter is quite commonly considered as waves, in duality with particles.

    The "duration of the present" is given to us within a correlative region of space, which is why the mind experiences space as defined by components such as shape, sound, color, etc. It's the fundamental frequency of your state machine, the carrier wave of the mind. You're atomic, inside and out.
    How does that fit in with the time-energy uncertainty ?
    Manasij Mukherjee | gcc-4.8.2 @Arch Linux
    Slow and Steady wins the race... if and only if :
    1.None of the other participants are fast and steady.
    2.The fast and unsteady suddenly falls asleep while running !



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