time

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Mariejozee, Feb 24, 2002.

  1. Mariejozee Registered Member

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    It is a shame no one is able to get their brains in gear.

    Who said: "there is no such thing as stones falling from the sky ! And even if thei are falling I still denie their excistence."

    mass = energy, why could time = distance not be true,`especially when you consider E =mc2
     
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  3. Bambi itinerant smartass Registered Senior Member

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    Originally posted by Mariejozee

    Can you move in time the way you move in space? Can you accelerate along time? Can you stop? Can you go backwards? No, no, no, and no (and no fiction, please.) Which makes time pretty different from space.

    As to your original question, I would give just about anything to know the answer.
     
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  5. Mariejozee Registered Member

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    I'm sorry, this is no fiction, your thinking frame is too small, I don't mean this offensive! There is no such thing as a negative distance, therefore you can't timetravel. The only way to travel in time is to be out of the threedimensinal world.

    People say I live an hours drive from my work, imagine you travel by lightspeed, the distance is the time.
     
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  7. (Q) Encephaloid Martini Valued Senior Member

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    Can you move in time the way you move in space?

    Yes. Time is a coordinate, just like the other 3 spatial coordinates. Mathematically you can manipulate any of those coordinates. The only difference is that the 3 spatial coordinates, as in mass and energy, will be undistorted when you bring two reference frames to the same state of motion.

    Time however, can not be brought back to its original state. It remains distorted in every frame of reference. In Special Relativity, the distortion of time is the fundamental cause of all the others.
     
  8. Bambi itinerant smartass Registered Senior Member

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    309
    Mariejozee,

    You mean there's no such thing as a negative interval (at least according to general relativity (GR)). But of course there is such a thing as negative distance. You can move along any one of the three spatial axes back and forth. You have no such freedom of movement along the fictitious time axis.

    If you're "out of 3D world", what the heck are you? You have no width, length, or height. Or perhaps you are in more dimensions than 3, but I don't see how that makes it any more possible to "travel" along time.

    Sure, you can measure distance in terms of light-seconds just as easily as you can in terms of meters. In fact, the meter itself is defined in terms of light speed these days. Still, either measure of length is only a measure of length; it has nothing to do with time. In GR (and SR) you use light to measure everything, including distance (via a lidar method.) Due to the fact that you're matter-energy trying to use matter-energy to measure your matter-energy environment, weird things start to happen with your measurements as your velocity with respect to the object you're measuring varies (length "contraction", time "dilation", etc.) However, such apparent transformations of your interactions with other matter-energy do not imply anything about dimensionality of the universe. Within your frame of reference, you are still free to move around the three spatial degrees of freedom but you have no freedom at all when it comes to the purported time axis.

    The apparent mix-up of space and time in GR stems from the fact that you use a property -- speed of light -- for your measurements which by definition entangles space and time (meters per second). That is only an artifact of the theoretical perspective.

    Q,

    Time may be a coordinate but it's still distinct from space. While you can imagine a time axis and measure "distance" along it, you have no freedom of movement along that imaginary axis.

    Concerning time "manipulation", there's something you don't realize. When it comes to GR, there is no longer pure relativism, there is indeed an absolute viewpoint of sorts in terms of acceleration. In other words, you are either inertial or accelerated, and whichever you are can be determined from any reference frame.

    This so-called "distortion" of time occurs during acceleration, and really has nothing to do with universal time but rather it has to do with time as measured within the accelerated frame. If you take a non-accelerated baseline, then accelerated frames will always have their measured time slowed down with respect to the baseline. This can simply be interpreted in terms of the baseline as one second of the accelerated frame elapsing within X seconds of the non-accelerated frame. In other words, there is still a one-to-one mapping between each instant of the two frames -- except that for the accelerated frame less state change can occur per each instant. So really, the "distortion" is not of time but of matter-energy reaction rates.
     
  9. Mariejozee Registered Member

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    I'll take some time to think over the answers of Bambi and Q

    see you soon !
     
  10. (Q) Encephaloid Martini Valued Senior Member

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    20,855
    Bambi

    Time may be a coordinate but it's still distinct from space. While you can imagine a time axis and measure "distance" along it, you have no freedom of movement along that imaginary axis.

    I partially agree.

    According to Einstein-Minkowski spacetime, the notion of absolute time, in which all observers agree on the elapsed-time between two given events, is replaced with the theory that the set of events that are simultaneous to one observer are not simultaneous to another observer thus, each inertial observer will have a different sense of which events are simultaneous. The concept of 'simultaneity has become a relative, observer-dependent concept.

    Therefore, one cannot 'measure distance' along a worldline if it cannot be determined who is at rest. You could expand on that and say that the distance is measured simultaneously between two events. But you cannot say that any two events are simultaneous. Each observer must project their version of events onto their own worldline (time axis) as well as their own plane of simultaneity (space axes).

    Concerning time "manipulation", there's something you don't realize. When it comes to GR, there is no longer pure relativism, there is indeed an absolute viewpoint of sorts in terms of acceleration. In other words, you are either inertial or accelerated, and whichever you are can be determined from any reference frame.

    Thank you for pointing out something I did not realize. However, I am curious as to how you presumed my ignorance. I have made no claims regarding GR. Of course, I am perfectly aware of the difference in reference frames from SR to GR. You're eluding to Einstein's Principle of Equivalency in GR where a local frame of reference is equivalent to a local frame of reference far removed from gravitational influence.

    You misunderstood my post somewhat. I did not mean the manipulation of time. I attempted to state that mathematically, one is able to manipulate values to determine derivatives within a given formula in which time is one of the values. I can't imagine how one could manipulate time. Perhaps HG Wells could help us on that one.

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    You may have missed a thread where I touched on the of subject of how time is dependent on ones velocity. I went on to show mathematically how it is possible to move into the future. In other words, I showed how it is possible to have 'freedom of movement along an imaginary axis.' That freedom of movement is unidirectional, there is no turning back.

    This so-called "distortion" of time occurs during acceleration, and really has nothing to do with universal time but rather it has to do with time as measured within the accelerated frame. If you take a non-accelerated baseline, then accelerated frames will always have their measured time slowed down with respect to the baseline. This can simply be interpreted in terms of the baseline as one second of the accelerated frame elapsing within X seconds of the non-accelerated frame. In other words, there is still a one-to-one mapping between each instant of the two frames -- except that for the accelerated frame less state change can occur per each instant. So really, the "distortion" is not of time but of matter-energy reaction rates.

    I like this interpretation. But how is that under acceleration, so-called 'matter-energy reaction rates' differ from an inertial frame to a non-inertial frame? Matter-energy reaction rates should be the same regardless of reference frame.

    We can imagine two clocks fixed in space near a large mass. One is at coordinate r=r1 and the other is at r=r2. If we compare the elapsed proper times of the two clocks, we find that the clock that is closer to the mass M, (r=r1) measures a shorter elapsed proper time than the clock that is further out (r=r2). The closer clock runs slower and as we move the clock closer to the mass M the elapsed proper time gets progressively shorter. In this scenario, have the matter-energy reaction rates changed?
     
  11. Mariejozee Registered Member

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    there is no such thing as a negative distance, there is no such thing as -1 meter, you would be beyond a singularity if you accept negative distances !
     
  12. Hoth Registered Senior Member

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    383
    There's no such thing as a negative distance or a negative time. There's only distance or time that's in a certain direction compared to your point of perspective. Distance to the left or right or up or down, and time to the past and future directions.

    Notice how time adds 2 directions -- past and future -- to space. That's just the way the 3rd dimension adds 2 directions -- up and down -- to flatland. The reason the addition of a single dimension adds 2 directions is because you're in the middle. You are a little dot contained within the dimensions, so it seems to you like there are twice as many directions as there actually are. (Thus past and future are just one, objectively.)

    The reason why time doesn't seem to be able -- based on our macroscopic laws -- to be reversable is hard to explain, but the idea is that at a small enough level every process is in fact just as possible in reverse as it is in the forward direction under the laws of physics. In other words, macroscopic time is like an arrow but microscopic time is not. The seeming forward flow of time would be a result of our macroscopic perspective.

    Try this site, it has a good explanation: http://www.utm.edu/research/iep/t/time.htm#FLOW
    An important section of that:
    If physical processes in time do have an arrow, and if the processes obey scientific laws, and if these laws are to be accounted for by the basic laws of physics (the laws governing the microscopic constituents of matter), then you might think that an inspection of these basic laws would readily reveal time's arrow. It won't. Nearly all the basic laws are time symmetric. This means that if a certain process is allowed by the equations, then that process reversed in time is also allowed. In other words, the basic laws of science are insensitive to the distinction between past and future.

    To illustrate, let's suppose you could have a movie of a basic physical process such as two atoms bouncing off each other. You can't have such a movie because the phenomenon is too small, but let's forget that for a moment. If you had such a movie, you could run it forwards or backwards and both showings would illustrate a possible process according to the laws of science. Time's arrow isn't revealed in this microscopic process. The reason why this result is so interesting to scientists and philosophers is that, if you had a movie of the mixing of hot, black coffee and cool cream, then you would have no trouble telling which way is the right way to show the movie. The arrow of time that was absent in the microscopic movie would be evident in the macroscopic movie. This difference between microscopic, basic movies and macroscopic, ordinary movies is odd because ordinary processes are supposed to be composed of more basic processes. Why does the arrow of time appear in one movie but not the other?

    Ludwig Boltzmann had an answer. He was the first to attempt to show how an irreversible macroscopic phenomenon may arise from reversible microscopic laws. He showed that macroscopic thermodynamic processes such as heat in a gas are irreversible because the probability of their actually reversing is insignificant. There are more lukewarm microstates of the set of its constituent molecules than there are microstates with hot and cold regions, so the system evolves in the 'direction' of what is most probable. Let A be the set of microstates of an isolated container in which one part of the container contains hot gas and a separate part contains cold gas. Let B be the lukewarm microstates. Assume all the microstates are equally probable apriori. The number of B states is dramatically larger than the number of A states, so the probability that one of the A states will soon lead to one of the B states is almost one whereas the probability that a B state will soon lead to an A state is almost zero. That is why the process of heat in a gas is irreversible, said Boltzmann.

    The law of physics describing heat processes is the second law of thermodynamics, an irreversible law that says a change occurring in an isolated, macroscopic system will most probably not lead it into a state of lower entropy. Entropy is approximately a measure of a system's disorder, so an entropy increase is a trend toward decay, running down, rusting, the conversion of useful energy into heat, etc. Isolated systems change toward disorder because disorder is so probable, Boltzmann would say; there are many more disordered states than ordered ones. So, entropy's relentless increase accounts for the irreversibility of thermodynamic processes, and this is the basis of time's arrow according to Boltzmann.

    Henri Poincare's recurrence theorem in statistical mechanics says every isolated dynamical system (a system defined by the values of the positions and velocities of all the system's particles--such as the places and speeds of the atoms in a cup of coffee) will eventually return to a state as close to the initial state as we might wish. Wait long enough, and the lukewarm brown coffee will separate into hot black coffee and cold black cream. In other words, if we observe long enough, then all processes reverse; there are really no irreversible processes. Entropy can't continually increase yet also return the system to the same value of entropy, so the second law needs revising, at least as its interpreted by Boltzmann. But because these Poincare periods (the period of time it takes to get back to the initial state) are absurdly long, even compared to the history of the universe, it's a good bet that the higher entropy state is the later entropy state. There seems to be a contradiction between Poincare's theorem and Boltzmann's proof. The second law implies that entropy increases, but Poincare's theorem implies that entropy remains the same over the long haul.


    etc., from the link...
     
    Last edited: Mar 7, 2002
  13. whatsherface imaginary entity Registered Senior Member

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    136
    I rather like how this dude put it:

    Once, in a past time, I spoke to the Dweller.
    Asked of the mystery of time and space.
    Asked him the question that surged in my being,
    saying: O Master, what is time?

    Then to me spoke HE, the Master:
    Know ye, O Thoth, in the beginning
    there and VOID and nothingness,
    a timeless, spaceless, nothingness.
    And into the nothingness came a thought,
    purposeful, all-prevading,
    and It filled the VOID.
    There existed no matter, only force,
    a movement, a vortex, or vibration
    of the purposeful thought
    that filled the VOID.

    And I questioned the Master, saying:
    Was this thought eternal?
    And answered me the DWELLER, Saying:
    In the beginning, there was eternal thought,
    and for thought to be eternal, time must exist.
    So into the all-prevading thought
    grew the LAW of TIME.
    Aye time which exists through all space,
    floating in a smooth, rhythmic movement
    that is eternally in a state of fixation.

    <b>Time changes not,
    but all things change in time.
    For time is the force
    that holds events separate,
    each in its own proper place.
    Time is not in motion,
    but ye move through time
    as your consciousness
    moves from one event to another.</b>

    Aye, by time yet exist, all in all,
    an eternal ONE existence.
    Know ye that even though in the time ye are separate,
    yet still are ONE, in all times existent.


    The Emerald Tablets of Thoth

    (my bold)
     
  14. esp Registered Senior Member

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    Time...

    It turns up again and again. The thing with time is that while it is a dimension akin to the spatial three, we and those three spatial dimensions move in one direction along it.

    This doesn't mean that it's impossible to go against the flow, just well beyond our capabilities for some time.
     
  15. Mariejozee Registered Member

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    OK, imagine a particle (of which we consist, a proton for instance)

    When does that particle doesn't exist anymore ?
     
  16. paulsamuel Registered Senior Member

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    The best definition of time is; time is change.

    Time is not distance, although there is a definite relationship between time and distance.

    Time is certainly not a human invention, it's a natural phenomenon. We didn't invent time just because we invented watches, no more than we invented distance because we invented rulers.
     
  17. Mariejozee Registered Member

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    It seems, no one is really thinking about my statements, Ph D or not, there are only kind of dogmatic replies like "there are no stones in the sky"

    can anybody grasp the idea, that time started with the big bang, and that the bang ocurred by popping up the three dimensions.
    When something is one or two dimensional IT DOESN'T EXIST !!!
    when something doesn't exist there is no time for it.
     

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