What is "time"

Discussion in 'Physics & Math' started by Saint, Nov 9, 2014.

  1. river Valued Senior Member

    So then the ability to still movement ?

    How would do this ?
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  3. Russ_Watters Not a Trump supporter... Valued Senior Member

    No. Time isn't a "thing". You can't store it.
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  5. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

    Your direction would lead to the misuse of terms that I think are theory specific. If I say "local environment", meaning the energy density of the rest frame. It does not carry with it the specific meaning that "inertial reference frame" carries which is theory specific to Special and General Relativity.
    What do you think time is relative to? It is relative, but I describe what it is relative to in a context that can be portrayed mechanistically. Can you describe what time is relative to in mechanistic terms?
    True, that is what you would have. Can you describe mechanistically the energy that an object has at rest, and then explain how added kinetic energy added by acceleration of the object relative to the rest frame occurs?
    That explanation is again theory specific. In GR, time can be manipulated by acceleration and deceleration, but the theory does not address the mechanisms of how that occurs.
    No it doesn't, not if the CMB is an energy density environment the is expanding relative the the greater universe surrounding it. In that case it becomes, in theory specific terms, and expanding inertial reference frame within a larger space.
    No, because at any given local energy density environment, a "rest frame" if you like, the inflow of gravitational wave from all directions is directional wave energy coming from distant objects. The motion of those objects relative to our local environment or rest frame determines the amount of gravitational wave energy arriving. If you then accelerate the object its local energy density environment changes. The change can be described as an increase in the directional gravitation wave energy density in the direction of motion.
    Clocks measure the passing of time. The difference in the rate that identical clocks will show time passing is variable in accord with their relative motion.
    No it doesn't. It assumes that the gravitational wave energy density of the local environment changes as a clock is accelerated relative to the other clock.
    The "error" you refer to is theory specific in General Relativity. In gravitational wave energy density terms there is no error.
    You are not acknowledging that GR predicts gravitational waves. Any change in the path of an object predicted by GR due to interaction with another object, requires that the momentum and energy are conserved. In GR, that requires gravitational waves. Right now the experiments are looking for waves produced by extremely energetic events like the death spiral of double stars or the collisions between black holes. But the cause of those huge and yet almost undetectable gravitational waves is not limited to such huge events. Every interaction between particles should produce gravitational waves relative to the energy of the interacting objects or particles. Particles within an object are continually interacting and thus all objects emit gravitational wave energy. They are looking for a ripple in space time, but the gravitational wave that they may eventually detect will be consistent with the concept of a spherically expanding gravitation wave emitted by massive objects and massive interactions, and those waves would be produced in much smaller degrees from all interations.
    GR accounts for the rest of the gravitational wave energy as a curvature of spacetime. Outside of GR, and without a curvature of spacetime, variable gravitational wave energy density replaces the concept of curvature.
    Are you talking from the specifics of GR which invokes the curvature of spacetime? Unfortunately there is no mechanistic explanation within the theory, and that is why I am mentioning the concept of variable gravitational wave energy density in relation to the concept of time as mentioned in the OP. The example of the relative motion between two identical clocks mentioned in my earlier post is based on a mechanistic principle that differs from spacetime.[/quote]
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  7. Waiter_2001 Registered Senior Member

    I believe time is a creation giving VALUE to all things. Without time things would be without density, weight, volume and value! As you wager on a roulette wheel your bet gives that number VALUE, and the more weight that number has effects the gravity on the wheel etc. and the result. It isn't just the pattern of the numbers resulting from the spin: the numbers have values depending upon how much is bet on them.

    You cannot "go back" in time unless you have first travelled through time!

    Please Register or Log in to view the hidden image!

  8. Landau Roof Registered Senior Member

    Very poetic, but where's the fact? Yes, I'd like another cup of science, please.
  9. sculptor Valued Senior Member

    Is not "Time" the 4th dimension?

    "Time flies" you say, but alas, it is we who fly and time that stays.
  10. PhysBang Valued Senior Member

    In a sense, it does. It addresses the very specific details of how much a certain acceleration of one given system of coordinates relative to another given system of coordinates must change how we compare the time as determined by one system to the other, assuming that they both write the laws of physics in the same way. This is a restriction on whatever mechanism one might hope to introduce. One can't wish away the actual behavior of physical systems based on the way one would like things to be or simply because one cannot imagine the specific mechanism behind the way that things are. I enjoy magic tricks, but I do not deny that they exist merely because I do not know how they were accomplished.
    The CMB is not, and cannot possibly be, a reference frame of any sort. It is equivalent to saying that an orange is three. We can speak of systems of coordinates in which the CMB is, to the greatest extent possible, isotropic. In, these systems of coordinates, we could say that the CMB is "at rest" in a metaphorical sense that is more-or-less correct.

    When one moves relative to such a reference frame, one discovers that the temperature of the CMB increases in the direction of travel and decreases in the opposite direction.The overall change in temperature should cancel out.
    In the same manner as changes to the CMB temperature are cancelled out be corresponding changes in the opposite direction, so too changes to this energy density should be canceled out as well. Only movement to a location where there is greater energy density should increase the density, not motion or acceleration itself.
  11. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    I'm an old fashioned "string and sealing wax" physicist. Did not "cotton to" GR even though know a little of it, but did not like working with tensor equations. Thus despite GR's four coordinates I think of time as a convenient, but not even necessary, parameter in equation of physic, at least classical physic.

    I.e. if you have a set of equations n in number which have time, t, as an explicit variable and a bunch of other variables like mass, m temperature, T, energy, E, altitude, h, etc.
    You can, in principle solve all n of them for t = F1(m, T, E, h, etc.) = F2(m, T, E, h, etc.) = F3(m, T, E, h, etc.) ... Fn(m, T, E, h, etc.) and then forget about the left end /side of this string of equations (never mention t again in your new set of n-1 equations).

    For example, you don't really need to say the day is 24 hours long. You can say the day is 48 inches of standard candle burning, but that is not nearly as convient as making the two "decoupled statements" with a convenient t parameter:
    (1) The earth rotates 360 degrees in time interval 24 hours. (Nothing about "standard candles" here. (1) is decoupled from that by use of parameter t.)
    (2) Standard candle burns (one lit just as the earlier one goes out) for total burnt length of 48 inches in 24 hours; or the standard candle burns two inches each hour.

    Time, t, is just a very convenient parameter in equations - it could be eliminated from a complete (classical at least) description of every thing that occurs in the universe.
    The existence of something with no observable quantities, like mass, volume, extent, etc. is very questionable - most likely a fiction - time does not exist, except as a convenient parameter that can "decouple" equations.

    OK - tell me where I must turn in my APS card. No need of a trial. I admit: I'm guilty of thinking too far out side the box.
    Last edited by a moderator: Nov 10, 2014
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  12. Beaconator Registered Senior Member

    Time is a summation of lights movements since static first coupled pairs of matter. It contains every physical constant and their realtion to every physical variable. It can be altered by both gravity and velocity in a delicate and dedicated ploy that appears to make time travel both foreward and backward theoretically possible. Since its beginning it has not stopped, tired, or dissolved like most of the variables contained within it but grown to an unimaginable size few can guestimate.

    All hail time! The closest you can get to God without loosing an odd fascination of curiosity.
  13. paddoboy Valued Senior Member


    And yet I defy anyone to point me to any realm, world or Universe, where time does not exist.
    As Albert Einstein said....
    "Time is an illusion, albeit a stubborn one"
  14. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

    I wouldn't mind getting into a discussion with you, though by reading your posts over time it might turn out not be in my best interest; but let's see how it goes. Let me start by addressing your statement:
    On the face of it, that statement doesn't imply that there is much room for discussion, but since you might be just supporting standard theory, in which there is no absolute reference frame, both you and Aqueous Id might be under the same impression, that the concept of a CMB rest frame violates the theory specific position that there is no absolute space. It doesn't. Being at rest relative to the CMB is a valid concept in cosmology and you haven't educated yourself on the subject. Far be it from me to presume to educate you on anything, but:


    See this topic:
    How come we can tell what motion we have with respect to the CMB? Doesn't this mean there's an absolute frame of reference?
    See this response:
    The theory of special relativity is based on the principle that there are no preferred reference frames. In other words, the whole of Einstein's theory rests on the assumption that physics works the same irrespective of what speed and direction you have. So the fact that there is a frame of reference in which there is no motion through the CMB would appear to violate special relativity!

    However, the crucial assumption of Einstein's theory is not that there are no special frames, but that there are no special frames where the laws of physics are different. There clearly is a frame where the CMB is at rest, and so this is, in some sense, the rest frame of the Universe. But for doing any physics experiment, any other frame is as good as this one. So the only difference is that in the CMB rest frame you measure no velocity with respect to the CMB photons, but that does not imply any fundamental difference in the laws of physics.

    End of quote.

    If you care to respond, and want to continue the discussion, tell me if you knew this already and still disagree. I have other replies to topics in your post, so I do intend to go back and cover them if we are able to agree on the concept of a CMB rest frame. It is not absolute space like you imply it is.
  15. danshawen Valued Senior Member

  16. brucep Valued Senior Member

    The CMBR rest frame is a valid coordinate system. Choice of coordinates has a lot to do with the physics you want to analyze. Like choosing a global time coordinate for the cosmological metric. We choose the global time coordinate because it's useful for evaluating the evolution of an expanding universe. It doesn't mean time isn't relative. It just means we're not interested in finding tick ratios between local and remote coordinate systems. We want a history of the evolution of the universe.
    Last edited: Nov 11, 2014
  17. brucep Valued Senior Member

    That's pretty much a load of nonsense your style. Quit trying to bastardized GR into something that supports your toy cosmology.
  18. PhysBang Valued Senior Member

    I think my professors in grad school would disagree. Regardless, I didn't say that things couldn't be at rest relative to the CMB, I just pointed out, correctly, that the CMB was not a mathematical construct. Reference frames are mathematical constructs. One can speak of a system of coordinates in which the CMB is isotropic, and often this is referred to in shorthand as "the CMB reference frame", but it is shorthand for a more complicated idea.
    You seem to have, willfully or otherwise, misinterpreted my post and ignored the actually important parts of my criticism.

    You claim that the temperature of the CMB increased with motion. That is not true. There is a change in the direction of motion exactly offset by a change in the opposite direction. So the overall change to temperature is nothing.

    The same should be true with any isotropic collection of radiation. Movement relative to this collection will break isotropy, but not with a net change in energy transmission from the radiation to the object in motion. This being the case, a project of trying to replace all of SR/GR with some sort of motion relative to radiation of some sort based solely on density of incoming radiation seems doomed to failure.
  19. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

    I agree, and it is relative.
  20. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

    That is not what I trying to do. I'm trying to address and discuss the mechanics of things that the standard cosmological model doesn't. The universe is as it is, and works the way it does, notwithstanding GR or my "toy" model, but I just think it has to be mechanistic. Nevertheless, our current consensus cosmological model represents the best empiricism that we have, and quantifies the observables pretty well.
  21. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

    Alright. My reference to the CMB rest frame was to use it as an analogy. In my earlier discussion of the gravitational wave energy in space, I wanted to make the point that it comes from all directions, similar to the CMB.
    I wasn't willful; I must have misinterpreted your statement, "The CMB is not, and cannot possibly be, a reference frame of any sort".
    Here's what I said. "in a similar fashion as the temperature of the CMB goes up as you move relative to the CMB rest frame". It wasn't worded clearly enough but I meant that the temperature that we measure in the direction of motion goes up.
    True, motion through the CMB does not heat up the CMB, the temperature that we measure is higher in the direction of our motion relative to the CMB rest frame.
    Except that the energy density of our environment, our reference frame, is measurable. By moving relative to some rest frame, the temperature of our measurements in the direction of motion goes up, or in the case of the gravitational wave energy of our environment, the wave energy density goes up around us in the direction of motion.

    The fact that the net temperature of the CMB itself, or the energy density of the gravitational wave energy as a whole in all directions is not changed by that motion, does not mean that there isn't greater gravitational wave energy density in the direction of motion, and in regard to my "toy" model, it is that effect that I am referring to. In fact, that effect is an observable, and in terms of gravity, as the gravitational wave energy increases, the object in its grasp accelerates in that direction.
  22. PhysBang Valued Senior Member

    We can easily demonstrate cases where the energy density goes down in the direction of motion; e.g., this happens every time we launch a rocket. Standard physics uses the presence of energy densities in different places to explain gravity, what do we gain by adding waves coming from these sources and tying directionality into the waves?
    I would need to see some numbers on this gravitational wave energy, I suppose. You seem to want it both ways, acceleration creates in creased density and increased density created acceleration. This doesn't mean that the theory is wrong, since there are feedback loops in physics.
  23. quantum_wave Contemplating the "as yet" unknown Valued Senior Member

    We could gain at least a hypothetical mechanistic description.
    In terms of wanting it both ways, i.e. acceleration increases the energy density of the local environment, and gravity's effect is to accelerate an object, then yes. SR and GR are quite accurate in regards to their quantification mathematically. The topic of the OP is what I am addressing. Time. We observe time being measured by identical clocks at different rates when they are in motion relative to each other. My response to the OP is that maybe time simply passes, and the variable measurement of time is mechanistically connected to the fact that the energy density in the direction of motion increases, causing the particles in the clocks to function more slowly, and thus causing the clocks to make it appear as though time slows down when they are used to measure the rate of time passing.

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