"Perception of time" is a psychological term, meaning the subjective perception of time by a human. Physics and especially the Theory of Relativity speak of an "observer", meaning someone with a clock measuring time. Due to relativistic effects, a clock in a satellite moving around the Earth shows another time than a clock on Earth. The difference can be observed, i.e. measured with precise (atomic) clocks. This is meant by the relativity of time, i.e. the measurement of time differs depending on the reference system in which the clock is located (e.g. on Earth or in a satellite).

Dear Preston Guynn

Thank you.

I have noticed my two mistakes: assuming that a physical theory refers to the perception of its supposed subject and attributing the imaginary example of twins to general relativity.

I have read that some researchers and papers consider the general theory to be refuted. Your answer also gives me new information about problems that are open and questions that have not been answered or perhaps need to be rephrased.

Dear Wolfgang R. Dick

I understand. Psychological issues are out of place here. I wonder, however, what difference there is between the measurement of time and time itself, although I don't pretend that answering what time is, or what time is for actual physics, or what it is for a particular physical theory is an easy question to answer either.

I also think that when we speak of "time" or "time measurement" it seems inevitable to associate those expressions with the meaning we give to the word intuitively, from our perceptual experiences, and that perhaps it would be better to use another word. I also hesitate about whether what is called time is a simple change of state or something else. Thank you

In Newtonian Physics, time is absolute, i.e. it is independent of its measurement (observation). In the Theory of Relativity, time always depend on the reference frame in which the observation is made.

You wrote to Preston Guynn: "I have read that some researchers and papers consider the general theory to be refuted." Please note that practically all of those physicists who work in fields where relativity play a role (e.g. astrophysics, particle accelerators, atomic clocks, etc.), base their calculations on the Theory of Relativity. It works in practice and gives the correct values. When you use a navigation device in your car, relativistic corrections are applied - otherwise the displayed positions would be biased. Only a few physicists refuse relativity.

Here are some other ResearchGate discussions on time:

https://www.researchgate.net/post/Does_time_exist_or_is_it_just_an_illusion_And_how_to_use_the_time_in_statistics

https://www.researchgate.net/post/Is_the_time_a_metaphysical_assumption_within_physics

https://www.researchgate.net/post/Books_on_the_concept_of_time

https://www.researchgate.net/post/Reversing_the_time

https://www.researchgate.net/post/Time_travel-A_possibility_or_not

https://www.researchgate.net/post/The_reality_of_time

That is very good question.

First thing I think we need to know is that, the time in General Relativity is not time at all, instead, it is reading of clock. The result of reading is right and is physical one, but, it is not TIME itself.

for example, the reading of a clock in summit of the mountain is not time, because it keeps changing its pace . in human society, only UTC is TIME, which is reading of a clock in a lab, in a constant physical environment.

In my opinion, yes there is. Time is always constant and true, meanwhile the time's perception can be latent and mistaken.

“Is there in general relativity a distinction between time and the perception of time?”

- to answer scientifically to this question it is necessary before to understand a few points.

First of all that now for most humans and in the mainstream philosophy and sciences, including physics, all really fundamental phenomena/notions, first of all in this case “Matter”– and so everything in Matter, i.e. “particles”, “fields”, etc., “Consciousness”, “Space”, “Time”, “Energy”, are fundamentally completely transcendent/uncertain/irrational, and

- because of the informational system “consciousness”, which can percept, i.e. can obtain information from, and analyze it by using logical rules, fundamentally can do that only limitedly, while in every case information about anything is infinite,

- so in every case, when somebody percepts anything the result is in most cases at least partially transcendent/uncertain/irrational.

Including really anybody in the mainstream, since really doesn’t know what is “consciousness”, really doesn’t know – what is “perception”, and why he “percepts” something at all.

The real understanding is possible, including most of fundamental phenomena/notions are really rigorously scientifically defined, only in framework of the 2007 Shevchenko-Tokarevsky’s “The Information as Absolute” conception, recent version of the basic paper see

https://www.researchgate.net/publication/363645560_The_Information_as_Absolute_-_2022_ed

- where it is rigorously proven that there exist nothing else than some informational patterns/systems of the patterns that are elements of the absolutely fundamental and absolutely infinite “Information” Set, including Matter and any consciousness are absolutely for sure some informational systems in the Set,

- and, despite that these systems are fundamentally different, there is nothing too surprising in that one informational system “consciousness” is able to observe and to analyze what exists and happens in other informational system “Matter”.

However outside the conception any consciousness makes that eventually only instinctively, i.e. completely transcendently, and so, including, there exist numerous interpretation of what is the observed phenomenon “time”,

- the “purely instinctive” of most of humans in everyday practice, and numerous “scientific” interpretations, which are fundamentally necessary in any science, since the dimension/variable “time” is fundamentally obligatory at description and analysis of every process.

Correspondingly scientific interpretations of time are postulates in the theories, first of all in physics, including in general [and special] relativity, and for mainstream physicists there are no a distinctions between time and the perception of time – they percept in accordance with these standard physical theories.

However, because of that for the authors of the SR/GR, and for mainstream physicists till now, the fundamental phenomena/notions “Space” and “Time” were/are fundamentally transcendent, the postulated in these theories “relativistic properties of space/time/spacetime” really are some transcendent mental constructions, which, besides, are really fundamentally non-adequate to the objective reality,

- while, say, the instinctive perception of space and time by other humans – and by other living being, though, that that is some “empty container”, where everything is placed and changes, and at that neither everything can affect on the space/time/spacetime, or space/time/spacetime don’t affect on anything, is really fundamentally more correct than the scientific perceptions in standard theories and in numerous “scientific theories” of the space/time/spacetime, mostly of some mainstream philosophers.

More see at least first dozen of pages in the link above.

Cheers

There are two terms "time" in General Relativity. Ideal time flows uniformly. Physically observable time depends on the properties of the observer's reference space. The latter is the "percepted time" registered by the observer's tools sch as a clock. Concerning an observer as an organism, each person has his own internal clocks that determines the perception of time. In terms of General Relativity, the own internal clocks are connected with the observer's internal reference space that depends on his biologcal standards. Therefore, both ideal time and percepted time are well founded in the framework of General Relativity.

Dear Larissa Borissova

Thank you for your clear answer. There is something here that I hadn't thought of and that gives more coherence to the matter: the distinction between ideal time and physically observable time.

I have this doubt: (according to the theory) if there were no humans, but there were recording instruments such as atomic clocks, would there still be this difference between ideal time and physically observable time?

My question is whether the reference space of the observer is only internal, or whether there can be a reference space of the clock - or something like it - without humans, on which the values it records depend.

The ideal time and the physicaly observable time are objective terms independent on whether a human or somene else performs measurements. Even if there is no an observer, such as a human, animal, plant or stone, the physically bservable time differs from the ideal time since the reference space exist. An internal reference space associated with the physic of an observer introduces additional corrections on the above, but does not remove the previous since the previous exist independently of the observer. For example, time intervals depend on the gravitational potential, rotation of the space as well as the biological clock inside us. The first is manifested in the Hafele-Keating experiment. The second is manifested in many psycholoical experiments.

Buenos dias Sergio,

questioning the relationship between "objective" ("real") physical time (as in, e.g., the Einsteinian concept of space-time) versus individually perceived time (i.e., time as perceived by conscious agents such as organisms) is, indeed, intriguing. Let me just raise a few thoughts here in addition to what has already been pointed out:

Whether space-time is, indeed, "real" and fundamental is questioned by scholars such as cognitive scientist Donald Hoffman (University of California at Irvine), arguing that space-time may merely be a "headset" through which we perceive and interact with a more fundamental reality. This line of argument - in my view - essentially constitutes a modern-day incarnation of Plato's classic cave analogy.

Irrespective of whether you buy into such "headset"/"matrix" arguments, physicists are on the constant lookout for structures and processes that may physically, indeed, proove more fundamental than spacetime. Here, you may follow, for instance, the work of physicist Nima Arkani-Hamed (Institute for Advanced Study at Princeton). Whether, at the end of the day, "time" will turn out here as something "objective" and/or absolute, as an emergent property of deeper structures, whether it will relativistically stay deeply intertwined with space or be "torn away" from it on a deeper, yet unknown level of physics/reality, no one knows.

For the time being, though, I do think it is important to carefully distinguish between physical measurements and their interpretations in models and theories, in which we use time as part of four-dimensional space-time very successfully on one hand and the intricacies and complexities of an as yet hardly understood (but surely very limited!) human consciousness and perception of "time".

So, is time simply an illusion or a fundamental trait of some form of "reality"? We just don't know...

PS: You may also take interest in this discussion we had last fall: https://www.researchgate.net/post/Has_time_existed_forever .

Best,

Julius

Despite that in the SS post above it is quite clearly explained what is the absolutely fundamental, and so absolutely really existent independently on – what some human thinks about what is “time”, and on there exist or not some humans and any living beings at all, phenomenon/notion “Time” – that is the “Logos” set element, while any informational pattern/system [again - everything absolutely for sure are some informational patterns/systems], can change, including as its creation, only in the actualization of this phenomenon as the “time dimension”,

- in the thread a few posts appeared, which are really rather strange; seems because that the posters either didn’t read this SS post, or didn’t understand what is that they read.

So, again – really there is no some “ideal” times, really there exist only one, universal for everything, time dimension, where all/every changing patterns/systems move in some time fundamentally non-zero intervals at every change, at that the dimensions fundamentally cannot, and so doesn’t move/flow to anywhere.

However, because of the really extremely mighty Galileo-Poincare relativity principle [i.e. because of the specific design and construction of Matter] acting, the direct observation of material objects - and so of practically material bodies of living beings - motion in this “true” time dimension is on Earth impossible [however that is possible – see https://www.researchgate.net/publication/259463954_Measurement_of_the_absolute_speed_is_possible ]

- so humans [and all living beings] in the everyday practice and in mainstream physics practically always use the specific, really the space dimension, the cτ-dimension of the Matter’s fundamentally absolute, fundamentally flat, and fundamentally “Cartesian”, [5]4D spacetime with metrics (cτ,X,Y,Z,ct), as a rule using specific material constructions “clocks”, which measure their motion in the cτ-dimension counting number of a clock pointer rotations – as odometer in a car measure passed way counting number of a car/s wheel rotations.

That happens, first of all, since the cτ-dimension fundamentally differs from the “directly observable” 3 space dimensions in that in everyday practice and most physics interactions of material objects happen only in 3D space, independently on – in what positions the objects are in the cτ-dimension.

However, because of in the mainstream philosophy and sciences the phenomenon/notion “Time” is fundamentally transcendent/uncertain/irrational, the mainstream scientists’ perception of what they see when see, say, a clock showings, and when they see an odometer showings are fundamentally different: while they really understand what odometer shows, their interpretation of clocks’ showings is completely transcendent fantastic one:

- they think that time constantly always for some mystic reason “flows uniformly” and that this flowing time for some transcendent mystic reason and by some mystic way forces clocks to tick correspondingly, and so “time is what clocks read”; moreover, this time flow, again for some mystic reason and by some mystic way, is “dilated” when something moves, and moving clocks tick slower, etc.

All that strange, and really simply fundamentally wrong, above exists because of that in the mainstream the fundamental phenomenon/notion “Time” is really transcendent/mystic something; while all other such phenomena/notions are transcendent/mystic as well, when they can be scientifically defined only together.

More see the SS post above and the basic paper where the really scientific – and, in fundamental contrast to mainstream philosophy, – really philosophical SS&VT “The Information as Absolute” conception is presented; for physicists concretely about how “Time” is actualized in a concrete informational system “Matter”, what are Lorentz transformations, etc., see at least https://www.researchgate.net/publication/354418793_The_Informational_Conception_and_the_Base_of_Physics ,

- and, if some questions appear – ask here; while posting - and reading – of posts that are in framework of the mainstream really is evidently senseless, while at that, the really senseless publications, YouTube clips, etc., of too numerous mainstream philosophers and physicists in this case are innumerous.

Cheers

In GR, there is of course a formal distinction between coordinate time t and proper time tau. But I doubt that answers your question. In mainstream GR today, the role of the observer is rarely taken into account. Thus, although time is different for different observers in any nontrivial gravitational metric, modern general relativists like to believe covariance means all coordinate frames are equivalent. My upcoming paper on gravitational wave theory refutes this.

An excerpt from the conclusion of my paper, highlighting the differences between space and time, may be of interest:

"Hence there arises the question: If time and space are categorically different, what exactly is different about them? To address this, we first consider special relativity, in which the time and space axes undergo hyperbolic rotation depending on the observer's velocity. Spacetime intervals, here to be called vectors, thus fall into three classes: timelike, spacelike, or null. To distinguish the properties of time and space, we are therefore tasked with identifying differences between timelike (or null) and spacelike vectors.

"Causality marks one difference. Timelike or null vectors can carry information, meaning the endpoints of such vectors are causally connected [136]. Spacelike vectors cannot carry information and are causally disconnected. Causality further dictates that a diagonal metric expressed in spacelike and timelike coordinates has but one timelike component. The uniqueness of the time component means time acts more like a parameter of change than a dimension. Furthermore, time is irreversible and has an arrow or unambiguous ordering, while space does not. This distinction transcends the principles of pseudo-Riemannian geometry, to which time's arrow must be added as an independent postulate [136].

"More concretely, mass-energy, electric charge, baryon number, lepton number and other quantities are conserved along timelike (or possibly null) vectors but not along spacelike vectors. Due to these conservation laws, our universe is filled with thin timelike fibers or threads of matter-energy that extend indefinitely in time (e.g. elementary particles and photons), while corresponding spacelike fibers or threads (i.e. tachyons) have never been proven to exist, a profound manifestation of the uniqueness of time.

"In a broader vein, the present moment of time defines a spacelike hypersheet that divides the 4D universe into past and future [138,139], where past events are determined, while future events are undeterminable due to quantum effects [136]. There is no such division of space. Hence it is maintained here that, due to the distinct natures of space and time, Riemann flatness does not necessarily preclude the detection of longitudinal metric plane waves . . . "

A real observer is always associated with a real reference frame (real reference space) since a real Riemannan space is curved, inhomogeneous, anisotropic, rotating, deforming, etc. Therefore, the measrement results of any real observer depends on the physical an geometric properties of his reference space. This concerns the physically observble time and the ideal time cordinate: the physically observed time depends on the properties of his reference space at the point of observation. This is an objective reality. Our consciosness just adds a lot to this difference.

Dear Sergio Aramburu,

Moving matter has the properties of extension and duration. Extension is movement between points in space. Duration is movement in a point. The body is at rest, but microparticles are moving (rotating). Otherwise, they must merge under the action of gravity. We call time the duration of rotation of the selected microparticle. Each body (me and you too) has its own time. It depends on speed and gravity. And why - read my article (of course, if you have free time).

Preprint Why time slows down

Yours

Valeriy Pakulin

Dear Kathleen Rosser

Thank you for your response. Unfortunately, I am not in a position to understand the technicalities of the actual scientific interpretations of the theory.

However, I think one of the underlying issues is that there are two meanings in use for "time" and for "space": one that coincides with human perceptions, which separates those two things, and one with the meanings of the theory itself, which allows it to speak of a "spacetime".

What exactly "spacetime" and "time" mean in the theory is something on which the researchers themselves seem to disagree, or at least some of them.

Despite that in the SS posts above in the thread it is already explained – what is the [absolutely] fundamental and universal, and so which exists absolutely objectively, i.e. without any relation to what some humans think about it, and there exist some humans at all, though, “Time/time”, in the thread a next post with a really strange claims appeared:

“…Time is a abstraction, which we use to characterize the capacity of matter to move (there is no matter in absolute stillness/rest)….”

- see above, and since that in the quote is rather strange basic claim, the grounding of the claim as

“ …Time reflects the sequence and continuity of the movement of matter. Time is the "distance" between the material states and events. But we observe not time itself, but the sequence and continuity of the events…”

- so is other strange claim, despite that the poster – since that is evident – writes about some “distance” - while some “distance”, of course, can be only in some “dimension”. And what is true in this case absolutely objectively really – one of the main traits of “Time” is that it is actualized in the absolutely objectively existent “time dimension”, which is unique universal for everything in the “Information” Set dimension, including for Matter and humans, where changes happen – in the dimensions points, if something is created and is fixed, and if something changes, it moves in this dimension change by change – and so time interval by time interval.

And in that

“….Time has two main characteristics: direction and rhythm (pace). The direction of time is due to the cause and effect sequence of interactions of matter, i.e. the cause precedes and produces the effect. The rhythm (pace) of time reflects the "density" of the observed states or events.….”

- while is correct in that the “characteristic: direction” is due to the cause and effect sequence of interactions of matter, however “characteristic rhythm (pace)” really fundamentally doesn’t exist. Time dimension is nothing more than a possibility for anything to change, and where all changing states of every changing objects have some “coordinates”, however time fundamentally hasn’t any other characteristic, including any intrinsic own “measure”, including of course, so any rhythms – if there is only one change it is senseless to say that that happened in a concrete time dimension interval. Any intervals can be defined only relatively, at least if there exist at least two changes, which can be “simultaneous”, started/ended “earlier” / “later”, etc.

To the above additionally: to read SS posts on pages 4, 5 and 6 in https://www.researchgate.net/post/What_is_time11#view=63c940bafa2ccd380d0b4943/6

- is useful for understanding what is time, and, of a lot of other fundamental things, though.

Cheers

Very unfortunately , they have NOT made such a distinction from the very beginning ...............

In my opinion, yes there is.

Dear Sergio Aramburu

I suppose that everyone can agree that the volume of a human envelopes all the existing influences (“forces”) that exist in our universe. Influences at the microscopic scale and influences at the macroscopic scale. These influences are described in theoretical physics (the Standard Model) although gravity isn’t yet part of the description. In other words, there is a conceptual framework that describes physical reality and we are part – and are aware – of the same physical reality.

The Noble prize physics 2006 was awarded to 2 physicists who discovered a dipole in the CMBR (Cosmic Microwave Background Radiation). The consequence is that we can measure the absolute velocity (about 368 km/s) and the direction of the motion of our solar system in relation to the rest frame of the CMBR. Actually, in practise it is impossible to argue that the CMBR rest frame isn’t equal to Newton’s absolute space. However, if space is absolute, time must be absolute too (quantum time).

Quantum time is really simple because it represents a fixed amount of change (Planck’s constant) and if this fixed amount of energy has a linear motion, the velocity of the quantum of energy in vacuum space is always the constant speed of light. Thus quantum time is the consequence of 2 universal constants and there is no variable "enclosed".

Einstein’s description of time is based on the constant velocity of the mediating “particles” between matter objects: the photons. The same fixed amounts of energy as described above (Planck’s constant). Because Einstein couldn’t describe the properties of vacuum space (the “aether” problem) he described the rate of change of matter objects. Matter that represents concentrations of energy (multiples of Planck’s constant) thus if an object nears the speed of light nearly all the energy of the object is “forced” into the linear motion. The consequence is the decrease of the internal rate of change of the object, for example a clock.

Thus if an unstable particle is accelerated its “normal” decay time (e.g. 1 second) is delayed and shows to be e.g. 2 seconds. However, this is not the concept of time as a universal property that exists everywhere in the universe, Einstein’s relative time is restricted to the rate of change of local compositions of energy (mass).

The Noble prize physics 2022 was awarded to a couple of theorists who proved that our universe is non-local. Non-locality means instantaneous influence. We can detect the instantaneous influence with the help of 2 entangled photons (electromagnetic waves). If one photon is forced to change its polarization, the other photon changes its (opposite) polarization at exactly the same moment, no matter the mutual distance between both photons. In other words, the normal causality between events – expressed with the help of a change of position and a change of time – doesn’t always develop like we expected.

The awareness of time by humans is described in other branches of science, like psychology. It shows that our experiences of time depends on the local conditions, inclusive our internal conditions. That is obvious although time as an instantaneous change is difficult to imagine.

Nevertheless there are descriptions of these kind of experiences too.

Some people who fell from a high building and survived, saw their whole live as a movie during their fall. Mostly a limited amount of seconds. We know the rate of time that the brain can signal information from one cell to another. We also know how we can simulate the impression of a fluent “display” with the help of “high lights”. But in spite of this a handful of seconds is not enough to explain their experience. Thus it seems that “quantum time” can be forced to reproduce some short cuts. Like the tunnelling of atoms through a barrier (faster than the speed of light).

Benjamin Libet has done experiments to get some insight in these confusing experiences and Sabine Hossenfelder published about “superdeterminism” (related to non-locality).

With kind regards, Sydney

Reflections on the nature of time in Relativity Theory will be hinted in reference to the new bridges recently proposed by Connes and by Rovelli’s ‘perspectival’ approach, two major steps towards a unification of quantum, thermodynamical and relativistic times. The so called “time of philosophers”, a time of the cognizing ego, from Saint Augustin to Husserl and Bergson, is based on a different, but relevant perspective and it has been traditionally opposed to the ‘time of physicists’.