Even WIKIPEDIA fails to provide un-ambigous determination. But RG has plenty of smart people, let them do their best on the subject.
1 second as the time that takes to up-vote a good answer in RG!
“No man ever steps in the same river twice, for it's not the same river and he's not the same man.”
Heraclitus (around 500 BCE)
So this means that time is real, has a direction and it´s impossible to travel back in time... Other explanations although extremely exiting and intellectually appealing appears regrettably to be nothing else but a science fiction...
I can see that people look into the question, vote up, but are too shy to post their opinion. So, I start with my modest attempt, determining the time unit, 1 SECOND, as required for the beam of light to travel the distance 300,000 km in open space (vacuum).
1 second as the time that takes to up-vote a good answer in RG!
OK, dear Alexander, but for what kind of light are you talking about? The light in a 'flat or Euclidean space' eta_{mu,nu}? The light close to a really massive object like a neutron star? The light at the inflationary expansion stage?
Ahed ! About 5 discussion on time go on RG in parallel, yours is the one of these. But no one asked for TIME determination, so, I appeal to the basics. Very nice quotes are provided by Svetlozar and by Behrouz.
RG does not deliever Messages to me, so, I have just e-mail for contact: [email protected]
Demetris, my light corresponds to Special Relativity Conditions. Fair enough to our Solar System, or, that may be just my illusion. In the case I had a good determination, I would not post the question.
The fundamental question of contemporary time studies: distinguishing between time as it is in itself (objective), and time as we humans perceive and experience it (subjective). One goal of the philosophy of time is to reconcile them.
In mathematics and especially in category theory, the domain (time) of a function that signifies change or motion, can be any structure.
The concept of time is too complex, and this is the reason that there are a lot of books dedicated to time. As an example we cite:
Heather Dyke and Adrian Bardon (Eds), A Companion to the Philosophy of Time. Wiley-Blackwell, 2013
One second, a little less than the light needs to show the moon rise here on the earth.
In the case we all agree that we exist in 4 - D Space-Time World, time is the only coordinate, which does not allow minus sign. Analytical Mechanics does allow minus sign for time, equetions are time reversible, but this approximation does not honor Second Law of Thermodynamics, as Entropy Production is beyound this approach.
And, sure, even if everyone agrees on 4-D Space-Time, this determination of time is insufficient.
If you want to know what time is to a physicist please read Einstein's paper: Electrodynamics of Moving Bodies:
http://www.fourmilab.ch/etexts/einstein/specrel/www/
especially the section:
I. KINEMATICAL PART
§ 1. Definition of Simultaneity
It is easy to read and understand.
On a slightly philosophical level, time is:
God's way of keeping everything from happening at once, or if you like, the Universe way of keeping everything from happening at once. :-)
Time is a very basic essence of our life & with our arrival on this earth ,the Time start .Sometime i feel the time is very basic control for our life ,we start every action of our life as the Time & Tide with for no more .
I believe the Time is dependent on our destiny as we are merely the visitors on this Earth .
I am sure that majority of those who posted on this page read original Einstein paper of 1905, Special Relativity Subject. And while Einstein treamendously expanded our understanding of time properties, including time re-calculation from one inertial system to another, he did not feel obliged to provide Definition of Time. For this reason, 5 pages on RG still discuss the understanding of time at this very moment.
Alexander, my friend,
I love Behrouz's post!! The only thing I really know about time is that it does not stop; hence "it does not allow a minus sign".
Some cultures such as the Aborigines were more alert to the, almost unseen by others, changes in foliage, wind direction, migrating birds, and how the tides change, to mark their years, months, and seasons.
Let's Consider: "Time is money" "The Clock is ticking" "Wasting our time". What I do know about time, in fact, is that it helps us as a society maintain structure and conduct business. But, out time here on Earth, is but a blink of an eye.
This reminds me of a joke told by comedian Paul Rodriguez, "Every time I get on a plane I sit next to a "White guy" reading a magazine about plane crashes" I asked him why, and he said, "I figure when your time is up, your time is up", "I said, yea, but, what if the guy three rows back time is up?"
See: http://www.theguardian.com/lifeandstyle/2012/jan/28/stop-clock-time-timepieces
On a quick note, Wikipedia, while full of brilliant writings, is an unacceptable scholarly reference due to the fact that anyone can edit (even a 10 year old). I love to use it for research and when the articles have a good reference section, the article can be extremely helpful.
Let me attached the table of contents and the introduction from the book: Heather Dyke and Adrian Bardon (Eds), A Companion to the Philosophy of Time. Wiley-Blackwell, 2013.
Hard to diasagree with you, Marilyn, but it is sad that no agreement on time definition exist. I can explain it as the ratio between the Entropy and the Rate of Entropy Production, but the determination should serve people on the level of Junior High Scool as well, and it does not.
See, please, the same question
https://www.researchgate.net/post/What_is_time
Maybe something we evolved to have to help us with a dynamic world, then we can be aware of changes around us.
Indeed, identical question was already posted on RJ, thanks to Sergey for referral.
I am not going to add anything to the philosophical and scientific replies to this questions, but I must say, whoever has divided time into hours, minutes and seconds has put us in a race to chase this undefinable thing!
Experimentally, using classical mechanics notions for a 1 d problem time one can defne a state of motion trough the knowledge of say (x(t), v(t), t) for all values of the parameter t. This parameter is named time and it can define a clock when the motion under study is a libration motion such that a period can be deduced. Then one must have a counter to be able to count the number of period and that is the way we have the practice of time since it seems ages. We have improved the clocks, using atoms or equivalent devices in place of of the sun moon and planetary motion in the sky, or the beating of our heart or respiration rythm.
In practice we have the use of time only when we define the device clock, then after we can base a theory on it.
I would like to add here a remark about "time" in Zermelo-Fraenkel set theory. In this theory there is no time. Everything is breezed. This is apparent since Set Theory is the category of constant sets, or Sheaves over a singleton. Variable entities exist only in Category Theory.It is like set Theory is the art of photography whereas sheaf theory is the art of mathematical movies!
Allow me to give an example: There is a security camera on each side of a house. One camera picks up a boy in view on one side of the house, WHILE the other camera AT THE SAME TIME picks up a dog approaching to attack the boy on the other side of the house. To see what occurs AT THE SAME TIME, one can only view each film sequentially (linearly). However, if instead there were one central camera zoomed out to capture all that has occurred, this would not be the case; in other words, all that occurred did happen at 'once'. Taking this line of thought further, therefore, if we were able (and this is where equivocating the absolute with the relative terms of time can enter) to zoom out to the entire universe, we would then see that in truth all does occur all at once!
http://www.abc15.com/news/local-news/water-cooler/amazing-video-cat-saves-boy-from-dog-attack-in-southwest-bakersfield-051414
Spanish philosopher Xavier Zubiri unambiguously defines time as an attribute of being: it is definable as being-there, giving of itself, in other words, emitting the essential qualities of a being. The more time a being (say an orange) lasts, the more it is giving of itself (its color, its juice, its sweetness, its roundness. etc.). Without beings, there could be no time. By talking in ontological terms, Zubiri avoids the pitfalls of talking in less radical terms, which are those of physical sciences, always dependent, in the last analysis, on underlying theories of being. See my English translation, Xavier Zubiri, "Dynamic Structure of Reality" (Urbana: Univ. of Illinois Press, 2003), pp. 193-99, 251n56.
Physics is good for MEASURING time, but not for telling you what time actually IS. Determining a time unit as one second does not answer the question that Alexander asked, any more than saying that the speed of light is a definition of light itself (let us say electromagnetic waves, for the sake of argument). One square kilometer of land is not a definition of land itself (soil composition, topography, etc.).
The tempo of a piece of music measures the time in that piece but does not tell you the essence of that piece, what it really means.
There is a same thread posted on April 4th by Ziad O. Abu-Faraj! maybe You should merge your threads!
https://www.researchgate.net/post/What_is_time
" The only thing certain is that as the sun rises and sets to mark another equinox, another day will pass with the complete answer of the site's origins still firmly lodged in the past. Perhaps that's how it's meant to be." (Re: Stonehenge).
I really hope my friends here take a moment to view this explanation: A short video moving through the history of human attempts to measure and record time. Daniel Boorstin, author of "The Discoverers" commented that "The first grand discovery was time, the landscape of experience."
http://www.youtube.com/watch?v=abog6ys7tDY
My definition of time: Time is the one and only one required, spatially dimensionless & independent variable that is needed in order to describe with accuracy and make (or not) predictions for all predictable (and not) systems of mutually interacting 'objects' in our local universe, while the latter also is included inside this extended set.
Of course my definition is not compatible with relativity theories, but that's another story...
So wonderful stories and the film! They say, it's very important for a human being to be in the right place at the right time.
I think that the definition of time is base on discipline.
for example, in computer algorithms the required time for an algorithm to perform a specific task is called time complexity of that algorithm. a challenging task is to reduce such time.
the solution of NP problems with large problem size need billions or trillions of years.
@ Demetris,
I really like your point of view on "time" as a fundamental physical quantity, without which it is impossible to properly describe the interaction, and especially the sequence of events in the universe.
But - if I understand your train of thought - you leave as a "a priori" boundary condition, that the beginning of the passage of time (t = 0), is the beginning of the Universe, in the form as we know it today (for example, starting from the Big Bang)?
I have no precise definition of "time", but I believe, that it is this parameter - when will be proper identification and definition in physics - which is the key to the answer to the question about which we talk in another topic - namely: What do we know about Initial Singularity? (https://www.researchgate.net/post/What_do_we_know_about_Initial_Singularity).
I do find some interesting consiederation on time by Michio Kaku! Wach his documentary, read his books on this issue!
http://www.brainpickings.org/index.php/2011/03/28/bbc-michio-kaku-time/
http://www.amazon.com/exec/obidos/ASIN/0393327000/braipick-20
A popular post-Einstein answer to “What is time?” is that time is a single dimension of spacetime.
Issam Sinjab is correct for the case definition of the time to serve those who understand Relativity. But those are tiny minority. Time describes nothing in the Static unchangable world. STATICS does not need time, no use. The 3-D space coordinate sistem is sufficient for Statics. That is in KINEMATICS, speed (velocity) and acceleration requres time for their definition. VELOCITY is the RATE of the Pozition Change in 3-D Geometrical System of Coordinates. ACCELERATION is the rate of Velocity Change.
In both examples TIME is the RATE of CHANGE, at least within the given Inertial System.
Sure, people perfectly understand that, but the more we know about time, the further away we are from a simple definition.
Time, it is sometimes said, is what keeps everything from happening at once. While, I suspect that is none too helpful, since we apparently need to understand "at once," to mean something like,"at one time," So, it seems circular. Still it is suggestive of the idea that there is a difference, of some importance, between time and the measurement of time. Units of time, it seems, are units of the measurement of time; and time is something distinct from its measurement. Time surely past before it was ever measured, and it does not depend on its measurement--as contrasted with the possibility of its being measured. A similar point is suggested by Sinjab, of time being one of the dimensions of space-time. The problem there is that we need to first understand what space-time is. That's no easy task.
An alternative idea is that time is a measure of change, or of rates of change. Things change, and that is the basic reality involved. A clock is then a device of regularity of change, by reference to which we give a measure of the rates of change of other things, The degree of regularity of change of a given clock, or type of clock, we can only judge by reference another clock. It seems clear that being in a position to judge that one clock is more regular or accurate than another proposed standard clock may involve quite a lot of detail--and physical theory. But we can only think of ourselves as starting on such a process of refinement, by taking for granted some standard of regular change.
Beyond that, speaking of change, we suppose that we can distinguish change of something from variations in the same thing. The point is, say, that a spot might change color, and that is different from its being one among various spots with various colors --and different locations. That suggests in turn that change contrasts on a basic level with location and things which contain variation over some local, spatially extended range. It seems, then, that our understanding of time and space are closely connected at a very basic level. Time presupposes change, and regularity of change, but understanding change requires distinguishing change and co-existing variation.
H.G. Callaway
According to the illustrious Kant: time is an internal perception and nothing more! What is it outside of the human confines of our minds? No telling...
Luis, Kant was a Subjectve Idealist, what else he could tell. Stalin rated subjective idealism as the most primitive philosophy.
Stalin was the King of all Subjectivist and Idealist! His narcissism was so overbearing that he would easily have killed all men in the world to vindicate his own ideas. In fact, are we not all radical subjectivists?
The continuum of experience in which events pass from the future through the present to the past (http://www.vocabulary.com/dictionary/biological%20time)
Dear Andrzej, I do not define any kind of a boundary value for time, for example I do not think that it is worth saying t=0, since I do not accept the concept of initial singularities at all. Every such singularity is due to our extreme (and failed) approaches of reality by using functional equations, such like O(1/r^2) or O(1/r) etc. The singularities most of the times are inside our wrong theories and not in nature (Otherwise we would observe 'explotions' of charged particles every day, since all our laws (Coulomb) are ~1/r^2 !).
Time is a spatially dimensionless independent variable with NO starting value at all ._
@Demetris,
my first idea is, to use time as an interval, I mean delta(t). In this option it defines developments and changes.
2. I do not really understand your hint to the coulomb explosions, because if approching a distance of zero, the forces are growing to infinity, so a nearer approach isn´t possible.
Luis, in the former USSR Philosophy was devided into Political Philosophy and the Natural one. The only kind of Political Philosophy officially supported was Marxism - Leninism. For natural Phylosophy all Communist Party members were compulsory Materialists, otherwise Party membership could be lost. For non-Party members people could have their preference, Hegel was most popular. Some followed Kant, were considered as stupid people with high ego.
Stalin personolly never realised that blind believe in COMMUNISM made him Idealist, as this believe was in IDEA, and not in Reality. He called Himself Dialectical Materialist, Hegel was in High Esteem in application to Materialism.
@Hanno, all reverse squared laws have this problem: As r-->0 => something -->infinity. In reality this does not happen, so the 'singularity' is a measure of our failure in such a theory. The use of Δt does not solve the problem of definition for time t.
***My argument focuses on the non spatial dimension of time: I totally disagree with the concept of space-time. Time is the non spatial dimension that we need in order to describe (or not) everything else. For simplicity you can take all the time derivatives: dy/dx or y'(t) and remember how accurately they work...
@Demetris,
my delta(t) proposal hints to a favoured practical use, like you show it with the derivates. We have to use "time" in physics whatever the clear definition will be.
As for the singularities, I´ve understood them as limits, like we learned it when doing our mathematical studies. I´m not sure, that the discussion of the origine of time will be very helpful for work in natural sciences. So I prefer, to do my accustomed job, using the parameter time as an valuable variable to solve my problems.
You see I´ve problems with the philosphy of time.
Dear Christopoulos, your last note reminded me of two quotations I've been thinking about, and which might help with your argument. The first is from Stephen Hawking. A Briefer History of Time:
"...we know that the theory of general relativity must be modified. Because the classical (i.e. non-quantum mechanical) version predicts points of infinite density--singularities--it prognosticates its own failure..."
At the least this, expresses considerable skepticism about the singularities of GR, and one may suspect that these are limited by QM, say, the Planck length.
The second quotation comes from Carlo Rovelli's paper, Quantum space-time: What do we know?" in Callender and Huggett (2001), p. 109, and it seems much less skeptical about GR:
Now, there is nothing in the basis of QM that contradicts the physical ideas of GR. Similarly, there is nothing in the basis of GR that contradicts the physical ideas of QM. Therefore, there is no a priori impediment in searching for a quantum theory of the gravitational fields, that is, a quantum theory of space-time. The problem is (with some qualifications) rather well posed: is there a quantum theory (say, in one formulation, a Hilbert space H, and a set of self-adjoint operators) whose classical limit is GR?
My sense of the matter is closer to Hawking here, I suspect, though I have also read Rovelli with much interest and delight. There seems to me to be some serious tension or contradiction between GR and QM. This is connected with the GR singularities--as at the center of a black hole.
Your proposal or argument may be more radical, and I am not sure that any of this above will help. But, at the least, I'd like to know what you make of the Hawking quotation.
H.G. Callaway
Time is a measure of a day, a month, ...a year, ...;an age, a life, a speed, a wave ... There is an earth time connected with sun, moon, seasons,...etc... behavior, a celestial time connected with universe features, and a God time connected with the creation behavior
One feature about time is that it has a speed! And the speed of time is one second per second :)
I don't think you can find a simpler answer to the question "what is time" than this:
Zeit ist das, was man an der Uhr abliest.
[Time is what a clock measures.]
Albert Einstein
@Hanno, I think Professor Costas Drossos will also be very happy to see more people to prefer working with non standard analysis, ie dx, dt, ... It is a promising area indeed. And the Leibniz formalism works fine most of the times.
Dear H.G., Professor Stephen Hawking was famous before some years for introducing the concept of imaginary time ('The arrow of time'), so, although we are accustomed for watching him changing opinions, I don't think that his definition for time is compatible with mine. Of course we end at rejecting conclusions for GR, but details are too important. I will come back tomorrow for more on time concept.
For a Steady State process Irreversible Thermodynamics states:
E / t = Ja Xa + Jb Xb + Jc Xc + ...................................
Where t is the time, E is the Entropy, the sum of Fluxes time Conjugative generalized forces X is the Entropy Production.
Thus, TIME is the ratio between the Entropy and Entropy production. When Entropy is ZERO, before big bang, the time is ZERO. When Entropy is no longer produced (Entropy Production is 0 ), the time is INFINITY. That what was predicted as the THERMAL DEATH of UNIVERSE by the Second Law of Thermodymamics.
Sure, simple people, whom scientists address, deserve better than that, but hard to come with.
Let's take for convenience the Cartesian coordinates (x,y,z). The infinitesimal distance is ds^2=dx^2+dy^2+dz^2 and of course it holds that dx^2+dy^2+dz^2=0=>dx=dy=dz=0, thus we say that the 3 spatial dimensions {x,y,z} are linear independent variables. Let's say now that light with speed c moves for an infinitesimal time interval dt, so the covered distance is ds=c*dt or ds^2=c^2*dt^2. Now we have that it holds:
dx^2+dy^2+dz^2=c^2*dt^2 =>dx^2+dy^2+dz^2-c^2*dt^2=0=>dx^2+dy^2+dz^2+dtau^2=0, where we put tau=i*c*t. Now for the set {x,y,z,tau} it holds that dx^2+dy^2+dz^2+dtau^2=0 without =>dx=dy=dz=dtau, so the set of variables {x,y,z,tau} are not linear independent. The such a way defined time, as a part of a space-time pseudo-basis, is simply false.
(Thanks to Johan Prins who helped me to clarify this by many conversations here in RG).
So, time is not what we are used to mean as a relativity origin object.
Alexander, thanks for posing this interesting question and even presenting here half of the answer! The world of special and general relativity, speed of light etc. is possibly only a degenerated case where the essence of time is invisible. Something is zero in these casess.
Your gut feeling about a (unique?) relation between time and entropy production is a fruitful start. Sort of integro-differential equation? I guess that thanks to Prigogine (you should know him personally, I guess, I once had the honor in Berlin), Haken, Ebeling and others, we maybe know enough phenomenology today about time and irreversiblity to make a step ahead. We should form a dedicated group for a crowd-funding project. Because, as an orgiginal inhabitant of olde Berlin once stated, "ohne Moos nix los" (no money - no honey) - a phenomenological truth because or travel costs.
An intl. project like "Physics of Time (PhoT)" should gather wise men like you, and some VERY young guys who are not yet poisened with the hunt for project applications, "permanent" positions, family obligations, and the like. Heavy curiosity and mental as well as physical mobility are enough. Let's take this as an hypothesis to answer your question: time is a derived variable which is closely linked with entropy variation, entropy production, or with combinations of the two.
The connecting equations need to be written in a way that the "normal" time of special and general relativity is recovered as special (degenerate case). The question of the cosmos seems to be still too far outside because we have no solid knowledge about initial and boundary (!) conditions. And speculation is entertainment, and for the latter we have huge industries today wherein we are not needed...
Helmut
Dear Genosse Helmut. Thanks for your nice words. I can see from your RG site that you are from former DDR, part of your education and training you obtained in former USSR, both, Moscow University and USSR Academy of Sciences, Novosibirsk are Top places.
I am Moscow born and educated, my major is Physical Chemistry. As the determination of time eluded even greatest ones in Physics, I try my best to use the fundamental field, developed largely by Lars Onsager, who was the Physical Chemist himself. Professor Prigogine generalised Onsager theory, both were honored by Nobel Prize in Chemistry for their Impact.
I use Onsager Theory in toughest cases, and it always works for me. As an example, every one knows anout Capillary Pressure between 2 fluids, Pc, which is the interfacial phenomenon. But Pc provides only pressure difference between 2 phases, measured outside meniscus. The concept itself does not tell proportion of pressure difference attributed to each fluid, and whether it depends on chemical composition of fluids or not.
But when Onsager theory is Honored within this phenomenon, it tells that each phase is equally responcible for this effect, each is responsible for 1/2 Pc. I attached the short paper, in the case you are interested.
In my post above I did mistake, claiming that TIME is ZERO before big bang. As before any kind of explosion, whatever initial state was, it was static and completely ordered, both Entropy and Entropy Production are ZERO. Thus Time t = 0 /0, and is either not determined or did not exist. The final state of thermal death is, indeed, results to time equal to infinity. Both results directly follow from the Onsager theory.
That would be nice to have an international group of Scientists, working on the DETERMINATION of TIME, some grant money to attract people, but I am largely retired, can't help in the sence of grant. That was in Canada, that I had $100 K per year to hire outside consultants to my liking. Not now in Tel Aviv. But I have a friend, Eugene Levich, Retired Professor of Astro-Physics, who can be very helphul for this task, in the sence of science. He is also very keen on Entropy in Application to Cosmology.
My e-mail is [email protected] So, we can discuss your idea in more detailes.
.
As I am not a poet, philosopher or physicist, but a simple engineer, will put a poem in response to one of the greatest Brazilian poets doing their reflections over time.
I will place poetry in Portuguese hoping someone more capable than me to translate into English because poetry is mistranslated worse than a poetry that could not read.
.
“Quem teve a idéia de cortar o tempo em fatias,
a que se deu o nome de ano,
foi um indivíduo genial.
Industrializou a esperança
fazendo-a funcionar no limite da exaustão.
.
Doze meses dão para qualquer ser humano
se cansar e entregar os pontos.
Aí entra o milagre da renovação e tudo começa outra vez
com outro número e outra vontade de acreditar
que daqui pra adiante vai ser diferente…
.
… para você,
desejo o sonho realizado.
O amor esperado.
A esperança renovada.
.
Para você,
desejo todas as cores desta vida.
Todas as alegrias que puder sorrir.
Todas as músicas que puder emocionar.
.
Para você neste novo ano,
desejo que os amigos sejam mais cúmplices,
que sua família esteja mais unida,
que sua vida seja mais bem vivida.
.
Gostaria de lhe
desejar tantas coisas
mas nada seria suficiente…
Então, desejo apenas que você tenha muitos desejos.
Desejos grandes e que eles possam te mover a cada
minuto, rumo a sua felicidade!!!”
.
.
Carlos Drummond de Andrade
Yes, Tovarishtsh Alexander, you correctly read the CV. However, I was born in imperialistic part of Germany (who's perfect?), and then was transferred to the eastern part by (almost) same practices like Angela Merkel: her father was a protestant pastor and so was mine. As an aside, my father still read old Hebrew. We have taken it as a nice challenge to make our ways under these given constraints, you know the story with the frog in the milk beaker - no alvernative. I was asked to go to Russia when the children of the leading Tovarishtshi preferred not to go there as for them the hardnesses of the daily life in USSR was unsuitable and the doors to Canada already open in 1984/85. I.e. the government has contracted more places than they could sell and filled them then with church people.
My Moscow time was extremely interesting, the people were ready for perestroika and drastic changes and spoke openly about Stalins crimes - very different from the government of east Germany. For me it was THE chance to have time for deeper studies, to meet academicians like Zeldovich, Samarskij, Vasiliev, Kolmogorov still in person! (Yaglom I missed, unfortunately.) I had/have friends at the Shternberg observatory, directed by Zeldovich that time, and in Siberia, who had again friends in San Diego and Hamburg... - strange situation in cold-war times.
But back to our topic, a physics of time, APhoT. You wrote that
>Both results directly follow from the Onsager theory.
Do you have a source to read more?
>I am largely retired,
Well, nobody is perfect, and this is no reason not to continue thinking about APhoT? But seriously, Dr. Levich is possibly a perfect partner. He worked with Zeldovich, one of the most brilliant brains of the last century, former student of Landau, if I am not in error?
Dear Asmat Ali, I am not sure that time is really independent on a fundamental level (which notion is relative, of course) or that it helps much to declare it as such. If you have a function y=y(x) which can be inverted to give x=x(y), then you are free to decide what you whish to call the dependent and the independent variable. We experience time via our irreversible course of life and we transfer our experience of time to the reversible world of few-particle physics of gravitation, relativity and QM where irreversibility is explicitely irrelevant. When many-particle aspects begin to play a role, time automatically apears in another form via entropy evolution and production. This would be a fundamental enough aspect to spend some time to think about it.
Dear Helmut, I can feel a Socialist Brother, regardless the distance.. I lived for decades in Canada, but my friends were largely immigrants from Continental China, the same background, no stress in communication.
I think you put Levich Father and Son in one person. V.G. Levich (the Father) was a PhD student of Landau. He, V.G. Levich, distinguished himself by his book, PHYSICOCHEMICAL HYDRODYNAMICS. I worked directly for him, have number of publications with him. He passed away in NYC in 1987. My friend Eugene Levich is his junior son, being 66 by himself now. He, indid, was a PhD student of Yakov Zeldovich, have a joint paper with him on Plasma in Astrophysics.
On the easy read book on IRREVERSIBLE THERMODYNAMIBS, I would recommend you Kachalskiy and Kedem on this subject.
There is little I can add about Stalin, exept that upon his death, his bank account had the balance of 600 Old Rubles, equivalent of $200. All his significant salary and the Author Honorarium for his 17 Volumes collection of works in politics and philosophy, printed in 100 languiges, he authomatically transfered into account of Stalin Prize, awarded for best works in Science and Arts. He completely funded monetary part of Prize, not taking any money from the treasury.
Never in Russian history, any Duke, Tzar or Secretar, less President, was called OTETS NARODOV. There was not any office for this title, the status was granted to him by people, Russians first. The explanation is simple. He was not CORRUPTED, worked hard, led modest live, people lived better every passing year under him. Russians, under him, passed Historical apogee, they have never been that great.
When I visit Russia on business I frankly tell to simple folks that they are lazy drunks and they need Stalin to tremple them. They are largely united in their responce: "Yes, let him ressurect and lead us, but no President will tremple us".
That is Khruschev, who, in their eyes, has the status below Judas Iscariot. Both betrayed their teacher, but Nikita did not hang himself.
Eddington suggest use of a thermometer, as a kind of "entropy clock," the increasing temperature of a system being a measure of its increasing disorder. One might think of this, of course, as also as a measure of the average energy of motion of a multitude of micro-particles. But I am somewhat doubtful on how well this suggestion generalizes. A gas expanding in a closed box is a common model or illustration of change of entropy. However, I have seen it argued that gravitational collapse also illustrates increase of entropy, and in such a case, another kind of change seems to be going on, though perhaps also a change in motion is involved. The point is argued extensively by Roger Penrose.
In any case, increasing entropy is often mentioned as defining the "arrow of time." It is not entirely clear, however, that time without its arrow would not still be time, in some sense. (Or a component of time, worth distinguishing?) So, if we imagine the universe in a final state of thermodynamic equilibrium, then, by definition, there is no increase of entropy, and one might then think, no arrow of time. But, at least at the level of quantum fluctuations, things still change. It is not clear to me that such change would also be a matter of motions. But even if this still involves motion, it is not clear to me that talk of motion captures all of what is going on. I imagine that quantum fluctuations involve change of state, on an extremely small scale, yet in a state of thermodynamic equilibrium, we also have no clock, and perhaps also no prospect of measuring motions?
I am considering extreme situations here, and not the everyday concerns of working scientists, but I submit that such things have their interest in relation to the question posed in this thread.
H.G. Callaway
Another aspect for a robust definition of time is that of the cosmological view. My view is of Cosmos that is a set of many local universes, each one with its own 'locked' physical constants and forces, but the superior image can only be explained by the most general mathematical abstract models, those we have and those we will find in the future. Our local universe is just another realization in my cosmos and is not the Cosmos itself. Sorry for downsizing our universe from U to u-niverse, but I think it is the natural road: We started from Earth as the center, we moved to Sun, then to Milky Way, then to Local Cluster and finally to ... Local Universe. So, the most general concept of time cannot be assigned to a local universe and have the fate of it, according to thermodynamics. It must be something more general. Any comment would be welcome, otherwise it is a monologue.
Dear Demetris, you are saying "We started from Earth as the center, we moved to Sun, then to Milky Way, then to Local Cluster and finally to ... Local Universe.". It seems to me that the "global" is the big entity, whereas the "local" is the small one!. I have the impression that you are going inversely!
As a joke, I suggest a simple way to determine time: Savvopoulos is saying that "...the true time, is my elder and my younger son! (..και ο χρόνος ο πραγματικός είναι ο γιός μου ο μεγάλος και ο μικρός...")
Demetris and Costas: Have either one of you read any ot the Ender's Game Series?
or do either one of you know Who is John Galt?
:-) Mariliyn
Dear Costas, we simply disagree here: What I meant is that the anthropocentric view is always losing during the history of science. Every attempt to accept something, relating to us the human beings, as a supreme 'concept', has been failed. So, the 'global' can be reached if we get rid of our belief that our locality is globality. Our local universe is just one more universe. The question of cosmos is still open, at least for me...
Dear Marily, I saw here:
http://en.wikipedia.org/wiki/Ender's_Game_(series)
What is your point, relating to this game?
[Probably I like the questions about time, anyway.]
Another aspect now: Starting from a new presentation for Plato's World of Ideas and by comparing it with the The World of Universals of Bertrand Russell we end up that, for both theories, the needless of time arises as a natural consequence. See here for details:
https://www.researchgate.net/publication/262817990_The_Line_The_Cave_from_The_Republic_of_Plato_and_the_The_World_of_Universals_from_Bertrand_Russell?ev=prf_pub
Maybe time is a 'constraint' for material entities only...
Article The Line, The Cave from The Republic of Plato and the The Wo...
You do a fine job, Demetris, on Time discussion, show different angles, provide great references !
Dear Marilyn,
I am so sorry, that I do not even know , Ender's Game Series and/or John Gailt. And even I did not read any of Ayn Rand's novels! Is this a fatal sin! I can list a lot of very important, in my view, documents that you did not read! In fact the thesis of Ayn Rand does not agree with my own theses.
The bottom line it is not how many books you have read, but how much time you spend to think deeply for the basic problems of Sciences and philosophy!
Thank you Alexander, you are welcome!
(I like your questions)
Demetris: Wiki cannot provide you with the scope of the Ender's series as it relates to the question, :What is time". One of the books "Speaker for the Dead" takes place around the year 5270, some 3,000 years after the first book, Ender's Game. However, because of relativistic space travel, Ender himself is only about 35 years old. (Obviously traveling faster than the speed of light). However, your response regarding the cosmos still being open, is exactly what the Ender's series is about. It is about time not being able to be assigned to a specific local universe.
Dear Costas:
Were you offended by my question "Who is John Galt"? Why would you exclaim in question of not reading Ayn Rand as a fatal sin? How do you know which documents I have read, that you can list them? What makes you think I have read a lot of Books? Can you define the basic problems of Sciences and philosophy? I am interested in the philosophies of deep and critical thinkers, such as you. You obviously knew John Galt was one way that Ayn Rand communicated her philosophy. If you have never read any of Ayn Rand's works, how do you know it does not agree with your thesis?
Ayn Rand's deserves her place as a great philosopher by the mere fact that she inspired a philosophical movement known as objectivism. (Not many who think philosophically, inspire movements, nor they grow stronger each day.) Does that mean I agree with Rand's theories about realism? Do I take sides with Plato or Aristotle, and the list starts there.......
I can only tell you one thing Dear Costas, the more I learn the more I realize I know very little.
Was it a requirement to think deeply for the basic problems of philosophy, when this conversation seems much more like psychology?
Best regards,
Marilyn
Dear Alexander, indeed as time passes [ :) ] I tend to believe that time and frequency are actually the same 'object', since by a simple Fourier transform we can go from signal x(t) to X(f) or X(omega) if you prefer. Thus, the question about time can be answered in the frame of next question:
" What is frequency and why is it necessary to the realization of our world?".
My answer to the second part of this question:
*Frequency is a need for stability of material world, that's the reason why all, but all, laws in Physics are just second order differential equations describing finite amplitude oscillations.
*If we do not need such a stability, then frequency (and so time) are needless.
Alexander: thanks for the "socialist brother" who lived in the distant past of the Vietnam war and learned meanwhile that the world has more colors than black and white. Regarding Katchalsky & Kedem, could you be more specific? I couldn't locate the title but read a couple of books on the topic, eg. Prigogine, Gyarmaty, Haken, Ebeling+Feistel and some others, but nowhere I've seen relations of time with entropy production. Would be nice to learn more.
H.G. Callaway: I fully agree with your carefully formulated thoughts. Without entropy production (which differs from simple entropy growth as entropy follows a common reaction-transport equation, if you want: also in relativistic formulation) time is boring, eternal repetition of the same. I insist that the essence of time is friction and its measurement by cyclic processes a sort of an experimentalists trick. Sir Eddington has had a fine nose and was already in the right lane. My guess: with the today's knowledge we can make a substantial step ahead if we bundle capacities.
Dear Marylin,
This post of yours is much better! I don not read Ayn Rand. I disagree in one basic point: She have Logic as her basis for her philosophy. It sound like analytic philosophy. I prefer to use both hemisphere of my brain, left and right. It seems that Ayn Rand dislike right hemisphere! Any way we are both travelers to the roads of knowledge and somtimes i sure we will meet!
"Let’s briefly explore other answers that have been given throughout history to our question, “What is time?”
Aristotle claimed that “time is the measure of change”. He never said space is a measure of anything. Aristotle emphasized “that time is not change [itself]” because a change “may be faster or slower, but not time…”. For example, a specific change such as the descent of a leaf can be faster or slower, but time itself can not be faster or slower. In developing his views about time, Aristotle advocated what is now referred to as the relational theory when he said, “there is no time apart from change….”. In addition, Aristotle said time is not discrete or atomistic but “is continuous…. In respect of size there is no minimum; for every line is divided ad infinitum. Hence it is so with time” .
René Descartes had a very different answer to “What is time?” He argued that a material body has the property of spatial extension but no inherent capacity for temporal endurance, and that God by his continual action sustains (or re-creates) the body at each successive instant. Time is a kind of sustenance or re-creation
In the 17th century, the English physicist Isaac Barrow rejected Aristotle’s linkage between time and change. Barrow said time is something which exists independently of motion or change and which existed even before God created the matter in the universe. Barrow’s student, Isaac Newton, agreed with this substantival theory of time. Newton argued very specifically that time and space are an infinitely large container for all events, and that the container exists with or without the events. He added that space and time are not material substances, but are like substances in not being dependent on anything except God.
Gottfried Leibniz objected. He argued that time is not an entity existing independently of actual events. He insisted that Newton had underemphasized the fact that time necessarily involves an ordering of any pair of non-simultaneous events. This is why time “needs” events, so to speak. Leibniz added that this overall order is time. He accepted a relational theory of time and rejected a substantival theory.
In the 18th century, Immanuel Kant said time and space are forms that the mind projects upon the external things-in-themselves. He spoke of our mind structuring our perceptions so that space always has a Euclidean geometry, and time has the structure of the mathematical line. Kant’s idea that time is a form of apprehending phenomena is probably best taken as suggesting that we have no direct perception of time but only the ability to experience things and events in time. Some historians distinguish perceptual space from physical space and say that Kant was right about perceptual space. It is difficult, though, to get a clear concept of perceptual space. If physical space and perceptual space are the same thing, then Kant is claiming we know a priori that physical space is Euclidean. With the discovery of non-Euclidean geometries in the 1820s, and with increased doubt about the reliability of Kant’s method of transcendental proof, the view that truths about space and time are a priori truths began to lose favor.
The above discussion does not exhaust all the claims about what time is. And there is no sharp line separating a definition of time, a theory of time, and an explanation of time."
-------------------------------------------------------------------------------
Time, Internet Encyclopedia of Philosophy
http://www.iep.utm.edu/time/
The above article discusses other important issues related to time such as time travel and many more. Good read.
Dear Sinjab, Many thanks for your useful quotations and suggestions --of a philosophical sort. I would like to come back to the questions, but for now, I would only suggest that whether we read Aristotle as holding that “time is the measure of change,” depends on the translation. It is sometimes rendered as "time is the magnitude of change." I take it that a magnitude is something that can be measured. In any case, he holds that time is something measurable, not the measuring of it or the product of measuring--not the seconds, hours, etc. which are recorded in measurements of time. Also, of course, he insists that time is not change itself, though there is no time without change. The "change" involved, includes both motion and alteration--which latter is the more general category.
I also think to say that time consists of the measurable relations in the magnitude of change. That suggests why it is that less accurate clocks are judged so only by reference to more accurate clocks (while we never know that we won't find a more accurate clock still), and it makes relationsalism explicit. I'm still not quite satisfied with this, though. I do like Einstein's "Time is what clocks measure," though this also avoids some problems.
I think there must also be a good article on time in the on-line Stanford Encyclopedia, though I am yet to check on this.
H.G. Callaway
H.G.
Earlier in this conversation I posted an interesting vid on Time. I was wondering if you had a chance to watch, a bit.
https://www.researchgate.net/go.Deref.html?url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dabog6ys7tDY
"Time is what a clock measures", is what Albert Einstein said. Although Einstein here was not trying to define what time is, you could equally ask the next question what does a clock measure? Time would be your answer but we have not really answered the question "what is time?", have we now?
Alexander, you are very right in asking for a simple answer to your question "what is time", and you are also right in saying that it is hard to come with a simple answer that the average simple man in the street can understand. I shall now illustrate this with another example. I could say:
Time is a measure of the interval between two events. But once again I have not really answered the question what is time, I have merely described time as a measure of the interval between two events. This is like saying time is time!!
It seems to me that such a simple question does not have a simple answer. It takes time to think about time and it takes time to answer your question!
Dear Sinjab et al.,
You are surely right, Sinjab, that the question about time does not have a simple answer.
I am disappointed that you say nothing about my (complicated) proposal; instead you point to problems Einstein avoided in his quip.
So, I hope that you'll have another look:
Time consists of measurable relations in the magnitude of change.
That suggests why it is that less accurate clocks are judged so only by reference to more accurate clocks (while we never quite know that we won't find a more accurate clock still), and it makes relationsalism explicit. I'm still not quite satisfied with this, though.
In another place, Aristotle says that time is "an aspect of change," and he makes it clear that it is a measurable aspect. I have been avoiding the word "aspect," and using "magnitude." (He insists that time is not to be identified with change.)
So, try this instead:
Time is a uniform and measurable aspect of change, which can be measured by relation to a standard of regularity of change, i.e., a clock. (Einstein returns!)
My sense of the matter is that we are getting closer here. The chief point in insisting on use of "change" is that without change there is no time. But we might call on Einstein again and on his emphasis on frames of reference in particular. Every frame of reference must have a zero point of its coordinates, and I suppose that implies that we must always measure time in relation to the zero point of some frame of reference or other. (Not that time must begin at this zero point!) This, again makes of time something relational.
Time measurements from different frames of reference will differ. Still, Einstein also provides us with a notion of "proper time" which is invariant, as I recall. Perhaps the physicists will help us along with this notion. I suspect that this notion will also prove to be relational in an important sense. Will it prove consistent with the Aristotelian flavor of the above proposals? (Progress in philosophy can be frustrating slow.)
H.G. Callaway
Why should we define the time first and not the frequency?
See the example in attachment for details.
Although a signal x(t) can be transformed to a Dirac delta signal X(f) in the frequency domain, the later carries all necessary informations about the original signal.
So, why not to focus on frequency and argue:
*Frequency is the principal object and we can classify the phenomena according to their frequency. When frequency is a discrete set, then the 'signal' is a superposition of harmonic oscillations. Otherwise the situation is more complicated.
Dear Christopoulos,
I do not, myself, see that your suggestion just above, is an answer to the question, "What is time?" You propose, instead, to define "frequency." How would this help answer the question about time? It strikes me that a frequency, or frequencies generally, are simply one example of change--regular change. How does it help us to understand time, if we know how to transform some information (or other) about time into some information (or other) about frequency?
You say, "a signal x(t) can be transformed to a Dirac delta signal X(f) in the frequency domain, the later carries all necessary informations about the original signal." Necessary for what? I suppose that this concerns a? some? "signal" or information about time, being transformed into another signal or information about frequency. But what information about time is in the domain of the variables?
Or, otherwise, put, what information about time is being transformed? Frequency is surely one kind of regular change, and time is to be measured in relation to some regular standard of change--so I've suggested. So, a relationship between time and frequency is not surprising. But, so far as I can see, this does not tell us what is being measured when we measure time. So, the question seems to return: What is time?
If I've missed something here, I hope you'll be so good as to let us know. My impression is that you could be helpful.
H.G. Callaway
Fellows ! What we really need is the time determination within 1 simple experiment, which can convince a simple man on the street. He cares about what he can see on Earth, let Relativity be domain of scientists.
Demetris referenced Aristotel, that time is the measure of change. Hard to disagree, but change of WHAT ? I agree with Issam that answer is hard to come with, but let us try, using position, velocity, acceleration, simplest kinematics possible. My problem is that determination of velocity already requires the time. Only determination of static position is time independent. There should be independent event, like 12 hours is the time an observer spends from monitoring interval between SunRise and SunSet either on 22 of March or on 22 of September each year. But even this determination is not presise, just more or less as a rough estimate. Each 4th year has one more day. I am sure that we can come with something simple and hard to reject.
Dear all, the definition of time unit in SI is very "simple", unique and and clear, at least for physicists.
"The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."
I confess, it will be to complicated for "the simple man on the street", but no doubts about the value, because the experiment to define the second is precise. And you don´t need definitions like Alexander voted it sunrise-sundown" and similar statements. Off course the definition of an accepted units doesn´t explain "What is time".
Dear Babchin, you wrote, just above;
"Demetris referenced Aristotel, that time is the measure of change. Hard to disagree, but change of WHAT ?"
It strikes me that this comment, in the present context, is somewhat misleading.
The change involved is any change, including motion, the physicists favorite sort of change. Also, you do not attend to the oft emphasized difference between "measure" and "measurable." The Aristotle scholar David Ross, put the "what" this way:
Change: "generation or destruction, growth, qualitative change, or locomotion."
It may be that all these kinds of change do not equally interest physicists, but in any case, they are equally relevant to time, according to Aristotle.
BTW: Demetris seems to find it very difficult to answer questions directed to him directly. If he has something to say about Aristotle, let him take responsibility for it directly.
Otherwise, I'm afraid, there will be just too much drama and theater on this thread --not enough of the question at hand. That, in my view, would be none too professional. It blocks up the road of inquiry.
H.G. Callaway
All, we possibly need to differentiate between time and its measurement. For the measurement we typically use periodic processes free of any "friction", e.g. clocks or atoms, processes with entropy conservation. It's like space and its measurement by centimeter scale. The measurement method tells us nothing about the actually curved character of space. Similar we might get also a time which is in a way nonlinear and depending on entropy production rate.
Dear Baumert, A distinction between time and units of time stand in much need of emphasis here. The question concerning the definition of units of time is relatively easy to answer, as Krieger illustrates above. It may be, of course, that Babchin would rather have asked a question about units--but I don't think so.
Units of time, seconds, minuets, hours, etc., I take it, depend upon human invention, and do not exist in nature unaided --though we define units by reference to natural processes taken as regular. So, it stands to reason that however valuable our definitions of units may be in science, this does not substitute for a good account of the meaning of the word "time." I expect, however, that an appropriate definition could only arise from consideration of our best theories involving the concept. Definitions may come and go with theories, as is illustrated by Einstein's way with F= ma.
H.G. Callaway
No, my question was on defenition of TIME, not units of time. And we still discuss it.
Physical Definition of Time
From the age of Newton up until Einstein's profound reinterpretation of the physical concepts associated with time and space, time was considered to be "absolute" and to flow "equably" (to use the words of Newton) for all observers. The science of classical mechanics is based on this Newtonian idea of time.
Einstein, in his special theory of relativity, postulated the constancy and finiteness of the speed of light for all observers. He showed that this postulate, together with a reasonable definition for what it means for two events to be simultaneous, requires that distances appear compressed and time intervals appear lengthened for events associated with objects in motion relative to an inertial observer.
Einstein showed that if time and space is measured using electromagnetic phenomena (like light bouncing between mirrors) then due to the constancy of the speed of light, time and space become mathematically entangled together in a certain way (called Minkowski space) which in turn results in Lorentz transformation and in entanglement of all other important derivative physical quantities (like energy, momentum, mass, force, etc) in a certain 4-vectorial way.
http://www.andersoninstitute.com/physical-definition-of-time.htm
Dear Babchin, Given the state of the discussion, and the various contributions, it strikes me that your clarification, though much needed, is extremely brief indeed.
H.G. Callaway
Dear H.G. Callaway, I apologize for not being all the time in front of my PC, sorry but I have to (at least partially) work in order to pay my bills! Is this OK for you? (Of course I have no problem to send you my IBAN and if we agree on the 'amount', I will be all time and every day in front of this topic ... :) )
So, let me continue my arguments.
Start of parenthesis: In mathematics and in physics it is very crucial the concept of an 'isomorphism', so we can study a different, more easy domain than the original 'ugly' one. Similar to this is the concept of 'transformation'. I remind the general theorem of Riemann, that of the existence for a transformation to unit circle in complex plane and its great applications, even in aerospace design mechanics. I cannot help you more on this, you should read pure and applied mathematics:
End of parenthesis.
Dear all, if we have a simple 2nd order differential equation with initial conditions, describing a typical system, by applying a Laplace transform we can go from y(t) to Y(s) and obtain a strictly algebraic equation. Then we solve it and finally by applying the inverse Laplace transform we get the solution of the original time dependent DE.
So, maybe there exist reasons, starting from the applied mathematics to try define frequency as the principal object.
How could such a definition be? Any idea?
Thanks all.
Dr. Marilyn B Field • 2.48 • Give Me Back My Energy; Life Coach, LLC (http://www.feelingnewcoach.com)
Demetris and fellow RG (ers):
This is a response from a private email that I have decided to share for those philosophers you may feel the same as the person who emailed me and some of the responses I have received to my posts. However, most are wonderful.
One person could not understand the relevance of the brief video I posted titled Time, Stonehenge and Sundials to the presenting question "What is Time?"
I am sharing my response here:
The question posted was "What is time?" Not what is time, according to Einstein, Barbour, or you kind Sir, or several other philosophers. Modern Physics has a very complex language, even when discussing the most basic philosophies, and those who are experts in the same, need to realize that outsiders sometimes might have difficulty deciphering an argument or friendly debate among those schooled in physics and/or philosophy. However, I would think that a "thinker" such as you should understand that American Intelligence is full of diverse and different thinking cultures. Much like one of your well-written articles, I do not have to understand everything about Ebonics to understand "what is going on" [sometimes through expression]. In South Florida one may someday find themselves with English as a SLA after Ebonics. The complex nature of the discussions on RG, whether they favor Platonism or Aristotelianism, or Randism, is fascinating. However, we must remember not every ResearchGate(er) is a mathematically or philosophically schooled member. I recognize this and simply posted a vid on time as it was the topic (as most people think of it in terms of "time to go".) I ask you sir. Here are 2 short videos (since you did not have the patience for the first and felt a need to let me know). I am sure you are far too advanced intellectually, to bear the patience to view the following 2.
However, only one of them is actually a time.
I suppose you would have had more patience for Julian Barbour:
https://www.youtube.com/watch?v=I5rExaKLEoU
or maybe this video defines time:
https://www.youtube.com/watch?v=Hf0Dm-OaTNk
However Sir, one thing is very clear to me...time's definition is open for debate.
---Marilyn
Dear Christopoulos, Please do take your time. As I say, its all a bit too much drama and theater for me. So, maybe I'll check in later.
I take it, though, that an interesting debate on any topic will have at least to sides, with statements and replies. It doesn't work if one side holds all the cards.
H.G. Callaway
Dear H.G.,
First of all I wrote about Plato and Russell, not about Aristotle. What is your opinion about my view?
Second, I presented my view of concerning 'equivalent' objects to time, like frequency 'f' or the variable 's' of a Laplace transformation. What is your opinion about it?
Finally, I tried to find your opinion about time and I found disagreements with other participants. So, what is time according to you?
Regards,
Demetris
Demetris, find determination of time, acceptable to simple folks. Your examples are for professional scientists only. You can do that !.
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