# Where in, Einstein’s “On the Electrodynamics of Moving Bodies” (Relativity), is “Time” reasonably shown to exist, or why is it a valid assumption? [closed]

Given the widespread acceptance that “Einstein’s Relativity” reasonably proves the existence of Space-‘Time’, and thus “Time”... Can any member of the Physics StackExchange please show precisely where, in "On the Electrodynamics of Moving Bodies", (or related core Relativity) papers, “Time” is actually, in any reasonable way shown to exist, as opposed to just, or only being (unscientifically) “assumed”? (added) or, why it is legitimate for the paper to make this assumption or axiom?

Many individuals and publications refer to Relativity as our best theory of Space, and “Time”, and thus imply it is a given that time exists... because Relativity intricately employs the concept of time.

But wherever such claims are made, they are rarely accompanied by any clear justification or specific reference to a specific section of SR or GR. At best, it is claimed that SR proves “Time dilation”, and thus the existence of “time” as a genuine dimension.

Therefore unless it can be shown that Relativity, ("On the Electrodynamics of Moving Bodies" etc), actually incorporates a reasonable proof of times existence, or cites such a proof, or even just gives a valid reason to “suspect” a thing called “time” might exist, then the “time dilation” shown may in fact prove only that moving things “are” changing “slower” (i.e just at a dilated rate), than stationary things, and not that a “temporal past”, and/or “temporal future”, or thing called “time” also exists. (As per space-“time”, block-“time”, growing block-“time” etc).

Precisely where Relativity is valid in assuming a thing called time exists, is a very important question, given the large number of theories based on the belief Relativity does proves time’s existence. And, the large number of fundamentally conflicting theories about time, problems resolving quantum and classical “time”, and even disagreement about time’s actual existence or not.

Therefore, if anyone here on the stack exchange can show just where "on the electrodynamics of moving bodies" actually, legitimately validates its use of "time", or why they accept its assumptions in the specific area of "Time", please clarify this not just for me, but I assume many others..

## closed as off-topic by David Hammen, Valter Moretti, Kyle Kanos, John Rennie, dmckee♦Oct 8 '14 at 21:26

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• Prove space exists. – Kyle Kanos Oct 8 '14 at 13:10
• You can't prove an axiom. (Alternatively, the proof of an axiom is trivial. "Axiom 1 is true via axiom 1. QED.") The existence of space and time as axiomatic in special relativity. It's a part of axiom #1. – David Hammen Oct 8 '14 at 13:15
• @DavidHammen: Not understanding the difference of types theorems does not make this non-mainstream though. "Unclear" or "specific concepts" are probably valid close reasons, I just don't see how lack of knowledge can be labeled non-mainstream. – Kyle Kanos Oct 8 '14 at 13:36
• The question is valid, but it would probably get good answers and upvotes if it wasn't phrased in such a hostile way, implying that the whole of 20th century physics is wrong because Einstein forgot to check if he had proved time exists. – Javier Oct 8 '14 at 16:04
• @MattMars: We assert that space exists as an axiom; in the same way, we assert that time exists as an axiom. You cannot prove axioms, they are definitions. For convenience, the metric combined all three spatial elements with the temporal one, creating the space-time manifold. – Kyle Kanos Oct 8 '14 at 16:34

First of all, physics does not ever talk about the question of existence, but about useful descriptions and predictions of observations. No physicist will ever prove to you he is not just a figment of your imagination but he can prove to you that Newton's law works pretty well for what you see.

In the scientific method, a theory is indeed used until it becomes useless because it does not describe facts properly. But relativity does describe facts properly and gives sound predictions. Hence in the eyes of the scientific method, there is no reason to throw it away unless a better proposal is put forward.

To sum it up, nobody in science cares whether time exists or not - unless you show hard facts which distinguish between the statement of the existence/non-existence of time. Obviously, this requires that the statement of "existence" is given a specific interpretation. However, if the given interpretation does not show a factual distinction between the statements, the question of their validity is non-scientific. So what factual distinction does the statement of non-existence of time represent?

Einstein does not prove time to exist and it is safe to assume he did not really aim to discuss it's "existence" in a philosophical sense. The work is a "mere correction" to the Newtonian paradigm with the Galilean transform where a parameter $t$ commonly called "time" is assumed. The need of such a parameter is assumed implicitly, the same way that it is commonly assumed that the world is not just a figment of your imagination.

So what does this parameter $t$ mean? Citing from Einstein's article on electrodynamics of moving bodies:

It might appear possible to overcome all the difficulties attending the definition of “time” by substituting “the position of the small hand of my watch” for “time.” And in fact such a definition is satisfactory when we are concerned with defining a time exclusively for the place where the watch is located; but it is no longer satisfactory when we have to connect in time series of events occurring at different places, or—what comes to the same thing—to evaluate the times of events occurring at places remote from the watch.

That is, for Einstein "time" is just the number you read off from a clock. Nothing more, nothing less, no discussion of existence of some abstract "time" entity is needed. A part of the body of the article then concerns itself with deriving how you can relate what does your clock show to things that other clocks show under certain synchronization procedures. (I described one such procedure in this answer.) You could eliminate "real time" and just talk about "change" and no-one can stop you. But the tacit fact still holds that you need a certain number $t$ to unambiguously label events.

I can already picture the comment which says things such as "But this is no proof the label $t$ is not redundant...". So ask yourself "How would I prove my dog exists?". You would say you see him in your living room. But you see an image in the shape of a dog in your head. Which means there are neurons flashing in your head somehow. How is this proof such a thing as a "dog" exists? And we could go on like this for a long time.

A truly scientific approach is to propose specific hypotheses associated with the fact of the existence and non-existence of your dog. E.g. "My dog exists if I hear him, see him, touch him, there is no logical inconsistency in these phenomena, and my psychiatrist is not telling me I am mad." But in the end these are only necessary, not sufficient conditions for the existence of your dog. You never gain sufficient conditions for the existence of anything from science.

The need of a fourth label "t" has a specific form and the proposal of non-existence of time would have to reformulate science in a specific and quantitative way to prove itself at least equally true as the proposal of need of $t$. The scientific method is open, it verifies only necessary conditions and this is also the case of the $t$ label. I.e. the necessary conditions for the "essentiality" of $t$ are given by it being a part of working scientific theories. As far as I know, this is not the case of "non-time" theories. (Even Barbour has a fourth parameter which is just not called $t$.)

• Thank you @void for your response. I added a reply to it and asked if that was ok, but it seems to have been removed without any communication. Re "the proposal of non-existence of time would have to reformulate science in a specific and quantitative way", politely, in science, it is not up to one to prove the "non-existence" of anothers theory. They need to provide some scientific evidence that 'clock' hands (dilated or not) do not just show things exist and move, but that there is also a 'thing' called 'time',and,how it is apparently 'passing'.We cannot just claim 'Time exists' is axiomatic. – MattMars Oct 10 '14 at 10:16
• But nobody is claiming "Time exists". The claim just is that "science without a time record is not possible" and this claim fulfills "only" the sufficient condition of not being contradicted by the whole body of science. I.e. to study a process scientifically, we have to write into the "time" column in our data - the "space" columns would not be enough. Yes, we do in fact write another "space" variable under $t$ corresponding to say the position of the clock hand. But you do get different records corresponding to different arrangements of all "space" variables. – Void Oct 10 '14 at 14:03
• Different means not identical, so the two arrangements are not the same which means we have a family of arrangements and we need a label to organize these arrangements. This label is commonly denoted $t$. – Void Oct 10 '14 at 14:06
• Thank you @Void that’s very clear. If I understand correctly, Nobody is claiming Time exists. We just live in a world in which matter 'is' just existing, moving and interacting in different ways, in all directions. And where studying complex motion it is useful to compare that motion to an example of simple motion, and use the symbol ‘t’. So the answer to my question is, ‘time’ (e.g. with a past, future, or arrow etc) is not shown to exist in Relativity, and it is not valid to assume ‘Time’ exists, other than as a useful system to explore the ways matter 'is' being arranged in the universe? – MattMars Oct 10 '14 at 16:17
• Well, matter? Does matter exist? Does energy exist? Does space/universe exist? In a sense yes, you have got the right gist, but similar statements can be made about any term X used in science: "In the light of plain scientific methodology, X is a useful term to explore and organize observations." Be X time, space, energy, matter... Existence of X is not commented upon (i.e. this is not a pro-timeless statement). Some adopt physical realism to establish a correspondence between science and the "really real" - but that procedure is ambiguous and out of the realm of plain science. – Void Oct 10 '14 at 19:49

The aim of special relativity and of spacetime (in particular: the Minkowski space time) is not to know about what time is. Spacetime is showing a relation between space and time from an observer's view only - and this whatever time is in reality (including the question if time exists or not). The result is that time (i.e. the value measured by clocks) may be different from one observer to the other.

In special relativity "time" does not mean anything else than that a clock is running.

• "OEMB" cannot scientifically be quoted as showing a relation between space and "time", unless somewhere it shows that a thing called time exists, as opposed to just observing motion in a simple spatial direction, and "calling" it time. Implying, without scientific proof that an extra unobserved phenomena with the implied attributes* of "time" exists. *”Time : The indefinite continued progress of existence and events in the past, present, and future regarded as a whole” (O.E.D) The value measured by “clocks” is only the movement or location of a motorised pointer rotating on a dial. M.M. – MattMars Oct 8 '14 at 16:05
• Re:”In special relativity "time" does not mean anything else than that a clock is running.” Therefore the “measurable quantity” (dimension), of the rotation of a motorised hand, is just the simple, spatial, directional “motion” of an object. And cannot just be “called” an extra “dimension” of a phenomena called “time”, or taken to prove a thing called “time” with a flow, direction, “past” and/or “future” exist...i.e 4dimensional “spacetime”. M.M. – MattMars Oct 8 '14 at 16:09
• This is exactly your misunderstanding! Special relativity does not treat all these issues you are mentioning, it just uses some clocks and some rulers (measuring always from the point of view of an observer) without bothering about the nature of what is measured. Calling "time" what is measured by clocks and "space" what is measured by rulers. There is no further truth within special relativity! – Moonraker Oct 8 '14 at 16:39
• Hi Moonraker. Thank you for your comment. I agree “"space" what is measured by rulers” Seems a valid observation by the paper. But you seem to jump to the conclusion that therefore “"time" [is] what is measured by clocks” is equally valid. This unchecked assumption seems to lead to scientific establishments like SA (goo.gl/qzmAVH) asking questions about “time”, where only simple rotational motion is described by the OEMB. And misleadingly implying “Einstein’s theories of relativity suggest not only that there is no single special present but also that all moments are equally real”.M.M. – MattMars Oct 8 '14 at 16:56
• Dear answerer "First of all, physics does not ever talk about the question of existence," thank you, i added a response to your answer post, becasue these comment boxes are too small to address the issues raised. (is that ok ?) m.m – MattMars Oct 8 '14 at 18:06

The question seems to imply that the OP has a fundamental problem with existential questions. Those are for psychology and philosophy to ponder. Physics simply observes that one can build very precise clocks that agree with each other reasonably well under certain circumstances and not at all under others. The theory of special relativity clarifies when these clocks will agree and by how much they will disagree, when they don't.

• But Relativity seems to imply that thus unobservable "instants" of a thing called time exist -- does it? How? Physics doesn't concern what "exists", only what results are predicted when you perform various experiments. "Existence" is a matter of metaphysics, specifically ontology (the view that only present things exist is called 'presentism' by philosophers, the view that events at all times have the same ontological status is called 'eternalism'--relativity doesn't comment on this, though it may make eternalism seem more appealing by occam's razor) – Hypnosifl Oct 8 '14 at 22:38
• I think requesting scientific proof to back up the theory that intangible unobservable time exists As I keep telling you, this is just a strawman, relativity makes no claims about what "exists". If you disagree, please point us in the direction of any paper by Einstein (or any paper or textbook by some other mainstream author) claiming that relativity proves different times "exist" in the eternalist sense. – Hypnosifl Oct 8 '14 at 23:04
• @MattMars - "and if we cant even provide an experiment" -- provide an experiment to show what?? If it's "other times exist" or "time exists" then you're asking for an experiment to prove something relativity never claimed in the first place. Are you familiar with the term "strawman argument"? – Hypnosifl Oct 8 '14 at 23:19
• @MattMars, nowhere in physics is it claimed that any element of any mathematical model used for predicting experimental results -- whether the element we're talking about is "time" or "the electromagnetic field" or "light waves" or "forces" or "space" -- "exists". Did you see my earlier comments about how existence is a matter of ontology, not physics? If I seemed a little frustrated, it's because I made this comment several times before and you didn't respond, but just kept on repeating the claim that relativity says time "exists". – Hypnosifl Oct 9 '14 at 2:21
• @MattMars - why do you think referring to a 'thing' in a scientific paper involves any belief that it "exists" in some ontological sense? One can just view it as an element of a mathematical model useful in making predictions. If a paper defines a particular coordinate system, must they believe the coordinate grid "exists"? If a paper defines the value of some number useful in physics (Avagadro's number, say), does that commit them to mathematical platonism, the view that numbers themselves have objective existence? – Hypnosifl Oct 10 '14 at 15:48