[Seafire (OP)]

Hi everyone, I have a question about space-time that I hope someone can explain properly.

Are space and time just two sides of the same coin?


If this is true and we live in a universe made up of different spaces then it must also be true that we live in a universe made up of different times, does every point in the universe exist at a different time?

[Halc]

Hi everyone, I have a question about space-time that I hope someone can explain properly.

Are space and time just two sides of the same coin?

In the space-time model, space and time are different dimensions of the same stuff, so they share geometric properties, such as ontology.

If this is true and we live in a universe made up of different spaces then it must also be true that we live in a universe made up of different times

Don't know what you mean by this, but it appears to not follow. Yes, there are different spaces: here is not the same location as there. Tuesday is a different time than Wednesday, but these are all true even in a model of separate space and time, so it doesn't follow from a spacetime model.

does every point in the universe exist at a different time?

Points in spacetime are called events, and events with spacelike separation can be simultaneous relative to some coordinate systems, and not simultaneous relative to others. There is no objective ordering of events with spacelike separation, but there is objective (not frame dependent) ordering of events with light-like or time-like separation.

[Seafire (OP)]

You seem to have misunderstood the question completely, the "space-time model" which you refer to is a mathematical mode which fuses the three dimensions of space and the one dimension of time into a single four-dimensional manifold. I wasn't asking about the mathematical model just the idea that space and time are two ways of looking at the same 1 thing.

If this is true and we live in a universe made up of different spaces then it must also be true that we live in a universe made up of different times

 
 

Don't know what you mean by this, but it appears to not follow

The question was not about a model so how could it folow?

[Seafire (OP)]

What I meant when I said I hope someone can answer my question properly was at least a Y or N, but further it seems that it needs to be explained that the idea produces the model not the other way around and YOUR IDEAs (the ones you're modelling) are what I am really interested in.

[Eternal Student]

Hi.

Are space and time just two sides of the same coin?

    The common answer is "yes" and Halc has already started to go over that idea.
    An alternative answer is "no".   In almost all situations space and time have different properties.   For example, in General Relativity the time dimension is identifiable because a unit vector in the time direction is going to be the only spacetime eigenvector that produces a negative eigenvalue for the metric g_μν.  A unit vector in any spatial direction will produce a positive eigenvalue.
    For example, you might have heard that at the event horizon horizon of a black hole the time and the spatial radial dimension swap their roles.   What does that mean?   It just means that the vector (1, 0, θ, φ ) in the Schawarzschild co-ordinates (t, r, θ, φ)  stops producing a negative eigenvalue and starts producing a positive eigenvalue.

     People tend to say  "yes" they are just much the same type of thing because that's the bit that needs more emphasis.   People already start with the idea that space and time are separate things and need persuasion that sometimes certain things can happen:   For example that some of the space co-ordinate can be rotated into the time co-ordinate and vice versa.   As already mentioned sometimes one thing can swap its character completely and become the other thing (Black holes at the event Horizon in Schwarzschild co-ordinates).   So the best answer, I think, is that space and time are similar and sometimes interchangeable, however there is a defining character for time which is different for space.  In the case of GR that is the eigenvalues.

   

If this is true and we live in a universe made up of different spaces then it must also be true that we live in a universe made up of different times, does every point in the universe exist at a different time?

    Well, maybe the idea of saying "no" space and time are not exactly the same will defeat the purpose of this follow-on question anyway.

Best Wishes.

[evan_au]

does every point in the universe exist at a different time?

There was an experiment conducted by the US standards laboratory (NIST). They built two extremely accurate clocks, and made sure they were keeping time with each other.

Then they raised one of them by 1 foot (30cm). This produced a measurable time drift between the two clocks. So you could say that points separated by 1 foot in altitude have a measurable difference in the rate that time progresses. You could say that they are in different "time zones" - the gravitational field of the Earth affects the passage of time, according to Einstein's General Theory of Relativity.

But it wouldn't be right to say that every point in the universe has a different time - after all, when the two clocks had the same altitude, they kept time with each other.

[JaffH_iii]

Space and time are separate dimensions of the same thing in the space-time concept.

[Seafire (OP)]

Thanks for your thoughtful answers guys, what I would highlight here is that an answer to this question can't be both Y and N it must be one or the other, or possibly neither.

What I sense is happening is the scientific evidence can produce both ideas Y and N  resulting in "the problem of time", the distinction between how QM and GR see time, absolute for QM and relative for GR.
wiki/Problem of time
 
If it seems unimaginable any two object can exists at a different time then you must reject GR, for in GR the speed of light or event horizon can stop your introduced flow of time idea for one object on Tuesday but then stop another object on Wednesday. These two objects are therefore frozen at two different points along the imaginary flowing timeline that you introduced and these two objects must therefore exist at different times by your own definitions.

How you and all of science seem to deal with this is to let the modelling create the idea and never ask why time is anything more than the moment an object exists in, you have introduced a timeline for objects to not only exist in but to flow along from an old Newtonian idea that is outdated has been rejected for decades. This is the result of letting the modelling produce the ideas.

Time and space for all practical purposes are just relationships between movement of objects, no movement-no time to measure. Space is the relationship between any two objects, no objects-no space to measure. Perhaps space and time don't exist at all and are just relationships between objects.

 

Are space and time just two sides of the same coin?

If you answer Y then considering space doesn't flow, space-time can't possibly flow either; leaving it up to the modelling and a preconceived idea of time to answer this deceptively simple question is getting us nowhere, I hope you understand this.

[Seafire (OP)]

Space and time are separate dimensions of the same thing in the space-time concept.

Space doesn't flow along a timeline so the concept of space-time shouldn't flow either. This concept is always modelled
as flowing along a timeline because the modelling is choosing the idea. This is not the order of things.

[Eternal Student]

Hi and welcome, I'm not sure I've seen you before.

resulting in "the problem of time", the distinction between how QM and GR see time, absolute for QM and relative for GR.
wiki/Problem of time

     That wikipedia article has the following warning on the top:

    !    This article needs attention from an expert in Physics. The specific problem is: his article has some interesting ideas in it, but some of it is wrong, and a lot of it reads like an attempt by someone without deep expertise to summarize half-understood stuff that they've read.....

If it seems unimaginable any two object can exists at a different time then you must reject GR,...

   I can imagine it.   A green door remains green until it is painted yellow then it's a yellow door.  The two objects existed at two different non-overlapping intervals of time.

...for in GR the speed of light or event horizon can stop your introduced flow of time idea for one object on Tuesday but then stop another object on Wednesday.....

    This is going to need some explanation.  Are you saying that time doesn't flow at the same rates for every object in every part of space?   That would be OK.   If you're trying to say something else then it wasn't clear to me.

Best Wishes.

[Halc]

If it seems unimaginable any two object can exists at a different time then you must reject GR

Nonsense. All enduring objects (anything lasting for more than an instant) exists at different times, else time/velocity/force etc. all would have no meaning. This is not unique to GR

for in GR the speed of light or event horizon can stop your introduced flow of time idea for one object on Tuesday but then stop another object on Wednesday.

Time isn't something that flows in GR. Time doesn't stop at an event horizon. An object falling into say a black hole has a very specific time (a reading on its clock, Tuesday say) when it crosses the event horizon. A second object is quite free to do the same on Wednesday. Neither object notices anything locally funny like physics working differently, clocks stopping, or anything like that.

These two objects are therefore frozen at two different points along the imaginary flowing timeline that you introduced

It seems you are the one trying to introduce said imaginary flowing something into a theory that doesn't posit it. The words 'flow' and 'timeline' do not appear in this topic until you introduce them.

You're using second-person language here, but are not replying to any specific post, so it is unclear who you think is introducing these things you appear to find contradictory. I mean, there are alternative theories which posit time as something that flows, which yes, does discard all of GR, but even these don't have time stopping anywhere. It marches on at some fixed (and totally unmeasurable) rate everywhere.

[Seafire (OP)]

 

Nonsense. All enduring objects (anything lasting for more than an instant) exists at different times, else time/velocity/force etc. all would have no meaning. This is not unique to GR

I think you can only see time as the procession of existence, not just a label assigned to a measurement of movement but  something much much more, a 4th dimension that carries the 3 spatial dimensions of the entire universe along a timeline( just a little bit being introduced here), this modelling is what you believe an you introduce it without question. You are filling out the lotto ticket after the draw and insisting it's right. Nonsense.

Your working backwards from your own conclusion about the nature of time and space to prove your idea is worthy of being introduced automatically, all I suggest is working forward without the preconceived ideas for a change and see what happens. The answers yes, no or they don't exist at all are what ifs; what if Y, what if N, what if X.

If Y, space and time are just two sides of the same coin,(without prior modelling), different spaces must also mean different times. Imagine a fifty cent piece where heads is time and tails is space, in a universe made of these coins space-time is everywhere just like in the real universe where clocks only ever measure the movement of objects.

Hi and welcome, I'm not sure I've seen you before.

Didn't know this site existed till a few days ago. Thankyou.

[Seafire (OP)]

(anything lasting for more than an instant) exists at different times, else time/velocity/force etc. all would have no meaning.

Do you have anything to declare sir before I check you bag for preconceived ideas, no, hmmmm, what's this then-
Instant by instant, flowing along a timeline
What do you mean it doesn't mean that?

It seems you are the one trying to introduce said imaginary flowing something into a theory that doesn't posit it.

Sir please leave your baggage here before proceeding to the question.

This is hilarious how invisible your own baggage is, when I point it out you try and say it's mine.
That baggage! What baggage? Right there

(anything lasting for more than an instant) exists at different times

Nup, not mine you must have planted it on me.

I think this is going nowhere. good luck.

[Eternal Student]

Hi.

   Firsty, I don't think anyone was or is challenging the idea that time is complicated and not well understood.  However, some of the phrases you ( @Seafire  ) have used and some of the descriptions were a bit inaccurate.  I think some of us were just trying to slow down development of any idea based on phrases like things getting frozen on a Tuesday when they fall into a Black Hole event horizon.
   

I think you can only see time as the procession of existence, not just a label assigned to a measurement of movement but  something much much more,

   That will be  "you"   as in   "human beings   .... can only see time as the procession of existence....".
Yes, that does seem to be the way we experience time.

Your working backwards from your own conclusion about the nature of time and space to prove your idea is worthy of being introduced automatically....

     I'm guessing that will be "you" as in  "Scientists.... work backwards from that conclusion to prove stuff about time....".
No, that's not usually done.   In many models there is no attempt to explain what time is, it's not required.   It is just something that can be observed and is used in the modelling.
    For example:   A population of bacteria might have a population growth modelled as   P = P₀.e^kt.  where t = time = that thing you can measure with a clock.    The scientist doesn't care what time is, you can measure it with a clock and the population model does seem to work.

If Y, space and time are just two sides of the same coin,(without prior modelling), different spaces must also mean different times.

   There are some bits of physics that imply some interesting relationships between space and time.  Special Relativity is usually where people encounter these results and ideas first.
    Something like what you have said does seem to hold.  They (Physicists) don't continue talking about coins but results appear that are saying this sort of thing.   For example, if length contraction happens then time dilation must also happen (and vice versa).


Overall:    Time is not well understood and there is quite a lot of research and many different ideas about what it is and why it behaves a certain way.
      Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars.   

[Taken from:  https://en.wikipedia.org/wiki/Time ]

   There are many PopSci articles, YT videos and such like that discuss time.  There are also a good number of more scholarly articles such as papers published in journals.   There are most definitely some Physicists that don't take time for granted or assume that it is well understood.

Best Wishes.

[Seafire (OP)]

Had some family issues so please forgive the length of time since my last post.

Generally time is defined as what a clock reads; vague and speculative as this may be  it means time is a real dimension that flows from past, through present to future carrying the three spatial dimensions along with it. The observable evidence is that a clock, using the construct of time, measures the movement between two objects, we create the idea in our heads that there is a dimension of time without a shred of evidence which to me is the opposite of what science does.



I would like to explore with you nothing more than the available evidence, that being the three observable dimensions of space and the three dimensional objects that move in it. Time therefore is just another way of expressing the three spatial dimensions. eg. I am 3 miles from home or I am 3 minute from home.

There is only evidence for three dimensions, the fourth time dimension is a huge speculation, so if space and time are two sides of the same coin we would only have three dimensions of space time, nothing more.

Firsty, I don't think anyone was or is challenging the idea that time is complicated and not well understood.

I am being challenged generally to accept the highly speculative idea that a clock is measuring an ACTUAL flow of time when the observable evidence only ever shows a clock measuring motion. I find it bizarre that this evidence is being trumped by pure speculation, perhaps once something is learned is is just too hard to unlearn.

[Colin2B]

I would like to explore with you nothing more than the available evidence, that being the three observable dimensions of space and the three dimensional objects that move in it. Time therefore is just another way of expressing the three spatial dimensions. eg. I am 3 miles from home or I am 3 minute from home.

Ignoring relativity for the moment, 3 miles is a fixed dimension - assuming say shortest distance, but 3 minutes is a variable depending on your speed. How does your model handle that?

[Seafire (OP)]

Ignoring relativity for the moment, 3 miles is a fixed dimension - assuming say shortest distance, but 3 minutes is a variable depending on your speed. How does your model handle that?

Wow you are right, i mixed an actual dimension- the spatial one, with an imaginary one that is just a measurement of movement, it's liberating to admit mistakes, you should try it.

 The only thing that can be observed or tested is that an object continues to exist in the present no matter what you do to it, if I were to define time according to this evidence then the only function of time is to give each individual spatial existence a temporal existence as well, there is no evidence that a forth time dimension exists, only that 3D objects are both spatial and temporal. Two sides of the same coin.

Lets not ignore relativity, when an object moves do you assume that there is a flowing time dimension carrying the universe along or do you stick to what can be observed- movement only.

Time dilation or slowed movement, what's the difference? Nothing, there is no difference except time dilation requires a flow of time which is the greatest speculation in the history of science.

[Colin2B]

[it's liberating to admit mistakes, you should try it.

I often do. Why do you assume I don’t?

[Seafire (OP)]

Maybe you just avoid this mistake.  .

Perhaps you're still convinced that movement needs a time dimension to facilitate it but are unwilling to stand up for your conviction. 

The idea that there is a past, present and future is speculation when all we know is the present. I remember where objects were before they moved (past), and I can predict where objects will be after they move (future) but memory and prediction of movement is far from being evidence of a time dimension. This is a mistake and one that is rearly admitted.

[Origin]

I remember where objects were before they moved (past), and I can predict where objects will be after they move (future) but memory and prediction of movement is far from being evidence of a time dimension.

That's kind of ironic, since that statement seems to be strong evidence that time is a dimension.