Perfect Frame of Reference ?

[NuTTyKid]

Hello guys

I had a question in mind and i wanted a pretty neat answer for it so thought i'd put it over to you guys

 

Okay , i wanted to know what would be the perfect frame of reference that could be used as the origin for motion . Some say time IS the best frame of reference.

 

But recently i read an article and ever since had this question in mind. Is time really the PERFECT Frame of reference for describing motion ? Or does even time lag behind in some aspect ?

 

Fill in the details as much as possible Thanks xD

[swansont]

Time isn't a frame of reference. The best frame of reference in physics is the one that lets you solve the problem most easily. But there is no (inertial) frame where the physics is different and would lead you to a different answer — no absolute rest frame or preferred frame. So there is no perfect frame, as such.

[Fred Champion]

Prove to yourself that there is only one actual (and thus perfect) frame of reference by considering this question:

 

You are moving along in what you call your frame of reference, your spaceship. You have your spacesuit on so that you can breathe and still have the windows in the spaceship down. (You do like to ride with your arm in the window, right?) Light is produced from a source somewhere outside your craft. You may observe the light enter your craft through one window and exit through another.

 

Does the light change its behavior in any way as it passes through your frame of reference?

[John Cuthber]

Yes. it bend slightly towards me due to gravitational lensing. But that's not the point.

But imagine that the same ray of light travels a zillion miles and then goes through someone else's spaceship.

Whatever is true of your ship is also true of his so his "best" frame of reference is just as good as yours.

Edited May 3, 2014 by John Cuthber

[swansont]

Prove to yourself that there is only one actual (and thus perfect) frame of reference by considering this question:

 

You are moving along in what you call your frame of reference, your spaceship. You have your spacesuit on so that you can breathe and still have the windows in the spaceship down. (You do like to ride with your arm in the window, right?) Light is produced from a source somewhere outside your craft. You may observe the light enter your craft through one window and exit through another.

 

Does the light change its behavior in any way as it passes through your frame of reference?

 

That's awkwardly worded. You can't observe the light in any other frame but your own, so how could you notice a change "as it passes through your frame of reference"?

[ajb]

Some say time IS the best frame of reference.

This reminds me of the idea of conformal time or cosmic time in cosmology. Both can be useful ideas of a global time in an expanding Universe, but this should not be confused with the notion of a preferred frame of reference. There maybe frames that are suited to the particular physics at hand, but this does not mean that the theory really singles them out, we do that.

[Fred Champion]

NuTTyKid "wanted to know what would be the perfect frame of reference that could be used as the origin for motion ."

 

My post was meant to encourage him to convince himself that there is only one actual frame of reference. Any other frame of reference must be imaginary (a geometric construct).

 

John Cuthber rightly makes the point that "Whatever is true of your ship is also true of his so his "best" frame of reference is just as good as yours." This is true, but more than just "as good as"; his actual frame of reference is the same as yours.

 

Swansot's point is absolutely right also and should help NuTTyKid lead to the realization that unless unless observation is obscured in some way, it is universal. What one sees, all see, albeit potentially distorted.

 

To me, the utility of isolating observation into a frame of reference other than the one universal frame of reference is in resolving (explaining) the distortion.

[swansont]

NuTTyKid "wanted to know what would be the perfect frame of reference that could be used as the origin for motion ."

 

My post was meant to encourage him to convince himself that there is only one actual frame of reference. Any other frame of reference must be imaginary (a geometric construct).

 

 

This is a physics discussion. There are an infinite number of inertial reference frames.

[Fred Champion]

 

This is a physics discussion. There are an infinite number of inertial reference frames.

No, there "are" not. They do not exist. They cannot be discovered because they are not here, there or anywhere. They must be constructed in the mind which means that they are imaginary. Geometric and mathematical constructs are imaginary, not physical, constructs. What is true is that it seems possibe to construct an almost unlimited "number of inertial reference frames" within the common geometry and mathematics.

 

And I believe you are correct that this is supposed to be a physics - not a geometry or math - discussion. Peace.

[ajb]

No, there "are" not. They do not exist. They cannot be discovered because they are not here, there or anywhere. They must be constructed in the mind which means that they are imaginary.

Okay, so all coordinate systems used in physics are somewhat imaginary. Your earlier assertion that there is only one true inertial frame must also be somewhat imaginary, so I don't see a clear distinction here.

 

Anyway, a simple example. Suppose a physicist sets up some experiment on a train. He waits until the train is moving a constant velocity relative to the tracks before he takes any measurements. To take his measurements he sets up an inertial frame of reference by placing a coordinate system, say three rulers at right angles to each other on the desk on which the experiment is being conducted and a watch which he also places on the desk. He defines t=0 whenever it is convenient to do so. He then measures and times his experiment with respect to this inertial coordinate system.

 

But what if he decided instead to set up his coordinate system by setting up a frame of three rules at some point on the track and a clock placed here also? This is also a valid inertial frame of reference. So which one is "the one" or is it none of these?

 

Remark: In the above we assume that the experiment is not a gravitational experiment and that all effects of gravity are small so we are okay setting up inertial coordinates on the scales of the experiment being conducted.

[swansont]

No, there "are" not. They do not exist. They cannot be discovered because they are not here, there or anywhere. They must be constructed in the mind which means that they are imaginary. Geometric and mathematical constructs are imaginary, not physical, constructs. What is true is that it seems possibe to construct an almost unlimited "number of inertial reference frames" within the common geometry and mathematics.

 

There are an infinite number of reference frames from which you can solve a problem using the same physics. That's what physics says. I never said they were physical constructs; that's a non-sequitur. To claim that there is only one frame is incredibly wrong from a physics standpoint.

[Fred Champion]

Okay, so all coordinate systems used in physics are somewhat imaginary. Your earlier assertion that there is only one true inertial frame must also be somewhat imaginary, so I don't see a clear distinction here.

 

Anyway, a simple example. Suppose a physicist sets up some experiment on a train. He waits until the train is moving a constant velocity relative to the tracks before he takes any measurements. To take his measurements he sets up an inertial frame of reference by placing a coordinate system, say three rulers at right angles to each other on the desk on which the experiment is being conducted and a watch which he also places on the desk. He defines t=0 whenever it is convenient to do so. He then measures and times his experiment with respect to this inertial coordinate system.

 

But what if he decided instead to set up his coordinate system by setting up a frame of three rules at some point on the track and a clock placed here also? This is also a valid inertial frame of reference. So which one is "the one" or is it none of these?

 

Remark: In the above we assume that the experiment is not a gravitational experiment and that all effects of gravity are small so we are okay setting up inertial coordinates on the scales of the experiment being conducted.

I suggest that the one and only "true" or actual frame of reference is the space that contains the universe. Every other frame of reference is a limited part of that one. The meaning of that is that every frame of reference we construct is directly connected to every other frame of reference we construct and any given frame of reference does nothing to isolate, physically, any object in or out of that frame of reference to any other object.

 

Any frame of reference you may construct may be "valid" for the experiment you prepare. The important thing is to present the results clearly as being from that frame of reference and not necessarily as universal. I expect this will seem obvious once you consider it, but I have seen some that just don't seem to get it.

[ajb]

I suggest that the one and only "true" or actual frame of reference is the space that contains the universe.

I have no idea what this means? You want to set up some global coordinate system for the Universe? The best I can think of then would be something like coordinates co-moving with respect to the CMBR or the expansion of the Universe, which is fine for discussing cosmology, but not great for physics on smaller scales. Also, this may provide a useful frame for cosmology, but other are just as valid.

 

 

Any frame of reference you may construct may be "valid" for the experiment you prepare. The important thing is to present the results clearly as being from that frame of reference and not necessarily as universal.

Right, unless you do get results that are frame independent. For example the speed of light is constant in any inertial frame.

[studiot]

 

I suggest that the one and only "true" or actual frame of reference is the space that contains the universe.

 

I suggest it would be a good idea if you were to explain what exactly you mean by a frame of reference.

 

I don't think you are using the conventional definition.

Edited May 5, 2014 by studiot

[Fred Champion]

I have no idea what this means? You want to set up some global coordinate system for the Universe? The best I can think of then would be something like coordinates co-moving with respect to the CMBR or the expansion of the Universe, which is fine for discussing cosmology, but not great for physics on smaller scales. Also, this may provide a useful frame for cosmology, but other are just as valid.

 

 

 

Right, unless you do get results that are frame independent. For example the speed of light is constant in any inertial frame.

Do we not already have a de facto global coordinate system for the universe? We may not have a zero point of origin (I mean the point where the singularity was just before or just after BB got started) to use as a zero, but the cosmo boys tell us any point is just as good as any other for a zero and any orientation of "horizontal", "up" and "forward" is as good as any other. Pick one and it works.

 

All results can be seen as frame independent ultimately. For any frame, there will be a translation to any other frame.

 

I suggest it would be a good idea if your were to explain what exactly you mean by a frame of reference.

 

I don't think you are using the conventional definition.

I can accept the explanations found in Wiki. I believe they are commonly accepted. I even accept the references to time as long as one recognizes that time is imaginary, just as the frame of reference is imaginary. I am a bit disappointed that Wiki doesn't explain that frames of reference are geometric or mathematical constructs. I hope the people at Wiki expected that to be generally understood.

[ajb]

Do we not already have a de facto global coordinate system for the universe?

Well there is a natural choice of comoving coordinates. They correspond to observers moving along the Hubble flow. I am not sure if they are truly global coordinates.

 

All results can be seen as frame independent ultimately. For any frame, there will be a translation to any other frame.

Right and this is why we use tensors in physics.

 

I am a bit disappointed that Wiki doesn't explain that frames of reference are geometric or mathematical constructs. I hope the people at Wiki expected that to be generally understood.

But then just about all concepts in physics are really mathematical concepts, they just happen to be useful in describing our world.

[studiot]

 

I can accept the explanations found in Wiki. I believe they are commonly accepted. I even accept the references to time as long as one recognizes that time is imaginary, just as the frame of reference is imaginary. I am a bit disappointed that Wiki doesn't explain that frames of reference are geometric or mathematical constructs. I hope the people at Wiki expected that to be generally understood.

 

 

This is not a satisfactory reference in that it is not specific.

 

Nor have you actually answered my question

 

What do you mean by a frame of reference?

 

It is your answer I am interested in, although of course it adds weight to your definition if it is backed up by authoritative reference(s).

[Phi for All]

I suggest that the one and only "true" or actual frame of reference is the space that contains the universe. Every other frame of reference is a limited part of that one. The meaning of that is that every frame of reference we construct is directly connected to every other frame of reference we construct and any given frame of reference does nothing to isolate, physically, any object in or out of that frame of reference to any other object.

 

Any frame of reference you may construct may be "valid" for the experiment you prepare. The important thing is to present the results clearly as being from that frame of reference and not necessarily as universal. I expect this will seem obvious once you consider it, but I have seen some that just don't seem to get it.

 

!

Moderator Note

Fred Champion, you're introducing a speculative concept into a mainstream physics discussion that threatens to hijack the original intent of the OP. Please open your own thread, in the Speculations section, if you wish to discuss your idea further.

 

Also please make sure to read the special rules governing that section.

[Fred Champion]

 

This is not a satisfactory reference in that it is not specific.

 

Nor have you actually answered my question

 

What do you mean by a frame of reference?

 

It is your answer I am interested in, although of course it adds weight to your definition if it is backed up by authoritative reference(s).

I think an acceptable and all-inclusive definition of a frame of reference is: a specified volume within which properties of objects may be observed.

 

I ask readers to note that there is no speculation in stating: 1) the space which contains the universe is our one actual frame of reference. 2) all other reference frames other than the one universal frame of reference are imaginary (geometric or mathematical constructs) 3) all imaginary reference frames are constructed as a limited part of the one universal frame of reference. 4) the action of constructing an imaginary reference frame establishes a direct translation to the one universal frame of reference and to all other imaginary frames of reference.

 

The method or methods used to conduct, record and describe observations in any frame of reference may be established by the observer.

[swansont]

I think an acceptable and all-inclusive definition of a frame of reference is: a specified volume within which properties of objects may be observed.

That's not how physics defines a frame of reference. In physics it's a choice of a coordinate system. Inertial frames of reference are coordinate systems that are not accelerating with respect to each other.

 

 

I ask readers to note that there is no speculation in stating: 1) the space which contains the universe is our one actual frame of reference.

No, that's not the case according to mainstream physics. All that follows in your post is similarly flawed, being based on this false premise.

[studiot]

 

space

 

Aye Captain Kirk, but The Enterprise still needs a heading to get to the Final Frontier.

 

 

a specified volume within which properties of objects may be observed

 

And how, pray, do you specify the volume?

 

This sounds more like the volume a free body diagram or a thermodynamic system than a frame of reference.

 

This is just one more instance where you are stating as fact non mainstream definitions or interpretations for the benefit (?) of those who are trying to learn mainstream physics. That is confusing for them.

 

I have already noted that some of your ideas have merit and would be very happy to discuss them with you in the proper place.

Science Forums is benevolent in that it dos not demand only mainstream comments but allows genuine debate on opinions.

But it must be clear they are personal opinions and it is best if you can back them up with a chain of reasoning/logic and/or references.

Edited May 6, 2014 by studiot

[Fred Champion]

That's not how physics defines a frame of reference. In physics it's a choice of a coordinate system. Inertial frames of reference are coordinate systems that are not accelerating with respect to each other.

 

 

 

No, that's not the case according to mainstream physics. All that follows in your post is similarly flawed, being based on this false premise.

The volume we choose for consideration is the frame of reference; the choice of a coordinate system is part of the methodology to be applied within that frame as is the decision of whether to include acceleration. For any portion of our universal frame of reference, we may construct any number of imaginary reference frames (such as inertial frames). It all dependes on how we choose to define them. We do not have the ability to re-define the universal frame of reference; it is what it is.

 

Are you saying that mainstream physics includes a notion that the universe is not all that there is, or that we are able to observe something that is not part of the universe or that we can observe outside the universe?

 

I suspect at least part of the problem here is that you accept that a frame of reference is the volume and the methodology combined whereas I consider them to be separate. I just have difficulty thinking of a room and what goes on in it as other than different things. I will conceed this: I accept that a specified frame of reference is the combination of a specified volume and a specified methodology. Will that satisy?

[swansont]

 

Are you saying that mainstream physics includes a notion that the universe is not all that there is, or that we are able to observe something that is not part of the universe or that we can observe outside the universe?

 

 

No, I'm just saying that this is not how we define a reference frame in physics and in this thread we're discussing physics. I'm trying to avoid discussing not-physics, since that's would not be what the thread is about. As Phi has pointed out, you are free to discuss alternatives in speculations.

[Fred Champion]

 

No, I'm just saying that this is not how we define a reference frame in physics and in this thread we're discussing physics. I'm trying to avoid discussing not-physics, since that's would not be what the thread is about. As Phi has pointed out, you are free to discuss alternatives in speculations.

Well, you have objected to the way I think of a frame of reference and obviously I think the way I think of what that term means is totally consistent with current thought in physics. I think the definition in Wiki is weak, but I can live with it understanding the source and the target audience. I do not have a physics book before me and even if I did I would be reluctant to say that any given textbook would provide an official definition.

 

You asked me for a definition and I gave you one. If you know of an official definition of frame of reference please share it with us and cite the source. Unless you can and will do that, you will have presented nothing other than objections. Please, tell us (me especially) how, in your words, "we define a reference frame".

 

I am most interested in learning how you think the definition I provided and the way I think about the term should be considered such an unacceptable "alternative" that I should be shuffled off the thread into the speculation section.

[swansont]

Well, you have objected to the way I think of a frame of reference and obviously I think the way I think of what that term means is totally consistent with current thought in physics. I think the definition in Wiki is weak, but I can live with it understanding the source and the target audience. I do not have a physics book before me and even if I did I would be reluctant to say that any given textbook would provide an official definition.

 

You asked me for a definition and I gave you one. If you know of an official definition of frame of reference please share it with us and cite the source. Unless you can and will do that, you will have presented nothing other than objections. Please, tell us (me especially) how, in your words, "we define a reference frame".

 

The explanation I gave previously, which jibes with the wikipedia description. It's a coordinate system. Nothing to do with volume. Furthermore, there are inertial frames and in accordance with relativity, there are no preferred frames. Any insistence for a universal reference frame is not within mainstream physics.

 

BTW, I'm not a fan of quoting out of context. My words were "this is not how we define a reference frame in physics"; this is about your definition, not mine. And, as you've been instructed, you are free to discuss that further in a speculations thread.