Clocks and rulers

[swansont]

Yes Relativity has been shown to be correct to a fairly precise level. There is no discussion about that.

 

But No, this is not what Relativity says.

Relativity says that what is observed in a frame can be translated in what is observed in another frame. That is all.

What more than that you believe it says, for example that what one observer IS "truly" happening, is not part of the equations of Relativity.

Relativity also says that the laws of ohysics apply in any frame, so there is no physics you can do to conclude that any one frame is the "correct" one. That's from the first postulate. So if two observers measure different things, neither one can claim their view is the "truth".

[michel123456]

And yet you are insisting that one specific measurement really represents reality over all others.

I say there is a better one.

For example you want to measure length, proper length is better than anything else.

 

Reality is much much^much more than the sum of all measurements.

[StringJunky]

Reality is much much^much more than the sum of all measurements.

Indeed, but that's the best scientists have to play with; measurements.

[swansont]

Thank you for your reply, that is pretty much what I thought you would say.

 

Now suppose the observer with the watch and standard rule slept whilst the changes occurred.

 

When he awoke he would have an unsynchronised watch and clock and a displaced ruler that still matched his standard.

 

How would he be able to tell whether the effect was due to relativity or heating and cooling?

 

With a thermometer.

 

Flawed or uncalibrated instruments mimicking a real effect is not particularly remarkable.

[michel123456]

Relativity also says that the laws of ohysics apply in any frame, so there is no physics you can do to conclude that any one frame is the "correct" one. That's from the first postulate. So if two observers measure different things, neither one can claim their view is the "truth".

So if an ET proclames that Swansont is flat like a piece of paper because his physics say so, it's ok to you?

Especially when you go to bed and suddenly the ET measures that you changed format and you are now short like a coin.

You yourself Swansont don't know better?

[swansont]

So if an ET proclames that Swansont is flat like a piece of paper because his physics say so, it's ok to you?

Especially when you go to bed and suddenly the ET measures that you changed format and you are now short like a coin.

You yourself Swansont don't know better?

Doesn't matter to me. That's what the measurements are, and that would be what should be used for any physics calculations.

 

One problem with the approach of "put everything into the rest frame" is that you have transform the data, but you would also need to transform the equations. These transforms would cancel each other, so what would be the point? Other than to address your personal issues and preferences.

[ajb]

So if an ET proclames that Swansont is flat like a piece of paper because his physics say so, it's ok to you?

Especially when you go to bed and suddenly the ET measures that you changed format and you are now short like a coin.

You yourself Swansont don't know better?

What are you asking? If length contraction is real?

 

Well, you need to carefully think about 'real'. If 'real' is what one measures and the aliens wizzing past measure Swansont's height to be x meters, then that is 'real' to them. Of course, Swanson does not change his height as he measures it.

[studiot]

Without significant relativistic effects. and adequately precise measurements of them, you cannot tell.

 

As always you hold good conversation and make excellent points.

 

Thank you.

 

Yes indeed you could consider the clock defective whilst it is running slow.

But my point is simply that put by Russell a century or so ago.

 

We have already met processes that can produce the results listed in the OP and many others in ordinary everyday experience.

So we should not be so surprised when Physics uncovers another.

Russell further establishes the point that many of the apparently strange results of einstinian relativity could (and should) have been anticipated pre M&M.

Indeed Newton knew some.

The greatness of Einstein was in drawing all this together in so simple and compact a way.

[Delta1212]

I say there is a better one.

For example you want to measure length, proper length is better than anything else.

 

Reality is much much^much more than the sum of all measurements.

Better in what way?

[michel123456]

Better in what way?

Simplicity.

It consists in making the statement that reality is a single thing that is observed differently by many observers.

It is already the case even without Relativity.

And suddenly Relativity is grounded. Relativity is simple. Relativity is comprehensible.

 

I really don't understand the need of the concept of multiple overlapping realities. It makes people think that the observer dictates what reality is (and it is wrong, the observer is passive, not active).

It makes people think that weird things do happen when in fact it is only an effect caused by observation.

It makes also people think that they can use this effect in order to get a blue cow or a shrinked ruler, as if the ruler had kept inside it a piece of contracted space. As if the internal structure of the ruler had become different from that of a regular ruler. And even worse, the contraction of the ruler depends on the direction of movement as seen by the observer....so guess how will the ruler be contracted.

I expected more critical thinking from the physicists.

[StringJunky]

Simplicity.

It consists in making the statement that reality is a single thing that is observed differently by many observers.

It is already the case even without Relativity.

And suddenly Relativity is grounded. Relativity is simple. Relativity is comprehensible.

 

I really don't understand the need of the concept of multiple overlapping realities. It makes people think that the observer dictates what reality is (and it is wrong, the observer is passive, not active).

It makes people think that weird things do happen when in fact it is only an effect caused by observation.

It makes also people think that they can use this effect in order to get a blue cow or a shrinked ruler, as if the ruler had kept inside it a piece of contracted space. As if the internal structure of the ruler had become different from that of a regular ruler. And even worse, the contraction of the ruler depends on the direction of movement as seen by the observer....so guess how will the ruler be contracted.

I expected more critical thinking from the physicists.

You are arguing against the culmination of a century's worth of research by God-knows-how-many brilliant minds. Just because you don't understand it doesn't mean it's wrong and nature couldn't care less either.

[swansont]

Simplicity.

It consists in making the statement that reality is a single thing that is observed differently by many observers.

It is already the case even without Relativity.

And suddenly Relativity is grounded. Relativity is simple. Relativity is comprehensible.

Science has no obligation to be understandable to you. Plenty of people already think basic relativity is comprehensible.

 

 

I really don't understand the need of the concept of multiple overlapping realities. It makes people think that the observer dictates what reality is (and it is wrong, the observer is passive, not active).

It makes people think that weird things do happen when in fact it is only an effect caused by observation.

It makes also people think that they can use this effect in order to get a blue cow or a shrinked ruler, as if the ruler had kept inside it a piece of contracted space. As if the internal structure of the ruler had become different from that of a regular ruler. And even worse, the contraction of the ruler depends on the direction of movement as seen by the observer....so guess how will the ruler be contracted.

It may make you think these things. Don't speak for others.

 

I expected more critical thinking from the physicists.

We've done pretty well with relativity as it stands. You've presented no compelling reason to alter it.

[Strange]

Simplicity.

It consists in making the statement that reality is a single thing that is observed differently by many observers.

 

 

That single thing is not what you claim it is though - i.e. not one of the arbitrary "distorted" views.

 

The "single reality" is the description that is invariant for all observers (as you have been told multiple times).

 

I really don't understand the need of the concept of multiple overlapping realities.

 

 

There is no such thing. If you stopped making up nonsense, and listened to the explanations you are being given, then you might be able to make sense of it.

[swansont]

 

I really don't understand the need of the concept of multiple overlapping realities.

 

You're the only one bringing up the subject of reality here.

[Markus Hanke]

As if the internal structure of the ruler had become different from that of a regular ruler

 

 

Except of course that this is not what relativity says or implies.

[J.C.MacSwell]

I say there is a better one.

For example you want to measure length, proper length is better than anything else.

 

Reality is much much^much more than the sum of all measurements.

What frame would you choose to evaluate and compare all these proper lengths of multiple objects, and predict the effects they would have on each other, if they all have different rest frames?

Edited August 2, 2016 by J.C.MacSwell

[swansont]

What frame would you choose to evaluate and compare all these proper lengths of multiple objects, and predict the effects they would have on each other, if they all have different rest frames?

 

 

Excellent point. If one is analyzing a collision between objects, one can't use the rest frame properties of both* — you will get the wrong answer. You have to use the properties you measure in whatever frame you are using. Worse still, "use the rest frame" keeps us from using the center-of-momentum frame, which is often quite useful.

 

It's not an approach that is based in any reasonable physics.

 

*unless one uses them and transforms them into the other frame, which gives you the same result and is more work. i.e. it's not simpler.

[michel123456]

 

 

Except of course that this is not what relativity says or implies.

Ah. So the ruler won't change after return.

 

 

That single thing is not what you claim it is though - i.e. not one of the arbitrary "distorted" views.

 

The "single reality" is the description that is invariant for all observers (as you have been told multiple times).

 

 

There is no such thing. If you stopped making up nonsense, and listened to the explanations you are being given, then you might be able to make sense of it.

But you believe that length contraction really happens. Don't you?

[ajb]

Ah. So the ruler won't change after return.

As far as the ruler is concerned it never changed - it was always 30cm tall as it measures itself.

[michel123456]

As far as the ruler is concerned it never changed - it was always 30cm tall as it measures itself.

Thank you.

 

Now, is there another reality than the ruler?

I mean, isn't the ruler already a 4D object, that is to say a ruler existing in space-time? Or is it a mystical "projection" of an unimaginable 4D object?

[ajb]

Now, is there another reality than the ruler?

What do you mean by reality?

 

For sure, in general other (inertial say) observers will measure the ruler to be a different length - and this depends on the relative velocity.

 

I mean, isn't the ruler already a 4D object, that is to say a ruler existing in space-time?

Yes, the ruler 'tracks out' a 4 dimensional world sheet - it has a 3d volume and exists for some time.

 

Or is it a mystical "projection" of an unimaginable 4D object?

I don't follow - maybe you are taking some earlier analogies too far.

[michel123456]

What do you mean by reality?

 

For sure, in general other (inertial say) observers will measure the ruler to be a different length - and this depends on the relative velocity.

 

 

Yes, the ruler 'tracks out' a 4 dimensional world sheet - it has a 3d volume and exists for some time.

 

 

I don't follow - maybe you are taking some earlier analogies too far.

Thank you for the straightforward reply.

OK.

Is there an upper bound for this length?

I mean, we know observers may measure the ruler contracted, but are there observers that will measure the object longer than it is measured in its rest frame?

[ajb]

Thank you for the straightforward reply.

OK.

Is there an upper bound for this length?

I mean, we know observers may measure the ruler contracted, but are there observers that will measure the object longer than it is measured in its rest frame?

The ruler will be measured as being shorter - hence the term length contraction.

[michel123456]

The ruler will be measured as being shorter - hence the term length contraction.

So there exist a frame that measures the upper value. The upper bound.

[ajb]

So there exist a frame that measures the upper value. The upper bound.

Yes, this is the proper length - which is the length as measured in the rest or comoving frame, i.e., the frame in which the ruler is stationary.

Edited August 2, 2016 by ajb