seeing events in reverse order???

[swansont]

Call that stubborness, but I disagree.

Your statement implies that there is no "one Reality" with a big R, but as many realities as there are observers.

To me, this is insane.

Observers do not change reality.

 

Nobody is changing reality.

 

This is science: if you disagree, show an experiment that justifies the disagreement.

[michel123456]

all observers are describing the same reality.

The only thing that changes are the labels we put on things.

Labels like 10:45 pm or 100 meters

That's the question.

Swansont doesn't seem to say that.

 

And that is not so simple. If it was simply a question of a scale factor, why not. But Relativity states that objects deform diferently along the direction of movement. The objects are deformed. And they are deformed not because some force is acting upon them.

No.

They are deformed because somewhere somebody is observing.

 

Nobody is changing reality.

 

This is science: if you disagree, show an experiment that justifies the disagreement.

I am on planet Earth and I observe my planet round (roughly)

You are on planet X and you observe planet Earth elongated.

 

If we are both right, then there are 2 realities. There is a round Earth and there is an elongated Earth.

 

This is not science, this is bad interpretation.

What is your problem to interpret Relativity as a deformation caused by observation?

Why does it have to be more profound?

Why does it have to describe what is really happening?

Edited April 1, 2014 by michel123456

[granpa]

remember that the lenghth of an object is the distance from the head to the tail at one simultaneous moment

 

if two observers disagree about what events are simultaneous then they will disagree about the length of objects

Edited April 1, 2014 by granpa

[md65536]

Swansont doesn't seem to say that.

[...]

They are deformed because somewhere somebody is observing.

swansont also never said what you claimed, that length actually being relative implies there are "many realities".

 

They are deformed (length contracted) because they're moving at a relative velocity. Of course, to move relative to something only makes sense if there IS that something, and that something can be called an observer, but the presence of the observer doesn't *cause* the length contraction.

 

You're standing near 2 trees. Relative to your position, one is nearer. Moving so the other is nearer doesn't cause an effect on the trees. But one *really* is nearer. According to another observer, a different tree may be the nearer one, but that doesn't require multiple realities. Nearness is a relative property. So is length.

 

I feel like this exact conversation has happened before with the exact same participants. Would you say that you reject relativity, or you don't understand it? (Or other, to prevent a false dichotomy, "it's presented wrong here" or something?)

Edited April 1, 2014 by md65536

[swansont]

And that is not so simple. If it was simply a question of a scale factor, why not. But Relativity states that objects deform diferently along the direction of movement. The objects are deformed. And they are deformed not because some force is acting upon them.

The inference that a force should be present is one reason why deform is not a good description; it implies there is some inherent length to an object. Relativity says that in a moving frame, an object is shorter in the direction of motion than for an observer who is stationary — that length is relative. Time runs at a slower rate, not something happens to the clock.

 

 

 

This is not science, this is bad interpretation.

 

Then come up with a better one, that's consistent with observation. Relativity works, and says nothing about a physical deformation, just that length is a relative measurement.

[michel123456]

Is there a FOR for which the observed lenght of an object is less than the lenght measured in the FOR of the object?

[Schneibster]

Let's start with the basics.

 

You can see that if you're over here, closer to where event A is going to happen, you'll see event A before event B which is over there somewhere, but if you are instead over there, by where event B is going to happen, you'll see event B first. Right? This seems extremely simple, but it is a lemma of relativity. Part of why Einstein was such a genius is because he never forgot that the simplest stuff is where it's easiest to make a big mistake you won't find out about until a lot later.

 

Now, that means you can define one "frame of reference" where zero/the origin is over here by where A is going to happen, and another frame over there by B. And that's because the speed of light is finite.

 

This is the simplest demonstration of the principle. You may be thinking of others, and should ask all about them to refine your understanding. That's the right thing to do on a forum like this.

Is there a FOR for which the observed lenght of an object is less than the lenght measured in the FOR of the object?

 

Yes; if you observe identical objects, moving at different speeds (note: not velocities! I mean the scalar!) relative to you, then the one with the higher speed will appear shorter along the direction of travel.

 

There is an exact mathematical relation that describes this; it's called the "Lorentz Transform" and was discovered a hundred and fifty years ago or so.

 

Above you expressed incredulity at this.

 

Perhaps you will find it easier to think that a moving object appears shorter to you for the same reason a stick appears shorter when you're looking along its major axis than when you see it from the side. In one view, the stick looks like a spot; you can't see the length. In the other, it's obvious that length is its major attribute. In no case, however, does the stick change, in its own frame. In exactly the same way, the speeding stick will appear shorter, because it's rotated some of its length into time. And this appearance is no more an illusion, than the change of the angular width of the stick is an illusion when you turn it.

 

What swansont and I are telling you is that, in fact, this is the real actual state of affairs. If the stick is flying past you at a large fraction of the speed of light, and you measure it using a super-fast theodolite (this is an automatic-tracking telescope that is used for, for example, tracking rockets in flight), you will measure it as considerably shorter than if the stick is then slowed down and brought back to you to measure at zero speed. Light is all you have to use to measure it, you see, and light's speed isn't infinite. And that's why things must be that way.

 

To me, the most amazing thing about relativity is that once you finally "get it" you feel like Captain Obvious, Master of the Foregone Conclusion.

Edited April 4, 2014 by Schneibster

[michel123456]

Let's start with the basics.

 

You can see that if you're over here, closer to where event A is going to happen, you'll see event A before event B which is over there somewhere, but if you are instead over there, by where event B is going to happen, you'll see event B first. Right? This seems extremely simple, but it is a lemma of relativity. Part of why Einstein was such a genius is because he never forgot that the simplest stuff is where it's easiest to make a big mistake you won't find out about until a lot later.

 

Now, that means you can define one "frame of reference" where zero/the origin is over here by where A is going to happen, and another frame over there by B. And that's because the speed of light is finite.

 

This is the simplest demonstration of the principle. You may be thinking of others, and should ask all about them to refine your understanding. That's the right thing to do on a forum like this.

 

Yes; if you observe identical objects, moving at different speeds (note: not velocities! I mean the scalar!) relative to you, then the one with the higher speed will appear shorter along the direction of travel.

 

There is an exact mathematical relation that describes this; it's called the "Lorentz Transform" and was discovered a hundred and fifty years ago or so.

 

Above you expressed incredulity at this.

 

Perhaps you will find it easier to think that a moving object appears shorter to you for the same reason a stick appears shorter when you're looking along its major axis than when you see it from the side. In one view, the stick looks like a spot; you can't see the length. In the other, it's obvious that length is its major attribute. In no case, however, does the stick change, in its own frame. In exactly the same way, the speeding stick will appear shorter, because it's rotated some of its length into time. And this appearance is no more an illusion, than the change of the angular width of the stick is an illusion when you turn it.

 

What swansont and I are telling you is that, in fact, this is the real actual state of affairs. If the stick is flying past you at a large fraction of the speed of light, and you measure it using a super-fast theodolite (this is an automatic-tracking telescope that is used for, for example, tracking rockets in flight), you will measure it as considerably shorter than if the stick is then slowed down and brought back to you to measure at zero speed. Light is all you have to use to measure it, you see, and light's speed isn't infinite. And that's why things must be that way.

 

To me, the most amazing thing about relativity is that once you finally "get it" you feel like Captain Obvious, Master of the Foregone Conclusion.

I agree on all except the conclusion.

If you say that perspective is NOT an illusion, then IMHO you are wrong.

Perspective is a geometrical deformation caused by the way we observe things. I call that an illusion.

IOW the world is not the way we look at it.

The edges of a road do not reach each other at the horizon.

THE SAME goes for Relativity.

We observe (and measure) a whole bunch of "deformations" that DO NOT happen.

It is all about observation and measurement.

 

What swansont and I are telling you is that, in fact, this is the real actual state of affairs.

 

The real state of affairs is that we are measuring things.

The conclusion is different.

Your conclusion is that things described by Relativity do happen, I understand that, because there are an infinity of FOR, an infinity of situations do happen and that is insanity IMHO.

My conclusion is that observers have no influence on what is happening, that there is only one thing happening, and that Relaivity describes accurately how that one thing is observed in each FOR.

Edited April 4, 2014 by michel123456

[Schneibster]

Let's try a one-liner:

 

In your frame, the stick is longer or shorter.

 

That means nothing to the stick.

 

Now I will read your post in detail and respond where appropriate. Please be patient while I experiment with pedagogical techniques until I find the one that works for you.

I agree on all except the conclusion.

If you say that perspective is NOT an illusion, then IMHO you are wrong.

Perspective is a geometrical deformation caused by the way we observe things. I call that an illusion.

IOW the world is not the way we look at it.

The edges of a road do not reach each other at the horizon.

THE SAME goes for Relativity.

We observe (and measure) a whole bunch of "deformations" that DO NOT happen.

It is all about observation and measurement.

 

The real state of affairs is that we are measuring things.

The conclusion is different.

Your conclusion is that things described by Relativity do happen, I understand that, because there are an infinity of FOR, an infinity of situations do happen and that is insanity IMHO.

My conclusion is that observers have no influence on what is happening, that there is only one thing happening, and that Relaivity describes accurately how that one thing is observed in each FOR.

 

OK, well I contend that perspective is, in fact, not an illusion but a measurable fact. And I have evidence to support my claim: I can measure an objective change in the stick, i.e. its angular width in my frame of reference, as observed from zero/the origin. This is undeniable. At no time does the stick change, in the frame of reference of the stick. This also is undeniable. So, which is "true?" Correct answer: yes.

 

So with Lorentz Transformed coordinates. WYSIWYG is, in fact, the truth.

 

Remember that mesons with known lifetimes show increased lifetime when their average velocity (dangnabbit, I keep doing this. I mean speed!) is higher. This is not an illusion. It is a measurable fact. We can measure the time dilation. It's not a theory. It's a measured fact.

 

Then remember that from the mesons' own frame, their lifetime is normal.

 

The only possible resolution of the paradox is that the rate of time measured on remote experiments is variable, but the rate of time measured on local experiments is not. IMVVHO, this is the central fact of relativity, but I expect there are many other perspectives.

Edited April 4, 2014 by Schneibster

[michel123456]

Let's try a one-liner:

 

In your frame, the stick is longer or shorter.

 

That means nothing to the stick.

 

Now I will read your post in detail and respond where appropriate. Please be patient while I experiment with pedagogical techniques until I find the one that works for you.

 

OK, well I contend that perspective is, in fact, not an illusion but a measurable fact. And I have evidence to support my claim: I can measure an objective change in the stick, i.e. its angular width in my frame of reference, as observed from zero/the origin. This is undeniable. At no time does the stick change, in the frame of reference of the stick. This also is undeniable. So, which is "true?" Correct answer: yes.

 

So with Lorentz Transformed coordinates. WYSIWYG is, in fact, the truth.

 

Remember that mesons with known lifetimes show increased lifetime when their average velocity (dangnabbit, I keep doing this. I mean speed!) is higher. This is not an illusion. It is a measurable fact. We can measure the time dilation. It's not a theory. It's a measured fact.

 

Then remember that from the mesons' own frame, their lifetime is normal.

 

The only possible resolution of the paradox is that the rate of time measured on remote experiments is variable, but the rate of time measured on local experiments is not. IMVVHO, this is the central fact of relativity, but I expect there are many other perspectives.

I say that measurement can be an illusion.

I say that when different FOR make different measurements of the same thing, then the measurements are illusions*, even if you have a scientific Theory that link all the measurements and explain how one FOR measures this and the other FOR measures that.

 

* not sure if the word "illusion" is correct.

Paramorphosis maybe?

[Strange]

It is all about observation and measurement.

 

Well, if all objective measurements tell you the same thing, and you want to call that an "illusion" then I suppose that is up to you. But illusion usually refers to something which has no objective reality.

 

Relativity describes the way the world really works. We know this because we have to use it to make things that wokr in the real world (e.g. your computer).

 

 

Your conclusion is that things described by Relativity do happen, I understand that, because there are an infinity of FOR, an infinity of situations do happen and that is insanity IMHO.

 

You are welcome to your opinion. But reality seems to disagree.

 

 

My conclusion is that observers have no influence on what is happening, that there is only one thing happening, and that Relaivity describes accurately how that one thing is observed in each FOR.

 

The last part of that is certainly true. The first part less so: if there is only One True Value for things, what is your present One True Velocity? (It had better not be zero, I won't believe you.)

[Spyman]

I don't see these two statements as necessarily in opposition to each others:

 

...this appearance is no more an illusion, than the change of the angular width of the stick is an illusion when you turn it.

...there is only one thing happening, and that Relaivity describes accurately how that one thing is observed in each FOR.

If two markers are placed in space at a shorter distance apart than the length of a spaceship, then if the spaceship passes those markers with high enough speed, it will fit inside between the markers from the view of an observer at rest with them.

 

This is not an illusion in that sense that the markers could be synchronized beacons with encoded light signals so that the observer can verify that when the spaceship was located between them, he recieved simultaneous signals with identical time stamps from both of them.

 

Thus the from the view of the observer the spaceship was shorter than the distance between the markers and not only looked such.

 

But there is still only one thing happening, the spaceship doesn't get physically "deformed" by someone with a relative speed looking at it.

 

There is only one spaceship and it only has one size that don't change, however this size is measured with different scaling depending on the relative speed of the observer doing the measurement, so it is the observer's view of the spaceship that is changing.

 

Consider the example with the stick that Schneibster brought up, if the spaceship is rotated slightly away from the observer without changing direction of travel, then it would appear to become shorter and fit between the markers, from the view of the observer.

 

In this case we could see from above how an "illusion" is made, but if the spaceship is instead rotated into the time dimension then due to that we can't see time directly, we aren't able to see how the spaceship is turned. Spatially it is still pointing towards the direction of travel but from our view it is shorter and the clocks on the spaceship ticks equally slower.

 

(Note: I am not an expert on Relativity so this is my personal uneducated opinion.)

[Schneibster]

I say that measurement can be an illusion.

 

That's solipsism. It's also anti-scientific. Measurement is the one and only way we have to understand the world.

 

Other relations to the world are possible; Zen and similar disciplines teach one to see the world without measuring. And they hold some wisdom. But they do not hold knowledge of the world; only knowledge of oneself. For knowledge of the world, we have only measurement and ignoring it breeds only confusion.

 

 

I say that when different FOR make different measurements of the same thing, then the measurements are illusions*, even if you have a scientific Theory that link all the measurements and explain how one FOR measures this and the other FOR measures that.

 

* not sure if the word "illusion" is correct.

Paramorphosis maybe?

 

Then how come the muons that are going faster take longer to disintegrate? And, can you predict how much longer? Is time an illusion too, according to you?

This is not an illusion in that sense that the markers could be synchronized beacons with encoded light signals so that the observer can verify that when the spaceship was located between them, he recieved simultaneous signals with identical time stamps from both of them.

 

 

Good explanation, +1, but you skated very, very close to the edge with "time stamps." You are in territory that has led many astray, including the younger me. Remember the relativity of simultaneity. You can probably make your statement completely correct and satisfy a fussy old man like me by saying "local time stamps that are simultaneous in the observer's frame."

 

Note on the quote system: weirdly, I quoted michel, then made an unlabeled quote of michel, then quoted Spyman-- and all three quotes now don't appear with names! So michel, the first two are for you, and Spyman, the third one for you. No doubt I'll figure all this out and get settled in soon. Edited to add: And now it works again!!! LOL. That was definitely weird.

Edited April 4, 2014 by Schneibster

[michel123456]

Is there a FOR for which the observed length of an object is more than the length measured in the FOR of the object?

[swansont]

I say that measurement can be an illusion.

I say that when different FOR make different measurements of the same thing, then the measurements are illusions*, even if you have a scientific Theory that link all the measurements and explain how one FOR measures this and the other FOR measures that.

 

* not sure if the word "illusion" is correct.

Paramorphosis maybe?

 

If measurement does not give you reality, then how do you do science? I mean, you can't trust your instruments. OTOH, science has done pretty well under the assumption that there something objective revealed by our instruments. And although relativity says that length and time are not absolute, it works really well. If you want to discard it, there's but one way to do so: come up with something better.

[michel123456]

 

If measurement does not give you reality, then how do you do science? I mean, you can't trust your instruments. OTOH, science has done pretty well under the assumption that there something objective revealed by our instruments. And although relativity says that length and time are not absolute, it works really well. If you want to discard it, there's but one way to do so: come up with something better.

I don\t want to discard Relativity.

There is a misunderstanding.

 

The part I do not accept from your statements is when you say that Relativity describes accurately what is really happening.

I remain on my statements that Relativity describes accurately what we are observing and measuring.

 

Sure there is a link between measurement and what is really happening.

But nobody says (or should say) that what we measure is what is happening.

It is a supposition, not an axiom.

 

That's solipsism. It's also anti-scientific. Measurement is the one and only way we have to understand the world. (...)

I am not a solipsist.

 

If measurement does not give you reality, then how do you do science? I mean, you can't trust your instruments. (...)

That is correct: never trust your instruments.

 

Science works on a vicious circle:

observation -measurement -Theory- confirmation through observation & measurement.

 

It is true that if you insert a doubt about the coincidence between reality & measurement, the actual scientific method is in trouble.

There must be some other method though. Mathematics for example are always helpful, geometry and all that stuff. Logic. And also exporation, new technologies, etc.

The world doesn't stop at philosophy.

[md65536]

The part I do not accept from your statements is when you say that Relativity describes accurately what is really happening.

I remain on my statements that Relativity describes accurately what we are observing and measuring.

What is really happening then, if a length-contracted meter stick traveling at .99c slips lengthwise between two posts 0.8m apart? Is the meter stick really longer than the hole it fit through?

[swansont]

I don\t want to discard Relativity.

There is a misunderstanding.

 

The part I do not accept from your statements is when you say that Relativity describes accurately what is really happening.

I remain on my statements that Relativity describes accurately what we are observing and measuring.

 

 

In science, the only available tool to find what is "really happening" is experimental measurement. Nature behaves as if length contraction and time dilation are real phenomena.

That is correct: never trust your instruments.

It's an understatement to say that I'm not a fan of selective quoting to make it seem like an argument is the opposite of what is intended. You make it sound like we agree, and we do not. That's dishonest.

 

If you can't trust your instruments, you can't trust data and you can't do science. Inductively speaking, it seems like we can trust our instruments, because science works.

 

 

 

Science works on a vicious circle:

observation -measurement -Theory- confirmation through observation & measurement.

 

It is true that if you insert a doubt about the coincidence between reality & measurement, the actual scientific method is in trouble.

There must be some other method though. Mathematics for example are always helpful, geometry and all that stuff. Logic. And also exporation, new technologies, etc.

The world doesn't stop at philosophy.

Exploration and new technology are based on science. If you have a new approach, let's have it. Absent that, science is the best game in town.

[michel123456]

What is really happening then, if a length-contracted meter stick traveling at .99c slips lengthwise between two posts 0.8m apart? Is the meter stick really longer than the hole it fit through?

So you are measuring from a distance a length contracted meter stick traveling at vertiginous velocity. And you know better than an observer upon the meter stick that observes for himself no contraction at all.

The observer on the meter stick believes it is you and your posts that are traveling at .99c. And he observes that you are contracting.

 

Both things cannot "happen" "simoultaneously", they are mutually exclusive.

As I said before, IMHO iy is all about observation (which is not exclusive) not about anything really contracting.

[swansont]

So you are measuring from a distance a length contracted meter stick traveling at vertiginous velocity. And you know better than an observer upon the meter stick that observes for himself no contraction at all.

The observer on the meter stick believes it is you and your posts that are traveling at .99c. And he observes that you are contracting.

 

Both things cannot "happen" "simoultaneously", they are mutually exclusive.

As I said before, IMHO iy is all about observation (which is not exclusive) not about anything really contracting.

 

How can we tell if anything has "really" contracted? What test can we do to find the inherent nature of something?

[Schneibster]

Is there a FOR for which the observed length of an object is more than the length measured in the FOR of the object?

 

No.

I am not a solipsist.

 

That is correct: never trust your instruments.

 

Science works on a vicious circle:

observation -measurement -Theory- confirmation through observation & measurement.

 

It is true that if you insert a doubt about the coincidence between reality & measurement, the actual scientific method is in trouble.

There must be some other method though. Mathematics for example are always helpful, geometry and all that stuff. Logic. And also exporation, new technologies, etc.

The world doesn't stop at philosophy.

 

I accept that you do not intend to be a solipsist, but if you don't believe in measurement you don't have a lot of choice about it.

 

The equations that say these effects on length, mass, and time are real, are the same equations that say nuclear weapons work. We have extremely dramatic proof of it, I'd say.

 

Furthermore the reality of these effects is how GPS works; the time differentials between the satellites' signals are the essential data. And those time differences have to be corrected both for Special Relativity (which is what we've been discussing here on this thread) and General Relativity (which is a whole other ballgame).

Edited April 5, 2014 by Schneibster

[michel123456]

 

No.

(...)

1.So, there exist a "nice" FOR that smart scientists can use to easily measure the longest dimension of an object. In no other FOR can such a length be observed.

 

2. It is the same FOR in which smart scientists measure the rest mass ("invariant mass") of an object.

 

3. Does this FOR also have some "nice" particularity about time?

 

Question: Is there a FOR for which an observed time interval is less than a time interval as measured in the FOR of the object? (I mean, instead of time dilation, time contraction)

[md65536]

So you are measuring from a distance a length contracted meter stick traveling at vertiginous velocity. And you know better than an observer upon the meter stick that observes for himself no contraction at all.

The observer on the meter stick believes it is you and your posts that are traveling at .99c. And he observes that you are contracting.

 

Both things cannot "happen" "simoultaneously", they are mutually exclusive.

As I said before, IMHO iy is all about observation (which is not exclusive) not about anything really contracting.

Alright so we know what different observers measured. What really happened though, if not what was measured?

[michel123456]

 

No.

 

I accept that you do not intend to be a solipsist, but if you don't believe in measurement you don't have a lot of choice about it.

 

The equations that say these effects on length, mass, and time are real, are the same equations that say nuclear weapons work. We have extremely dramatic proof of it, I'd say.

 

Furthermore the reality of these effects is how GPS works; the time differentials between the satellites' signals are the essential data. And those time differences have to be corrected both for Special Relativity (which is what we've been discussing here on this thread) and General Relativity (which is a whole other ballgame).

My position is not against Relativity, it goes about the interpretation.of Relativity.

[Schneibster]

1.So, there exist a "nice" FOR that smart scientists can use to easily measure the longest dimension of an object. In no other FOR can such a length be observed.

 

2. It is the same FOR in which smart scientists measure the rest mass ("invariant mass") of an object.

 

3. Does this FOR also have some "nice" particularity about time?

 

Question: Is there a FOR for which an observed time interval is less than a time interval as measured in the FOR of the object? (I mean, instead of time dilation, time contraction)

 

That frame is called an "inertial frame." And yes, such a frame is always perceived by an observer in it to be experiencing undilated time. However, you must also understand that two such frames can be moving relative to one another; there is no one "master frame" or any reference from which to measure "absolute motion."

 

No, just as you cannot observe a length contraction less than zero due to motion, you also cannot observe time compression due to motion, only time dilation.