1 Simplifying Einstein's Thought Experiments

But it "simplifies" the experiments by going through them step by step and performing the same experiment in different ways so that the results can be compared and analyzed. And it uses virtually NO mathematics.

2 Simplifying Einstein's Thought Experiments

Rethink your Thought-experiment.

3 Simplifying Einstein's Thought Experiments

The paper already has 27 illustrations, it would have taken one or two more to explain that minor detail. I didn't expect anyone to be confused by it.

Ed

[Moderator's note: Yes, it would move forward relative to the GROUND when it bounces, as it says in the paper. However, at least if ignoring friction, in the case of the moving train the stone would NOT take longer to reach the ground. Also, ignoring friction, neither OT nor OE would see it moving forward reletion to the TRAIN. Again, ignoring friction, OT's observations would be the same even if the embankment were moving. Since there is no new physics here, I suggest that further comments be mailed to the original poster. -P.H.]

4 Simplifying Einstein's Thought Experiments

Thanks for the response, though. I'll try to think of a way to improve the Figure 3 illustration.

Ed

5 Simplifying Einstein's Thought Experiments

6 Simplifying Einstein's Thought Experiments

If the stationary observer were to drop a ball would the moving observer on the train see the ball fall twice as fast? Hmmm.

7 Simplifying Einstein's Thought Experiments

8 Simplifying Einstein's Thought Experiments

>	I'd be very much interested in any thoughts anyone might have here about how to improve my paper titled "Simplifying Einstein's Thought Experiments." Here's the link: http://vixra.org/pdf/1805.0251v1.pdf Ed

The article starts with the following sentence:

"A thought experiment (or in German: \_Gedankenexperiment_/) is a scientific experiment which is conducted entirely in one's mind."

I have always had certain misfeelings about thought experiments, because how you can do an experiment solely in your mind. Ofcourse you can discuss any experiment in the development phase of a projec with your colleques.

The next sentence reads:

"It is *snip* in that the experiment must obey all the rules of physics,"

What are the rules of physics? (Is the uncertainty principle a rule of physics?) This can be specific be a problem if you want to challange a certain existing law.

The next sentence reads:

"Einstein's train-embankment experiments, for example, involve a train (snip) that travels at about thirty or forty percent of the speed of light."

This sentence raises a serious problem and it is related to the issue how to perform an experiment in your mind. What is the reason that the experiement is not done at 0.001% of the speed of light? and how do you know in that case that the experiment is done at 0.001% of the speed of light. The problem is that it is relatif simple to perform this experiment in your mind, but very difficult in reality? What exactly (physical) means 0% of the speed of light?

The next sentence reads:

"The experiment is not really about trains (or embankments), *SNIP* and what another observer would see from a stationary location as the vehicle passes close by."

Again here: how can you do this in your mind. In most cases the prediction is that different observers will see something different. The issue is which observer has the correct view about the reality. Is that the 'stationary' or 'moving' observer and are all the moving observers equally wrong? Maybe all are wrong.

At page 3 we read: "Something is correct if it agrees with the laws of physics and has been demonstrated to be correct by experiments. "

I would rewrite this as such: A certain prediction is correct when it is demonstrated by experiments. (not thought experiments). The descriptions of these predictions we call the law of physics.

This terminates my contribution.

Nicolaas Vroom

9 Simplifying Einstein's Thought Experiments

[Moderator's note: Quoted text snipped. -P.H.]

Thought experiments can not be used to learn anything about the world, only to gain insight into the laws of physics as you understand them. Einstein's though experiments about the train allow you to understand the implications of the assumption that the speed of light is a constant for all observers, even observers moving wrt each other. These "experiments" prove nothing by themselves except what the assumptions imply. You still have to do real world experiments to verify that the real world gives the same results as the thought experiment. If they do not, then there is a faulty assumption somewhere. The value of the thought experiment is to understand the implications of an hypothesis (i.e. assumption).

Rich L.

10 Simplifying Einstein's Thought Experiments

>	Einstein's though experiments about the train allow you to understand the implications of the assumption that the speed of light is a constant for all observers, even observers moving wrt each other.

This sentence describes one possible assumption. A different assumption is: that the physical speed of light is local the same in all directions, assuming that no gravity is involved. This implies that the speed of light is comletely observer independent. A different assumption could be to consider an observer on earth at rest and that the speed of light in his frame is the same in all directions. Such an assumption makes the issue observer dependent

IMO a thought experiment can not decide which one is right or wrong.

>	You still have to do real world experiments to verify that the real world gives the same results as the thought experiment.

IMO that is the real strategy to follow. Study real world experiments, give the details of how they are performed and try to understand them (based on certain assumptions if required).

Nicolaas Vroom.

11 Simplifying Einstein's Thought Experiments

< snip >

Einstein's thought experiments produced papers which showed that time is variable: The faster you travel, the slower time advances for you, i,e., the slower your clocks will tick, the slower you will age, the slower your hair will grow, etc. It took a long time for actual experiments to confirm that. But they did.

Einstein's thought experiments about time also showed that if clocks tick slower when they move faster, then the ether is "superfluous" (i.e., "not needed"), since you can measure how fast you are going relative to someone else by the difference in tick rates for identical clocks.

If you have five people with identical clocks traveling at five different speeds, their clocks will tick at five different rates. You can rank the five by their relative speeds - A is moving faster than B, B is moving faster than C, C is moving faster than D, and D is moving faster than E.

Unfortunately, when Einstein said he made the ether "superfluous," some people inexplicably interpreted that to mean that motion is reciprocal, i,e., if I am moving faster than you in my frame of reference, you are moving faster than me in your frame of reference. And no matter how many ways you show that belief to be absurd, they still believe it.

Ed

12 Simplifying Einstein's Thought Experiments

You don't move in your frame of reference.

Dirk Vdm - show quoted text -

13 Simplifying Einstein's Thought Experiments

What the actual experiments showed is that not all physical clocks behave the same. Considering a physical clock which use lightsignals and assuming the clock at rest. In such a case it is easy to explain by means of a sketch that a second identical moving clock ticks slower.

>	If you have five people with identical clocks traveling at five different speeds, their clocks will tick at five different rates. You can rank the five by their relative speeds - A is moving faster than B, B is moving faster than C, C is moving faster than D, and D is moving faster than E.

The first issue is that you should consider your five clocks from one reference frame. The second issue is to answer the question: which clock ticks the slowest. This raises immediate an new issue: is it possible to introduce a sixth clock which ticks more slower? The answer could be: that clock should have a slower speed. This pops up a new question: How is the speed of each clock measured? To measure the speed you need clocks, which makes this discussion more complex and somewhat circular (if that is the good wording)

In any way you can not solve this problem by means of a thought experiment.

Nicolaas Vroom

14 Simplifying Einstein's Thought Experiments

This is just plain not true, and Einstein's thought experiments and papers show no such thing.

These thought experiments describe Special Relativity (SR), which predicts that no matter how you might move (relative to anything), your clocks tick at their usual rate, you age at your usual rate, your hair grows at its usual rate, etc. -- all as measured BY YOU (as your words say).

The underlying reason for this prediction is very basic: the first postulate of SR says that the laws of physics are the same in every inertial frame. So the laws that govern the ticking of your clocks, your ageing, and the growing of your hair, are ALWAYS THE SAME in your rest frame, regardless of how your frame might be moving (relative to anything). Since the laws are the same, the ticking, ageing, and growth rates must all be the same, TO YOU (i.e. as measured in your rest frame).

>	It took a long time for actual experiments to confirm that. But they did.

Hmmm. Experiments have NOT confirmed what you said above, but they have confirmed many times the ACTUAL predictions of SR. This includes "time dilation": clocks tick at their usual rate when measured in their rest frame, and are observed to tick more slowly by observers relative to whom they are moving.

[Note that in SR this is due to the geometrical relationship between relatively-moving inertial frames, and not any effect on the intrinsic tick rate of clocks.]

>	[... further confusions and incorrect claims]

These thought experiments describe and illuminate Special Relativity. In order to improve the quality and accuracy of your paper about them, first you must learn what Special Relativity ACTUALLY predicts. At present, your paper is completely useless because it describes YOUR mistakes and confusions, not Einstein's thought experiments and theory.

[A major error is thinking that some observations are "correct" and others are "incorrect" (in your unusual sense that they are consistent with the laws of physics). So for a stone dropped from a moving train, on page 5 you claim the embankment observation is "correct" while the on-train observation is "incorrect". You have failed to grasp the first postulate, and the FACT that the relevant laws of physics are INDEPENDENT of frame -- BOTH descriptions are "correct" (in your unusual sense of consistent with the known laws; it's just that you did not apply the ACTUAL laws as they are known). How can an observation possibly be "incorrect"?? -- after all, observers observe what they observe. Even with your unusual meaning of "correct", how can an observer possibly violate the laws of physics???]

Tom Roberts

15 Simplifying Einstein's Thought Experiments

< snip >

>

These thought experiments describe and illuminate Special Relativity. In order to improve the quality and accuracy of your paper about them, first you must learn what Special Relativity ACTUALLY predicts. At present, your paper is completely useless because it describes YOUR mistakes and confusions, not Einstein's thought experiments and theory. [A major error is thinking that some observations are "correct" and others are "incorrect" (in your unusual sense that they are consistent with the laws of physics). So for a stone dropped from a moving train, on page 5 you claim the embankment observation is "correct" while the on-train observation is "incorrect". You have failed to grasp the first postulate, and the FACT that the relevant laws of physics are INDEPENDENT of frame -- BOTH descriptions are "correct" (in your unusual sense of consistent with the known laws; it's just that you did not apply the ACTUAL laws as they are known). How can an observation possibly be "incorrect"?? -- after all, observers observe what they observe. Even with your unusual meaning of "correct", how can an observer possibly violate the laws of physics???]

If a moving observer notices no difference in the passing of time in his reference frame, but then COMPARES his time to the time of a non-moving observer, there will be a difference. The moving observer's time passed at a slower rate.

So, his view that there was "no difference" in the passing of time while he was moving was INCORRECT. There WAS a difference. Time passed at a slower rate while he was moving.

If the moving observer drops a stone and sees it fall straight down, while a stationary observer sees that stone fall in a parabolic curve, their conflicting views cannot both be "correct."

The view that the stone falls straight down is INCORRECT because that view fails to notice the effects of inertia.

If the two observers sit down and discuss what they saw, they will agree that the stone did not and could not fall straight down from a moving train. So, that view was "incorrect." It was an "illusion."

It is also an "illusion" that you age at your "normal" rate when moving fast. That "illusion" is understood when the moving and stationary observers sit down together and compare what happened. The faster you move, the slower time passes for you - even though you notice nothing different happening.

Einstein made that very clear in his 1905 paper: "Thence we conclude that a balance-clock at the equator must go more slowly, by a very small amount, than a precisely similar clock situated at one of the poles under otherwise identical conditions."

You move faster at the equator due to the spin of the earth. You can argue that the slightly flattened shape of the earth actually offsets that effect, but Einstein was using a "thought experiment" which involved a perfectly spherical Earth.

Ed

16 Simplifying Einstein's Thought Experiments

Yes.

>	The moving observer's time passed at a slower rate.

No. All known laws of physics are valid in the "moving observer's" frame, with their standard constants, so time passes at its usual rate for him -- one second is still 9,192,631,770 oscillations of CS-133.

A major part of your problem is saying "moving observer" without saying what he is moving with respect to. You are implicitly attempting to use some "absolute" or "God's eye" view of the world. That's invalid, as there is no such thing in modern physics.

Do you seriously think a train embankment is at rest in some "absolute" sense????

>	If the moving observer drops a stone and sees it fall straight down, while a stationary observer sees that stone fall in a parabolic curve, their conflicting views cannot both be "correct."

This is simply not true. Both observers observe what they observe. Both MUST be correct.

But in your paper you attempt to redefine "correct" to mean "consistent with the laws of physics", and seem to be using that here. Leaving aside the absurdity of such unusual redefinitions, it is not possible for either observer to violate the laws of physics, so again, BOTH OBSERVATIONS MUST BE CORRECT.

>	The view that the stone falls straight down is INCORRECT because that view fails to notice the effects of inertia.

There's your problem -- you do not understand the laws of physics. Here, in the context of Newtonian physics, there is no "law of inertia", there are just: * conservation of energy * conservation of momentum * Newton's three laws * Newton's law of universal gravitation BOTH observations are fully consistent with all of these.

All of these laws are valid in EVERY inertial frame. So they are valid in the frame of the embankment, and they are ALSO valid in the frame of the train. (The initial conditions of the stone are different in these frames, fully accounting for the difference in observations.)

>	[... further incorrect claims based on the same error]

>	Einstein made that very clear in his 1905 paper: "Thence we conclude that a balance-clock at the equator must go more slowly, by a very small amount, than a precisely similar clock situated at one of the poles under otherwise identical conditions."

This is one of his (minor) errors in that paper. In 1905 nobody knew that the earth is an oblate spheroid, and the effect of that exactly cancels the effect of the motion due to rotation, when comparing clocks to the Earth Centered Inertial frame. He also did not specify how the comparison is made -- in 1905 it was not understood that this is essential; today it is.

>	[... further incorrect claims based on the same error]

You MUST learn to avoid implicitly using "God's eye", as there is no such thing in modern physics. Practically everything you write does that, making it wrong. You cannot understand relativity, or intelligently discuss Einstein's thought experiments, without abandoning "God's eye" and learning what SR actually says. Your paper discusses YOUR OWN MISTAKES, not Einstein's thought experiments or theory.

Redefining a basic word like "correct" OUGHT to be a big red flag that you are doing something wrong.

Tom Roberts

17 Simplifying Einstein's Thought Experiments

It's clearly stated. The moving observer was moving relative to the "non-moving observer."

>	Do you seriously think a train embankment is at rest in some "absolute" sense????

No one suggested that. You are creating baseless arguments. It simplifies things to refer to an embankment as being "stationary" even though in the grander scheme of things it is traveling around the Milky Way galaxy at 486,000 miles per hour. The "grander scheme of things" isn't part of the discussion.

> >	If the moving observer drops a stone and sees it fall straight down, while a stationary observer sees that stone fall in a parabolic curve, their conflicting views cannot both be "correct."

>	This is simply not true. Both observers observe what they observe. Both MUST be correct.

Another baseless argument. Observers observe what they observe, but that doesn't automatically make anything "correct." A man a block away may appear smaller than someone a foot away, but that doesn't mean it is "correct" to say that the person a block away is actually smaller than the man next to you.

>

But in your paper you attempt to redefine "correct" to mean "consistent with the laws of physics", and seem to be using that here. Leaving aside the absurdity of such unusual redefinitions, it is not possible for either observer to violate the laws of physics, so again, BOTH OBSERVATIONS MUST BE CORRECT.

Obviously not. It violates the "conservation of momentum" for a stone dropped from a moving vehicle traveling parallel to the earth's surface to fall straight down. So, the observation that the stone traveled in a parabolic arc is the "correct" observation.

> >	The view that the stone falls straight down is INCORRECT because that view fails to notice the effects of inertia.

>

There's your problem -- you do not understand the laws of physics. Here, in the context of Newtonian physics, there is no "law of inertia", there are just: * conservation of energy * conservation of momentum * Newton's three laws * Newton's law of universal gravitation BOTH observations are fully consistent with all of these. All of these laws are valid in EVERY inertial frame. So they are valid in the frame of the embankment, and they are ALSO valid in the frame of the train. (The initial conditions of the stone are different in these frames, fully accounting for the difference in observations.)

> >	[... further incorrect claims based on the same error]

Within two closed inertial frames of reference *experiments* work identically. HOWEVER, when one frame of reference is observed from another frame of reference, the experiments may not work identically. The same laws are valid in EVERY inertial frame, but they can produce different results if one frame is moving relative to the other. The laws involve variables, such as the length of a second.

< snip > pointless argument

>	You MUST learn to avoid implicitly using "God's eye", as there is no such thing in modern physics. < snip > more of the same.

No one but you is saying anything about "God's eye." Einstein's theory says that if B is moving faster than A, then time will move slower for B. And if C is moving faster than B, then time will move slower for C than for B. And if D is moving faster than C, then D time will move slower for D than for A, B and C. Etc., etc., etc.

There is no "God's eye" involved. Einstein just said that a "luminiferous ether" is "superfluous" if the faster an object travels, the slower time passes for that object. Time comparisons can be used to determine who is moving faster than whom. That works until the speed of light is reached, at which point time stops for the object moving at that speed.

Ed

18 Simplifying Einstein's Thought Experiments

>

Within two closed inertial frames of reference *experiments* work identically. HOWEVER, when one frame of reference is observed from another frame of reference, the experiments may not work identically. The same laws are valid in EVERY inertial frame, but they can produce different results if one frame is moving relative to the other. The laws involve variables, such as the length of a second. < snip > pointless argument

> >	You MUST learn to avoid implicitly using "God's eye", as there is no such thing in modern physics. < snip > more of the same.

>

No one but you is saying anything about "God's eye." Einstein's theory says that if B is moving faster than A, then time will move slower for B. And if C is moving faster than B, then time will move slower for C than for B. And if D is moving faster than C, then D time will move slower for D than for A, B and C. Etc., etc., etc. There is no "God's eye" involved. Einstein just said that a "luminiferous ether" is "superfluous" if the faster an object travels, the slower time passes for that object. Time comparisons can be used to determine who is moving faster than whom. That works until the speed of light is reached, at which point time stops for the object moving at that speed. Ed

For the Gedanken experiment, time comparisons cannot be used to determine who is moving, period. You are almost there with your descriptions that used letters instead of train and embankment.

So, I like to pose the experiment as 2 trains with windows only on the side facing the other train. Nothing else to reference. Tracks and embankments are out of sight. Of course also extremely smooth ride, not vibrations to indicate movement.

We can even imagine both trains are infinitely long, or at least long enough to conduct our thought experiments.

Each car of both trains contains an observer, watching the other train and and an experimenter conducting an experiment to watch.

The trains move at speed V relative to the other.

Experiment 1 In one of the cars of train A, the experimenter drops a ball. The observer in train B also records the experiment.

Experiment 2 In one of the cars of train A, the experimenter shoots a ball at speed V in the same direction as train B. The observer in train B also records the experiment.

Experiment 3 In one of the cars of train B, the experimenter drops a ball. The observer in train A also records the experiment.

Experiment 2 In one of the cars of train B, the experimenter shoots a ball at speed V in the same direction as train A. The observer in train A also records the experiment.

SO what do they conclude? Both conclude that a ball falls at a given rate (the acceleration of gravity).

Both agree that when they drop a ball in their own train, it falls straight down. and the both agree that combined motions work the same within their own train.

The same goes for light and time.

Particular observations may be different, but are symetrical.

IOW, they agree that the laws of physics are the same in both trains. If they published ballistics tables, both trains would come up with the same results.

They do disagree on who is moving, and no experiment can tell them the "correct" answer. There is no "illusion" to dispel.

Ed

19 Simplifying Einstein's Thought Experiments

No, it is not "baseless" at all -- that is what those words mean.

Have you never been on a train and dropped something while it is en route? -- if not, go find a train and do it (or use a car).

It is QUITE CLEAR that a dropped object on a train falls straight down RELATIVE TO THE TRAIN [#]. And it is also QUITE CLEAR that the same object falls in a parabolic arc RELATIVE TO THE EMBANKMENT. BOTH observations are correct, because that is what those observers actually observe.

NOTE: I reject and ignore your outrageous attempt to redefine the word "correct". Instead, I will write out your meaning, "consistent with the laws of physics". Such egregious redefinitions only serve to obscure the argument and confuse the participants.

[#] Here the context is Newtonian physics, and I ignore the distance the train travels during the fall compared to the radius of the earth. That is, here gravity points straight down, even though on earth it actually changes direction slightly as the train moves. I do this to avoid getting bogged down in irrelevant minutiae. Note that a more careful analysis that includes this does NOT change the basic conclusion.

>	Observers observe what they observe, but that doesn't automatically make anything "correct."

Sure it does, because that is what those words mean. Both observer's observations are also consistent with the laws of physics. After all, no observer or physical phenomenon can possibly violate those laws.

You claim that the train observer's observation is not consistent with the laws of physics -- how do you suppose that the train observer or the stone can violate those laws?????

Hint: If it is possible to violate them, then they aren't really "laws of physics".

>	So, the observation that the stone traveled in a parabolic arc is the "correct" observation.

Sure, RELATIVE TO THE EMBANKMENT. But it is not the only correct observation -- the observation of the train observer is also correct. Both are also consistent with the laws of physics.

>	Within two closed inertial frames of reference *experiments* work identically. HOWEVER, when one frame of reference is observed from another frame of reference, the experiments may not work identically.

This is nonsense. You do not understand what frames of reference actually are.

A frame of reference is a set of coordinates relative to which an experiment can be DESCRIBED. The frame is PURELY IN THE MIND OF THE ANALYST, and used FOR DESCRIPTION ONLY; nature does not use frames in any way. So whichever frame is used by the analyst/observer, that choice cannot possibly affect the results of the experiment (here the trajectory of the falling stone).

The trajectory of the stone before it is dropped is important to how the laws of physics determine its trajectory after it is dropped. But the fact that it is initially at rest in the train frame is IRRELEVANT to those laws [@], and to the its subsequent trajectory. But being initially at rest in the train frame is important to the DESCRIPTION of the stone's trajectory relative to the train frame. Similarly, the initial forward motion of the stone relative to the embankment frame is IRRELEVANT to those laws [@], and to its subsequent trajectory, but is important to the DESCRIPTION of the stone's trajectory relative to the embankment frame.

[@] Because the laws of physics are INDEPENDENT of frame; nature does not use frames in any way.

IOW: the dropped stone moves in a fashion determined by the laws of physics. Those laws can be described in ANY frame of reference, and necessarily must give THE SAME trajectory of the stone -- after all there is only one stone and it is dropped only once, so it can have only one trajectory. If the laws are accurate, they MUST predict this one trajectory, and must do so using ANY frame of reference.

The train observer describes the stone as falling straight down, and the embankment observer describes it as falling in a parabolic arc. BOTH descriptions are correct (in that they accurately describe what is observed by each observer), BOTH descriptions describe the ONE trajectory of the stone (from different perspectives using different frames), and BOTH descriptions are consistent with the laws of physics.

>	The same laws are valid in EVERY inertial frame, but they can produce different results if one frame is moving relative to the other.

Hmmmm. The laws of physics are INDEPENDENT of frame, and they yield a result that is INDEPENDENT of frame (I use the normal meaning of "result"). But the DESCRIPTIONS of the result using different frames can certainly be different.

If by "result" you mean the normal "what actually happened", then your statement here is just plain wrong; if by "result" you intend the unusual meaning "DESCRIPTION of what actually happened", then of course different frames can yield different descriptions.

[Do not expect me to continue. You clearly do not understand very basic concepts of physics, or even basic English usage. It is useless to try to continue until you learn the basics.]

Tom Roberts

20 Simplifying Einstein's Thought Experiments

What is the point of such self-proving experiments? If you remove all means of telling who is moving and who is not, obviously you will not be able to tell who is moving and who is not. It's an absurd experiment.

Einstein's theories say that if you perform your experiments inside an inertial reference frame, you will get the same results as someone else inside a different inertial reference frame moving at a different speed. So, you created a complicated set of experiments to prove what everyone already knows.

The point of Relativity, however, is that, if you have a situation where you CAN tell who is moving and who is not, or who is moving faster than whom, then the laws of physics will still be the same, the tests will still produce the same results, but you can see that while the results APPEAR identical, they are actually different because they used a variable: the length of a second. Thus, the test results are actually different and definitely NOT symmetrical. The comparison between frames will show that one is moving faster than the other and therefore one used longer seconds than the other.

In Einstein's thought experiments he specifically says that you can open the window and SEE who is moving and who is not, even though you cannot tell that when the windows are closed.

Ed

21 Simplifying Einstein's Thought Experiments

You argue, "Because the laws of physics are INDEPENDENT of frame; nature does not use frames in any way."

Correct. But HUMANS use frames. And they can APPEAR to get the same results in different "frames" while actually getting very different results. That is what Relativity is all about.

If they can compare the length of a second as used in their different frames, they will find that they used different lengths for seconds. The length of a second is a variable in the laws of physics. It is a COUNT of "periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."

If within your lab you count 9,192,631,770 such periods, you consider it to be one second. I do the same in my lab. But if we can compare clocks, we can find that you reached a total of 9,192,631,770 periods long before did. Thus our seconds are actually of different lengths, even though we both consider a second to have same length: "9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."

Time passes slower for whichever object is moving faster. You can prove that by comparing length of seconds on atomic clocks. They work the same way as cesium 133 atoms and all other atoms. They tick at a specific rate that slows down when they move faster. And they stop when they reach the speed of light.

Ed

22 Simplifying Einstein's Thought Experiments

I created a gedanken experiment that mirrors reality, such as two planet earths passing each other in remote space.

>	What is the point of such self-proving experiments? If you remove all means of telling who is moving and who is not, obviously you will not be able to tell who is moving and who is not. It's an absurd experiment.

No it is what we actually face in astronomical studies. We can use earth as our reference frame, but that does not mean we represent the embankment of the experiment.

>

Einstein's theories say that if you perform your experiments inside an inertial reference frame, you will get the same results as someone else inside a different inertial reference frame moving at a different speed. So, you created a complicated set of experiments to prove what everyone already knows.

Good. It is not more complicated, just clearer as to the real situation we face.

>

The point of Relativity, however, is that, if you have a situation where you CAN tell who is moving and who is not, or who is moving faster than whom, then the laws of physics will still be the same, the tests will still produce the same results, but you can see that while the results APPEAR identical, they are actually different because they used a variable: the length of a second. Thus, the test results are actually different and definitely NOT symmetrical. The comparison between frames will show that one is moving faster than the other and therefore one used longer seconds than the other.

Not symmetrical as to the details. But the results that both derive are the same, namely: the laws of gravity and inertia and E&M are the same.

>	In Einstein's thought experiments he specifically says that you can open the window and SEE who is moving and who is not, even though you cannot tell that when the windows are closed. Ed

But the conclusion derived from the experiment is that there is NO preferred frame. Your comments about "correct" path of an object is the mistaken impression that I hoped this example would demonstrate. If you think there is a "correct" path for a dropped ball to fall, then using the results of the four experiments tell us which train is not moving and which train is moving.

Then consider a real example, the relative motions of the Milky Way galaxy and the Whirlpool galaxy. Which galaxy is not moving and which one is moving? Please kindly share how you reach your conclusion. Oh one caveat: no fair using a third reference frame, such as the CMBR or Galactic clusters or God's eye view.

Enjoy, Ed

23 Simplifying Einstein's Thought Experiments

To see the absurdity of your claims, just unwind your VERY UNUSUAL AND OUTRAGEOUS meaning of "correct":

Ed Lake said: If you set down a rule that you cannot tell what is consistent with the laws of physics and what is inconsistent with the laws of physics, what is the point?

It OUGHT to be clear that NOTHING we observe can be inconsistent with the laws of physics -- we and any physical process we observe are necessarily constrained by those laws. I did not "set down a rule" that is not already contained in the phrase "laws of physics".

Ed Lake said: Science and physics is [sic] about determining what is consistent with the laws of physics and what is inconsistent with the laws of physics.

The absurdity of this is manifest -- EVERYTHING we observe is consistent with the laws of physics, there is no possibility of "determining".

[Note also that everything we observe is correct (standard meaning) -- it simply is not possible to make incorrect observations. It is possible to interpret observations incorrectly, and when that happens competent scientists fix the error.]

In fact, science and physics are about modeling the world we inhabit. We have learned that the phrase "the laws of physics" is a chimera, and today we formulate MODELS, not "laws". For the simple reason that we now know that humans can never know the actual Laws used by Nature, the best we can possibly do is to approximate them, and that is not at all the same.

Also note that when you attempt to redefine common words, you confuse yourself and your readers. DON'T DO THAT.

>	You argue, "Because the laws of physics are INDEPENDENT of frame; nature does not use frames in any way." Correct. But HUMANS use frames. And they can APPEAR to get the same results in different "frames" while actually getting very different results. That is what Relativity is all about.

No, that is NOT "what relativity is all about", because your previous sentence is blatantly false.

When we use different frames to DESCRIBE an experiment, the RESULT is unchanged -- for the example being discussed there is ONE stone, it is dropped ONCE, and it has ONE trajectory -- THAT TRAJECTORY IS THE RESULT OF THE EXPERIMENT. But of course the train and embankment observers describe this trajectory differently, using their different= perspectives.

>	[... further nonsense that ignores the lessons above.]

Tom Roberts

24 Simplifying Einstein's Thought Experiments

You seem to have fundamental misunderstandings of Relativity. Everything in our observable universe is moving. So, the question "Which galaxy is not moving and which is moving?" is absurd and meaningless. The question should be: Which galaxy is moving FASTER than the other? The same with the moving trains: Which is moving FASTER than the other?

You ask absurd, meaningless questions. According to Einstein's Special Theory of Relativity, there is no need for a "lunimiferous ether" to use as a "preferred reference frame" to measure all movement against. Instead, you can measure all movement by how slow clocks tick. The faster an object moves, the slower a clock on that object will tick.

So, clocks aboard an object will tick slower and slower as the object moves faster and faster, until the speed of light is reached. At the speed of light, time stops. You cannot go faster than the speed of light. That is one key to understanding Einstein's Special Theory of Relativity.

If you have two trains moving at different speeds, experiments aboard those trains will produce identical results even though time moves at different rates aboard the two trains. And you cannot tell that time is moving at different rates unless you compare clock rates. Then you will see that, while both clocks tick 9,192,631,770 times per second, the clock aboard the slower moving train will reach that count long before the clock aboard the faster moving train. The faster a train moves, the slower clocks will tick aboard that train.

That is the other key to understanding Einstein's Special Theory of Relativity.

Ed

[[Mod. note -- Many of your statements need to be qualified with who (which observer or frame-of-reference) is making the observation:

Notably, your question "Which galaxy is moving FASTER than the other?" has different answers depending on the observer or frame-of-reference.

Also notably, "clocks aboard an object" will be observed *by a "co-moving" observer who is also aboard the same object* to tick at precisely their normal rate.

-- jt]]

25 Simplifying Einstein's Thought Experiments

< snip > more of the same.

So, if the world appears flat, then it is flat - because it is what we observe? And if it appears that the sun goes around the earth, then that must be correct because it is what we observe? And if the earth beneath our feet appears motionless, then it must be so - because "it simply is not possible to make incorrect observations"?

Hmm. Then what is the purpose of science? I thought it was to explain inconsistencies in observations. The earth appears flat, yet ships somehow disappear over the horizon. The sun appears to go around the earth, but observations of other planets indicate they orbit around the sun. The earth beneath my feet feels motionless, but if I am inside a vehicle moving at a constant rate, the floor beneath my feet also feels motionless, even though I know I am moving.

All those inconsistencies can be resolved by understanding the laws of physics. Gravity enables a spherical world to APPEAR locally flat. The sun is vastly larger than the earth, thus its greater gravity requires that the earth orbit around the sun. The earth beneath my feet feels motionless ("stationary") because the earth and I are moving in unison in the same direction at the same speed.

A stone dropped from a moving train cannot drop straight down because inertia will cause it to move with the train until gravity stops it. The observation that the stone fell straight down was "incorrect" because it was inconsistent with the laws of physics. When you understand how events can APPEAR inconsistent with the laws of physics while still obeying the laws of physics, then all observers can agree on what actually happened.

Ed

26 Simplifying Einstein's Thought Experiments

What I am trying to explain is that time moves slower when an object moves faster. And when you reach the speed of light, time stops. Period. That is what Einstein's Theory of Special Relativity says.

The speed of light can be used as a "preferred" reference frame.

When you talk about "frames of reference" where observers are imagined to be "stationary," you create a FICTION where each observer sees the other observer as moving.

Instead, you should do as Einstein recommended and have the observers COMPARE the tick rates of their clocks. The clock that is moving the fastest will tick at the slowest rate. Thus, instead of fantasizing that you are stationary and the other observer is moving, you can determine who is ACTUALLY moving faster than whom.

The only objects that are "stationary" in our observable universe are objects that move at the same speed in the same direction. Their clocks will tick at the same rate, so they are "stationary" relative to one another, even if both are traveling at 486,000 miles per our around the center of the Milky Way galaxy.

Ed

27 Simplifying Einstein's Thought Experiments

>

All those inconsistencies can be resolved by understanding the laws of physics. Gravity enables a spherical world to APPEAR locally flat. The sun is vastly larger than the earth, thus its greater gravity requires that the earth orbit around the sun. The earth beneath my feet feels motionless ("stationary") because the earth and I are moving in unison in the same direction at the same speed.

Note there is an assumption above that is not explicitdly stated: That the laws of the universe are consistent everywhere.

>

A stone dropped from a moving train cannot drop straight down because inertia will cause it to move with the train until gravity stops it. The observation that the stone fell straight down was "incorrect" because it was inconsistent with the laws of physics. When you understand how events can APPEAR inconsistent with the laws of physics while still obeying the laws of physics, then all observers can agree on what actually happened. Ed

You still persist in this "correct'/"incorrect" paradigm that begs for a god-like reference frame.

you are right, unless, of course, the train is standing still on the tracks! ;) Or in my two train example, both trains move with the same velocity.

Ed P.

28 Simplifying Einstein's Thought Experiments

> > >

The point of Relativity, however, is that, if you have a situation where you CAN tell who is moving and who is not, or who is moving faster than whom, then the laws of physics will still be the same, the tests will still produce the same results, but you can see that while the results APPEAR identical, they are actually different because they used a variable: the length of a second. Thus, the test results are actually different and definitely NOT symmetrical. The comparison between frames will show that one is moving faster than the other and therefore one used longer seconds than the other.

> >	Not symmetrical as to the details. But the results that both derive are the same, namely: the laws of gravity and inertia and E&M are the same.

> > >

In Einstein's thought experiments he specifically says that you can open the window and SEE who is moving and who is not, even though you cannot tell that when the windows are closed. Ed

> >

But the conclusion derived from the experiment is that there is NO preferred frame. Your comments about "correct" path of an object is the mistaken impression that I hoped this example would demonstrate. If you think there is a "correct" path for a dropped ball to fall, then using the results of the four experiments tell us which train is not moving and which train is moving. Then consider a real example, the relative motions of the Milky Way galaxy and the Whirlpool galaxy. Which galaxy is not moving and which one is moving? Please kindly share how you reach your conclusion. Oh one caveat: no fair using a third reference frame, such as the CMBR or Galactic clusters or God's eye view. Enjoy, Ed

>

You seem to have fundamental misunderstandings of Relativity. Everything in our observable universe is moving. So, the question "Which galaxy is not moving and which is moving?" is absurd and meaningless. The question should be: Which galaxy is moving FASTER than the other? The same with the moving trains: Which is moving FASTER than the other?

IOW, you can only measure speeds relative to some other frame. You cannot, in the real universe, open the train window to see some at rest embankment, because both the window and the embankment are not there.

>	You ask absurd, meaningless questions.

Your comments about "correct" motion of the ball prompted my question. So it seems reasonable to ask you: which observer in which train observers the "corect" path of motion according to you?

>

According to Einstein's Special Theory of Relativity, there is no need for a "lunimiferous ether" to use as a "preferred reference frame" to measure all movement against. Instead, you can measure all movement by how slow clocks tick. The faster an object moves, the slower a clock on that object will tick.

I did not mention nor do I see a need for "lunimiferous ether". I totally agree that in SR, moving clocks run slower. Why would you suggest I accept any other conclusion?

>	So, clocks aboard an object will tick slower and slower as the object moves faster and faster, until the speed of light is reached. At the speed of light, time stops. You cannot go faster than the speed of light. That is one key to understanding Einstein's Special Theory of Relativity.

Yes, no object there. I hope you have a point.

>

If you have two trains moving at different speeds, experiments aboard those trains will produce identical results even though time moves at different rates aboard the two trains. And you cannot tell that time is moving at different rates unless you compare clock rates. Then you will see that, while both clocks tick 9,192,631,770 times per second, the clock aboard the slower moving train will reach that count long before the clock aboard the faster moving train. The faster a train moves, the slower clocks will tick aboard that train.

Still nothing new. Still also avoiding my question.

>

That is the other key to understanding Einstein's Special Theory of Relativity. Ed [[Mod. note -- Many of your statements need to be qualified with who (which observer or frame-of-reference) is making the observation: Notably, your question "Which galaxy is moving FASTER than the other?" has different answers depending on the observer or frame-of-reference. Also notably, "clocks aboard an object" will be observed *by a "co-moving" observer who is also aboard the same object* to tick at precisely their normal rate. -- jt]]

Yes the entire point of the two train gedanken experiment is to emphasize that there is no preferred frame of reference. this is something that the wording Ed prefers to use about "correct" results is meaningless in SR. So I am basically Asking Ed Lake which frame of reference will produce his "correct" results.

Ed P.

29 Simplifying Einstein's Thought Experiments

You repeatedly omit important information in your descriptions. Here you omitted WHO is doing the observing. To the train observer, the stone DOES drop straight down [#]; to the embankment observer it does not. BOTH are correct (in that this is indeed what they observe). BOTH are consistent with the laws of physics (how could they not???).

(And, of course, "gravity" does not stop it, the floor of the train stops its fall.)

[#] Ignoring the distance the train moves during the fall compared to the radius of the earth; I also omit many details.

>	The observation that the stone fell straight down was "incorrect" because it was inconsistent with the laws of physics.

Not true (ignoring your OUTRAGEOUS AND UNUSUAL meaning of "incorrect"). The train observer's observation that the stone fell straight down is fully consistent with the laws of physics. You clearly do not know what those laws ACTUALLY are.

Hint: If an observation is inconsistent with the "laws of physics", then those "laws" MUST BE WRONG. After all, that is what science is.

Here are two different DESCRIPTIONS of a single fall of the stone, by two observers using two different inertial frames and Newtonian mechanics; they apply THE SAME law of physics (F=ma). Both begin when the stone is dropped [#]:

Embankment observer: The force of gravity F points straight down, and I apply F=ma to the stone with mass m; the initial condition is the stone's initial velocity in the train's forward direction relative to my embankment frame, and the trajectory is a parabolic fall relative to my embankment frame (constant horizontal velocity, accelerating downward).

Train observer: The force of gravity F points straight down, and I apply F=ma to the stone with mass m; the initial condition is the stone's initial velocity of zero relative to my train frame, and the trajectory is a fall straight down relative to my train frame (zero horizontal velocity, accelerating downward).

Newton's second law, F=ma, is a differential equation that can be solved for the position of an object in terms of an inertial frame's coordinates. Applying this equation requires initial conditions, which must of course be expressed in terms of the frame used. It applies to ANY inertial frame within the domain of Newtonian mechanics (e.g. NOT to Einstein's thought experiments).

[This has wandered very far from Einstein's thought experiments, and it is useless to continue until you improve the precision of your thinking and writing, and also learn some very basic physics. Goodbye.]

Tom Roberts

30 Simplifying Einstein's Thought Experiments

If you want it explicitly stated, here it is: As far as we know, the laws of the universe are consistent everywhere. (However, the laws include variables - such as time and the length of a second. So, the laws work consistently with the variables to produce the same results every time. However, due to the variables the actual results can be different when you compare results obtained under difference time-related conditions (when one body is moving faster than the other).)

>

>>

A stone dropped from a moving train cannot drop straight down because inertia will cause it to move with the train until gravity stops it. The observation that the stone fell straight down was "incorrect" because it was inconsistent with the laws of physics. When you understand how events can APPEAR inconsistent with the laws of physics while still obeying the laws of physics, then all observers can agree on what actually happened. Ed

>	You still persist in this "correct'/"incorrect" paradigm that begs for a god-like reference frame.

No, it just requires being able to tell the difference between what is "real" and what is an "illusion." You may think that the train you are on is stationary and the railroad station and embankment outside are moving, but that is just an "illusion." If you understand that energy was required to make the train move, and the amount of energy used by the engine could not possibly make the planet move while the train stands still, then you can understand how to tell the difference between an "illusion" and reality.

Of course, it can be argued that it is also an "illusion" that the embankment and station are standing still, since both are moving as the earth spins on its axis and travels around the center of the galaxy at 486,000 miles per hour, but the energy produced by the train's engine has nothing to do with that movement. So, it all depends upon what you are arguing.

>	you are right, unless, of course, the train is standing still on the tracks! ;)

My statement was about "A stone dropped from a moving train". Note the word "moving."

>	Or in my two train example, both trains move with the same velocity. Ed P.

Your experiment was about "2 trains with windows only on the side facing the other train. Nothing else to reference. Tracks and embankments are out of sight. Of course also extremely smooth ride, no vibrations to indicate movement."

What is the purpose of such an experiment? To show that you can create a situation where no one can tell what is really happening? Everyone knows that. You can do it by performing an experiment in a closed lab where you have no way to know if the lab is moving or not.

The point is: If you CAN tell who is moving (by opening the window, for example) then you can ALSO determine who is moving faster than whom. You can do it by comparing clock tick rates (if you have identical clocks). The person whose clock ticks slowest is the person who is moving fastest.

Ed

31 Simplifying Einstein's Thought Experiments

yes, we agree so far.

>	The speed of light can be used as a "preferred" reference frame.

That will be hard to do because the clock on the light beam always reads 0.

>	When you talk about "frames of reference" where observers are imagined to be "stationary," you create a FICTION where each observer sees the other observer as moving.

The only way to remove that "FICTION" isd to find an absolute reference frame. But wait Einstein said there is NO absolute frame of reference.

>

Instead, you should do as Einstein recommended and have the observers COMPARE the tick rates of their clocks. The clock that is moving the fastest will tick at the slowest rate. Thus, instead of fantasizing that you are stationary and the other observer is moving, you can determine who is ACTUALLY moving faster than whom.

That is the problem, You cannot tell who is "ACTUALLY" moving. Einstein never made such a statement that it would tell you who is "ACTUALLY" moving.

>

The only objects that are "stationary" in our observable universe are objects that move at the same speed in the same direction. Their clocks will tick at the same rate, so they are "stationary" relative to one another, even if both are traveling at 486,000 miles per our around the center of the Milky Way galaxy. Ed

I can agree with the last statement. It's unrelated to the other points you tried to make.

Do you agree that some of your statements, especially with the CAPITALIZATION, are describing an absolute reference frame. Or at the least seem to imply it?

Enjoy, Ed P.

32 Simplifying Einstein's Thought Experiments

> >>

A stone dropped from a moving train cannot drop straight down because inertia will cause it to move with the train until gravity stops it. The observation that the stone fell straight down was "incorrect" because it was inconsistent with the laws of physics. When you understand how events can APPEAR inconsistent with the laws of physics while still obeying the laws of physics, then all observers can agree on what actually happened. Ed

> >	You still persist in this "correct'/"incorrect" paradigm that begs for a god-like reference frame.

>

No, it just requires being able to tell the difference between what is "real" and what is an "illusion." You may think that the train you are on is stationary and the railroad station and embankment outside are moving, but that is just an "illusion." If you understand that energy was required to make the train move, and the amount of energy used by the engine could not possibly make the planet move while the train stands still, then you can understand how to tell the difference between an "illusion" and reality.

You fail to keep in mind that the train is a star or planet and the embankment is another star or planet. IOW, you are making reference to an absolute frame, the planet Earth, in the above comment.

The point Tom and I are both trying to make is: there is no illusion!

>

Of course, it can be argued that it is also an "illusion" that the embankment and station are standing still, since both are moving as the earth spins on its axis and travels around the center of the galaxy at 486,000 miles per hour, but the energy produced by the train's engine has nothing to do with that movement. So, it all depends upon what you are arguing.

I am arguing that both observations are real. Both observations are consistent with SR.

>

> >	you are right, unless, of course, the train is standing still on the tracks! ;)

>	My statement was about "A stone dropped from a moving train". Note the word "moving."

> >	Or in my two train example, both trains move with the same velocity. Ed P.

>	Your experiment was about "2 trains with windows only on the side facing the other train. Nothing else to reference. Tracks and embankments are out of sight. Of course also extremely smooth ride, no vibrations to indicate movement."

yes, or if you prefer, two space trains on an interstellar line

>

What is the purpose of such an experiment? To show that you can create a situation where no one can tell what is really happening? Everyone knows that. You can do it by performing an experiment in a closed lab where you have no way to know if the lab is moving or not. The point is: If you CAN tell who is moving (by opening the window, for example) then you can ALSO determine who is moving faster than whom.

There is the point: you can NOT tell who is moving in any absolute manner. There is no window in this universe to open.

>	You can do it by comparing clock tick rates (if you have identical clocks). The person whose clock ticks slowest is the person who is moving fastest. Ed

This last point is not clear. You seem to be taking a vote with multiple observers. So Alice, Bob, and Dan all agree that Charles has the slowest clock and therefore is moving fastest of relative to the other three. That is a valid observation.

But the complimentary conclusion that Charles, Bob, and Dan all agree that Alice has the fastest clock does not lead to the conclusion that Alice is not moving. Alice is still at best only an agreed-to reference frame.

And one more point: It may be that the others are moving as a group away from Charles. The observations of the clocks will be the same. You really cannot know the absolute motion. And it isn't an illusion.

HTH, Ed

33 Simplifying Einstein's Thought Experiments

>>>>	You still persist in this "correct'/"incorrect" paradigm that begs for a god-like reference frame.

>>>

No, it just requires being able to tell the difference between what is "real" and what is an "illusion." You may think that the train you are on is stationary and the railroad station and embankment outside are moving, but that is just an "illusion." If you understand that energy was required to make the train move, and the amount of energy used by the engine could not possibly make the planet move while the train stands still, then you can understand how to tell the difference between an "illusion" and reality.

It's easy to see that this is wrong.

For simplicity, let's say the tracks are at the equator, running east to west, and the train has a speed of 100 kph. You want to say that the train is moving faster than the embankment.

But wait. At the equator, the Earth is rotating at about 1600 kph from west to east. So the embankment is moving at 1600 kph. If the train is also moving west to east, its speed is about 1700 kph, so it's moving faster than the embankment. But if the train is moving east to west, its speed is about 1500 kph, slower than the embankment.

But wait. The Earth is also orbiting the Sun at about 100,000 kph. So the embankment is moving at about 100,000 kph. For about twelve hours a day, the train will be moving in the same direction as the Earth's orbit, so it will be going faster than the embankment. But for the other twelve hours, it will be moving in the opposite direction as the orbit, so it will be going slower than the embankment.

But wait. The Solar System is also moving, so you'd better account for that. And the galaxy is moving, and so is the local group of galaxies,...

Unless you have an absolute reference frame, you have no way to account for all the velocities to decide what is moving "faster" than what.

[...]

>

Okay, once again: Comparing clock tick rates will show the following: Alice is moving slower than Bob. Bob is moving slower than Dan. Dan is moving slower than Chuck. Chuck is moving slower than Fred. Fred is moving slower than Albert. Albert is moving slower than Henry. Etc., etc., etc, until you get to Louie. Nobody seems to have a clock that ticks faster than than Louie's. Is Louie "stationary"? Until you can find someone whose clock ticks faster than Louie's, you can measure all velocities as relative to Louie. And, if you know Louie's location, you can measure all movement as being relative to Louie.

>	That is what SR says.

No, that is not what SR says. SR says that in Alice's rest frame, Bob's clock appears to tick slower than Alice's, and in Bob's rest frame, Alice's clock appears to tick slower than Bob's. *You* don't get to decide which clock is "really" slower, unless you want to claim that your reference frame is better than anyone else's.

Steve Carlip

34 Simplifying Einstein's Thought Experiments

I would like to comment on this in a rather 'open' sense. First of all identical processes (experiments) have identical descriptions. Different processes have different descriptions. Almost identical processes have almost identical descriptions. The differences in these descriptions we call the parameters of the processes. That all seems simple but the reality is more complex. The first problem is we humans. We humans write the descriptions based on our observations. Consider a train which travels in a straight line from A to B. Observer A at A sees the train fading away and becoming smaller. Observer B at B sees the train awaking at the horizon and becoming larger. Both tell the truth, but is it the reality? Is the actual train becoming smaller or larger? No. What you need is one reality, one world, one reference frame, one coordination system that both observers agree to use as the basis for all descriptions of all processes.

That means you need some sort of translation of transformation to transform the observed (measured) reality to this real reality. In this real reality the process will evolve. At the end you again need an (inverse) transformation to describe what you actual will observe (measure). This recognition between what we observe (which is observer dependent) and what actual is, is very important, because it is observer independent. In this real reality the actual processes take place. One of the best examples is astronomy i.e. the movement of the stars etc.

In this real reality there is also a clear distinction between processes based on electromagnetic phenomena and gravitational phenomena. The first are related to radiation and light. The second are not related to light, only to gravity i.e. gravitons.

However there more. Many processes take place at microscopic level i.e. at a scale we humans are unable to observe (directly).

Not only that. Our observations are primarily based on light. This is an issue if the processes we want to understand use light signals or radiation, which behaviour itself is also a process. A typical case is a clock.

SNIP

>	The absurdity of this is manifest -- EVERYTHING we observe is consistent with the laws of physics, there is no possibility of "determining".

This is a tricky issue. All our knowledge evolves by try and error. It is a struggle. A typical case is our birds-eye view about the Universe. First we think it is geocentric then heliocentric and now some think it is a multiverse.

>	[Note also that everything we observe is correct (standard meaning) -- it simply is not possible to make incorrect observations. It is possible to interpret observations incorrectly, and when that happens competent scientists fix the error.]

Most important is the accuracy of our observations and measurements. i.e. to make a difference between qualitative and quantitative. As such the distinction between classical mechanics and quantum mechanics is vague.

>

In fact, science and physics are about modeling the world we inhabit. We have learned that the phrase "the laws of physics" is a chimera, and today we formulate MODELS, not "laws". For the simple reason that we now know that humans can never know the actual Laws used by Nature, the best we can possibly do is to approximate them, and that is not at all the same.

The meaning of chimera is illusion (Webster 1967). Models, Mathematical equations, Laws are each an approximation of the physical reality. It is wrong to claim that the world is controlled or operate accordingly to any law (Newton's Law, SR, GR). Related to chemical reactions the laws that describe these reactions enforce certain limitations. We humans are 'controlled' by DNA. These three laws mentioned only describe a small subset of the full physical total. In many cases starting point should be a model (of a human, a plant, our economy or life on earth) of what we want to study, in order to understand how it mechanical or physical (economical) functions and or operates. The main objective (if possible) is to try to improve the processes involved.

Above I have mentioned to try to describe the physical processes in a certain abstract manner, independent of human observations. Electromagnetic and mechanical processes (the movement of falling objects) are clearly different. In that sense I'm also not in favour to try to unite these processes into one. That does not mean that the mathematics that describe these processes can not be the (more or less) the same. When you remove the observation aspects, the underlying mechanical processes become simpler. Also when all observations are based on one clock (or a set of synchronised clocks, which its own problems) you have the same effect. My philosophy is that mechanical processes don't use photons nor a clock in order to evolve as they do. For human processes this is different. Just some 'random' thoughts.

Nicolaas Vroom

35 Simplifying Einstein's Thought Experiments

> >	The speed of light can be used as a "preferred" reference frame.

>	That will be hard to do because the clock on the light beam always reads 0.

And every other clock in the universe ticks at a faster rate relative to that zero.

> >	When you talk about "frames of reference" where observers are imagined to be "stationary," you create a FICTION where each observer sees the other observer as moving.

>	The only way to remove that "FICTION" isd to find an absolute reference frame. But wait Einstein said there is NO absolute frame of reference.

Einstein said NO SUCH THING. He said that the ether was "superfluous," which means it is "not necessary." If you use clock tick rates to measure motion, and clocks stop at the speed of light which is also the speed limit in the universe, then you do not need the ether. All motion is relative to the point where time stops.

Personally, I would use the other end of the scale. Instead of using a moving spot that travels at the speed of light as zero, I would use a place where clocks tick at their FASTEST rate because a clock is stationary at that point. All speeds in the universe would be relative to that point. Where is it? I could tell you, but it would just generate a new argument. Scientists used Einstein's equations to determine its existence.

> >

Instead, you should do as Einstein recommended and have the observers COMPARE the tick rates of their clocks. The clock that is moving the fastest will tick at the slowest rate. Thus, instead of fantasizing that you are stationary and the other observer is moving, you can determine who is ACTUALLY moving faster than whom.

>	That is the problem, You cannot tell who is "ACTUALLY" moving. Einstein never made such a statement that it would tell you who is "ACTUALLY" moving.

That is because, in Einstein's universe, EVERYTHING IS MOVING. So, the question is not who is actually moving, the only question is: Who is moving FASTER or SLOWER than whom?

>	Do you agree that some of your statements, especially with the CAPITALIZATION, are describing an absolute reference frame. Or at the least seem to imply it?

I have no problem with using a time of zero at the speed of light and/or an imagined stationary point in space where time ticks at its fastest rate as an "absolute reference frame." For hundreds of years mathematicians used an IMAGINARY ETHER as a "preferred reference frame." Until they find something better, why can't they use an assumed stationary point in the universe where time ticks at its fastest rate as a "preferred reference frame"? We KNOW there is no ether. We do NOT know that there is no stationary point in the universe. Supposedly the universe sprang from such a point.

Ed

[[Mod. note -- As Tom Roberts (& others) have pointed out, in order to directly compare clocks A and B, A and B must be colocated for the duration of the comparison, i.e., they must be at the same position and (be observed by *all* observers to be) moving at the same velocity.

If these conditions don't hold, then we can't directly compare A and B. We may be able to compare (say) A to signals broadcast by B, but that's a rather different sort of (indirect) comparison. -- jt]]

36 Simplifying Einstein's Thought Experiments

>	Nicolaas Vroom

Very nice commentary. I cut it short because I have a short and simple comment.

Of course the first variation of this that I learned is in the form of two of Murphy's laws

Mother nature sides with the hidden flaw. and Mother nature is a b!^(#

I have heard other variations on this idea, but a good friend of mine sums it up this way:

All theories are wrong. Some are useful.

Keeping that idea in mind has hopefully helped me be humble in some of these discussions. I don't have the ANSWER. I don't KNOW the TRUTH. I can only accept the best information and best interpretation available.

Ed P

[[Mod. note -- Another variant on this idea is: The Three Laws of Thermodynamics: 1) You can't win, only lose or break even. 2) You can only break even at absolute zero. 3) You can't get to absolute zero. -- jt]]

37 Simplifying Einstein's Thought Experiments

yes, but this statement:

>	All motion is relative to the point where time stops.

is nonsense. You cannot calculate relative to that clock because you end up calculating 0/0. NAN

>

Personally, I would use the other end of the scale. Instead of using a moving spot that travels at the speed of light as zero, I would use a place where clocks tick at their FASTEST rate because a clock is stationary at that point. All speeds in the universe would be relative to that point. Where is it? I could tell you, but it would just generate a new argument. Scientists used Einstein's equations to determine its existence.

But there is no such clock (reference frame). If you have some mystical revelation providing this, please share.

>

> > >

Instead, you should do as Einstein recommended and have the observers COMPARE the tick rates of their clocks. The clock that is moving the fastest will tick at the slowest rate. Thus, instead of fantasizing that you are stationary and the other observer is moving, you can determine who is ACTUALLY moving faster than whom.

> >	That is the problem, You cannot tell who is "ACTUALLY" moving. Einstein never made such a statement that it would tell you who is "ACTUALLY" moving.

>	That is because, in Einstein's universe, EVERYTHING IS MOVING. So, the question is not who is actually moving, the only question is: Who is moving FASTER or SLOWER than whom?

You are still grasping for an absolute frame. Einstein did not say everything is moving. (If you have a quote, you can correct me) He said motion is measured relative to a frame of reference.

> >	Do you agree that some of your statements, especially with the CAPITALIZATION, are describing an absolute reference frame. Or at the least seem to imply it?

>	I have no problem with using a time of zero at the speed of light and/or an imagined stationary point in space where time ticks at its fastest rate as an "absolute reference frame."

We can imagine such a point, but I honestly see no way to locate it except as the place where I sit right now

>	For hundreds of years mathematicians used an IMAGINARY ETHER as a "preferred reference frame."

Well philosophers, not mathematicians, discussed the idea and it started about 2 millenia ago.

>

Until they find something better, why can't they use an assumed stationary point in the universe where time ticks at its fastest rate as a "preferred reference frame"? We KNOW there is no ether. We do NOT know that there is no stationary point in the universe. Supposedly the universe sprang from such a point. Ed

Even if the universe began as a point-like location, it now has no definable/observable center point.

>

[[Mod. note -- As Tom Roberts (& others) have pointed out, in order to directly compare clocks A and B, A and B must be colocated for the duration of the comparison, i.e., they must be at the same position and (be observed by *all* observers to be) moving at the same velocity. If these conditions don't hold, then we can't directly compare A and B. We may be able to compare (say) A to signals broadcast by B, but that's a rather different sort of (indirect) comparison. -- jt]]

Thank you, jt.

Ed P.

38 Simplifying Einstein's Thought Experiments

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>

[[Mod. note -- As Tom Roberts (& others) have pointed out, in order to directly compare clocks A and B, A and B must be colocated for the duration of the comparison, i.e., they must be at the same position and (be observed by *all* observers to be) moving at the same velocity. If these conditions don't hold, then we can't directly compare A and B. We may be able to compare (say) A to signals broadcast by B, but that's a rather different sort of (indirect) comparison. -- jt]]

Sorry, Moderator, but I can make no sense of your post. It seems to require having the same observers in two different places at once.

The problem is to compare a moving clock to a clock that is considered "stationary" (or moving at a slower rate). According to Einstein, that is done by first placing clocks A and B side by side to make certain they are identical and synchronized. Then clock B is moved away and brought back. Due to its movement, the time shown by clock B should then "lag behind" the time shown by clock A. I.e., clock B ran at a slower rate WHILE moving.

How can you compare a moving clock (B) to a "stationary" clock (A) if "A and B must be colocated for the duration of the comparison"?

[[Mod. note -- My apologies for an overly-simplified and (in hindsight) insufficiently clear explanation.

My point was that such a comparison necessarily requires either
(i) some way to transmit B's time readings to A (or A's to B) while the two clocks are in different locations -- in this case the comparison is somewhat indirect, and we need to take the time transmission into account in the comparison; and/or
(ii) waiting until B returns to A to compare their readings (which doesn't give us any information about when/where any difference in readings originated).

If you can get a copy of it (alas I think it's paywalled), the article