At the risk of "question flooding"...

RussT,

3A. (35, 91) What is a paradox?

3C. (35, 91) Why is it impossible to consider the Earth to be in motion if we have ten other objects to consider?

3D. (35, 91) Is it impossible to consider the Earth to be in motion if we have to consider the other planets, Pluto, and the Sun?

The galaxies only seem to move relative to him. He does not cause them to move! The word is Relative. Relative velocity.

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“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

He IS not 'suddenly' at rest, he IMAGINES he is at rest. He CHOOSES to IMAGINE that the X, Y and Z axis that he uses to measure stuff against have the origin in HIS location, moving WITH him as HE moves. He still moves. He only IMAGINES that he does not, and that the axes do not.

He does NOT cause anything to move by IMAGINING to be at rest. If he IMAGINES to be at rest, then the rest of the universe SEEMS to move.

In reality? Everything moves. But it only makes sense to speak about how it moves, by choosing a reference point.

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"Ignorance more frequently begets confidence than does knowledge" -- Charles Darwin
"Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
Meet the OOONG TOE.

I don't think that Russ will be able to grasp the concept (sorry, Russ),
but every citation of a speed of something could be replaced with a
citation of the speed between that thing and some other thing.

For example, instead of saying that a car is moving at 65 mph, say that
the relative speed between the road and the car is 65 mph.

This applies to every speed in every situation, everywhere.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

Maybe we should add, that if I am on a bicycle moving at 15 mph towards the car, the car seems to be coming at 80 mph towards me... I did not make it move faster...

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“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

I could turn it around and ask, why is the simple obvious concept of relative velocity not something you understand when it's so simple to us?

Is it the problem of trying to explain by example, where you don't understand which part of the example are idealized away as irrelevant for explaining the concept?

When trying to explain relative velocity by talking about e.g. a car and a bicycle, you may not get that we're ignoring gravity, the rotation of the earth, whether it's raining or not, air resistance, that light moves slightly slower in air than in vacuum, that the car is red and that the driver's name is Bob, and that we, for this example is using speeds where relativistic effects are negligible, because none of those things are relevant to get an initial idea about the concept of relative velocity.

When talking Twin Paradox, putting one twin on the Earth will hopelessly complicate things if you start including the mass of the Earth and it's rotation and movement around the Sun, which is why I explicitly ignored them because I was trying to explain the concept of relative velocity.

It may be that you've missed one of the lies-to-children steps, so you're thinking at things at a complicated level without the required basis of an understanding of the simpler version first to keep you grounded.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

I can only offer the thought that simple and obvious are not always closely related. Humans are macroscopic creatures subject to gravity and observant of a world where friction rules and the earth doesn't move. Constant velocity in normal life doesn't really exist (to keep the car going you have to press the gas pedal). Walk away from someone just standing there and you can SEE his legs aren't moving and he occupies the same spot on the ground. Making the leap to relative velocity in the face of such things really does require a significant mental rearrangment.

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If they can get you asking the wrong questions, they don't have to worry about the answers.

I think you don't get the whole idea of explaining a concept by taking the simplest possible scenario where that concept is relevant and look at it in that context before trying to use it to explain something complicated.

I stopped looking at your setup once I realized that you don't understand the concept of relative velocities and have been trying to explain that, not your setup, since a basic understanding of the concept of relative velocities is crucial to making sense of any explanation of your complicated thing.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

RussT from my point of view the Earth is still and the Sun and all the Stars move round. Is the Earth moving them?

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Really? Even after using the bathroom on a plane?

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There are 10 types of people in the world. Those who understand ternary, those who don't, and those waiting for a bus.
If logic doesn't work, then surely it does.

First, let me compliment and commend everyone for the very high degree of diplorum that is evident in this thread!!! Obviously the "Rules Discussions" have accomplished a great deal... Everyone is handling "just dealing with the issues" very nicely!

Actually, this is an excellent example/point of just how tricky and crucially important it is to consider anything "At Rest"...

I fully understand that all motion is Relative, and that everything in our Universe is moving. All of these Earth examples you guys are using are not even SR or GR or SR>>GR.

I am simply saying that the SR set up of swapping one observers motion for the others motion, when at least one of them is considered 'at rest' results in GIGO...No proper picture/description of "Reality".

Half of you are saying two different things.
1. that the 'earth onbserver'/earth/sun are NOT really moving in the way the rocket observer sees them moving...and
2. that what the rocket observers see as their motion is them really moving at the speeds he/she sees them/earth/sun moving...as per Northern Boy.
SO, for #1, just as in Captains Swoop's example, we "Know" that the earth/sun are NOT moving as "Imagined" by the rocket observers, therefore GIGO....Non-Reality!

And for #2 same thing,... GIGO...just flat impossible.

The ONLY way what you guys are saying works is IF you are in Einstein's "Empty Universe", where the At Rest Observer(s) are not gravitationally bound to anything.

Jeff Root, this just goes directly to my statement in our other thread...

That our 'Earth Rest Frame' observer, you know, the ones that see light travel at 186,282.397 mps, to specified known distances, is the only one seeing "Reality"

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

You need to point out why. Your argument so far as to why you think that it is incorrect seems to boil down to personal incredulity, and repeated assertions that it makes no sense to you.

You seem to be making the truly bizarre assertion that the motion of this speck of dust orbiting a nondescript star somewhere out towards the periphery of one unspectacular galaxy somehow defines what is "real" for the rest of the universe.

You are going to need to justify this assertion. So far, you have not done so. In fact, all that you have done so far is to keep adding complications as soon as you appear to be getting backed into a corner.

So, here's a direct question. A rocket is approaching earth at 0.5c, as agreed by the guy on the rocket, and me on earth. Why do you claim that the observer in the rocket is wrong to consider himself stationary?

And is this anything other than semantics on your part? Do you believe that the preferred frame of the earth means that we can design an experiment to be done on the rocket that will show that is definitely moving, rather than just to say that ot is moving relative to the earth?

This is going to make physics quite an interesting challenge for the scientists at the Grr'kt Institue on the planet Tharg. I suppose eventually they will fugure out that those pesky humans are at the center of the universe, and that will explain all their anomolous results.

Yep. You just can't think about it in an abstract way without going wrong.

That is exactly right, and already you're running into trouble. We're not even close to time and space and gravity doing their funny thing yet.

RussT, you don't even understand Newtonian relativity. Before you understand this level of abstract thinking, and this geometry, the trick of imagining looking from other perspectives, you don't have a snowflake's chance in a warm place of getting Einstein's, and trying to get Einstein now will only detract you from getting Newton/Galileo understanding of relative motion right.

All of us are saying exactly the same thing. Exactly. Really. It is your misunderstanding that makes you think we don't.

As long as you can't agree with all the posts in this thread, you don't understand the concept of thinking of velocities in an abstract way. Without spacetime doing funny things. Just looking at relative motion from different perspectives, and choosing the origin of your coordinate system to be there, is beyond you. And that's nothing to do with Einstein. Not even close.

__________________
"Ignorance more frequently begets confidence than does knowledge" -- Charles Darwin
"Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
Meet the OOONG TOE.

If you understand relative velocity, you must admit it is OK to swap between the two points of view (frames of reference) for "normal" movement - e.g. you can calculate relative speed and the effect of an impact between two cars by considering them both heading towards each other at 50kph or by assuming either is stationary and the other is doing 100kph. The results are the same. (OK, there might be some really tiny effects like static friction, air resistance, etc. but they aren't relevant - make them air hockey pucks, if you prefer.)

Why is it suddenly not valid to do that for SR?

You seem to see some sort of difference between the observer imagining their rocket is in at rest and the earth moving towards them and their rocket "really" being at rest and the earth actually moving towards them.

This is a false dichotomy - the observer in the rocket knows he is in control of the velocity between them and his puny engine cannot move the entire universe. But that doesn't matter. If he chooses to do the calculations as if he is at rest or as if the earth is at rest ... well ... I don't know what to say ... it all just works ... that's just the way it is.

I guess it might be different if the earth really was the stationary point at the center of the universe, as you seem to imply, but it isn't.

Exactly. That is the nub of the whole thing.

If the earth is truly stationary and everything else in motion, you should be able to measure that. Can you?

I like the idea of Clint Eastwood delivering that line, "well punk, can you?"

Do you disagree that if I carried out an experiment, purely internal to the rocket (but in a vacuum chamber) that has a relative velocity of 0.5c relative to the Earth, that I would measure the speed of light to be 299792458 m/s?

RussT, everyone sees light travel at 299,792,458 m/s (please use accurate numbers), that's another thing you don't get.

That's a measurable fact of how the universe really behaves.

Your refusal to believe this makes everything you think you know about SR and GR irrelevant to this universe, and every thought experiment you make based on a disbelief in this will be utterly useless for talking about this universe.

With "this universe" I'm talking about the one we're physically inhabiting, not about one in anyone's head.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

Henrik, I'll have to jump to Russ' defense here. I believe he is using accurate numbers. I think his mps is MILES per second, not meters per second. Of course, that begs the question of why in the world he's using the English system when everything in science uses the Metric system.

As to Russ' misconceptions, it was obvious a couple of years ago that he didn't fully understand relativity (his claims to the contrary not withstanding). He would be upset with me telling him he didn't understand relativity. Now he's got a whole thread of posters telling him that.

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Some try to tell me, thoughts they cannot defend,... - Moody Blues.

Neptune- The original Dark Matter.

The author feels that this technique of deliberately lying will actually make it easier for you to learn the ideas. - Donald Knuth

I knew the speed of light as 186,282 miles per second long before I learned
that it is 299,792,458 metres per second. And since I learned it in scientific
notation I annoyingly always stick a decimal point after the initial '2', then
have to puzzle out where I really want the commas.

Russ,

Can you clarify what you meant by your remark:
It isn't possible that you would think observers on Earth are the only ones
who see things as they actually are, and you know that observers in all
locations measure the speed of light the same, namely 186,282.397 mph
as you say, so I can't imagine what you meant by that remark.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

I knew he was talking miles per second, but since he in a previous post was talking about going .99999999999999c, he needs a value of c that's at least that precise, which 186282.397 miles per second or .999999999725c isn't, 299,792,458 m/s is precise however.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

After finding how fundamental your misunderstanding of mainstream physics is, it'd be silly to continue the original questions since it's clear you don't understand them and we wouldn't understand your answers.

Trying to build the foundation for a common language is the only way likely to get useful results.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

I explained this in Post #81...
And, The reason I use .999999999999999c (Without counting the 9's) is just to stipulate travel as close to "c" as possible without actually reaching it, to avoid the obvious arguements that always come when saying anything with 'mass' is/can travel at "c".

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

Ahhhhh, I stand corrected. Thanks for enlightening me.

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Some try to tell me, thoughts they cannot defend,... - Moody Blues.

Neptune- The original Dark Matter.

The author feels that this technique of deliberately lying will actually make it easier for you to learn the ideas. - Donald Knuth

What I think RussT is saying (correct me RussT if I am wrong), is that there is no such thing as an inertial frame of reference, because all objects in the universe are subjected to some gravitational pull.

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______________________________________________
“He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever”
Chinese proverb
"All you need in this life is ignorance and confidence - and then success is sure." - Mark Twain.

Perhaps, but how would you verify that those words mean the same to him as to us?

__________________
"Ignorance more frequently begets confidence than does knowledge" -- Charles Darwin
"Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
Meet the OOONG TOE.

Is that actually the original or is it translated from German?

Yes, I know we're talking the speed of light in an absolute vacuum, speed of light without a qualifier is a shorthand for that.

I've seen this quote used several times by people believing in an absolute rest frame and they always fail to get that Einstein is actually saying that the speed of light in a vacuum as measured by everyone regardless of their movement is constant.
This is the basis of SR and it's experimentally verified. It doesn't matter if you don't want to believe this, this is how light actually really behaves in the universe you're actually really living in.

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‘To those who regard “crime fiction” as some sacred icon which must follow a rigid formula, I will always be the man who writes 18-syllable haiku.’Trying to make sense of computers, The Error Log.

While this is probably correct...ie: everything in space is either speeding up or slowing down, it is not my main point.

My main point is that none of those 'spaceships' motions, accelerating or inertial, has absolutely any effect on any 'earth rest frame' observer.

But it even goes farther than that...IF all of those ships took off from the ISS, with their twins left on board, if after 1 minute they all turned off their engines and became inertial... considering each of the traveling ships twins to be 'at rest' has no effect what-so-ever on the ISS's motion...we've got billions of observers verifying the ISS is still following it's same path.

Consider a manned flight to mars with the twins on board...same thing...the ship is just following it's arced path, with twins weightless and engines off...if the rockets with the twins took off from that mars bound ship, and after 1 minute of travel, turned off their engines and became inertial, would the mars bound twins/ship's motion be altered.....NO

In fact, just because one thing is moving, there is NO relationship between something else moving....UNLESS there is some force "Causing" it to move.

Newtons Law...Now, maybe you guys/mainstream think that because in Einstein's SR/GR universe, gravity is NOT a force, so you think you have been able to justify this for the past 100 years....then I will ask the question this way, to satisfy slangs...
Perhaps, but how would you verify that those words mean the same to him as to us?

Please explain how, in the different scenarios I have presented, that the "Geodesics" of the stay at home twins have been altered...

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RussT
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Everything is, as it should be, otherwise, it wouldn't be!

That isn't anything we don't already know, Russ.

Nobody has EVER said that that the changing views of one observer
have any effect on other observers, or on the thing being observed.

What has been said, and what special relativity says, is that when an
observer's frame of reference changes, such as by accelerating, what
that observer sees will change.

You have been arguing over and over and over for something that we
all already agree with.

The observers on Earth see the path of the ISS as unchanged relative
to THEM. The observers on the rockets see the path of the ISS change
relative to THEM.

Nobody has EVER claimed that they have been altered. The relationship
between the stay at home twin and the travelling twin is what is altered,
in the way that has been explained many, many times.

-- Jeff, in Minneapolis

__________________
http://www.FreeMars.org/jeff/

"I find astronomy very interesting, but I wouldn't if I thought we
were just going to sit here and look." -- "Van Rijn"

"The other planets? Well, they just happen to be there, but the
point of rockets is to explore them!" -- Kai Yeves

And this is the point of special and general relativity. It is one of the fundamental principles of relativity theory and it is spelled out very explicitly in every textbook.

But this does nothing to answer my questions.

3A. (35, 91, 120) What is a paradox?

3C. (35, 91, 120) Why is it impossible to consider the Earth to be in motion if we have ten other objects to consider?

3D. (35, 91, 120) Is it impossible to consider the Earth to be in motion if we have to consider the other planets, Pluto, and the Sun?

120A. How is it legitimate to introduce gravity into a scenario to produce a paradox for a theory that very explicitly does not cover cases where gravitation is a factor?