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# Relativity And Simple Algebra

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So M, there are a list of statements. Which is the first one you find is in error. Don't be afraid to use your own mind to formulate a thought. It's not really math even though I use the number 15 a lot. Don't you want to learn something?

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So M, there are a list of statements. Which is the first one you find is in error. Don't be afraid to use your own mind to formulate a thought. It's not really math even though I use the number 15 a lot. Don't you want to learn something?

what "list of statements"?  where?

But why have you just done what you always do, skip over my claims of why you are wrong?

Pleas reply to my post #56.

post 56 is my challenge to you, if you have no answer that is rational, then please admit it. Just don't pretend its not there.

show me where its wrong please.

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So M, there are a list of statements. Which is the first one you find is in error. Don't be afraid to use your own mind to formulate a thought. It's not really math even though I use the number 15 a lot. Don't you want to learn something?

I thought you wanted me out of this thread, Ralf.  Like I said, it's not worth even starting on.  There's no way your confusions could all be corrected.  You need to START with some understanding.  Like I said, read up on the difference between relative velocity and absolute velocity, for a start.

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So you can't even point out one mistake then. That's what I thought.

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Some people think that "relative motion" simply means that you have to say what an object is moving "relative to."   That  is incorrect.  Even absolute motion is "relative to" something.

Sometimes it is said that absolute motion is "relative to" absolute space, but that's an over-simplification.  It could be relative to the CMB, for example.  It can be any frame which is designated as a preferred frame.  The main idea is that it is not "frame-dependent."  That  means that all observers will see your speed as being the same, no matter what frame they are in.  You won't have one million different speeds just because there might be one million observers.  But it doesn't have to relate to speed, per se.  Acceleration is considered to be absolute motion, because all observers will agree when an object is accelerating.  Acceleration is an "absolute" effect.

Relative motion, on the other hand, is said to be strictly frame dependent.  Whether an object is moving or not, and at what speed, (allegedly) depends on what frame you're looking from.  It's "relative" in that sense, not absolute.  In SR, this is exemplified by the claim of "reciprocity," i.e that each sees the other guy as moving.

Relative velocity has a meaning outside of SR, of course.  It is simply a consideration of relative speed without regard for absolute speed.  If one guy is going down the road at 100 mph and the other at 80 mph, both will agree that their "relative" speed is 20 mph. They would be able to say that even if neither one had any idea about what his own speed (or the other guy's) actually was.

Does that help, Ralf?

Nothing in the definition or concept of relative velocity has anything to do with imposing an absolute speed limit on anything.

Edited by Moronium
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No we're speaking two different languages and you believe yours is the correct one.

So you don't believe in the relativistic velocity combination formula. So you think 2 ships separating at .5c from earth in opposite directions have a relative velocity to each other  of c not .8c. If they separate from each other at .8c relative to earth, their relative velocity to each other is 1.6 c and not 40/41 c. Oh wait, I forgot you can't do math. That might be the problem.

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No we're speaking two different languages

No question about that.  You seem to have your own *special* language, eh?

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So you don't believe in the relativistic velocity combination formula.

Absolutely not.  It's mathematical bullshit, invented to try to explain other mathematical bullshit.  Believe it if you want.

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So you think 2 ships separating at .5c from earth in opposite directions have a relative velocity to each other  of c not .8c. If they separate from each other at .8c relative to earth, their relative velocity to each other is 1.6 c and not 40/41 c. Oh wait, I forgot you can't do math. That might be the problem.

I don't believe that their true (absolute) speeds have anything to do with their relative speeds (measured as against each other, only).

But, yeah, assuming they were going in opposite directions, if you posited earth as the preferred frame, their "relative" speed would be 1.6, and their absolute speed would be .8.  It would be different if one guy was going north, and the other east (perpendicular to each other).

It's no different than one guy heading south at 100 mph and another guy heading north at 100 mph.  Their relative speed would be 200 mph

That's just one more example of  what relative speed is, and how it differs from absolute speed, btw.

Speaking of math, you are misapplying the relativistic speed formula.  It has no application when you're only considering 2 objects.  It comes in with 3 or more.  If you're trying to include the earth as a 3rd object, then your 40/41 ratio makes no sense out of context.  What would that apply to?

Edited by Moronium
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Using you're example, lets call one of the .8c objects A, and the other B.  Call the earth E.

Now, tell me, if you care to.

1.  What does A calculate his speed to be relative to E?

What does A calculate his speed to be relative to B?

2.  What does B calculate his speed to be relative to E?

What does B calculate his speed to be relative to A?

3.  What does E calculate his speed to be relative to A?

What does E calculate his speed to be relative to B?

Have fun!  If you like doing math problems you'll love that.   Your answers will be meaningless, but, still.....

Edited by Moronium
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But, just to be clear, the imposition of an absolute speed limit still has nothing to do with the concept or definition of "relative velocity."

A word, let's just say the word "gasoline," could be given a definition which would basically encapsulate the concept.

After that, a question like "how much gasoline is in this tank?" would in no way alter the definition of gasoline.

Failure to recognize that seems to be one source of your confusion.  I see now that you're confusing quantity with quality.

Edited by Moronium
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.8c, 40/41 c, .8c, .9756c, .8c, .8c

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.8c, 40/41 c, .8c, .9756c, .8c, .8c

Great work!  Now, do you think that, as a matter of physics (not math) ALL those relative speeds are correct?

Edited by Moronium
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Another question.  Let's get these figures in here too.

What would earth say the relative speed of A and B is?

What would A say say the relative speed of E and B is?

What would B say say the relative speed of E and A is?

More math for you!  You should be in hog heaven, eh?

Edited by Moronium
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everyone know that.

What I'm saying is that you are making a fatal mistake to TRY to use a distance in the vertical axis, it the horizontal axis is already a distance axis.

With both axies being distance axies,  you no longer have a GRAPH, you don't have any vectors that represent velocity.

What you do have now is just a ordinary 2D map of Cartesian coordinates.

It is a MAP, showing locations ONLY, its can't show speed vectors,  any lines would represent ROADS traveled on.

any school child KNOWS that!

Please admit that fact, and lets move on to something more interesting that has SOME chance of being real.

Yes, it is a map of paths through spacetime and the velocities are shown by the inverse slope of the path lines.

For example, a photon moving at c will cover the vertical distance ct and that will be the same distance it travels along the X axis. So, the run is equal to the rise on the diagram and the inverse slope is equal to 1, indicating the velocity is 1c, as it must be for a photon.

Note that It is the inverse slope because run/rise is used instead of the more familiar rise/run ratio.

Real particles always move slower than c, and their paths will travel less distance along the X axis, so the angle the path makes with the X axis is greater than 45 Degrees and the inverse slope is less than 1.

Another example, If the angle is 60 degrees, the run/rise ratio is .577 and the velocity is 0.577c

You might consider understanding these ideas first, before you criticize them and sound foolish.

Just a suggestion.

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"Another question.  Let's get these figures in here too.

What would earth say the relative speed of A and B is?

What would A say say the relative speed of E and B is?

What would B say say the relative speed of E and A is?

More math for you!  You should be in hog heaven, eh?"

1.The first question is tricky. The standard answer is 1.6c if they're separating but it would be 0c if they were moving side by side. But that's not the trick because we're only talking about them separating. The trick in relativity is if relative velocity causes reciprocal time dilation then knowing the time dilation, one should be able to work back the relative velocity which caused it. Time dilation is not dependent on the direction of the relative velocity. The Earth would calculate them to have the same age whether they flew side by side or apart so it would see 0 time dilation between them from its perspective which means 0 relative velocity.

There are errors in this paragraph corrected in post #89

In the Hafele Keating experiment, two planes  flying together in a polar orbit would have a different relative velocity between each other from the earth's perspective flying in polar orbits in opposite directions but the Earth's perspective of their time dilation would be zero indicating zero relative velocity between the two. Their time dilation relative relative to their earth orbit must be the same so their time dilation relative to each other must be zero. I've stated this contradiction many times but relativists, just like any crank, redact it from consideration because this question is outside their recited scripts.

2. The same trick but different answers. Alice, from her 3rd party perspective of E and B's relative velocity would see .8c between them which would be consistent with the time dilation result between them from A's perspective. In the H-K experiment above, Alice's perspective of Bob's time dilation relative to the earth would be consistent with his linearized orbital speed around the earth.

3. Similarly, B would say E and A's relative velocity would be .8c which matches the time dilation result  between E and A from B's perspective.

I had to spend a lot of time thinking on these answers. I'm sure there will be a great deal of disagreement on them.

Edited by ralfcis
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I had to spend a lot of time thinking on these answers. I'm sure there would be a great deal of disagreement on them.

Well, doesn't sound right, Ralf.  If B says A and E are going .8c relative to each other, and sees himself going .97 relative to A, that only leaves .17c between him and E, right?

But earlier you said he saw himself going .8 relative to E, didn't you?  How can both answers be right?

Edited by Moronium

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