Re: The train and the light inside.


PD wrote:
tomgee wrote:
PD wrote:
tomgee wrote:
PD wrote:
tomgee wrote:
PD wrote:
tomgee wrote:
Spaceman wrote:
"Igor" <thoovler@xxxxxxxxxx> wrote in message
news:1140550474.168851.260960@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
And when did you do your experiment that proved that they don't measure
the same speed c?
SNIP

It is not "apparent" that they are not at CV wrt each other. In fact,
it
would look as if they are, since they are moving abreast of each
other and in the same direction (assuming you meant to say that).
Let's say they are moving at CV as they accelerate,

"Moving at CV" with respect to what? The road? Wouldn't that be
incompatible with the fact that they are accelerating?

With Each Other, PD! That's what you said and I said, "at CV wrt each
other". Please try to stay focused, will you?

Then, as I said in the *next line*, that's what I said originally. Note
this does NOT mean they move at "CV" with respect to the road.


"Moving at CV" with respect to each other? That's what I said. They are
not moving *relative* to each other, but that does not mean they are
moving at CV with respect to the road (or anything else). Please reread
what I said and pay attention.

and in such a
case, it can be said that they are at "relative motion" wrt each other.

They cannot be at CV with just "constant relative motion" unless they
are also moving in the same direction as well as moving at the same
speed at any given moment. The difference between CV and your
"constant relative motion" is that CV requires not only that the speed
be identical but that the direction be identical as well.

TomGee, please don't be an idiot. If they are keeping abreast of each
other, of course they are moving in the same direction.

Then why do you ask "Moving at CV with respect to what", fool?"

Because depending on what the "with respect to" refers to, the motion
may or may not be constant velocity. That's why, tomgee.


IOWs, you
can
have "constant relative motion" without having CV if the two cars are
moving opposite each other at the exact same speed.

Example 2: I'm sitting on a train headed east at 97 mph. While I'm
sitting, both the train and I have the same constant speed relative to
the earth (97 mph) and our relative speed is zero.

Yes, you do, but you and the train are not at CV wrt to the earth.

What do you call a *constant* 97 mph while I sit there???

What the hell do you think CV means?

CV is a vector and as such requires the same speed and direction
between two or more objects. Since the train is moving wrt Earth, you
and it cannot be at CV wrt each other.

Do you or do you not think that CV means "constant velocity" with
respect to something?

Yes, of course, but it applies to two or more objects. You cannot have
constant velocity wrt a single object.

Do you or do you not think that a zero velocity with respect to
something is constant velocity?

Only if that "something" is another object moving in the same direction
as the first object.

Do you or do you not think that an unchanging velocity of 32 mph
eastward with respect to a stop sign is constant velocity?

Not unless the unchanging velocity refers to a visible object and the
stop sign is also moving at the same speed and in the same direction as
the other object.

SNIP

One more time: You are in a train stationary at the station. The
earth is moving through space at say, 30000mph, and so you and the
train are also moving at that very same speed as you sit still upon the
earth. You and everything else on the surface of the earth that is
stationary are at CV wrt the earth because you are all moving through
space at the same speed and in the same direction as the earth. If and
when anything stationary moves upon the surface of the earth at, say,
30 mph, it is no longer at CV because it is no longer moving at the
same speed as the earth, but it is now moving at 30 mph faster than the
30000 mph it was moving when it was at CV wrt the earth. Now, it is
moving at 30030 mph (if my math is correct).

Are you sure? If the earth is moving through space from "left" to
"right" in whatever picture you want to make of that motion at 30000
mph (it's not that value, but I'll let you figure out what a better
value might be), and then the train moves on the surface of the earth,
but from "right" to "left" in the same picture, is it going 30030 mph
or 29970 mph?

It does not matter in which direction the earth is moving or at what
speed. An object on its surface is at constant velocity wrt earth only
so long as it is stationary upon the surface of the earth, regardless
of the earth's direction and speed. If the train is moving at 30 mph,
it is no longer at constant velocity wrt the earth, but now it is
moving 30 mph faster than the earth plus or minus the speed gained or
lost by any differences in the directions of the motion of the earth in
space. Any object moving on the earth's suface cannot move at a slower
speed through space than the earth; it can only move faster through
space than the earth.

In order to move about the planet, one must increase their speed from
the speed at which the planet is traveling through space. Wait til you
hear my ideas about AE's silly notion of the spaceship that appears to
us to be sitting on its platform while it is traveling along in curved
space-time!! I don't recommend you get into that until you master CV.

During the time you went off and returned, time for you passed slightly
slower than it did for your TV and the Earth. Meaning that you aged
slightly less than did your TV or the planet. I know it's hard for you
to believe all this, but it's based on SR and the second law of
thermodynamics.

If it so happens that the train is
traveling west, then I think I can argue that the train is traveling
*slower* than the fella on the tracks. Do you see why?

Assuming the experiment declared a certain direction in which the train
is moving, the experiment did not depend on the direction at all since
the two observers were not said to be at CV wrt each other. Direction,
then, does not enter into the experiment, only the fact that one
observer is moving faster than the other.

So, regardless whether I walk to the front of the train or toward the
back of the train (see example 2 above), I'm still traveling faster
than the train.

Yes.

I see. So both 94 mph and 100 mph are both faster than the train's 97
mph with respect to the track.

That's not what I said. They are faster than the earth's motions
through space.

You're not getting it. If by walking in the opposite direction as the
train's motion while inside the train makes me go slower (94 mph) than
the train (97 mph) relative to the earth, then don't you think you
could apply the same idea for motion on the earth that is done in a
direction opposite the earth's motion? Don't you think that could
result in motion that is slower than the earth's motion?

No, not possible for it to move slower than the earth's speed through
space. The earth's motion is through space and any object on its
surface moves at the speed the earth moves _THROUGH SPACE_ plus the
speed at which the object moves.

.

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