Re: The train and the light inside.


tomgee wrote:
PD wrote:
[snip]

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.

Tom, you're a hoot. I ask you if an object A can have a constant zero
velocity with respect to another object B, and you say only if object B
has the same speed and direction as object A. I then ask you if an
object A can have a 32 mph eastward veloocity with respect to another
object B, and you say only if object B has the same speed and direction
as object A.
Do you have ANY idea what you're babbling about when you spend so much
time babbling it? Is your time really so worthless that you've got
nothing better to do with it than babble?


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.

Oh dear, Tom. You've outdone yourself in patently stupid remarks.

Let's back up. When I walk backward at 3 mph in a train going 94 mph,
is my speed relative to the tracks greater or less than the train's
speed relative to the tracks?

You do know what "speed relative to the tracks" means, don't you?
You do know what 94 mph is measured with respect to, don't you?


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.

Not so, Tom. You've not explained why I need to do *plus* or *minus*
for the train, depending on which way I walk in the train, but I have
to do plus and plus only, regardless of which way I walk on the Earth.

PD

.

Relevant Pages

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