# relative... but how relative?

• February 19th, 2008, 07:17 AM
DivideByZero
relative... but how relative?
A space ship traveling 1,000 miles per hour
and another space ship traveling 100,000 miles per hour
have relative time right?
each has its own time?

But how far can one go when explaining time?
person A has a different time than person B.
person A's right hand has a different relative time than his left hand.
His pinky has a different time than his thumb.
you see where I'm going with this..?
how far does time break up?
• February 19th, 2008, 07:36 AM
Quantime
At infinitely small and infintely large distances. Every object in the universe has its own relative time.
• February 19th, 2008, 08:20 AM
mitchellmckain
Re: relative... but how relative?
Quote:

Originally Posted by DivideByZero
A space ship traveling 1,000 miles per hour
and another space ship traveling 100,000 miles per hour
have relative time right?
each has its own time?

But how far can one go when explaining time?
person A has a different time than person B.
person A's right hand has a different relative time than his left hand.
His pinky has a different time than his thumb.
you see where I'm going with this..?
how far does time break up?

This is nonsense. The relativity of simultaneity can only apply to objects moving at a speed relative to you. If your hands are moving at relativistic speeds with respect to your eyes and brain, then you are in big trouble.

In other words person A only sees a time differental across person B, and person B only sees a time differential across person A. No one sees a time differential between his own right hand and left hand.

How much is this time differential? if they are going in the same direction then the relative speed is 99,000 mph = 44000 m/s = .000147 c
The contraction factor gamma for this is 1.000000011
So assuming that the right hand of B is 1m ahead of his left hand, which is .000000003 light seconds.
Then person A will see the right hand of B as lagging in time behind B's left hand by about (using the lorentz transformations)
tBright = 1.000000011(0-.000147*0) = 0
tBleft = 1.000000011(0-.000147*.0000000033) = -.49 picoseconds
with a physical separation of
xAright = 1.000000011(0+.000147*0) = 0
xAleft = 1.000000011(.0000000033+.000147*(-.49x10^-12))
= 1.000000011(.0000000033 - 7.2x10^-17)
= 3.2999999642999996e-009
which is a discrepancy of 3.57x10^-17 light seconds
or 1.07x10^-8 m = 107 Angstroms
Which is about 36 oxygen molecules lined up end to end.

An easier way to calculate the physical separation alone is with the length contraction formula
1m/1.000000011 = .999999989
which is a discrepancy of 1.1x10^-8 = 110 Angstroms
This is the more accurate answer because there is round off error in the previous calculation.
• February 19th, 2008, 03:42 PM
DivideByZero
Re: relative... but how relative?
Quote:

Originally Posted by mitchellmckain
Quote:

Originally Posted by DivideByZero
A space ship traveling 1,000 miles per hour
and another space ship traveling 100,000 miles per hour
have relative time right?
each has its own time?

But how far can one go when explaining time?
person A has a different time than person B.
person A's right hand has a different relative time than his left hand.
His pinky has a different time than his thumb.
you see where I'm going with this..?
how far does time break up?

This is nonsense. The relativity of simultaneity can only apply to objects moving at a speed relative to you. If your hands are moving at relativistic speeds with respect to your eyes and brain, then you are in big trouble.

In other words person A only sees a time differental across person B, and person B only sees a time differential across person A. No one sees a time differential between his own right hand and left hand.

Well, the left had has a relatively different time than the right hand.
you can compare it to two people holding a rope. person A on one end, person B on the other. Although a rope is connecting person A to person B, the personal relative speeds of A and B are not the same.
So think of person A as left arm, person B as right arm and the rope as your chest.