---

Map of a Moving Reference Frame - Implications

---

• Newton's picture
• Clock sychronization
• Einstein's picture
• There is no such thing as "now"

Maps of Space

---

Newton: Time is the same for all observers no matter how fast they are moving.

They all agree on which events happen at t=0 --- They all have the same space axes.

Shifting to a moving frame of reference just means drawing a new time axis.

Implications --- Example: --- Question:

---

Observer A sends a radio message to B. If B replys immediately, then A can figure out exactly when B replied.

The speed of light never changes, so the reply must have happened exactly halfway between the sending time and the receiving time.

Implications --- Example: --- Question:

---

Spacetime diagram of a moving reference frame from Einstein's point of view:

Move the time axis and the space axis.
The world-line of a light signal from the origin stays exactly between the new axes.

Implications --- Example: --- Question:

There is a price for having all observers agree on the speed of light. Events which are simultaneous in one inertial reference frame are not necessarily simultaneous in another.

Implications --- Example: --- Question: