David and Lily's presentation for iSPI

1. Invariant speed of Light—
second postulate of special
relativity
David
Lily
P
Proton,
Photon,
Pion,
Physics,
...
[ ] Ding

2. Light speed is...constant ？
Suppose ：
A proton is
running at 99% of
the light speed.
Its name is Poppy
1
A beam of light
passes by
Poppy
2
As observers, we
see Poppy goes
almost as fast as
light
3
However, Poppy
feels that light
goes as fast as it
used to be
4
P

3. Stellar Aberration
2 methods to approach
Michelson-Morley
Experiment(1887)

4. Michelson-
Morley
Experiment

5. Assumption: one fixed star emits
two types of light with different
speed----c and C (c>C)
Because c and C are both
constant, observer can receive
them at the same time.
As a result, c and C didn't depart
simultaneously from the star.
Stellar
Aberration

6. If the
difference
is 13 m/s,
1
the star, which is 30 lower
light yr far away, will exist at
the same time BOTH at site
A and B where the angular
distance is 10'.
2
If the star light is
changing
constantly in the
range C~c,
3
the star should
look like a LINE
which is 10' long.
4
But this line is
never seen,
5
so...
6
Conclusion

7. The speed of light seems to never change
RESULT

8. In fact, vacuum speed of light
is constant----Maxwell Equation in 1861

9. Lorentz Transformation (1892-1904)
in order to explain the baffling outcome of the
1887 ether-wind experiment of Michelson and
Morley. In 1892, Lorentz independently
FitzGerald-Lorentz contraction hypothesis

10. ☺
POPPY → US
→

11. P P
WE → POPPY
→

12. How Lorentz Transformation works
Invariance of speed of light (Second Postulate of Special
Relativity):
For two events A and B
(x1,x2,x3,t) and (y1, y2, y3, s) on one inertial reference
frame M, and
(x1’, x2’, x3’, t’) and (y1’, y2’, y3’, s’) on another inertial
reference frame N
---->space-time interval is invariant

13. Derivation

16. Mysteries and Further development
1. EPR paradox
2. Gravity, General Relativity,
and Black Hole
3. Relationship between light
and space&time

17. THANKS!