Date post: | 20-Jan-2016 |
Category: |
Documents |
Upload: | lynne-french |
View: | 229 times |
Download: | 1 times |
• Special theory of relativity (1905)• general theory of relativity
M.C. Chang
Dept of Phys
Space and time
Newton Post-Newton
Inertial frame and noninertial frame
The velocity of light
100+200=300
C+C=2C?
C=299792458 m/s
The velocity of light is the same to all observers (in inertial frames)
Simultaneity
There is no unique “now”.
Time dilation (a moving clock ticks slower)
ct
vtct’
2 2 2( ) ( ) ( ')ct vt ct
An optical clock
ct’
In 1971, experimenters from the U.S. Naval Observatory undertook an experiment to test time dilation .
Eastward Journey Westward Journey
Predicted -40 +/- 23 ns + 275 +/- 21 ns
Measured -59 +/- 10 ns + 273 +/- 7 ns
The twin paradox
Relative point of view
Length contraction
(a moving object shrinks)
The barn-pole paradox
Relativistic mass
(a moving object becomes heavier)
Nothing m
oves faster than the speed of light
The most famous formula in the world
由氘及氚組成的靶
Nuclear fusion
deuterium
tritium
L. Livermore National Lab.
核融合設施 (NIF)
• Special theory of relativity• general theory of relativity (the theory of gravity, 1916)
Objects of different weights fall at the same speed
The principle of equivalence
=
The bending of light by gravity
Gravitational lens
Relativity in GPS (Global Positioning System) with on-board atomic clocks
Accuracy: 30 nanosecond → 15 meters
USD 350
Relativistic effect:
Faster by -7+45=38 microsec per day = an error of 11 km!
(g/4)
Gravity slows down a clock
Gravity balanced by pressure
a space-time singularity
Gravitational collapse will always occur on any star over 5 solar masses, inevitably producing a black hole
Schwarzschild radius (1916)
Black hole
LIGO
Laser Interferometer Gravitational Wave Observatory, Hanford, WA + Livingston, LA
Detecting gravitational wave
Lisa (launch > 2018 )
20xx?
Laser Interferometer Space Antenna
a resolution of 20 picometers over a distance of 5 million kilometers !!
The milky way
Our galaxy
2.6 ± 0.2 million times the mass of the Sun
• 2.5 MLYs away
• 0.2 MLYs in diameter
• 10^12 stars
Cluster of galaxy
Large-scale structure of the universe (each blue dot is a galaxy!)
"Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is." The Hitchhiker's Guide to the Galaxy
Shape of the universe
Einstein’s field equation
Cosmological constant (<-> vacuum energy)
http://abyss.uoregon.edu/~js/cosmo/lectures/lec15.html
Λ>0 leads to repulsion
Hubble’s law (1929)
Red shift
1 pc=3.26 ly
(The name was given by Hoyle, 1950)
From Mather’s slide
Age ~ 13 billion yrsOldest galaxy known
Penzias and Wilson 1978
Background radiation (COBE satellite)
Dipole due to earth motion 10-3
Galactic plane 10-5
1% TV static
2006
The universe at age 389000 years
Mather & Smoot
COBE (launched 1989)
WMAP (launched 2001)
angular resolution ~ 0.3°
Space travel
Caution:Slippery ahead
The matricide (or grandpa) paradox
Thank you