2. Electromagnetism
• It is necessary to understand that
electrical charge (positive/negative) and
magnetism (north/south) are different
aspects of the same force --
electomagnetism.
• Oppositely charged objects, such as a
proton and an electron, attract one
another, while particles with the same
charge repel each other.
9. Light energy is carried by particles called
Photons, which move at –the speed of light!!
All photons move in waves-
The distance between wave “peaks” is
called the Wavelength
Different energies of light have longer or shorter
wavelengths…
10. ***The shorter the
wavelength, the
more energy the
photon has
**Remember, no matter what
the wavelength, all light
travels the same speed
11. Speed of light
• Light travels at 300,000,000
meters/second
• It takes 8 minutes for a light wave (or a
photon) to travel from the sun to the earth.
• We see the moon because it reflects the
sun’s light
• It takes 1 second for light reflected off the
moon to reach the earth.
14. Radio
(Low Frequency & Very High
Frequency)
• Emitted by
– Astronomical
Objects
– Radio Station
transmitters
• Detected by
– Ground based
radio
telescopes
– Radios
16. Infrared
(Near and Thermal)
• Emitted by
– Sun and stars
– TV Remote
Controls
– Food Warming
Lights (Thermal)
– Everything at room
temp or above
• Detected by
– Infrared Cameras
– TVs, VCRs,
– Your skin
17. An animal, or a human body, for example, emits
some infrared radiation that can be detected
by an infrared camera
Color is related to temperature
18.
19. Visible
• Emitted by
– The sun and other
astronomical objects
– Laser pointers
– Light bulbs
• Detected by
– Human eyes
– Cameras
– Plants
– Telescopes
20. Color
• White light is not a single colour; it is
made up of a mixture of the seven
colours of the rainbow.
We can demonstrate this by
splitting white light with a
prism:
This is how rainbows are
formed: sunlight is “split up”
by raindrops.
21. The colours of the rainbow:
• Red
• Orange
• Yellow
• Green
• Blue
• Indigo
• Violet
22. Adding colours
• White light can be split up to make separate colours.
These colours can be added together again.
• The primary colours of light are red, blue and green:
Adding blue and red
makes magenta
(purple)
Adding blue and
green makes cyan
(light blue)
Adding all
three makes
white again
Adding red
and green
makes yellow
23. Seeing colour
• The colour an object appears depends on the colours
of light it reflects.
For example, a red book only reflects red light:
White
light
Only red light
is reflected
24. A white hat would reflect all seven colours:
A pair of purple trousers would reflect purple light
(and red and blue, as purple is made up of red and blue):
Purple light
White
light
25. Using coloured light
• If we look at a coloured object in
coloured light we see something
different. For example, consider a
football kit:
White
light
Shorts look blue
Shirt looks red
26. • In different colours of light this kit would look different:
Red
light
Shirt looks red
Shorts look black
Blue
light
Shirt looks black
Shorts look blue
27. Using filters
• Filters can be used to “block” out different colours of light:
Red
Filter
Magenta
Filter
28. Ultraviolet
• Emitted by
– Tanning booths (A)
– The sun (A)
– Black light bulbs (B)
– UV lamps
• Detected by
– Space based UV
detectors
– UV Cameras
– Flying insects (flies)
29. X-ray
• Emitted by
– Astronomical objects
– X-ray machines
– CAT scan machines
– Radioactive minerals
– Airport luggage scanners
• Detected by
– Space based X-ray
detectors
– X-ray film
– CCD detectors
30. Chandra X-ray Observatory
• Chandra is designed to
observe X-rays from high
energy regions of the
universe, such as the
remnants of exploded
stars.
• The most sophisticated
observatory built to date.
• Deployed by the Space
Shuttle Columbia on July
23, 1999,Chandra X-ray
Observatory
31. Gamma Ray
• Emitted by
– Radioactive materials
– Exploding nuclear
weapons
– Gamma-ray bursts
– Solar flares
• Detected by
– Gamma detectors and
astronomical satellites
– Medical imaging detectors
32. Sources of g-ray Emission
• Black holes
• Active Galaxies
• Pulsars
• Diffuse emission
• Supernovae
• Gamma-ray bursts
• Unidentified
33. The potential energy in this rock is about to be
converted to kinetic energy (energy of movement)
Each type of element, due to its unique size, gives
off its own unique wavelengths of light- this allows
astronomers to determine what elements they are
observing
34. Exploring the EMS with
NASA Missions
ASTRO-E2
Chandra
CHIPS Con-X
GALEX
GLAST
HETE-2
INTEGRAL
MAP
RXTE
SWAS
XMM-Newton
Swift
Energy
(eV)
Radio Infrared Visible UV X-ray Gamma ray
35. The sun gives off
the full range of
wavelengths of
light (called the
Electromagnetic
Spectrum)
40. Dicke and Gamov calculated that if the Universe is
cooling, we should be able to detect microwave
radiation throughout the sky …
I’m Gamov
I’m Dicke
42. In 1964, the radiation predicted by Gamov was
detected with this antenna by Penzias and Wilson
antenna
Penzias
Wilson
43. In fact, the snow that you can see on an untuned TV
is also due in part to that radiation emitted by the
Universe!
We’ve a lot of
work today !
44. Original temperature of the radiation : 3000 K
Today, it is only 3 K
The cooling says how far the light has travelled
13,7 billion years : the age of the Universe
45. In 2003, the WMAP satelite took a picture of the
universe with small fluctuations of temperature
46. WMAP measured the same data everywhere.
So, the big-bang must have taken place at the same
time everywhere
48. f Don Lincoln, Fermilab f
Doppler Effect
• The Doppler effect
says that things
moving away from
you look redder than
they would if they
weren’t moving.
• Things moving
towards you look
more blue.
49. f Don Lincoln, Fermilab f
Edwin Hubble
• Using the Doppler effect, Edwin
Hubble discovered that when we
look at the universe everything is
redder.
• The only explanation for
everything moving away from us
is that the universe is expanding.
50. f Don Lincoln, Fermilab f
If the universe is cooling and
the universe is expanding,
the simple explanation is that it
used to be smaller and hotter
51. f Don Lincoln, Fermilab f
So what does heat have to do
with anything?
52. f Don Lincoln, Fermilab f
Heat is Energy and according to
Einstein…
53. f Don Lincoln, Fermilab f
E = m c2
Energy is Matter
Matter is Energy
Lots of energy makes
lots of matter
and vice versa!!!!!!
54. f Don Lincoln, Fermilab f
Consider an Ice Cube
• Heat it and it
– Melts
– Boils
– Turns to steam
– H2O breaks up into hydrogen and oxygen
atoms
– The electrons get ripped off the atoms and
electrons and atomic nuclei scurry around
– Atomic nuclei get broken up into protons and
neutrons
– Protons and neutrons get ripped apart into
particles called quarks.
56. When the universe wasWhen the universe was
young and hot…young and hot…
infinitely dense point notinfinitely dense point not
governed by our physical lawsgoverned by our physical laws
or timeor time
all matter and energy containedall matter and energy contained
in one pointin one point
57. When the universe wasWhen the universe was
young and hot…young and hot…
Everywhere—all atEverywhere—all at
once—space wasonce—space was
filled with all matterfilled with all matter
No fireNo fire
No soundNo sound
Just energy turnedJust energy turned
into matterinto matter
