English project hukic_damir_03
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Transcript of English project hukic_damir_03
The UniverseThe Universe
Seconde F
Order of MagnitudeOrder of Magnitude
Order of MagnitudeOrder of Magnitude
1 Gm = 1 gigameter = 10^9 meters = 1 000 000 000 m1 nm = 1 nanometer = 10^(-9) meter = 0.000000001 m
Order of MagnitudeOrder of Magnitude
Nucleus of an atom
nucleus
AtomBacteriaHumansEarthSunSolar System
Interstellar distanceGalaxyObservable universe
1000 kg 1 Kg
Order of MagnitudeOrder of Magnitude
Filling of space by the matter is essentially incomplete, at both tiny (atom) and big
(cosmos) scales (essentially void around us)
Speed of lightSpeed of lightSpeed of light in vacuum is a phyical constant : c = 3.10^8 m/s = 300 000 000 m/s The light is composed of photons and is propagated in straight line
Speed of light (speed of propagation) depends only on the medium
speed(vacuum) = speed(air) = c = 3.10^8 m/s
speed(water) < cRefraction index n : quantity without
unit
A.Einstein 1879 - 1955
Speed of lightSpeed of lightGalilée, Romer, Cassini, Newton,
Michelson.. using astronomy The meter is the distance travelled
by the light in the void during 1/299 792 458 second
v = c (m/s)
m
s
Speed of lightSpeed of light
d = 1m
d = 150 000 000 Km
Even if the light of speed is great, the gigantic distances at the cosmos scale cause delays (we don’t
see things in ‘real time’)
s m
m/s
s km
km/s
Light-yearLight-yearA light-year is the distance travelled
by the light in vacuum during one year
The light-year (ly) is not a new unit, it’s used only because it’s handy with the gigantic distances we
have in the cosmos
m
m/s
s
1 year converted in seconds
1 ly
roughly
Light-yearLight-year
I see dinosaurs
How far are we from this planet?Extinction of the
dinosaurs : 65 millions years ago
The aliens are at least 65 000 000 light-years away from us
Watch far = Watch in the past
Light-yearLight-year
Questions ?
Homework