English project hukic_damir_final

The UniverseThe Universe

Seconde F

Order of MagnitudeOrder of Magnitude


Humans


1 Gm = 1 gigameter = 10^9 meters = 1 000 000 000 m


1 Gm = 1 gigameter = 10^9 meters = 1 000 000 000 m1 nm = 1 nanometer = 10^(-9) meter = 0.000000001 m


Nucleus of an atom

nucleus


Atom


Bacteria


Humans


Earth


Sun


Solar System


Interstellar distance


Galaxy


Observable universe


1000 kg 1 Kg


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 light

Speed of lightSpeed of lightSpeed of light in vacuum is a phyical constant :

Speed of lightSpeed of lightSpeed of light in vacuum is a phyical constant : c = 3.10^8 m/s = 300 000 000 m/s

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

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


A.Einstein 1879 - 1955


Speed of light (speed of propagation) depends only on the medium




speed(vacuum) = speed(air) = c = 3.10^8 m/s

speed(water) < c




speed(vacuum) = speed(air) = c = 3.10^8 m/s

speed(water) < cRefraction index n : quantity without

unit


Speed of lightSpeed of lightGalilée, Romer, Cassini, Newton,

Michelson..


Michelson.. using astronomy


Michelson.. using astronomy The meter is the distance travelled

by the light in the void during 1/299 792 458 second


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


d = 1m


d = 1m

s m

m/s


d = 1m

d = 150 000 000 Km

s m

m/s


d = 1m

d = 150 000 000 Km

s m

m/s

s km

km/s

t = 500 sec = 8.3 min


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

t = 500 sec = 8.3 min

Light-yearLight-year

Light-yearLight-yearA light-year is the distance travelled

by the light in vacuum during one year



m

m/s

s



m

m/s

s

1 year converted in seconds



m

m/s

s


1 ly

roughly



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 ly

roughly


I see dinosaurs

How far are we from this planet?


I see dinosaurs

How far are we from this planet?Extinction of the

dinosaurs : 65 millions years ago


I see dinosaurs



The aliens are at least 65 000 000 light-years away from us

(6.5 * 10^22 meters)


I see dinosaurs



The aliens are at least 65 000 000 light-years away from us

(6.5 * 10^22 meters)

Watch far = Watch in the past


Questions ?

Homework

English project hukic_damir_final

Documents

Transcript of English project hukic_damir_final