Learn about cutting-edge research

over lunch with cool profs

January 13-17, 2020

11:30 AM

Redpath Museum

More information:

www.mcgill.ca/science

Next peergrade assignment due Friday, January 17!

The Universe is expanding but it also seems to accelerate!

The Hubble diagram for SN Ia. The lines show the predictions for cosmologies with varying

amounts of Ωm and ΩΛ.

Robert P. Kirshner PNAS 1999;96:8:4224-4227

The expansion is slightly slower for “old objects” (far away galaxies)

The expansion is slightly faster for “new objects” (close galaxies)

Hubble law: velocity=H0* distance

=> The expansion of the Universe is accelerating

velocity

dis

tan

ce

Hubble constant

Current Universe expansion: Hubble constant (H0)

Recessional velocity: v=H0d

H0=2.2×10−18 s−1distance

The closest known independent galaxy to us is the Andremeda Galaxy, at 2.4*1022m (2,500,000 light years) from the Sun.

http://responseware.turningtechnologies.com/responseware/

http://www.mcgill.ca/polling/

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How fast does Andromeda move from us?

A. About 300km/s away from us

B. About 50km/s away from us

C. About 1km/s away from us

D. About 0km/s

E. About 1km/s towards us

F. About 50km/s towards us

G. About 300km/s towards us

How fast does the closest galaxy move away from us?

Wiki

Rec

essi

on

al v

elo

city

[km

/s]

How fast does the closest galaxy move away from us?

Wiki

Closest move towards us

Rec

essi

on

al v

elo

city

[km

/s]

(Andromeda moves at 300km/s towards us)

Current Universe expansion: Hubble constant (H0)

Recessional velocity: v=H0d

H0=2.2×10−18 s−1distance

The closest known galaxy to us is the Canis Major Dwarf Galaxy, at 2.36*1020m (25,000 light years) from the Sun.

Some of the close galaxies are anomalies in the sense that they move towards us and will eventually collide with us. Most galaxies move away from us.

OMMCOM NEWS

Do we know the size of the Universe?

A. Yes

B. No

C. Cannot be determined

Our solar system

(4.6B years ago)

mucholderthen.tumblr.com

Our solar system

(4.6B years ago)

mucholderthen.tumblr.com

Main phases of life on Earth

t (BYears) h Event

−4.6 0h Formation of Earth

−4.5/−4.0 1h/3h Formation of oceans

−4.0? 3h? First unicellular organisms

−1.3 17h First multicellular plants

−0.6 21h Cambrian explosion (1st animals)

−0.4 22h Life gets out of oceans

−0.1 23h30m First mammals

−0.0005 23h59m50s Homo Sapiens

Big Splash:

Our moon forms

wiki

Here we are:

image t

aken fro

m G

alil

eo o

rbite

r

Are there other Universes?

A. Yes

B. No

C. Cannot be answered

Are we alone in the Universe?

A. Yes

B. No

Meteorite demo

Oman

200kg

Melted rock crust from the atmospheric entry

Metal grains

Chondrules

How do we know how old a rock is?

Extremely precise dating of old rocks and meteorite (isotope dating due to radioactivity)

How do we know how old a rock is?

Jerome Walker, Dennis Myts

Callahan et al. 2011Nucleobases in meteorites

Wikipedia Commons Space.com

Asteroid belt

Michel MayorDidier Queloz(Obs. Geneva)

6.10.1995

Public announcement of the discovery of the first extrasolar planet:51 Pegasi

OMMCOM NEWS

51 Pegasi

Geneva team

Gero Rupprecht

Jupiter

mass=

317.8

Eart

h m

ass

Other discovered exoplanets

Question: Are we alone in the universe?

In general:

Decompose the question:

What do we mean with alone?

How do we define life? (Amino acids, proteins, DNA, virus, cell, plant, animal,…AI)

How is life created?

What is the likelihood that a sister planet earth will have some life form?

What is the likelihood to find a sister planet earth?

Can life exist under other conditions?

How common are these conditions?