by Reina Reyes, Ph.D. Talk given at The Mind Museum, Taguig, Philippines on Feb 11, 2012 In this talk, I show the latest astronomical observations and cosmological simulations to tell the story of how galaxies formed over the last ten billion years, and how our own Milky Way galaxy will meet its end a "mere" three billion years from now. (Slides have been edited for the web.)

1. The
Birth
and
Death
of the
Milky Way
Reina Reyes, Ph.D.

2. * What are we? (Where are we?)
* Where did we come from?
These are questions
* Where are we going? people have been asking since
time immemorial...

3. * What are we? (Where are we?)
* Where did we come from?
Now, we can begin to
answer them. Let’s start with a
* Where are we going?
journey through space...

4. * Where are we?
We are on a planet (Earth),
one of 8 going around a star (the Sun),
one of a 100 billion in a galaxy (the Milky Way),
one of a 100 billion in our Universe
We live in a vast
Universe, which itself may be just
one in an even vaster
multiverse!

5. * What are we? (Where are we?)
* Where did we come from?
On to the next question:
* Where are we going? Where did galaxies come
from?

6. This is a map of the Universe soon after its birth, a “baby
photo”. The red and blue spots show 1 in 100,000 differences.
The early Universe was extremely smooth-- no galaxies, no
planets, no people.

7. This is the Universe today. There are galaxies everywhere.

8. This is a map of the Universe today, a “current photo”.
Each green and red dot is a galaxy. Galaxies are clumped
together-- forming the cosmic web.

9. smooth
clumpy
The question is then: How did
the Universe go from smooth to clumpy in
13.7 billion years?

10. How to build a galaxy?
Let’s build one in 3 steps!

11. How to build a galaxy?
• Step 1: Build a Universe

12. * What are the “ingredients” of the Universe?
Atoms-- all of chemistry and biology-- make up only 4%.
The dominant stuff is unseen, dark matter. (And then there’s
the 73% we neither see nor quite understand, dark energy.)

13. Every galaxy is l

14. How to build a galaxy?
• Step 1: Build a Universe
• Step 2: Turn on GRAVITY
We can do this in a
computer simulation.
Roll tape...

15. smooth
clumpy
As gravity pulls matter together, the Universe gets
clumpier. After 13.7 billion years, we get a cosmic web like
what we see today.

16. How to build a galaxy?
• Step 1: Build a Universe
• Step 2: Turn on GRAVITY
• Step 3: Add ordinary matter (the hard part)
This, we can start to “guess” in
a computer simulation.
Roll tape...

17. * What are we? (Where are we?)
* Where did we come from?
* Where are we going? Where is the galaxy going?

18. This is our galaxy’s neighbor,
another big (and beautiful) spiral galaxy-- 3
million light-years away.

19. Get the hint? Roll tape...

20. * What are we? (Where are we?)
* Where did we come from?
* Where are we going? We have some of the
answers, but we will never stop
asking...

21. Thanks for watching!
You can find me on:
• Facebook: www.facebook.com/reinabelle
• Twitter: www.twitter.com/reina_reyes