Transcript Expanding Universe

“Dark” Energy
R DARK G
Cosmology is the study of the Universe's
1. Shape
Cosmology is the study of the Universe's
1. Shape
2. Size
Cosmology is the study of the Universe's
1. Shape
2. Size
3. Age
Cosmology is the study of the Universe's
1. Shape
2. Size
3. Age
4. Structure
Cosmology is the study of the Universe's
1. Shape
2. Size
3. Age
4. Structure
5. Evolution
Cosmology is the study of the Universe's
1. Shape
2. Size
3. Age
4. Structure
5. Evolution
6. Fate
Cosmology is the study of the Universe's
1. Shape
2. Size
3. Age
4. Structure
5. Evolution
6. Fate
7. Galaxies
Edwin Hubble (1889 – 1953)
HUBBLE ULTRA
DEEP FIELD
DOPPLER EFFECT
PING PONG BALLS
If this is the size of the pastry at time zero….
… and this is the size of the pastry one hour later….. Two things are obvious.
1. The raisins have not moved
as individuals, but the dough
between them has gotten
larger.
A
B
1. The raisins have not moved
as individuals, but the dough
between them has gotten
larger.
2. Raisin “A” has
moved away at 5 cm
per hour. Raisin “B”
has moved away at
10 cm per hour.
Newton said that gravity is
going to be attracting all things.
This means that the Universe
would do one of two things.
The universe has enough gravity to stop the expansion of the universe, and
pull it back together
The Universe has reached escape velocity, such that it can continue
to expand forever, while continuing to slow down. It would never
quite reach the point of stopping.
But how would one see what was happening 10 billion years ago?
But how would one see what was happening 10 billion years ago?
100 Watt Bulb
Both have the same luminosity
100 Watt Bulb
But how would one see what was happening 10 billion years ago?
10 Watt Bulb
10 x the distance
1000 Watt Bulb
Find two supernova, with known characteristics, in a galaxy with a known distance,
and a target galaxy.
A galaxy happens about every 100 years in an average galaxy.
Find two supernova, with known characteristics, in a galaxy with a known distance,
and a target galaxy.
A galaxy happens about every 100 years in an average galaxy.
So every year is you look in 100 galaxies,
Or 10 per year if you look in 1,000 galaxies.
Katzman Automatic Imaging
Telescope
It was expected to find galaxies
here, because of gravity and them
slowing down. They were not.
Galaxies would be here, if they
were not slowing down at all.
They were not here either.
Galaxies were here. Much, much
farther away than they had any
right to be.
Einstein believed in a static universe. He kind of had to, to make his numbers work.
Lambda = 8 pi x G x density of the vacuum
Fgrv
Albert Einstein's own numbers
said that the Universe would
implode upon itself.
Fgrv
Fgrv
Fgrv
Albert Einstein introduced his
cosmological constant, or the
“density of the vacuum” as a
needed evil, to keep a static
universe in the face of his own
numbers and theories of gravity
and time.
17 years later, Edwin Hubble showed that the Universe was in fact expanding, and
Einstein called the cosmological constant his “biggest blunder”.
Now, it seems pretty sure that the Universe is expanding at an increasing rate, and if he
made a mistake, it is only that the repulsive force of the cosmological constant was of the
wrong magnitude. It was not equal to gravity.
In this room the down arrow of gravity dominates, but the up arrow of dark energy is not
non-existent.
Gravity still dominates in our local group of 14 galaxies, but dark energy is
emergent.
But in the Universe as a whole, at that
great distance, the force of the
density of the vacuum, the
cosmological constant, dark energy,
overwhelms.
Dark energy is stronger at large distances, and now, because of two reasons.
Dark energy is stronger at large distances, and now, because of two reasons.
At distance, gravity is weaker because of the laws of inverse squares.
Dark energy is stronger at large distances, and now, because of two reasons.
At distance, gravity is weaker because of the laws of inverse squares.
Dark energy appears to be a property of space itself, and as the universe expands, there
will be more and more space.
Dark matter is thought to be non-luminous, weakly interactive matter that does have
gravitational attraction.
Fritz Zwicky first postulated Dark Matter.
He lived from 1898 to 1974. He was
arrogant, abrasive, abusive and
absolutely brilliant.
Dark matter, he said, supplies the gravity
needed to stop galaxies from flying
apart.
What is dark energy?
It may be the quantum fluctuations of virtual particles that cause the evaporation of black
holes. Absolutely no one knows for sure.
Any explanation of Dark Energy must include a solution for quantum mechanics (for
which time is an integral part)……
Any explanation of Dark Energy must include a solution for quantum mechanics (for
which time is not wanted nor needed)……
And also for general relativity, in which time is an integral part.
This is the reason that Einstein hated quantum mechanics. He called it spooky changes at
a distance.
How will the galaxy end?
It will end in fire or ice.
The direction of the dark energy could change (again) and
we could actually end in a crunch.
The direction of the dark energy could change and we
could actually end in a crunch.
About a billion, billionth of a second
after the big bang, gravity changed
from a repulsive fore, into the
attractive force we now see.
Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To know that for destruction ice
Is also great
And would suffice.
By Robert Frost (1874-1963) (Poem first published in
Harper's Magazine, December issue 1920)