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Transcript of Dark Energy
-Ordinary Matter (4.9%)
-Dark Matter (26.8%)
-Dark Energy (68.3%)
- Density of Dark Energy = 6.91 x 10^-27 kg/m^3
- Very low compared to density of ordinary matter or dark matter within the Universe
- However, despite its low density, it dominates the mass-energy of the Universe because it is uniform across all of space
Evidence of the Existence of Dark Energy...
Doesn't emit light...
Doesn't exert gravity...
Spreads uniformly throughout the universe
Einstein and Hubble
- Dynamic quantities whose energy density can vary in time and space.
- Quintessence is a type of Scalar Field – (Quintessence is a second theory that says dark energy is a new force and will eventually fade away)
- Newton’s theory of Gravitation is a Scalar Field
Morgan, Aaron and Ashley
War Between Dark Energy and Dark Matter
If dark energy expands the universe, and dark matter pulls it together, what will the universe look like in the future?
Will the universe expand or collapse?
The Current Belief of the Composition of the Universe...
Theories of Dark Energy
Dark Energy Expanding the Universe Over Time
What is Dark Energy
"The Biggest Mystery in the Universe"
An unknown form of energy permeating all of space
Expanding the Universe
Working against Dark Matter
WE CANNOT SOLVE OUR PROBLEMS WITH THE SAME THINKING WE USED WHEN WE CREATED THEM
- A constant energy density filling space homogenously
- A constant that characterizes an extra, repulsive force in the Universe due to the vacuum of space itself
-The cosmological constant theory says, dark energy has been steady and constant throughout time and will remain that way.
-Energy density of the vacuum
2. Scalar Fields
The Nature of Dark Energy??
- Type 1a Supernova act as 'Standard Candles' and are key to measuring vast distances across space
- This type of Supernova is consistent, exploding nearly the same way and with the same brightness
- This allows us to observe their Redshift
- Redshift allows us to evaluate how much the Universe has expanded
Discussing the incredible topic of Dark Energy...
Today we will learn:
What Dark Matter Potentially is
How it appears to affect the Universe
Einstein and Hubble's contributions
Theories of Dark Energy
We Have Shared With You Today
What it is... No One Knows!
How it affects our Universe
Who was instrumental in our current knowledge
Theories associated with it
WE DON'T KNOW!!!
What Does it Look Like?
- Think of a chimney...
- Has both kinetic and potential energy. Pressure depends on the ratio between the two
- What is it made of?
- Quintessence is a repulsive force
- Did not know the Universe was expanding
- General Relativity Equation didn't quiet work for a static Universe
- Threw in a hypothetical repulsive force that would fix the problem
- This hypothetical repulsive force he called the Cosmological Constant
- In 1920 was using a Cepheid Variable as a Standard Candle to measure distances to other galaxies
- Discovered that the Universe was expanding (Revolutionary to astronomy)
- If the Universe is expanding... was it once smaller?
- Led to the Big Bang Theory
THE HISTORY OF ASTRONOMY IS A HISTORY OF RECEDING HORIZONS
- After finding out the Universe was expanding, Einstein discarded the Cosmological Constant
- He deemed it an unnecessary "fudge factor" and called it 'the biggest blunder of his life'
- Today's astronomers refer to one theory of dark energy as Einstein's Cosmological Constant
-This theory says that Dark Energy has been steady and constant throughout time and will remain that way.
- The second theory, Quintessence, says that dark energy is a new force and will eventually fade away the same as it arose.
If the Cosmological Constant is correct... Einstein wins again. He would be proven right about something even he thought was a mistake!!!
1. Cosmological Constant