Vacuum Energy in the Universe. Scott Dodelson April 5, 2000. A long time ago in a galaxy far, far away. Einstein and General Relativity. Idea: Matter affects the structure of Space-Time. E.g. A massive star attracts nearby objects by distorting space.
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April 5, 2000
galaxy far, far away...
Idea: Matter affects the
structure of Space-Time
E.g. A massive star
attracts nearby objects
by distorting space
Leading to confirmation of Einstein's theory ...
And widespread adulation ...
London Times Nov 8, 1919
The Revolution in Science:
Einstein vs. Newton
Expanding Sphere ...
Energy = Kinetic Energy + Gravitational Energy
0 = (½) m v2 - G m M(r)/ r
How did Einstein make the universe static?
0 = (½) m v2 - G m M(r)/r
Changed the energy to be negative
Introduced vacuum energy. Ordinary matter: M(r) = constant Vacuum energy: M(r) ~ r3
Born: June 1888, St. Petersburgh, Russia
Died: September 1925, St. Petersburgh
Published paper on Bernoulli Numbers at age 17.
WWI: Join volunteer aviation detachment.
I have recently had a chance to verify my ideas
during a flight over Przemysl; the bombs turned
out to be falling almost the way the theory predicts.
To have conclusive proof of the theory I'm going to
fly again in a few days.
Letter from Friedmann, Feb 28, 1915
June 29, 1922: Friedmann introduces the expanding universe, abandoning the vacuum energy Einstein put in by hand.
September 18, 1992: Einstein publishes a comment on Friedmann's paper: result ``seems suspect to me'', ``solutions do not appear compatible''
May 31, 1923: Einstein retracts his criticism: ``My objection rested on a calculational error.''
BUT ... ...
M(r) = r v2 / 2G
Vacuum Energy in
the Universe !
After billions of years light from the distant supernova reaches Earth
Supernovae are standard candles reaches Earth
The apparent brightness of a supernova is therefore a measure of its distance from us.
Can get Hubble relation for very distant objects!
Since M remains reaches Earth
slows, like a rocket
Since M increases
with R, universe is driven to expand
faster and faster
Fainter -> reaches Earth
Far Away ->
Scale Factor (redshift)
What are we up to now? reaches Earth
We are observing
Measuring the distribution of galaxies
Measuring anisotropies in the cosmic radiation
Sending up satellites to observe more supernovae
Searching for exotic, dark matter
First light from the Sloan Digital Sky Survey, will map reaches Earth
a million galaxies on the sky
Satellites will map cosmic radiation reaches Earth
Photo of the universe when it was very young
Proposed satellite will observe thousands of supernovae reaches Earth
Dark Matter searches continue ... reaches Earth
February 26, 2000
Deep, profound questions remain reaches Earth
We are thinking ..
Large extra dimensions?
What should we make of Einstein? reaches Earth
The Man of the Century…
• Missed the expansion
• Almost suppressed it
• Blundered into vacuum energy
Even Einstein’s Greatest Blunder ... reaches Earth
teaches us about the importance of tackling big problems. Even though Einstein was wrong, his audacity laid the groundwork for future work.