prof martin hendry university of glasgow. a long time ago, in a galaxy far, far away…
TRANSCRIPT
Prof Martin HendryUniversity of Glasgow
A long time ago,
in a galaxy far, far away…
The nature of the nebulae?…
Early 20th Century
Gas clouds within the Milky Way, or Island Universes?….
Galaxy
Laboratory
Hubble’s Law
Einstein’s RelativityEinstein’s Relativity
Matter causes space Matter causes space to to curvecurve or or warpwarp
“Space tells matter how to move, and matter tells space
how to curve”
Gravity in Einstein’s Universe
Will the Universe expand forever?...
It depends how much matter there is
Weighing the Solar System
Johannes Kepler
Isaac Newton
Vera Rubin
1970s: studies the rotation of
spiral galaxies.
Weighing galaxies
Galaxies were spinning faster than they should be!
What we seeWhat we see
What we think is really there….
10 times as much as the luminous matter in the visible galaxy
Will the Universe expand forever?
Answer depends on the density of matter in the Universe.
Density high enough to cause re-collapse, leading to ‘Big Crunch’
Density too low; Universe expands forever
‘Critical’ density
So, is the expansion slowing down?...
Answer depends on the shape of the Universe
Answer depends on the shape of the Universe
Closed
Answer depends on the shape of the Universe
Closed Open
Answer depends on the shape of the Universe
Closed Open Flat
redshift
‘Speeding up’ model
‘Slowing down’ model
Hubble’s law for nearby supernovae
Hubble diagram of distant supernovaem
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So what exactly is this dark energy?...
So what exactly is this dark energy?...
redshift
Latest results: still speeding up...m
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Early Universe too hot for neutral atoms to exist
Free electrons scatter light (as in a fog)
Early Universe too hot for neutral atoms to exist
Free electrons scatter light (as in a fog)
After ~380,000 years, Universe cool enough for neutral hydrogen to form: the fog clears!
Background radiation predicted in 1950s and 1960s by Gamov, Dicke, Peebles.
Discovered in 1965 by Penzias and Wilson
Arno Penzias and Robert Wilson
Robert Dicke
Jim Peebles
COBE map of temperature across the sky
CMBR ‘ripples’ are the seeds of today’s galaxies
Galaxy formation is highly sensitive to the pattern of CMBR temperature
WMAP map of temperature across the sky
Adapted from Bassett & Nichol (2006)
Coming attractions...
Coming attractions...• Multi-wavelength (messenger)
• Ground- and space-based
• Multiple cosmological probes:
• Many opportunities for better constraining dark matter and dark energy models
Supernovae Gamma-ray bursts GW ‘Sirens’ Baryon Acoustic Oscillations Galaxy Cluster Statistics Weak Gravitational Lensing
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