The universe: why does it exist? Why is there something rather than nothing? Where and why did structure arise: galaxies, and clusters of galaxies. This slide show is a full history of enquiry into how structure arises in the universe. It goes from Plato and Aristotle to the Nobel Prize in Physics 2011. The title Heart of Darkness refers to a book that has the full story: Heart of Darkness, by Jeremiah P Ostriker and Simon Mitton, ISBN 978 0691134307
1. Hay Festival
2013 June 1
HEART OF DARKNESS
Unraveling the Mysteries of the Invisible Universe
Dr Simon Mitton
St Edmund’s College,University of Cambridge
Vice President, Royal Astronomical Society
Guest Lecturer Astronomy, RMS Queen Mary 2
Website www.totalastronomy.com
Email simon@totalastronomy.com
2. The nature of the universe. What the ancients achieved, and why we should be
impressed
• Plato and Aristotle taught that the heavens can be subjected to rational
enquiry. Our book Heart of Darkness presents the full history of attempts to
understand why the universe has structure
• The Greek geometers changed the nature of that enquiry forever.
Geometry became the key to understanding the mechanics of the
universe. Geometrical argument remains at the heart of understanding
structure in the universe.
• Hipparchus of Rhodes: first star catalogue (850 stars!); discovered
precession of the equinoxes. Our narrative stresses the great importance
of astronomical surveys for revealing the structures within the universe.
4. ISAAC NEWTON
Newton’s universal law of
gravitation means each object
in the universe is attracted to all
other objects
Universal attraction of gravity means
the solar system (and the universe) is
unstable
6. explores objects beyond the solar
system
1755 Immanual Kant proposes “island universes.”
From 1782 – 1802 Herschel undertakes sky surveys
to catalogue and examine the nebulae.
WILLIAM HERSCHEL 1738-1822
9. WILLIAM PARSONS, THIRD EARL OF ROSSE
1845, Discovery of spiral structure in the nebula M51
10. SIR JOHN HERSCHEL 1792-1871
At the Cape of Good Hope he completes his
father’s work on surveying the heavens
11. Vesto Slipher 1875 – 1969
VESTO SLIPHER 1875-1969 – clocks the speeds of galaxies
Lowell Observatory, Flagstaff, Arizona.
Dome and 24-inch telescope
In 1917 Slipher announced the measurement of the velocities
of a dozen galaxies, all of them rushing away from our Milky
Way galaxy
12. ALBERT EINSTEIN 1879-1955
In1915 Einstein published the
General Theory of Relativity, a
theory of gravity that includes the
“time” dimension
Arthur Eddington in Cambridge
understands that GR can be used to
model the properties and behaviour
of the entire universe
At the Total Eclipse of 1919
Eddington confirms GR – a
geometrical theory, which joins the
cosmologists’ toolkit
13. EDWIN HUBBLE 1889-1954
1920s, Hubble measures the
distances to nearby galaxies, his
greatest achievement
Edwin Hubble 1889 –1954
14. The data of Slipher and Hubble combined
The velocity-distance relation (Hubble Law)
SpeedSLIPHER
Distance from us HUBBLE
15. GEORGES LEMAîTRE 1894-1966
1923-24. Georges Lemaître joins
Eddington in Cambridge. As
mathematicians, they work
together on geometrical models of
the universe using GR
1924 Lemaître the theorist goes to
the other Cambridge to work at
Harvard and MIT. He meets
observers Vesto Slipher and also
Edwin Hubble, with both of whom
he discusses model universes
16. The FIREWORKS UNIVERSE 1927
1927 Lemaître has an explanation for Hubble’s results.
Publishes in 1927 a paper (in French) on the
expansion of the universe in which he demonstrates
that the model is an allowed solution to Einstein’s
GR equations
Einstein regards this as preposterous but Eddington
supports his former student
1930 Lemaître speaks in London on the expanding
universe, and publishes the Primeval Atom concept in
Nature
Lemaître called his model the “Fireworks Universe”.
The moniker “Big Bang” came later, in 1948,
courtesy of Fred Hoyle.
17. FRITZ ZWICKY 1898-1974
1933 Coma cluster, measures
internal velocities, proposes
Dark Matter
1935 Pioneers the use of
Schmidt cameras for survey
work
1942 Caltech. 1948 First
astronomer to use the 200-inch
at Palomar
1960s Catalog of Galaxies and
Clusters of Galaxies
18. ALLAN SANDAGE 1926-2010
Hubble’s successor at Palomar
Devoted his career to a “search
for two numbers”, the Hubble
constant and the deceleration
parameter. These two numbers
would specify the type of
universe we are in.
The work was a quest for
“standard candles” to provide
the distance scale of the
universe
19. BEATRICE TINSLEY 1941-1981
1966 Awarded PhD Univ Texas at
Austin, and received a postdoc
Fellowship
Her 1968 paper in Astrophysical
Journal brings Sandage’s house of
cards crashing down! Stellar
evolution implies galactic evolution,
therefore all galaxies are not the
same. She destroys the “search for
two numbers”.
Further papers follow; she
published 11 papers in 1972
20. ARNO PENZIAS AND ROBERT WILSON
Arno Penzias and Bob Wilson
1978 Nobel Prize Physics
1964 This strange radio
telescope accidentally
discovered that the entire sky
emits a weak microwave signal
The microwaves are a form
of heat energy at a very low
temperature
What had been discovered was
heat energy, in the form of
microwaves, released in the Big
Bang
26. The Hubble eXtreme Deep Field (2012)
5,500 galaxies
up to 13.2 billion light years away
27. Clusters of galaxies are weighed down by dark matter
Unseen dark matter is ten times more
common than ordinary matter
28. An enormous ring of dark matter surrounds
a great cluster of galaxies
29. NOBEL PRIZE PHYSICS 2011
Discovery of the accelerating universe
Saul Perlmutter Brian Schmidt Adam Reiss
30. A great discovery:
the expansion of the universe
is accelerating!
Distant galaxies - 10 billion light years away -
are going more slowly than expected
Nearer to home, the rate of expansion
has speeded up in the last 5 billion
years. This cosmic jerk is driven by
mysterious Dark Energy!
31. The universe: what’s in the pie?
Just over one quarter
of the universe is
unseen dark matter
Less than one-twentieth
of the universe is visible
matter
Two thirds of the
universe is present
as mysterious dark
energy
32. The Universe: What we know
1. It is expanding, and the rate is speeding up
2. It had a hot beginning - the Hot Big Bang
3. Its age is 13.82 billion years
4. It contains ordinary matter (5%), dark matter (27%),
and dark energy (68%)
33. The Universe: How galaxies formed
1. The microwave background radiation shows
that structure existed 380,000 years after the Big
Bang2. This structure must have been present before
the inflation era
3. Dark Matter provided the gravitational attraction to
allow formation of structure on the scale of clusters of
galaxies
4. Without Dark Matter, the Dark Energy would
have propelled the expansion too fast. No
galaxies, stars, or planets would exist!
34. “Why is there something rather than nothing?”
• The universe grew from a singularity, or quantum fluctuation, at the scale
of the Planck length 10-43
m. The resulting expansion could not have been
infinitely uniform
• The universe went through cosmic inflation 10-36
– 10-33
seconds.
Fluctuations preserved – baryon acoustic oscillations
• The First Three Minutes – origin of light elements. The next 700,000
years – era of recombination
• Fine tuning of the universe: expand too fast -> no structure, too slow ->
collapse under gravity.
• The Goldilocks solution: conditions “just right”. But honey and nice words
do not work in cosmology …
• … Dark matter to the rescue! Amount detected is “just right” to allow
structure to develop via the gravity of dark matter – the visible matter
alone is insufficient
• Let’s see the dark matter simulation
35. The Universe: What we do not know
1. In cosmology, the current generation always
claims to have the “right” model
2. Can we really believe our models of the universe
when it was 10-36
seconds old? Is it not hubris to
proclaim in these terms?
3. We do not know what dark matter is. Our searches
have been fruitless.
4. Dark energy is a complete mystery. Is it a new realm
of physics?
37. Hay Festival
2013 June 1
HEART OF DARKNESS
Unraveling the Mysteries of the Invisible Universe
Dr Simon Mitton
St Edmund’s College,University of Cambridge
Vice President, Royal Astronomical Society
Guest Lecturer Astronomy, RMS Queen Mary 2
Website www.totalastronomy.com
Email simon@totalastronomy.com
Editor's Notes
Title slide
Expansion of Universe Our story begins almost a century ago, in the railroad town of Flagstaff, in northern Arizona. In 1913 VS made the first attempt to measure the velocity of a galaxy wrt Milky Way. Extremely difficult. 1917 announces that a dozen galaxies are distancing themselves from the MW. He had expected half to approach, half to recede. What could this mean he wondered?
Edwin Hubble used 100-inch Mt Wilson. First success M31, used star magnitudes. Then started on Slipher ’ s sample. A pattern slowly emerged in which galaxies at greater distances had higher velocities.
A few years later. Hubble law low redshift. With more data, astronomers accepted that the universe is expanding, our first great discovery. From the Hubble diagram it is possible to assign an age to the universe, 13.7 Gyr
Second discovery Telescope Holmdell, New Jersey, about 20 miles from NYC Penzias and Wilson noticed that the telescope always picked up a faint signal, no matter what. [Time step] They eliminated all local sources. [Time step] When they told colleagues of their strange discovery, one at Princeton University realised immediately that they had discovered the heat radiation released in the Big Bang, now weak and dilute Confirmed Hot Big Bang
Astronomers immediately realised that if they could observe this radiation in much greater detail they could understand some of the situation in the Big Bang. Thus this scientific satellite was launched with the sole purpose of mapping the sky in microwaves. [Time step] Here you see one of the results, as a colour coded map of the whole sky. The microwaves have a temperature: blue = cooler, red = hotter. [Time step] Shows structure emerging in the early universe.
WMAP 5 yr NASA 21st century This map brings us completely up to date Describe what people are looking at Results are highly technical. Give an accurate result for age of universe. [Time step], and reveal dark matter and dark energy
Planck March 2013 Three years ago the European Space Agency launched an even better microwave probe, named Planck. And a few weeks ago astronomers were enthralled with the all-sky image you see here. This is the most precise map ever made of the oldest light in the universe, emitted just 380,000 years after the start of the Big Bang. The grainy structure here took 15 months to analyse in order to measure just six numbers that specify the properties of our universe. One of those numbers is the Age of the Universe, which came out at 13.82 billion years, a hundred million years older than previously thought. The map also has solid evidence about dark matter and exotic dark energy.
Describe the picture - what people are looking at, and how this image was made - ten days of HST time There are more than one thousand galaxies, many of which are seen just 100 million years after their formation Demonstrate how small the area of sky is This image made such a big impact that it was repeated recently.
One click to bring up the comparison of XDF and Moon
Galaxy cluster CL 0024+117 HST More about dark matter Notice the distorted images of galaxies How galaxies move within the cluster depends on mass. These galaxies are moving sufficiently fast that the cluster should have dispersed long ago. But it is not flying apart. [Time step] Dark matter weighs it down.
CL0024+17 Ring of dark matter. Distance 5 bly. Diameter 2.5 mly. This stunning x-ray image shows hot gas as wisps. A ring of dark matter blocks our view to some of this gas.
Third great discovery - accelerating universe Explain
Inventory of the universe Astronomers are truly in the dark, only 5% of the universe is visible Speculate on dark matter and dark energy Mention LHC