COSMOLOGY HOW IT BEGAN. Chris Impey University of Arizona. Norton, 2010. Space. Science is Seeing. A Scale Model. Set the Earth to the size of a walnut, or a 1:500,000,000 scale model. =. The Moon is a pea at arm ’ s length The Sun is a 3 m ball 300 m away
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HOW IT BEGAN
University of Arizona
Science is Seeing
Set the Earth to the size of a walnut, or a 1:500,000,000 scale model
And at this scale, light is reduced to very slow walking speed. There’s no way information in the universe can travel any faster
Scattered in a universe 46 billion light years across
The Milky Way is typical with 400 billion stars
Almost all the simple elements hydrogen and helium
A billion photons for every particle
If the speed of light were infinite, light from everywhere in the universe would reach us at exactly the same time and we would see the entire universe as it is now.
But it is not, so we see distant regions as they were in the past.
Distant Light = Old Light
Hubble Ultra Deep FieldHST•ACS
When we look at the CMB, we look at the surface of the glowing “fog” that filled the entire early universe!
1% of the specks on any TV tuned between stations are interactions with the big bang
Science is Seeing
The big bang was extraordinary― the instantaneous creation of all of space and time, containing energy to drive the expansion and enough matter for 100 billion galaxies.
The initial state was so compact that it can only be described by a theory that unites gravity and the quantum world. We do not have such a theory at present.
The big bang can be thought of as a quantum event, originating from very chaotic space-time in which the other quantum fluctuations might have led to other parallel universes.
The standard big bang has trouble explaining why the universe is as smooth and flat as it is, leading to the idea of an epoch of extremely rapid inflation, just 10-35 sec after the big bang. The mechanism is unclear but probably associated with the Grand Unified theories that seek to unite all the forces except gravity.
Inflation makes the universe flat and smooth (by design!), and it implies vast region of space that are beyond view. It has tentative support from CMB satellite data.
The universe is bounded in time and not space. General relativity sets no speed limit to the expansion. As time goes by, ever more distant regions come into view.
At z = 1.3, an object was moving away from us at c at the time the light was emitted.
At z = 1000, two distant points were moving apart at ~60c at the time the radiation was emitted.
Consequence of standard big bang: The physical universe is much
larger than the observable universe, we are subject to a horizon.
Consequence of the inflationary big bang: A microscopic region of
space-time became our universe; the universe is a quantum entity.
Science is Seeing
Life occurs in
a range of scales that extends from galaxies to the atomic nucleus, as symbolized by the ancient symbol of the ouroboros, the snake that eats its own tail
Quantum fluctuations are a mechanism for multiple realizations of the universe
…leading to the concept of the “multiverse”
Perhaps 10 different vacua
de Sitter expansion in these vacua create quantum fluctuations and provide the
initial conditions for inflation. String theory provides context for the “multiverse”
The “ekpyrotic” universe has a big bang, but it is not ever at an infinite temperature and density, and it is not the origin of all space-time…
So our universe emerged from a collision of two 4D branes that are embedded in 5D space-time. The collision is the engine for expansion and matter creation.
Dark matter binds galaxies and dark energy is currently driving the cosmic acceleration.
The early expansion was rapid, driven by intense radiation. It slowed down as the dark matter began to dominate, and more recently has begun to accelerate due to the relative growth of dark energy.
Within the expanding and cooling universe gravity formed stars, galaxies
, and people.