science and creationism 2. cosmology © colin frayn, 2008-2011

Science and Creationism

2. Cosmology

© Colin Frayn, 2008-2011www.frayn.net

What is Cosmology?• Cosmology deals with the origins and large-scale

structure of the Universe

This is totally unrelated to evolution!

• The Theory of Evolution is part of biology• Biology is the study of living organisms

• Beware – cosmology is a very hard subject!


The Big Bang• Our Universe is expanding• We see all distant galaxies moving away from us

– It’s called red-shift– Caused by the Doppler effect

• If you run this backwards…– All galaxies were at one point– This is known as the Big Bang

• Science of the early Universe is very strange– But we have plenty of good theories– And observations to back them up



What we know

• Things we don’t yet know:– The exact composition of the Universe– The nature of dark matter– What happened during the first second?– Are we alone in the Universe?

• Things we can never know:– What happened before the big bang?– Why does the Universe exist?


Evidence for an old Universe• Nearby Universe

– Variable stars• Variable stars can be seen up to 50M light years away• Minimum age of Universe > 50 million yrs

– Oldest visible stars• Some very low-mass stars in globular clusters are 13 Bn yr old• Based on well-established stellar models

– White dwarf cooling times• The oldest white dwarfs have been cooling for 13 Bn yr• Based on very well understood cooling laws

• Cosmological arguments– Most distant discovered supernova = 11 Bn light years– Directly measuring expansion speed

• Hubble constant gives us an age estimate– Based on matter, energy densities of Universe– Value is slightly under 14 billion years

• All these methods agree very well at ~13.8 billion years


Homogeneity• Why is the Universe so homogeneous and isotropic?

– It seems very similar wherever you look

• Cosmological models predict this• Computational simulations show how structure arose

– Starting with tiny fluctuations– Leads to structure today

• Early Universe inhomogeneity can be seen in the Cosmic Microwave Background

Fluctuations in the cosmic microwave background, measured by the COBE satellite (1989-1992). The fluctuations are exaggerated in the image: they are actually less than one part in 100,000!


Sir Fred Hoyle• Famous Astronomer (1915 – 2001)

• Worked on stellar nucleosynthesis– Formation of various heavy elements within stars

• Converted from atheism to theism– His justification was the ‘fine tuning problem’ (see later slide)

• Was wrong on pretty much everything after this point– Rejected the Big Bang (and coined the phrase as a joke)– Rejected naturalistic explanations for abiogenesis

• He believed that life originated in space and was carried on comets

– Later rejected natural selection as a mechanism for evolution– Supported the (now disproved) ‘steady state hypothesis’

• Claiming that the Universe didn’t begin, but has always existed in a steady state

• ‘Hoyle’s Fallacy’– The common misunderstanding that evolution is a random process


Fine Tuning• The Universe has (probably) 25 fundamental constants

• Even a tiny change in some of them would be disastrous– The Universe could not have existed in its current state

• Why are they so well tuned? Does this prove a god did it?– No, of course not– For a start, how could a god exist without being ‘in’ some Universe with

its own parameters that needed tuning?– This is just the ‘no first cause’ fallacy

• Several explanations (none very satisfactory):– Parallel Universes– Anthropic principle – Fundamental parameters do seem to change over time

• Bottom line: We don’t know, but we’re looking


Redshift is Unreliable?• Arp (1967), Burbidge (1969) etc.

• Claimed “Quasars seem statistically more common near galaxies that are close to us”

• Shouldn’t be the case if they are all very distant• Results based on very poor data and bad statistics

• This has since been rejected• We now know of 10,000s of quasars• We see no statistical correlation with nearby galaxies• Most quasars are not associated with visible galaxies at all• Those that are, seem to have accurate redshift values

• Galianni et al (2005) • Quasar in a galaxy of much lower redshift?• May be caused by the ejection of quasar from the galaxy• We genuinely don’t know the solution

• Note:• The publication of these works and the consequent debate

completely destroys the Creationist argument that papers that disagree with the status quo are suppressed!


Varying speed of light• The Universe is very large

– We see distant objects as they were a long time ago• …because the speed of light is finite

– What if the speed of light used to be a lot faster?– Could that explain why the Universe looks old?

• Prof João Magueijo– Cosmologist, Imperial College, London

• Suggests ‘c’ was much larger in the early Universe• An alternative to ‘inflationary’ models

• What effect would that have on distances?– None – it deals with the very early Universe– SoL is definitely constant back to very high redshifts

science and creationism 2. cosmology © colin frayn, 2008-2011

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