Saturday, June 09, 2018

Friday Science: Just Six Numbers (book review)

I have pretty much finished Hawking, but will post the rest of his book next Friday, dv.

1. I took my son to Clinton, Iowa Tuesday for him to meet in person some online friends of his that have played video games together for about six years. (Interesting development in this new world, where you go to meet some of your best friends for the first time after years of playing together. I have a nephew that first met a friend in person for the first time this spring... as best man in his wedding.) So while I was sitting in a hotel room, Starbucks, parking lots, etc, I finally read/skimmed Martin Rees' Just Six Numbers.

In the last few decades, a strong argument for the existence of God has emerged called the "fine tuning" argument. It falls under the category of an argument for design. There are a number of ratios and constants in the universe that are necessary for us to be here. An atheist at this point invokes the anthropic principle--we wouldn't be here to discuss them if there weren't. So if there are universes in the "multiverse" that do not have these precise ratios, there is no one there to talk about them. In other words, we are just the lucky ones.

By contrast, the theist says, "We are fearfully and wonderfully made." "Oh the depth of the riches of the knowledge and wisdom of God!"

Rees' book is about these constants. I am now working on my third Gabriel novel. This one is called Gabriel's Diary: The Creation. It is going to be truly spectacular and probably a bit controversial. I am hypothesizing what creation might look like from a Christian point of view that engages with contemporary science. I'm not saying it's right. But it will be a book for people who are convinced about the science but not so convinced about God. The first three chapters will embody the fine tuning argument and engage my feeble apprehension of modern cosmology.

2. Here is a summary of my take-aways from Rees' book. I have put them in the order that is most helpful for my writing. Fine tuning arguments are in bold.

Chapter 1: The Cosmos and the Microworld
  • Rees goes with the anthropic principle and the multiverse model: "An infinity of other universes may well exist where the numbers are different. Most would be stillborn or sterile. We could only have emerged (and therefore we naturally now find ourselves) in a universe with the 'right' combination" (4).
  • He uses an "ouraborus" to picture the scale of the universe. The breadth of size is 1060. The smallest size imaginable is about 10-33 cm. The universe is about 1028 cm across. (These are my numbers, not his.)
Chapter 3: The Large Number N: Gravity in the Cosmos
  • He calls the constant discussed in this chapter, N. I've never heard of it but he is referring to the ratio between the electromagnetic force and the force of gravity. It turns out that the electromagnetic force is about 1036 times more powerful. 
  • Gravity is always attractive, while electromagnetic forces can be either attractive or repulsive. So with large objects, gravity accumulates a large attractive force, while the electromagnetic forces more or less even out.
  • There is an inverse square law that applies to these two forces. The force weakens as the square of the distance increases. More on the significance of this fine tuning in chapter 10.
  • Gravity makes objects as big as the Moon and larger spherical.
  • If the ratio were less, everything would be smaller--smaller stars, smaller planets, potentially smaller life. Galaxies would form quickly and would be miniaturized. They would be more densely packed.
  • Stellar lifetimes would be much shorter, which according to Rees would not have given enough time for complex life to evolve. 
  • A weaker gravity might have allowed more elaborate and longer-lived structures to develop, but a stronger gravity would not have allowed enough time for humanity to emerge.
  • A little on Einstein - the speed of light is the speed limit of the universe. Near large masses time slows down relative to elsewhere.
  • Millions of black holes in our galaxy, the remnants of large stars that have already burnt out. Slightly smaller stars become neutron stars. Our Sun will become a white dwarf when it burns out.
  • Some explanations of black holes, event horizons, etc., atomic sized black holes.
Chapter 10: Three Dimensions (And More)
  • The number he discusses in this chapter is 3, three-dimensions of space.
  • In a three dimensional world, forces like gravity and the electromagnetic force obey an inverse-square law mentioned above.
  • William Paley used the inverse square law as part of his argument from design. If it were an inverse cube law, there could be no orbiting of planets or electrons around a nucleus.
  • There is an asymmetry of the arrow of time. "No such asymmetry is built into the basic laws governing the microworld" (153). The asymmetry is linked to the expansion of the universe. [Hawking calls this the cosmological arrow. Entropy is another basis for the arrow, which Hawking calls the thermodynamic arrow.]
  • The expansion of the universe was fast enough to end nuclear reactions before they could convert more than 23% of the hydrogen into helium. This left fuel for suns.
  • There was just the right asymmetry in the earliest phase to leave a slight excess of matter over antimatter. Otherwise, nothing but energy would be here.
  • He also talks a little about Planck units. The smallest length is 1019 times smaller than a proton, 10-35 the length of a meter. The smallest unit of Planck time is 10-43 seconds. Space and time are arguably granular, not continuous. Take that, Zeno.
  • He mentions superstrings. I believe this approach is increasingly discredited.
Chapter 9: Our Cosmic Habitat III: What Lies Beyond Our Horizon?
  • Helium was formed at about the three minute threshold.
  • grand-unified (all forces united) to quarks (strong from electroweak) to leptons (electro from weak)
  • magnetic monopoles?
Chapter 8: Primordial Ripples: The Number Q
  • Q is the ratio between the rest mass energy of matter and the force of gravity. It is 1 to 100,000. 
  • It has to do with the "roughness" of space, the "ripple amplitude" of the gravitational waves of cosmic inflation.
  • It has to do with the energy that would be needed to break apart galaxies.
  • The slight asymmetry of the universe seems to relate in some way, enabling things to form structures.
  • If Q were smaller, galaxies wouldn't form. If Q were larger, galaxies would crunch much sooner and the universe would be a rougher place.
Chapter 6: The Fine-Tuned Expansion: Dark Matter and Ω
  • What Rees calls Ω is the ratio between the force of universe expansion and the force of gravity. This ratio determines whether the universe will expand forever, expand steadily, or eventually contract again. These correspond to whether the ratio is less than 1, exactly 1, or greater than one.
  • Because of gravity, if there were five atoms for every cubic meter in the universe, it would contract one day. As it is, there only seems to be 0.2 atoms per cubic meter, at least as far as ordinary matter is concerned.
  • All the indications are thus that this number is less than 1. But it is likely that there is "dark matter" out there, stuff we can't see. It is thought that about 26.8% of the universe is dark matter.
  • Candidates for dark matter include brown dwarfs (suns less than 8% of our sun's mass), neutrinos, black holes, "axions," but more likely something we don't yet know about.
  • At about one second after creation, Ω could not have differed from 1 by 1 in 1015. If the expansion force were greater, there would have been no time for stars and galaxies to develop. If the mass were greater, the universe would have collapsed too soon for life as we know it to develop.
    • Another fine-tuned factor is the slight asymmetry between matter and antimatter. If there were perfect symmetry in the early universe, they both would have emerged in equal amounts and completely annihilated. But there must have been a slight asymmetry.
    • There are different suggestions for the asymmetry. Rees suggests the K° decay, associated with the weak nuclear force, may be the reason. What if, for every billion quarks and antiquarks generated in the earliest universe, one extra quark were produced?
    Chapter 7: The Number Λ: Is Cosmic Expansion Slowing or Speeding
    • As far as I can tell, Λ doesn't contribute much more than the discussion of omega in the previous chapter. 
    • Einstein added Λ to his general relativity equations with the hope of a universe that wasn't expanding. He regretted that when Hubble showed it was. But there does seem to be an unknown force that is affecting comic expansion. This was apparently confirmed in 1998.
    • It is relatively small, about 0.7. It is a force driving expansion.
    • [It seems to relate to what scientists now are calling "dark energy."]
    Chapter 5: Our Cosmic Habitat II: Beyond Our Galaxy
    • Galaxies are the building blocks of the universe. Stars and their solar systems collect together to form galaxies. Galaxies often have huge black holes at their centers. Galaxies cluster (our cluster is the "Local Group").
    • Galaxies crash into each other. The kind of galaxy known as elliptical galaxies may be the result of galaxies that have crashed into each other. [Hawking had a different thought here in the 80s.]
    • There are bigger aggregates like the "Great Wall."
    • At every point we look in space, everything is speeding away from us, often faster than the speed of light, which suggests that space itself is expanding, since nothing can move faster than the speed of light in its own reference frame.
    • The expansion of space has been well established in the last fifty years. [When Hawking wrote, he hoped it might crunch again but we seem rather headed for a cosmic rip from accelerating expansion.]
    • Cosmic Microwave Background radiation (CMB) discovered in 1965 points to a Big Bang. Together, the fact that the universe had a beginning coupled with the fact that it won't re-compress fits well with the notion of creation.
    • CMB comes not from the creation itself but from some 380,000 years after the beginning (13.8 billion years ago) when the universe cooled down enough for electrons and protons to form neutral atoms, releasing a massive amount of energy in photons.
    Chapter 4: Stars, the Periodic Table and ɛ
    • A third number is ɛ, which I've never heard called that, but which is the percentage of mass released as energy when hydrogen is fused into helium. 0.007 or 0.7%
    • This has to do with the strength of the strong nuclear force that binds protons and neutrons together in a nucleus. This force is the strongest of all the forces but it only works within the space of a nucleus. It is thus just strong enough to hold a nucleus together without interfering with the electromagnetic forces that are essential for the overall working of an atom or the weak nuclear force that comes into play with large atoms with atomic numbers over about 50.
    • Helium is fused in two stages. First, a proton and a neutron fuse together to form deuterium (heavy hydrogen). Then two deuterium atoms fuse together into helium. 
    • If the percentage converted to energy were any more, no hydrogen would have survived the big bang. It would have all become helium or heavier, leaving no fuel for stars. If it had been less, no helium would have formed and the universe would just consist of hydrogen.
    • Carbon only forms from a helium and beryllium nucleus because the carbon nucleus has a resonance with a very specific energy that can fuse just before primitive beryllium decays. Without carbon, life as we know it would not exist.
    • The Earth is thought to be about 4.5 billion years old. The universe about 13.8 billion.
    • When a star's hydrogen has all been converted to helium, the core pulls inwards. Prior to that time, the energy from the fusion pushed back against the gravity of the mass.
    • When it contracts, it heats up more and heavier nuclei are formed. Iron is the most tightly bound nucleus. When it gets to a critical size, it implodes to a neutron star and supernovas the overlying material. In this material are the trace elements of heavier elements.
    Chapter 2: Our Cosmic Habitat I: Planets, Stars and Life
    • Stars start as warm blobs ("protostars"). They contract over millions of years under their own gravity. 
    • Any slight spin is amplified under a collapse, like a skater pulling in arms. The resulting disks are the precursors of planetary systems. (14)
    • Small wobbles in the orbits of stars may indicate planets. Christiaan Huygens in 1698 suggested every star might have planets around them. These are now considered certain.
    • A "barycenter" is the center of mass of an orbiting pair like the sun and Jupiter.
    • The early history of a solar system is filled with crashes. (A huge crash 65 million years ago (crater underwater in Gulf of Mexico near Chicxulub is thought to have killed the dinosaurs.) This event paved the way for mammalian life to emerge as winners.
    • The Moon is thought to have been formed from the earth by a collision with another protoplanet. Uranus' weird axis spin also explained by such collisions.
    • For life to exist on a planet like Earth, gravity must pull strongly enough to prevent the atmosphere from evaporating into space but it can't really be any stronger than Jupiter (cf. 32).
    • For water to exist on the surface, planets must be neither too hot or too cold.
    • The orbit must be stable, not crossed by a Jupiter-like planet in an eccentric orbit.
    • The oxygen of our environment is thought to come from primitive bacteria early in earth's history.
    • Cf. p32. Gravity makes objects Moon sized and larger spherical.
    Chapter 11: Coincidence, Providence - Or Multiverse
    • Rees goes with the multiverse theory. It is a logical option for someone who doesn't believe in God as creator. It doesn't preclude God, although it might push creation back further. It seems more philosophical in some ways rather than scientific per se.
    • He suggests that the values of these constants might be difference in other universes.


    Martin LaBar said...

    Thanks for the review. I've never gotten around to reading the book.

    Pretty impressive parking lot/hotel room/etc. reading.

    Ken Schenck said...