Life in a Finely-Tuned Cosmos

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Some time back, I read Geraint F. Lewis and Luke A. Barnes, A Fortunate Universe: Life in a Finely Tuned Cosmos (Cambridge: Cambridge University Press, 2016).  Here are just a few of the passages from the book that I marked for future use:

Consider gravity.  Newton described gravity with his famous ‘inverse square’ law:  any two masses attract each other, with a force that decreases with the square of the distance.  Einstein’s General Theory of Relativity is a more accurate and more difficult improvement on Newton’s theory.  In both theories, a quantity known as Newton’s gravitational constant appears, which is usually given the symbol of G and has a value of  6.67 x 10^-11 m³ kg^-1 s^-2.

If the value of G were different, what would happen?  We need to be a bit careful here.  Suppose we’ve transported you to another universe and asked you to measure G.  You’ll need to calibrate your instruments to measure metres, seconds and kilograms.  But wait . . . that platinum-iridium lump is back in our Universe!  Thankfully, changing G doesn’t affect the elements, so we can (in principle!) make what we need.  With some caesium 133, you can calibrate your clocks to measure seconds.  Measuring the speed of light gives the metre:  the distance light travels in 1/299, 792, 458 of a second.  We can then construct a replica platinum-iridium lump to give us the kilogram.  You can then measure G.

Nothing in Newton’s or Einstein’s theory tells us the value of G.  We have to ask nature, measuring from experiment.

In Newton’s theory, if G were twice as large, the gravitational force between masses would be twice as large.  In Einstein’s deeper understanding of gravity, G measures how strongly mass and energy distort the geometry of spacetime.  Changing the value of G affects just about everything in astrophysics, from the expansion of the Universe and the formation of galaxies to the size and stability of stars and planets.

Similar constants appear in all of the force laws, where they are called coupling constants.  The only way we have of knowing the value of these constants is to measure them from nature.  (pages 30-32)

Let me repeat two of those sentences:  (1) “Nothing in Newton’s or Einstein’s theory tells us the value of G.  We have to ask nature, measuring from experiment.”  (2) “The only way we have of knowing the value of these constants is to measure them from nature.”

In other words, important as these constants are to the emergence of the Universe and of life within it, there is (so far as we now know) nothing inevitable about them.  Neither Newton’s theory nor Einstein’s theory predicts their specific values.  That is — once again, so far as we know — they’re both contingent.  They could have been otherwise.  And, in many cases, had they been even slightly different than they actually are, neither we nor the planets, stars, and galaxies would be here.

‘Almost everything is already discovered’, a young Max Planck was told in 1874.  Planck, who would become one of the greatest scientists of the twentieth century, had travelled to Munich to embark on a career in physics, only to be told by Professor Philipp von Jolly to study something else, as ‘theoretical physics was approaching a degree of completion which geometry had possessed for hundreds of year.'”  (p. 183) [Quoted from Friedel Weinert, The Scientist as Philosopher: Philosophical Consequences of Great Scientific Discoveries (New York: Springer, 2004), 193.]

Science is facing a seemingly simple question whose answer would completely change what we think about the physical world.  And that question is ‘Why is the Universe just right for the formation of complex, intelligent beings? . . .  Why, in the almost infinite sea of possibilities, was our Universe born with the conditions that allow life to arise?’  (pp. 1, 2)

Also, even our best and deepest physical theories have loose ends.  There are numbers in the equations that the theory cannot predict.  We just have to measure them.  They are called the constants of nature.  Why do they have the value that we measure?  If that question has an answer, it must go beyond our current theories.  (p. 8)

Luke:  Maybe it’s like the lottery — a winning ticket isn’t too unlikely because lots of people buy different tickets.

That last idea, applied to the fine-tuning of the Universe for life, is rather ambitious.  It supposes that a universe that is right for life exists because there are untold multitudes of universes with different properties.  In the cosmic lottery, we got lucky.

Geraint:  Sounds like science fiction.

Luke:  Some think so.  Others, seeing the lack of plausible ideas for explaining the values of the constants of nature, take the idea seriously.

Geraint:  And us?

Luke:  We’re writing a book about it.  (p. 9)

Every cell in your body, for example, has molecular machines for moving itself, tagging and transporting molecules, processing food, defending against invaders, DNA duplication and repair, producing proteins and receiving and processing outside signals.  On top of all that, this entire machine can tear itself in half and produce a complete working copy in about 20 minutes.  A modern computer is pretty great, but it can’t do that.  (pp. 11-12)

Our models are mixtures of well-tested theories, reasonable assumptions and guesses; as Richard Feynman [d. 1988; 1965 Nobel laureate in physics] noted, ‘it is not unscientific to make a guess.’  Science happens when we ask the Universe whether we guessed right.  Otherwise, the experimenter is doing little more than stamp collecting, and the theorist is just playing with numbers!  (26)

A bank vault is robbed.  The armoured door was opened without force; the robbers used the access code.  The police arrive on the scene.

Drebin:  Maybe they guessed the code.

Hocken:  No way, Frank.  There are a trillion combinations.  The system shows that they entered the code correctly on the first attempt.  Surely the odds agains that are astronomical.

Drebin:  But it’s still possible, right?  (28)

The fine-tuning of the Universe for life, then, is fine-tuning applied specifically to the fact that this universe supports life forms.  The claim is that small changes in the free parameters of the laws of nature as we know them have dramatic, uncompensated and detrimental effects on the ability of the Universe to support the complexity needed for physical life forms.  (29)

Here’s one of those parameters for consideration:

The electron is one of the fundamental particles of the Universe.  Electron orbits around the nuclei of atoms dictate the processes of chemistry.  With the appropriate experimental equipment, we can measure the mass of an individual proton:  9.109 382 15 x 10^-31 kg (and, with our most accurate equipment, we know this value has an uncertainty of 0.000 000 45 x 10^-31 kg).  If you measure the mass of any electron in the Universe, you get the same answer!

When we measure the mass of an object in kilograms, we are implicitly comparing it to a lump of platinum-iridium alloy held in uniform conditions at the International Bureau of Weights and Measure laboratories in the outer reaches of Paris.  There is nothing special about this lump, and so nothing special about the kilogram.  Nothing changes if we were to express the mass of the electron in pounds, long tons, grains or carats.

However, the mass of the electron relative to other particles in the Universe is important.  Each member of the menagerie of fundamental particles comes with a mass, and while some are zero, many are just plain, unexplained numbers.

Here we can play our ‘what if?’ games.  If we change the relative masses of the fundamental particles, what effect does this have on a complex, multi-cellular, balding primate sitting and typing on a planet orbiting a star?  We’ll see in later chapters that the existence of life depends critically upon particle masses.  Universes with different mass ratios are often sterile.  (29-30)