Final post summarizing this Brian Greene book. Earlier: post 1, post 2, post 3, post 4.
The final three chapters return to the cosmic scope of the book’s overall theme, exploring what we’ve concluded about the far future and the possible end of the universe, and addresses the idea of ‘meaning.’ Plus some closing comments of my own.
Ch9, Duration and Impermanence: From the Sublime to the Final Thought, p244
In this chapter Greene speculates on the deep future, all the way to the final possibility of life, and thought. He employs a new way of representing deep time (somewhat analogous to Carl Sagan’s “Cosmic Calendar”). He imagines the timeline of the universe as the floors of the Empire State Building. Each floor represents 10 times the number of years as the previous floor. Each single floor thus dwarfs all those below it. At 13.8by since the Big Bang, we’re just a few steps above floor 10.
He considers evolution and entropy, again. Evolution might be avoided, through modern medicine. Entropy is almost certainly inescapable.
The sun will age, use up its hydrogen, and implode, and become even hotter as the helium burns. Swelling, it will swallow Mercury, likely Venus, and maybe Earth. Further cycles of burning will occur, until things run down, and the sun fades to black. The discovery in the 1990s that the rate of the expansion of the universe is speeding up led to the proposal of “dark energy.” Even if that rate is steady, eventually stars and galaxies will disappear from each others’ view. Big stars burn quickly, smaller stars longer, and over great lengths of time, a few will collide. Eventually galaxies will collide. Black holes, predicted by Einstein and detected in 2015, will sweep most galaxies clean of stars by the 30th floor.
What about life? Matter itself will eventually disintegrate, through proton decay. Could thought persist beyond the existence of matter? Freeman Dyson calculated the link between entropy and information. Any hypothetical thinker would have to slow down… perhaps hibernate. Is it possible to ‘think’ without generating any energy at all? Likely the last thought of the universe will occur around floor 50.
Greene takes this as meaning our current moment of thought rare, wondrous, and precious.
Ch10, The Twilight of Time: Quanta, Probability, and Eternity, p280
This chapter consists of speculation about the far future of the universe, even beyond life and thought. With vast timescales, many unlikely events can be considered. For example:
- The disintegration of black holes. Recalling Hawking radiation.
- The disintegration of extreme black holes. Even those at the center of galaxies will eventually fade to black.
- The end of time. Interactions among particles will become so rare it will be as if time has stopped.
- The disintegration of emptiness. Greene recalls the significance of the discovery of the Higgs particle. If the value of the Higgs field changed, it would destroy everything, at the speed of light — you wouldn’t know it until it hit you. Data suggests this might happen 10^102 years from now.
- Boltzmann Brains. Given enough time, random events might recreate all previous states of existence, including your own brain; this is called a Boltzmann brain. Say, within 10^10^68 years. Given enough time, it’s more likely for you to form as a Boltzmann brain, than as the ordinary one you think you are. That mean we can’t trust our own thoughts or memories… [[ These ideas are similar to those of Roger Penrose, in The Emperor’s New Mind and others books; but Penrose has apparently retracted some of those speculations, and Greene does not mention him at all. ]]
Yet the universe might end more speedily, in a ‘big crunch,’ perhaps one that bounces into another expansion; the universe would always exist, as an infinite spiral. This kind of cycle would occur at about the 11th or 12th floor. It’s possible certain observations could resolve the competition between this theory, and the inflationary theory.
If space is endless, infinite space would be a patchwork of separate bubbles with no sight or influence upon one another. A kind of multiverse, in which some universes would repeat, and every alternate universe we can imagine would exist. [[ This is slightly different, I think, than the standard of idea of the multiverse. ]] Greene mentions David Deutsch, who thinks this plan is hopeless, in terms of imagining ourselves still alive in some future reality. [[ I haven’t read Deutsch’s second book yet. ]]
Ch11, The Nobility of Being: Mind, Matter, and Meaning, p310
Finally, Greene addressed the idea of “meaning.”
He is confidant that nature is lawful. But that doesn’t mean our mathematics is the language of reality. Certain concepts like right and wrong, value and meaning, are inventions of the human mind. Have our cognitive powers enabled us to transcend innate, Darwinian beliefs? Or are we rationalizing? We are good at recounting the story of our existence, beginning 13.8bya. Particles and fields, initial conditions and physical laws, life and behaviors, and eventually thought, self-awareness. Language, and seeking significance and meaning.
Would it be better to overcome death? Speculations about what would happen if we do haven’t come out well. We might easily become listless and bored. Author thinks we could become well-adjusted immortals, continually inventing new things to do. Of course, we wouldn’t be literally immortal, since the universe will end. Knowing that life is finite gives life a certain value.
A common priority of humans is to leave descendants. Author recalls a play about what would happen knowing the earth would shortly be destroyed by an asteroid. More to the point: which would be worse, you dying in a year, or the whole world being destroyed in a year? (We know each of us will die, but we realize the race, and likely our family, will live on, so that doesn’t make individual deaths so bad.) But in changes of scale, our rationalizations become trivial: over time, our race is ephemeral and evanescent.
Again, Greene interprets this realization as meaning that our moment is rare and extraordinary. That we exist and have realized this is wondrous.
So: it seems that the universe does not exist for the sake of life and mind; those are just a couple things that happen to happen, until they don’t. We exist while an infinite number of other possible people do not. And we have the ability to step outside of time, and realize these things.
Yet there remain deep questions for which we have no definitive answers. Perhaps our brains are not structured to answer such things. [[ Pinker made a similar point. ]] Or perhaps our perspective will change.
So: there is no grand design, no purpose, no final answer lurking out there. we create purpose within our subjective worlds. We must look inward. We construct our own meaning. The human species contemplates itself, telling a story that stirs the soul. There is perhaps, he suggests, only story. Final para:
As we hurtle toward a cold and barren cosmos, we must accept that there is no grand design. Particles are not endowed with purpose. There is no final answer hovering in the depths of space awaiting discovery. Instead, certain special collections of particles can think and feel and reflect, and within these subjective world they can create purpose. And so, in our quest to fathom the human condition, the only direction to look is inward. That is the noble direction to look. It is a direction that forgoes ready-made answers and turns to the highly personal journey of constructing our own meaning. It is a direction that leads to the very heart of creative expression and the source of our most resonant narrative. Science is a powerful, exquisite tool for grasping external reality. But within that rubric, within that understanding, everything else is the human species contemplating itself, grasping what it needs to carry on, and telling a story that reverberates into the darkness, a story carved of sound and etched into silence, a story that, at its best, stirs the soul.
\\\
Comments. A lot to unpack here. I’ll be thinking about this a while. Superficially this is a standard, non-religious answer to life’s “meaning”: you create your own meaning. Through family, dedication to causes, etc. There is no external meaning, in the sense of your life being for some higher purpose. (What purpose would that be? Adoration of some ‘god’ who created you? That’s too similar close to a slave/master relationship, for many of us.)
More deeply, Greene’s perspective is that “meaning” is understanding our place in a vast universe, a place which is infinitely unlikely. And it’s only by understanding the nature of the reality we live in, that our actual purpose or meaning makes any sense. Most people live in fantasy worlds — and that is completely understandable through the evolution of the human race, and its propensity to tell stories (about ‘meaning’) in order to make sense of our reality.
