Brent and 1Z, The paper you referenced says the following: "No doubt life, as we know it, depends sensitively on the parameters of our universe. However, other forms of life might exist under different conditions."
I agree with that statement. Certainly there are other arrangements of laws which would permit life to exist. The question is how often is it, among all possible structures, that intelligent life is possible? It does not appear easy. Try inventing your own set of physical laws which if followed from the beginning to the end which would permit life to evolve and exist. It takes a lot of consideration and thought for people to design virtual realities which support artificial life (alife), even when it is very simple compared to the life we know. Consider what is necessary just to support evolution: 1. An chemistry rich enough to construct self-replicating machines 2. The ability for life to reliably encode, read and copy information (necessary to record results of natural experiments, as DNA does for us) 3. Unreachable entities (in our case stars) which provide limited energy/resources at a fixed rate for life forms to compete over during the course of trillions of generations 4. This energy source must not easily attainable or duplicated by life (if fusion were biologically possible life would consume all the potential energy long before it could evolve intelligence) 5. No easy shortcut to get an unlimited or infinite amount of energy (Something like the laws of thermodynamics, otherwise life has no incentive to increase in complexity once it discovers such a trick) 6. Re-usability or resupply of materials used by life (If biological material or waste can't be broken down to be reused by other life forms then such material or resources would run out) 7. Long term stability of environment and constancy of physical laws, otherwise life would be quickly wiped out or the validity of the information recorded from natural experiments becomes invalidated I think the above rules are necessary not just for life as we know it in this universe, but life anywhere. Our own universe seems just complex enough, but no more complex than is necessary, to provide each of these requirements. What do you think the chances are that any random object in Plato's heaven, or any random Turing machine will support intelligent life? 1 in 10, 1 in 1000, 1 in a billion? I think the universe's apparent Fine-Tuning is controversial only to a few general types of audiences: 1. Physicists who believe in a grand theory of everything which will explain logically why this universe has to have the physical laws it does, and why no other physical laws are possible. 2. Those who consider the idea that there are multiple universes to be ridiculous or unscientific. 3. Those who consider it only as a justification for intelligent design theories. Fine-tuning is a direct consequence of the anthropic principle once one assumes multiple universes. Say you were completely agnostic on the question of there being other universes, but you decided the probability of any random universe having those seven necessary properties necessary for life was 1 in 1000. You must then decide between there being only one universe (the one you see) and wonder why we were fortunate enough to hit the 1 in 1000 chance to be alive, or you conclude multiple universes exist, and there is no mystery or luck involved. One's confidence that there is only 1 universe should be roughly proportional to the likelihood that life exists in any randomly selected possible universe. That the Anthropic Principle + Mathematical Realism explains the appearance of Fine Tuning is just one of its many attractions. Among the other appeals of mathematical realism are that it answers some longstanding questions: Eugene Wigner's "The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve." Einstein's "The most incomprehensible thing about the world is that it is at all comprehensible." John Wheeler's "Why these particular equations, not others?" If mathematical reality is taken as true the appearance of a physical reality is a direct consequence. If one starts with a physical reality, however, one I am curious to know at what point do you consider the items in this progression to no longer be real and what point you begin to apply the label of immaterial or abstract: 1. The matter and space beyond our cosmological horizon which we can neither see nor interact with 2. Other theorized cosmic inflation events (new big bangs) happening elsewhere or very far away 3. Events or people which exist in the distant past 4. Other branches of the multiverse as postulated by Everett 5. Other solutions to string theory which define other possible physics 6. Altogether different physical laws and universes, defined by the equations completely unlike those of string theory 7. Universes which exist with simple rules, finite state automata like John Conway's game of life 8. Turing machines executing programs 9. Mathematical structures defined by equations, such as the Mandelbrot set 10. Simpler mathematical structures, spheres, circles, triangles 11. Integers If Mathematical objects have an objective reality then what is abstract vs. what is physical becomes a matter of perspective. You call this world physical because it is the abstract mathematical object you find yourself in, someone in another mathematical object / universe might consider this one we inhabit to be abstract. I see no value in placing labels of existence of "physically real" to anything which is possible, but a lot of value from deciding possible things exist too. It answers many questions and eliminates the apparent arbitrariness which is required for this to be the only possible reality. Have scientists discovered any principle or evidence which suggests this is the only possible universe? If not what is your motivation for believing it? Jason On Wed, Feb 9, 2011 at 1:15 PM, Brent Meeker <meeke...@dslextreme.com>wrote: > On 2/9/2011 7:57 AM, Jason Resch wrote: > >> 1Z, >> >> How do you define existence? For something to exist must it be something >> you can see and feel, or would you say it has to be something that can be >> studied objectively? Would you agree that for something to have objective >> properties, it must exist? Clearly there are things humans have discovered >> which we can't see or feel, but we think they exist because we see their >> effects: wind, dark matter, black holes, etc. Or theories suggest their >> existence: extra-solar life, strings, and so on. >> >> I would argue that mathematical objects exist because this universe's >> existence does not make sense in isolation. Imagine you were in a >> windowless bathroom. Should you doubt the existence of the rest of the >> world because you cannot see it, or would there be clues to support the >> existence of things outside that room? The finely tuned physical constants, >> laws, dimensions, etc. of this universe suggest that this universe is one of >> many, perhaps one among all possible structures. Just as we see the affects >> of wind and know it exists, one can look at the fine tuning of this universe >> and believe in the existence of all possible structures. Every such >> structure is a mathematical entity. If you doubt the existence of >> mathematical objects, how do you explain fine tuning? ( >> http://en.wikipedia.org/wiki/Fine-tuned_Universe ) >> >> Jason >> > > Fine-tuning is a very speculative and poorly supported peg to hang > existence on: > > http://www.colorado.edu/philosophy/vstenger/Fallacy/FTCosmo.pdf > > Brent > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To post to this group, send email to email@example.com. > To unsubscribe from this group, send email to > everything-list+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/everything-list?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to firstname.lastname@example.org. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. 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