by ILoveTTATT 130 Replies latest jw friends
Ilovett: The energy of a system as a whole always decreases, and the entropy always increases.
actually the energy is conserved. The second law is irrelevant for biology on earth for a number of reasons already mentioned.
also, perry, open an effing book allready.
FWIW, I've been going over in my mind whether Lenski's experiment (which CLEARLY demonstrates evolution via adaptation), reflects "natural selection" or "artificial selection". I'm leaning more towards "natural selection" now, although that term implies changes that occur without influence of humans, but due to nature; in the experiment, scientists are obviously playing the role of God....
However, the team didn't actually select for those bacteria that could metabolize citrate, since that finding caught them off-guard (it was added as a culture media), so it's not an adaptation that arose via artificial selection.
The key is the term "selection": who's doing the selecting? If it's a result of changes in the environment, even those changes controlled or even caused by scientists, it's an adaptation that falls under the category of "natural selection".
http://wiki.answers.com/Q/What_is_the_difference_between_natural_and_artificial_selection
Natural selection is the result of natural factors, which favour certain variations. Artificial selection is the deliberate selection of certain traits (by humans), for example a Poodle is the result of artificial selection.
Natural selection occurs when a particular feature gives an organism a survival or mating advantage-- so for example, giraffes with longer necks were better able to feed themselves than those with shorter necks. Over time longer necked giraffes were better able to survive and breed. So longer necks were selected for naturallly.
Artificial selection is when humankind chooses certain traits and breeds organisms for that trait. Example-- the domestic dog. The original organism was the wolf. Humans chose certain traits, such as size or temprement and bred together those with the desired trait(s). Hence the various breeds we have today.
Natural selection is largely determined by environmental factors, where nature chooses organisms with the best traits for survival.
Artificial selection is controlled by humans, where a person chooses which traits of the organism that he wants it to have.
I take exception to Adamah's suggestion that we've bred for fat cows. We've bred for square, meaty cattle.
What we started with:
"The energy of a system as a whole always decreases, and the entropy always increases. Eventually the sun will run out of fuel, the planets will stop spinning, etc... eventually all will be cold, energy-less, and life-less. (If you take the 2nd law of thermo to its logical conclusion)."
If I understand the direction of your thinking, you're taking what we learned in Thermo and follow it to it's "logical" conclusion. All the fuel is depleted and nothing is left to power any systems. We're doomed to a certain death... in the next hundred billion years or so. Consequently, don't go buying any green bananas, eh?
That's where theoretical physics comes in. I won't pretend to know much about it, but at it's basis is the realization that everything we know (including the laws of thermo), is still limited. As one ChemE to another... How much did we really learn about gravity? Oh, we learned the equations and the effects are evident, but it's still an active area of research to understand mass attraction. In my flawed opinion, gravitons could be found to be in disagreement with a generalization of the second law, or rather, shed "new light" on where the second law does and doesn't apply.
Before I go further with thoretical physics, is this the type of thing you're wondering about?
ILuvTTATT said-
The energy of a system as a whole always decreases, and the entropy always increases. Eventually the sun will run out of fuel, the planets will stop spinning, etc... eventually all will be cold, energy-less, and life-less. (If you take the 2nd law of thermo to its logical conclusion).
That's exactly WHY the 2nd law doesn't apply here, since the system isn't devoid of an energy source: as you say, the Sun is our predominant energy source, that is IF abiogenesis even occurred within our solar system (and not due to energy derived from another source besides the Sun, but anywhere, due to gravitational forces within planetary bodies, as seen in the PBS video about astrobiology I linked to).
There's some who think the original 'seed' molecules formed on meteors in deep space, which accounts for the enantiomer bias noted in amino acids, since the conditions under which they form doesn't yield 'racemic' (i.e. 50/50) mixtures, but are more biased towards a certain chirality over the other.
Jgnat said- I take exception to Adamah's suggestion that we've bred for fat cows. We've bred for square, meaty cattle.
Yeah, you're right, but those are not my words, but a website I quoted.
The explanation is not intended to be a guide to animal husbandry (!), but only an explanation of principles of artificial selection, saying how certain traits can be intentionally selected for by humans.
It's possible to select for dairy cows (ie. those with more adipose tissue in their udders), to towards greater milk production; however, it's also possible to select for those with a more muscular build, not only via direct genetic manipulation ("intelligent design" i.e. insertion of specific genes that are known to code for protein expression, resulting in a beefier animal), but also via insertion of steroids and growth hormones into their feed, resulting in animals designed to yield more beef (beef cows).
Adam
the system is the cosmos, then the universe.
The sun loses mass as it radiates energy, but the radiation when absorbed, increases the mass of the absorber (all around the sun) look at the deep (old, no young) space pictures of packed galaxies. space is curved and solar radiation will not leave the universe.
At the beginning, before the first effect, energy was packed into the universe, life is a unique way of packing, using energy on the run.
The beginning, the BB and life's beginning are the 2 outstanding examples of something special going on.
gravity can be a force, a tensioning of space or gravitons cavorting about, triply confirmed by these models.
Hormones in the feed?
traces in the food we eat.
it is not over until that fat(tened) lady sings.
Prologos said-
At the beginning, before the first effect, energy was packed into the universe, life is a unique way of packing, using energy on the run.
You're already on shaky ground with that claim, since some theoretical physics say that statement is malformed, since time started AT the Big Bang, and hence time itself came into existence with the event. Therefore, it's meaningless to say 'before' what was the very start of time.
Of course, your World-view is likely based on trying to syncretize the Bible and science, trying to blend Genesis 1:1 ("In the beginning, God created the Heavens and the Earth"), with a God who existed before the Big Bang. Good luck with THAT!
MOVEMENT THROUGH time started at the big bang when energy moved out of the plank-size singularity.
I'm not so sure the OP is even reading this thread, but for anyone else who's following with interest, some more answers to ILTTATT's questions about how/why complexity develops, and what speeds up evolution, from Wikipedia's "Evolution of biological complexity":
"Organisms that reproduce more quickly and plentifully than their competitors have an evolutionary advantage. Consequently, organisms can evolve to become simpler and thus multiply faster and produce more offspring, as they require fewer resources to reproduce. [Parasites] often dispense with traits that are made unnecessary through parasitism on a host."
"More generally, the growth of complexity may be driven by the co-evolution between an organism and the ecosystem of predators , prey and parasites to which it tries to stay adapted: as any of these become more complex in order to cope better with the diversity of threats offered by the ecosystem formed by the others, the others too will have to adapt by becoming more complex, thus triggering an on-going evolutionary arms race towards more complexity."
"In this hypothesis, any appearance of evolution acting with an intrinsic direction towards increasingly complex organisms is a result of people concentrating on the small number of large, complex organisms that inhabit the right-hand tail of the complexity distribution and ignoring simpler and much more common organisms. [...] Consequently, in this view, microscopic life dominates Earth, and large organisms only appear more diverse due to sampling bias."
Apo, quoting Wiki, said-
"More generally, the growth of complexity may be driven by the co-evolution between an organism and the ecosystem of predators , prey and parasites to which it tries to stay adapted: as any of these become more complex in order to cope better with the diversity of threats offered by the ecosystem formed by the others, the others too will have to adapt by becoming more complex, thus triggering an on-going evolutionary arms race towards more complexity."
Yeah, I bristle whenever I see phrases like those in bold above. It reflects an all-too-prevalent misconception of how evolution actually operates, since organisms cannot "try to stay adapted", even if they wanted to; they either are adapted sufficiently to the selection pressure of the environment via prior random mutations, and if they don't possess the capability to survive, they don't. Very cut-and-dry. Many that ARE adapted sufficiently to survive are also not guaranteed to survive, due to encountering some random bad luck and misfortune.
Adam
