Original Message: ----------------- From: Doug Pensinger brig...@zo.com Date: Sun, 25 Jan 2009 15:15:44 -0800 To: brin-l@mccmedia.com Subject: Re: Galactic Effect On Biodiversity
Dan wrote: If you really believe that, then you would throw most of evolutionary > theory out, beause we've only been making good scientific measurements over > a very limited scope of time, say the last 150-200 years. >The difference in limits of scope between evolution on earth and universal >evolution, if you will, are vast. Not that vast. Now, as Charlie pointed out, I'm no expert in biology, but everything I've read indicates the timescale of the universe and the timescale of life on earth are best estimated to be within a factor of 10 of each other. Wikipedia (not the best source I know but probably good for an estimate) has single cell life existing on the earth for > 3 billion years. >We have data points from near the beginning of life on earth to the present, but >in UE we have comparatively few data points. A couple of things. First, I've long understood that fossil records are not critical to the theory of evolution (just to reinforce the point that I've long in _agreement_ with Charlie's point on this). Second, fossil records are not measurements made in the past, but measurements made in the present that fit a model that extends far into the past. Similar things can be done with cosmology. I'd be happy to show why other models, that assume that the age of what is observed is vastly shorter than is assumed by the astrophysics community, have been fasified by the array of available data. >Beyond that, where in EE we can observe and experiment >upon the entire real time scope, in UE we must make our observations from >a minuscule point within the system. I return to my analogy about the tiny >observer 1000 feet beneath the sea. How much of earths evolution could that >observer deduce? Well, that observer can't see very far. How far can we see with our orbiting telescopes (tuned to various wavelengths)? >> The arguement against this is entropy, but that's statistical. The chance >> of this happening is 1 in 10 to the zillinth power, but not zero. >Isn't this kind of a straw man? A fair coin will come up heads half the >time, but an unfair coin is far from inconceivable. No, but if we observe billions upon billions of fair coins(galaxies), why would we live on one of the few unfair coins? In the sense I was talking about, we know that galaxies are receding from us at the same distance/pace rate (to within 1 part in 10,000) in every direction. The simplest assumption is that this is true for an observer in any given galaxy. Now you could assume that the earth just happens to be in the middle of the universe, or in another extremely rare spot, but then I think you need to explain why. Now, if you were arguing that there is variation in the universe and things like the speed of light varies, then that is a different story. People have made up models with variable fine structure constants, etc. Those have testable results, and up to now, they have provided results that do not match observations. >Ah, but if you read the article on the cosmological principal you would have >found in the last section (sorry about the font): I read that. But, maybe the implications are not clear. Inflation is genrally thought to occure in the 10-34 sec to 10-32 seconds after the big bang. http://aether.lbl.gov/www/science/inflation-history.html from the Lawarance Berkley Lab is my source for these numbers. I'm guessing that we don't have these numbers down cold, and the length and time of inflation might vary a good fraction of an order of magnitude here. The paper that's being discussed indicates that the data might point to events happening before 10^-34 seconds. It presupposes the big bang, in other words. It is fair to say that inflation has explained a lot. As one of my references pointed out, there were quantitative predictions made by the inflationary model that have later been varified by experimentation. So, while we still have a lot of uncertainty concerning the first small fraction of a second after the big bang, we've done a nice job matching the observed universe down to a universe that existed, say, 1 second after the big bang. It has been stated that aspects of the inflationary universe and anything before inflation involve guesswork. But, assuming that the general framework is wrong and we have to start over would take a lot more. >You don't have to show me, I'll take your word for it. That merely makes >the Big Bang the most correct of all the _proposed_ possibilities and says >nothing about the possibilities we can't even imagine because our powers of >observation and our ability to conduct experiments is so abysmally limited. But, all science does is model observations. Rich and I have very different metaphysical viewpoints, but we agree (as does virtually every physicists I have talked to or corresponded with, science doesn't describe truth, it models observations. >What you could help me understand is how well the Big Bang works if the >universe is not homogeneous and isotropic? First, because the inhomogenaity is at the 10^-4 level. Other models need a lot of manimpulation to produce as much homogenaity as we see. Second, the inhomogenaity has been quantitatively predicted by a modification to the big bang theory that covers the very very early universe. The energy densities there are very high, and if you were to tell me that at those energy densities the laws of physics work a bit differently than they do at lower densities, that's not unreasonable. So, additional theory was developed, tested with new data, and thus verified. So, as long as the modifications to the theory keep on happening at higher densities, and even earlier after the big bang, with even small observables, we are in the process of refinment by exploring areas that we didn't know about. In a sense, the big bang is a good name for a family of theories, with refinements accepted as new data comes in. This family should be rejected if and only if modest refinements do not work. Now, it is reasonable to ask when we are just adding epicycles? If you can come of with a consistent simple theory back to 10^-50 seconds, that would be better than three seperate sets of structure. But, that would be part of the big bang family, because it is basically a theory that starts with the universe at close to a singularity. The real alternatives are theories like the steady state theory, which was the big bang's competitor until the background radiation was found. Dan M. -------------------------------------------------------------------- mail2web.com What can On Demand Business Solutions do for you? http://link.mail2web.com/Business/SharePoint _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
