Something extremely valuable to any blogger is regular readers. It's also something really hard to quantify.
But I know I have at least one, and I therefore value him quite highly. (Hey, not that way, now...don't get the wrong idea...) I just mean I really like that he's here...uh...you know what I mean. Right? (Koff) Anyway, I'm talking about Rob. (No snarky jokes, you guys.)
I owe him at least two posts, and I must apologize for my tardiness. Part of the problem is that I haven't gotten the whole "how to be a blogger" thing down pat yet--in order to write well (well, relatively speaking), I have to be "inspired" or otherwise get "in the groove." I've forced myself to post when I didn't feel like writing, and the result always seemed wooden and uninspired to me. I therefore tend to wait until I feel like I have to write about something, and I can easily fall victim to procrastination. I am a guy, after all.
Sorry for the digression. The subject at hand this time is this comment made in response to my post entitled "Predictions, schmedictions," referring to a recent genetic confirmation of a prediction made by the theory of evolution, of which Rob is highly skeptical. I was writing a response to follow his comment, and the more I wrote the more I realized that it should be on the main page rather than buried in the comments. So here goes.
OK, why did God make everything seem like it's billions of years old? Well, first of all, I don't have much of an opinion on the new earth, old earth thing.
Okay, good. We can dispense with the "young Earth" concept, although there are very likely some reading this who believe it. If necessary, we can address it more directly in the future.
But, I'll say this.. What proof do we have that the universe is as big as we think it is? Since rangefinding using paralax is useless beyond the solar system we rely on spectral lines and red-shifting. What solid proof do we have that this is a valid method of determining distance? None.
Okay. First of all, whenever I hear a skeptic use the words "solid proof" my spider-sense starts tingling big time--as a rule, this means he is applying a stricter standard of "proof" than he applies to things with which he agrees. We'll just have to see whether that's the case here.
I mean, what "solid proof" do I have that Rob exists? Have I ever seen him? Nope. I could be wasting my time writing a response to a mere figment of my imagination. Why then am I writing? Simply put, it's because I have more than enough evidence to believe that he is a real person. I don't need "solid proof" any more than he needs "solid proof" of my existence.
The truth is that the only sciences that can offer absolute, solid proof of anything are mathematics and logic--and logic is limited in that any proofs it can offer are contingent on the validity of the postulates one starts with. No one can actually prove that he exists, or that the doorknob he just turned exists anywhere outside of his mind. So we need to lay to rest this idea of "solid proof" in favor of something actually achievable: compelling evidence. And the evidence must be better than enough to convince just one person--that's what "peer review" is all about. The evidence must be sufficient to convince pretty much everyone in the field. Evidence "beyond a reasonable doubt." That's the standard we use in our justice system to send a man to jail--or to death row.
But proof, in this sense, also goes beyond even "reasonable doubt," and that's where the importance of scientific theory comes in. I suspect that Rob underestimates the importance of theory (although I don't know that for a fact). Science is far more than a collection of facts; otherwise it would be useless. We need to know far more than just what is true. We need to know why it is true--to construct a theory in which the facts make sense, and which makes predictions regarding what facts we should discover in the future, thereby validating--or invalidating, as the case may be--the theory.
From the Wikipedia entry on "Theory":
According to Stephen Hawking in A Brief History of Time, "a theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations." He goes on to state, "any physical theory is always provisional, in the sense that it is only a hypothesis; you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory."
A theory is not an "educated guess" in scientific parlance. There's no such thing as something being "just a theory." The word "theory" in popular usage is completely different from what a scientist means by a "theory."
But "solid proof" isn't attainable by anyone, so it's off the table. Agreed? Ok.
Back to range-finding and red-shifting. Yes, Virginia, we do have considerable evidence that redshift ranging is accurate.
Since rangefinding using paralax is useless beyond the solar system
Actually, parallax is useful to about 100 light-years, and there are about 1000 stars whose distances can be measured this way, with a resolution of about .01 arcsecond. In 1997 the satellite Hipparchus was launched in order to improve parallax measurements, and increased the number of stars we could range by parallax to 118,000, with a parallax resolution of 0.001 arcsecond.
We have other ways of measuring star distances because certain types of stars have consistent brightnesses, and we can therefore measure their distances according to their apparent brightness (how bright they appear from Earth). "Main sequence stars" and Cepheid variables work this way, and give us an accurate "yardstick" we can use to great distances. For example, Cepheid variables are stars whose brightness varies from hour to hour at a constant rate. It has been discovered that the star's average brightness is directly connected to its rate, or frequency--therefore, when a Cepheid variable is discovered in a particular galaxy, the distance to the galaxy can be calculated using the apparent brightness of the variable star.
This is how we can verify how well redshift ranging works. Calculate the distance to a galaxy using redshift ranging, then compare that to the distance you get using a Cepheid variable or a main sequence star in the same galaxy. The two should match. Guess what? They match.
One excellent presentation of how this works is here, although it's in Powerpoint format, and you have to have Powerpoint to see it. (Using "view as HTML" you lose the graphics, which are quite valuable in understanding the subject matter.)
Redshift ranging itself depends on the fact that certain elements in a star produce characteristic lines in the star's spectrum at exactly certain places, and if the star is receding from us, general relativity predicts that these characteristic lines will move, or shift, toward the red end of the spectrum. It would be beyond a mere blog post to go into how this is calculated, but you can easily look it up if you're interested.
The bottom line is that we do in fact have repeatable experimental evidence to back up the distances we get in redshift ranging. But like all things, we're still refining this method. Just because we haven't perfected our knowledge of something doesn't mean that it's useless.
According to this method we find that everything is receeding from us. So, once again, science puts us at the center of the universe, huh?
We can see only so far out into space, although that distance is increasing all the time with better instruments. Since we can see the same distance all around us, it is reasonable that we should appear to be at the center of the observable universe. This is far from claiming that we are at the center, of course. In fact, due to the nature of the way the universe is expanding, there really is no center as we would ordinarily understand it. There's an excellent Flash illustration of this concept here, showing that the center is, well, everywhere, depending on your point of reference.
If the Big Bang occured then wouldn't all matter in the universe be in a spherical shell expanding outward like a balloon inflating?
You're close. But the matter in the universe isn't what is expanding. It's the space that's expanding, carrying the matter with it. Consider your balloon illustration; inflate a balloon to about 4" diameter, then draw spots on its surface to represent galaxies, stars, whatever. Then blow the balloon up to 12" diameter. The spots are now farther apart--they all have receded from each other. But the spots themselves remained where they were--the balloon, representing the fabric of space, expanded, carrying the spots along. This is an imperfect illustration, but it gets it basically right. If you were able to draw spots in the interior of the balloon as well as on the surface, this would be closer to the real universe.
We should see some things actually closing on us in one direction but we don't.
Well, yes, actually we do. For example, looking at our "local group" of galaxies, we see that M31, or the Andromeda galaxy, is moving towards our own galaxy at about 130 kps (300,000 mph) and will begin to collide with us in about 3 to 4 billion years. But, as a rule, everything is receding from everything else, as shown in the preceding Flash illustration.
Hubble added his "Hubble Constant" (which is hardly constant, btw) as a correction for observed data not matching theorized prediction.
(Sigh) You seem to be claiming that the Hubble Constant is a "fudge factor" added to an equation just to make it come out as desired, which is hardly the case. It is true that its exact value is debated, but this is due to our limited knowledge of the exact rate of expansion of the universe. (There was a time when we weren't sure of the speed of light either, you know.) The Hubble Constant, simply put, is the "rate of recession of distant astronomical objects per unit distance away," meaning that the farther away an object is, the faster it is receding from us. We're still refining that value, but that doesn't mean it was pulled from thin air.
(UPDATE, next day: It occurred to me that you may have been thinking of Einstein's Cosmological Constant, which is a fudge factor as you described. Einstein also later called it "the greatest blunder of my life." Ironically, this constant is being re-examined by modern cosmologists, but no conclusions have been drawn yet.)
In alot of cases in science they start with a conclusion and work backwards. ID folks don't have a lock on that concept.
Here's where I would really appreciate some cites. If people are doing this, they shouldn't be. But the point is that if scientists are doing it, it's an aberration--a rarity, while ID and Creationism are totally based on this kind of research. Big difference.
Sorry for the length of this post. I still owe Rob another post, though, regarding his skepticism of the concept of "dark matter." It will involve a bit of history and four planets: Neptune, Pluto, Mercury, and Vulcan--which doesn't exist, unless you count a certain fictional planet circling 40 Eridani. And sorry, but it won't be very short.
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I pulled the redshift/parallax thing out of the air as an example. But let's keep with that. The proof of redshift being accurate seems to rely on alot, and I mean alot of assumptions. We assume that certain stars are all going to be the same size and brightness. What makes us think that? If we see two start and assume that because one is half the brightness then it must be twice as far (not making any attempt to make the number work here). Why can't it be 50 times as bright but 100 times the distance? Since it's presumeably much much older than the closer star (since we're seeing the light from it from deep in the past). Since we can't run out to the stars in question and measure them then how can we know for sure? We come up with hypothesis and test them and if we're reasonably close then we call that truth. Then years later someone comes up with evidence that we were not correct and then what? (fighting the urge to bring up dark E/M ;-} )
darn it.. I have a meeting to go to.. I'll pick this up later. sorry
Posted by: Rob | Wednesday, 07 September 2005 at 09:18 AM