Models or systems can be tested to see if they give the right answers, that is they can be compared to observaton and experience. Models that do not compare to observation of course do not give the right answer. For specific examples, the above quote is excellent in comparing the geocentric model and the heliocentric model. It makes it clear that the geocentric model simply doesn’t give the right answers, and the heliocentric does. It is also simpler, easier to calculate, parsimony.
For some people it might stop there–the heliocentric model is used because its answers correspond to observation and is easier to use. Now if Galileo had stopped there, he wouldn’t have gotten into trouble. But he presented it in such a way as to indicate he believed the earth actually DID go around the sun, not just as a convenient way of calculating.
I’m not understanding your point here. You concede that a geocentric model of the solar system doesn’t match observation yet it should be adhered to anyway? You seem to think that these models are nothing more than mathematical constructs which cannot tell us anything substantive about what we observe, and that simply isn’t the case. The heliocentric model works while the geocentric one does not, so we properly conclude that the Earth does orbit the Sun.
So that’s the question I’m asking. Do our scientific models correspond to reality, are they true with a capital T, or are they merely useful devices for predicting? Analogies for a reality that keeps retreating as new theories come into being, to explain new observations?
The heliocentric model of the solar system has not “retreated”. Modifications have been made to some specifics, such as Kepler’s laws concerning elliptical orbit, but these modifications have not changed the underlying principle that bodies of smaller mass orbit bodies of larger mass.
I think most scientists believe that their theories actually do correspond in some way to “out there,” and don’t exist just as convenient methods for getting the right results. That is how they differ from engineers. The main concern of an engineer is to use a formula that will give the right results, that is, guarantee that the bridge he builds will not collapse, nor the airplane wing fall off. Whether or not his formula in some way describes a real “out there” isn’t to the point, in his view.
That engineers apply theoretical physics to a practical setting doesn’t change the fact that the underlying theories
do explain reality. I highly doubt you will find any engineer who says something along the lines of “I design my transistors with Lenz’ Law in mind (a law which relates the induced electrical current in a wire due to the magnetic field of another wire) but I don’t really believe that there’s some force called ‘magnetism’.”
twinc mentioned that NASA engineers used formulas that assumed the geocentric model, and those formulas give them the answers they need. I can’t imagine a NASA engineer actually holding a geocentric world view (Truth with a capital T), but he simply uses what is handy.
He has yet to substantiate his claim that NASA uses a geocentric model for all their calculations, and I’d safely bet my house that he won’t be able to as it’s complete rubbish. Despite the claim being false, it does touch on a matter that I think needs addressing: assumptive calculation.
Cassini, in an attempt to vindicate twinc’s claim, posted an op ed which addressed how
pilots (not astronauts or astronomers)
assume that the Earth doesn’t move when making certain calculations. I don’t know whether this is true, but I have no reason to necessarily be skeptical since it would make sense that someone for whom a problem’s scope doesn’t extend outside Earth would find the Earth’s orbit
irrelevant. Saying that something is irrelevant isn’t the same as denying its existence.
We could use another physics example for this: It’s generally well known that Einsteinian physics has superseded Newtonian physics, yet physics students are still taught the basic Newtonian formulae for motion. Newton’s formulae do not take into account that space can contract and time can dilate as Einstein showed through relativity, so does that mean there’s an inherent contradiction in physics? Not at all. The effects of relativity matter only when an object is moving
close to the speed of light, which as you could imagine doesn’t occur with most common objects. Since my car cannot travel even 1/100th the speed of light, I can completely ignore relativity and use x(t) = x₀ + v₀t + at² to model the motion of my car. Does that mean I don’t accept relativity since I’m seemingly ignoring it? No, it only means relativity makes a negligible contribution to my car’s motion
in that situation.
In many cases, we also ignore that the Earth is round! Oh my we must be secret flat-Earthers too! The curvature of the Earth can be safely ignored in most scenarios since we aren’t typically calculating the motion of an object over a significant distance. While modeling a projectile, such as a baseball which will only go a couple dozen meters, I can
assume that the Earth is flat
even though I know well that it isn’t!.
Now I cannot make these
assumptions if I’m modeling the motion of, say, a photon which travels at the speed of light, has no mass, and exhibits wave-particle duality. I cannot make these
assumptions when modeling the motion of a rocket launched from North Korea to New York City. In these cases Newtonian mechanics would actually produce a
wrong answer, which stands as more evidence that relativity is correct and that the Earth is not flat.