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Opposition to Galileo was scientific, not just religious

aeon.co

221–226 of 226 posts

Re: Opposition to Galileo was scientific, not just religious

#221

Stupid question: given General Relativity, and in particular that all reference frames are equally valid , including rotating and accelerating ones, in what sense is heliocentrism more 'true' than geocentrism? E.g. you can pick a geocentric reference frame and all the math works out (albeit you'd need to define large fictitious forces, etc., but again, they are only 'fictitious' from the perspective of a different re…

Of all the answers offered here, the only ones that get to the heart of the matter are those that make the distinction between inertial (non-accelerating) frames of reference, and those that rotate (and therefore have at least centripetal acceleration). In Newtonian and post-Newtonian mechanics, only inertial frames are equivalent. A geocentric frame (with a rotating Earth) spins the whole universe once a year; fix t…

You can have accelerating frames of reference in Special Relativity; for example, one can set Rindler coordinates on a body that is uniformly accelerating.

Addtionally, you can have locally inertial frames of reference that are inequivalent. Consider two space stations orbiting Earth at different altitudes. The occupants are in free-fall in both cases, but there is a relative acceleration between them.

Rotating frames of reference tend to distract users into confusing coordinate artifacts with physical ones. As a trivial example, suppose we vary the Minkowski metric by introducing a rotation into Cartesian coordinates: dS^2 = -\left(1 - \omega^2 ({x}^2 + {y}^2) \right){dt}^2 + 2 \omega (- y dx dt + x dy dt) + {dx}^2 + {dy}^2 + {dz}^2. Here a non-massless object far from the origin will have |d\vec{x}/dt| > 1, or in other words a coordinate velocity greater than c.

This is essentially the same as your last sentence.

However, when we calculate the four-velocity \eta^\mu of any non-massless object, even far from the origin, we will see that dS^2 We can certainly do Standard Model physics (or classical particle dynamics) in a rotating system of coordinates, using a number of approaches.

However, it is usually easier to use a different system of coordinates, and even better to abandon the idea of using any global system of coordinates in a spacetime that is not Riemann flat.

Re: Opposition to Galileo was scientific, not just religious

#222

Stupid question: given General Relativity, and in particular that all reference frames are equally valid , including rotating and accelerating ones, in what sense is heliocentrism more 'true' than geocentrism? E.g. you can pick a geocentric reference frame and all the math works out (albeit you'd need to define large fictitious forces, etc., but again, they are only 'fictitious' from the perspective of a different re…

Are these "large fictitious forces" the same thing as Dark Matter today? That would be pretty interesting, if so.

That's a good question, but the short answer is no.

Fictitious forces relate to particular choices of coordinate systems (and their origins). For example, the centrifugal force is an easy way to think about the tendency to be pulled "down" by an astronaut aboard a spinning space station; that astronaut can think of a set of cylindrical coordinates with the origin at the centre of rotation of the station, or of a set of Cartesian coordinates with the origin at some point on the "floor" and centrifugal force is simply natural-seeming. However, if the astronaut uses a non-rotating set of Cartesian coordinates whose origin is outside the entire station, for example, centrifugal force no longer seems very natural as an explanation. Alternatively, close inspection of the path traced by a dropped tablet would also conflict with expectations from a real centrifugal force.

Careful study of the movement of stars in the outer reaches of certain types of rotating galaxies threw up a surprise: the linear velocities of stars orbiting far from the centre should be much faster in order to maintain their roughly circular orbits than observational evidence of their speed allows. This difference does not change with a change of coordinates, so it is not an artifact of a choice of coordinate systems. Thus it is not really fixable with a fictitious force; so far the only "fix" we know is to either use known real forces that are generated by the non-gravitational content of the universe (possibly adding not-previously-known matter) or to keep the matter content constant but modify one or more forces. (Hybrid approaches are also possible). The space for introducing truly new long-range forces has been heavily constrained by experiment on Earth, and a "fifth force" is essentially ruled out. We have not yet ruled out many viable forms of previously undetected matter, however some forms are no longer plausible.

Dark Matter introduces invisible mass far from the centres of galaxies that help to suspend these surprisingly slow-moving stars. Modifications of gravity have also been proposed that bend the trajectories of such stars less towards the centres of their galaxies.

Dark Matter also explains the peculiar velocities of galaxies within several clusters; they move as if attracted to unseen mass in the cluster. Previously mentioned modifications of gravity have to be further modified to incorporate these observational results.

Collisionless Dark Matter also explains the behaviour of several known (past) galactic collisions where gravitational lensing preceeds the visible matter and especially the energetic gas and dust that collided as the galaxies passed through one another. This so far has not been fixable by yet more modifications of gravity, however people are trying that approach too (e.g. https://arxiv.org/abs/1606.09128).

Re: Opposition to Galileo was scientific, not just religious

#223
post #22

Earlier quoted context omitted.

Interesting. Does the barycenter then have a barycenter over time?

By definition a barycenter is a center of mass, so since a barycenter itself has no mass, it would not have it's own barycenter. It could have a "mean location" though!

Ah, that's what I mean!

Re: Opposition to Galileo was scientific, not just religious

#224
post #194

Earlier quoted context omitted.

> I have yet to meet a scientist who [...] And yet you've also never met a scientist who says: "This is my current hypothesis so I've vanquished all possibility of doubt. I'm going to publish it without even testing because it MUST be right." You should entertain the notion that the word means something entirely different to religious people than to others. > The fact of the matter is that everyone still believes in…

You should entertain the notion that the word means something entirely different to religious people than to others. You have a very narrow definition and/or experience of what religious people are like. You should entertain the possibility that there are religious people who are more open-minded than you think. Even if that were true, the only reason you're saying it is to show that even scientists make that mistake…

> Everyone at the end of the day relies on faith

> We should not propose that we know what's going on in other people's minds.

Both are you, and incompatible with each other. It seems that you think you should tell other people what's in their minds, but that nobody should tell you what you think...

And yes, we should not under normal circumstances. But when someone tries to tell us something crazy, such as that we are belief focused, we should examine their motives and see if they have a reason to want us to think we do... You obviously do because you're trying to normalize the idea of belief.

> I don't say this lightly: you have issues, man.

Yes, apparently you do. You don't even read the thread again before saying it, to see if you were the one throwing stones.

Re: Opposition to Galileo was scientific, not just religious

#225
post #108

Earlier quoted context omitted.

Scientists do not generally have faith in their hypotheses in the same way that religious believers have faith in the claims of their holy book or their religious leader. That would be an equivocation on the usage of the term 'faith', one usage being merely confidence or trust, which can be apportioned to the available evidence, and the other usage being a religious belief in doctrines regardless of available evidenc…

It sounds as if you've taking your conclusion that religious faith must be blind and ignorant and worked backwards from there. I remain unconvinced that people who consider themselves religious are any worse at adjusting their world view to scientific evidence than people who do not.

> It sounds as if you've taking your conclusion that religious faith must be blind and ignorant and worked backwards from there.

Faith must be, yes. All faith. It's what exists in absence of, or despite, evidence.

> I remain unconvinced

Thankfully that's a bridge we don't need to cross. We've led you to water, your unwillingness to drink it isn't anyone else's failure.

Re: Opposition to Galileo was scientific, not just religious

#226
post #153

Earlier quoted context omitted.

> certain interpretations of the Koran lead to terrorism No, any belief in it or any other religion, leads to killing and oppression. As Old Man Jay says, it's the act of believing, not the belief per-se that's the issue. When you believe that there's a god above who will reward you infinitely it's going to skew your worldly actions one way or the other. You'll do what you're told, right or wrong, and that's the #1 i…

And yet you seem to have no problem making normative judgements. . .

Of course I don't. I grew up in and around religions. This isn't like me trying to tell some single African woman about child rearing or anything.

I have insider knowledge, as much as anyone else, and I resent your implication that I'm not allowed to have an opinion.

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