I haven’t taken this position just to be difficult. To look around, the world does appear to be flat, so I think it is incumbent on others to prove decisively that it isn’t. And I don’t think that burden of proof has been met yet.
-- Daniel Shenton, President of the Flat Earth Society as of 2010
the world does appear to be flat, so I think it is incumbent on others to prove decisively that it isn’t.
I haven’t yet tracked down a good quote on this type of “asymmetric intellectual warfare”, where one advances some outlandish claim that lays waste to large portions of a consistent belief network, and then insists it’s the victim’s obligation to repair the damage. I’m pretty sure the idea has been around for a while, perhaps not in terms of that military metaphor. Is that topic covered somewhere in the Sequences?
It’s not presented in terms of information warfare, and it doesn’t explicitly cover “insist[ing] it’s the victim’s obligation to repair the damage”, but the original article on Dark Side Epistemology (now known as “anti-epistemology”, I hear) sounds similar to what you’re getting at. Specifically, the point that to deny one scientific fact, you need to deny a massive network of principles and implications, to the point that your entire epistemology ends up either contradictory or useless.
As long as people are prepared to take on unpalatable ideas, and really push to see if they have merit, then we might just make significant NEW discoveries, instead of the slow and detailed clarification of what we already know.
It really doesn’t matter if the Earth proves not to be flat. :-) There are other, equally crazy, ideas out there, and a few of them are true! THEY are the ones we want to find, if we can.
As Richard Feynman (the pre-eminent scientist of the modern era, in my opinion) said: “If we will only allow that, as we progress, we remain unsure, we will leave opportunities for alternatives. We will not become enthusiastic for the fact, the knowledge, the absolute truth of the day, but remain always uncertain. … In order to make progress, one must leave the door to the unknown ajar.”
-- PatternChaser0, commenting on the story about Daniel Shenton.
Its embarrassing but I have to say that honestly the centripetal force argument never occurred to me before. Rough calculations seem to indicate that a large man 100Kg should be almost half a pound heavier in the day time as he is at night. Kinda cool.
Now I am dying to get something big and stable enough to see if my home scale can pick it up.
As you stand on the equator, with the Sun directly overhead, its gravity is pulling you away from the Earth’s center. On the other side of the Earth, the Sun’s gravity pulls you in towards its center. Consequently you weigh slightly less at noon than at midnight. However, since the force of the Sun’s gravity on a 100-kg mass 1 AU distant is about 0.006 Newton, an average bathroom scale is not going to notice.
And the Earth is slowly curving in its orbit, generating an apparent centrifugal force that decreases your weight at midnight, and increases your weight at noon. Except for a very tiny tidal correction, these two forces exactly cancel which is why the Earth stays in orbit in the first place. This argument would only be valid if the Earth were suspended motionless on two giant poles running through the axis or something.
The Earth is a (fairly) rigid body held together by its internal structure, and is not required to be moving at orbital velocity at every point on its surface. That is, the effect you mention exists, but it is not clear that it exactly cancels the gravitational effect. (Or equivalently, it’s not obvious that the tidal effect is small.) Don’t forget that the Earth’s rotation is reducing your effective orbital velocity on the day-side, and increasing it on the night-side.
Now, if you have some numbers showing that the cancellation is close to exact for the specific case of the Earth, that’s fine. An argument showing that it’s always going to be close to exact for planet-sized bodies in orbit around stars would also be convincing.
According to Wikipedia, solar tides are about 0.52*10^-7 g, as opposed to lunar tides of about 1.1*10^-7 g. One part in twenty million and one part in ten million, respectively.
The non-cracking of the Earth demonstrates only that the tidal force is small relative to that required to crack the Earth apart, which may not be a particularly strong upper bound on human scales. :) However, RobinZ’s numbers show that it’s also small relative to human weights, so there we go.
I feel like an idiot for not seeing this earlier: you’re right; this is the tidal force problem.
More precisely, the lunar tidal acceleration (along the Moon-Earth axis, at the Earth’s surface) is about 1.1 × 10−7 g, while the solar tidal acceleration (along the Sun-Earth axis, at the Earth’s surface) is about 0.52 × 10−7 g, where g is the gravitational acceleration at the Earth’s surface.
In other words, the measured weight of 100-kg human changes from Solar gravity by 5.2 [edit: milli]grams between equitorial solar noon or midnight and equitorial dawn or dusk.
This would only be relevant if you were accelerating relative to the Earth. The scale measures the normal force keeping you at rest relative to the Earth’s center; the force being exerted on the Earth does not change that. (Modulo the orbital-velocity argument, which I’ll respond to separately.)
I got 0.6N (=6.7e-11 2e30 100/(1.5e11)^2). Still small, but potentially measurable. (Er, except for the whole frame-of-reference thing mentioned above.)
Don’t forget to adjust your calculations for not being on the equator, and to take into account that ‘nighttime’ is not equivalent to ‘the Sun pulls you directly towards the center of the Earth’. Both tend to make the effect smaller.
-- Daniel Shenton, President of the Flat Earth Society as of 2010
Even this isn’t true!
I haven’t yet tracked down a good quote on this type of “asymmetric intellectual warfare”, where one advances some outlandish claim that lays waste to large portions of a consistent belief network, and then insists it’s the victim’s obligation to repair the damage. I’m pretty sure the idea has been around for a while, perhaps not in terms of that military metaphor. Is that topic covered somewhere in the Sequences?
It’s not presented in terms of information warfare, and it doesn’t explicitly cover “insist[ing] it’s the victim’s obligation to repair the damage”, but the original article on Dark Side Epistemology (now known as “anti-epistemology”, I hear) sounds similar to what you’re getting at. Specifically, the point that to deny one scientific fact, you need to deny a massive network of principles and implications, to the point that your entire epistemology ends up either contradictory or useless.
It’s clearly an abuse of the concept of the Burden of Proof. Along with some motivated skepticism.
In a similar spirit:
-- PatternChaser0, commenting on the story about Daniel Shenton.
I just read their website.
Its embarrassing but I have to say that honestly the centripetal force argument never occurred to me before. Rough calculations seem to indicate that a large man 100Kg should be almost half a pound heavier in the day time as he is at night. Kinda cool.
Now I am dying to get something big and stable enough to see if my home scale can pick it up.
Quick look didn’t find it, but I don’t see why this follows (and at a wild guess, I’m guessing it doesn’t). Can you link?
It doesn’t. My though process was too silly to even bother explaining.
As you stand on the equator, with the Sun directly overhead, its gravity is pulling you away from the Earth’s center. On the other side of the Earth, the Sun’s gravity pulls you in towards its center. Consequently you weigh slightly less at noon than at midnight. However, since the force of the Sun’s gravity on a 100-kg mass 1 AU distant is about 0.006 Newton, an average bathroom scale is not going to notice.
And the Earth is slowly curving in its orbit, generating an apparent centrifugal force that decreases your weight at midnight, and increases your weight at noon. Except for a very tiny tidal correction, these two forces exactly cancel which is why the Earth stays in orbit in the first place. This argument would only be valid if the Earth were suspended motionless on two giant poles running through the axis or something.
The Earth is a (fairly) rigid body held together by its internal structure, and is not required to be moving at orbital velocity at every point on its surface. That is, the effect you mention exists, but it is not clear that it exactly cancels the gravitational effect. (Or equivalently, it’s not obvious that the tidal effect is small.) Don’t forget that the Earth’s rotation is reducing your effective orbital velocity on the day-side, and increasing it on the night-side.
Now, if you have some numbers showing that the cancellation is close to exact for the specific case of the Earth, that’s fine. An argument showing that it’s always going to be close to exact for planet-sized bodies in orbit around stars would also be convincing.
According to Wikipedia, solar tides are about 0.52*10^-7 g, as opposed to lunar tides of about 1.1*10^-7 g. One part in twenty million and one part in ten million, respectively.
This was my original thought until I realized that of course it cancels or else the earth would crack into pieces.
The non-cracking of the Earth demonstrates only that the tidal force is small relative to that required to crack the Earth apart, which may not be a particularly strong upper bound on human scales. :) However, RobinZ’s numbers show that it’s also small relative to human weights, so there we go.
No, because it pulls you, your scale and the Earth all (very close to) equally.
I feel like an idiot for not seeing this earlier: you’re right; this is the tidal force problem.
In other words, the measured weight of 100-kg human changes from Solar gravity by 5.2 [edit: milli]grams between equitorial solar noon or midnight and equitorial dawn or dusk.
This would only be relevant if you were accelerating relative to the Earth. The scale measures the normal force keeping you at rest relative to the Earth’s center; the force being exerted on the Earth does not change that. (Modulo the orbital-velocity argument, which I’ll respond to separately.)
I got 0.6N (=6.7e-11 2e30 100/(1.5e11)^2). Still small, but potentially measurable. (Er, except for the whole frame-of-reference thing mentioned above.)
Oops, added a zero typing the numbers into my calculator. :oo
Don’t forget to adjust your calculations for not being on the equator, and to take into account that ‘nighttime’ is not equivalent to ‘the Sun pulls you directly towards the center of the Earth’. Both tend to make the effect smaller.