I had to ‘defriend’ myself from an old university mate who, with the assistance of twenty years of weed-smoking in idyllic Bali, had taken on every conspiracy theory out there - and his contempt for science or even common sense was too much for me to bear. But his weird Earth-shape belief was that the Earth was a hollow sphere, with an opening at the North Pole which some pilot had once flown over (just the once presumably, very hush-hush).
It makes me wonder whether he’s ‘graduated’ onto Flat Earth thinking with its recent resurgence. And what happens when a Flat-Earther meets a Hollow-Earther?
It’s actually quite easy to navigate if you assume the Earth is flat (provided you don’t need to go over the edge. If you have a Mercator projection map, you only need to measure the heading you need to take, then stick to that heading. (You might need to do that several times if you need to navigate around land or something, but that’s true with any map.) You won’t go on the shortest route which, ignoring currents, would be the great circle route, but the navigation to get there works fine. It’s actually easier to plot a course than on a sphere.
In the days before longitude could be measured accurately, it was common to sail to teh right latitude, then just sail due east or west.
But what if you assume the earth is round - as huge numbers of celestial navigators have done? This ought to fail badly on a flat earth - but it appears to have consistently worked well.
There’s nothing wrong with that sentence as a general description. It is not even in the same ballpark as a Flat Earth. Of course it is incomplete and without going into orbital mechanics and the inverse square law of gravity it is never going to be a full explanation but I guess that’s what the rest of the text book is for.
Yes. I once engaged with one of those idiots who had a YouTube video and asked him whether the Earth was adding mass from the outside, adding mass from the inside, or becoming less dense. He said it was adding mass from the inside. I asked how that worked. He deleted the whole exchange. Tsk.
On the surface of the earth, around 6400 km from its center, gravity is strong enough to give weight to everything that has mass. Is it plausible that increasing the distance by around 6% (low earth orbit) renders this negligible?
The weightlessness experienced in low-earth orbit has exactly nothing to do with any reduction in the earth’s gravity there. It’s a consequence of the fact that orbital motion is essentially “freefall”.
But it didn’t say anything about an orbit did it? That gravity decreases with distance is an absolute fact and I would read “outer space” as meaning interstellar space rather than a low earth orbit.
Yeah, just about any tall building in Chi., especially overlooking the lake show it. I bet in any coastal city with tall buildings the idea of a flat earth will be a hard sell even for a child. Hell. even a tall building surrounded by corn fields would show it. Not to mention any view from an airplane.
The flat earth idea is so wrong, even to someone with no scientific background, that there have to be ulterior motives in promoting it.
Novelty Bobble, how many astronauts do you think have been in interstellar space?
Zero. Only Voyager 1 has made it to interstellar space, and there are no astronauts onboard.
OK, Novelty Bobble, how many spacewalks (aka EVAs) in the history of spaceflight do you think have been conducted that were NOT in low-Earth orbit?
Answer: Out of the approximately 400 spacewalks that have been conducted, just four (4) have been conducted that were not in low-Earth orbit, all on Apollo missions. Two were conducted in lunar orbit on Apollo 15, and two were conducted on the return flights of Apollo 16 and Apollo 17.
In any event, Xema’s point is well-taken. The force of gravity in low-Earth orbit is something like 0.88g (at the altitude of the International Space Station). Even at the orbit of the Moon, the force of Earth’s gravity is 1.62 m/s[sup]2[/sup] (i.e. 0.165g). Even at that far distance, astronauts have not “escaped Earth’s gravity.” The reason that they are weightless in space is NOT because they are farther from the center of the Earth, where “gravity decreases - until, in outer space, you’re weightless!”. It is because they are in orbit and are in freefall.
I really think you are taking things far too literally. It is single sentence and one that…without a drawing, is absolutely fine. That is exactly what happens with the gravitational force and you could theoretically be far enough away from the earth that its gravitational effect is negligible and you are effectively weightless. It doesn’t say anything about earth orbits at all. Had it said “here is a picture of a modern-day spaceman in earth orbit…he is weightless” then that seems egregiously incorrect. The sentence as it stands? not so much.
The world of scientific literature is full of what-if’s and thought experiments that, though technically correct, aren’t necessarily accurate reflections of how we experience the world currently nor examples of a situation we may ever be able to experience.
I remember an early book of mine on space showing a little cartoon Laika with just a glass bubble over her head under a paragraph about early Soviet space exploration. Naturally, seeing as the caption was at odds with the picture I threw it in the fire as it was an affront to common sense with worthless scientific insight.
Actually if you delete a point from a sphere, the space that’s left is equivalent to a plane and has a flat metric. You could therefore built accurate navigational tables based on it. Of course, it is conceptually easier if you assume the earth is a sphere (or nearly so).
