Mixing
![What general questions can I expect on an in-person developer interview? [closed]](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjbpfN9tAutmK93bJRC3ZoROZzi2TJDms5n8_qJuhgE0a9b52OOHayv3NGT8igAdFL7byXNst-_1DZK5SjrIJ28_6RQPUpBROqMs5s6jo-ZsjX8kjDwfxJufIitH3TaQRXWaGSQKRQib-f/s72-c/1.jpg)
Simple check for the global shape of the Earth
Clash Royale CLAN TAG#URR8PPP
up vote
5
down vote
favorite
I have been on a date recently, and everything went fine until the moment the girl has told me that the Earth is flat. After realizing she was not trolling me, and trying to provide her with a couple of suggestions why that may not be the case, I've faced arguments of the like "well, you have not been to the space yourself".
That made me think of the following: I myself am certain that the Earth is ball-shaped, and I trust the school physics, but being a kind of a scientist, I could not help but agree with her that some of the arguments that I had in mind were taken by me for granted. Hence, I have asked myself - how can I prove to myself that the earth is indeed ball-shaped, as opposed to being a flat circle (around which the moon and the sun rotate in a convenient for this girl manner).
Question: Ideally I want to have a proof that would not require travelling more than a couple of kilometers, but I am fine with using any convenient day (if e.g. we need to wait for some eclipse or a moon phase). For example, "jump an a plane and fly around the Earth" would not work for me, whereas "look at the moon what it is in phase X, and check the shape of the shade" would.
Trick is, I know that it is rather easy to verify local curvature of the Earth by moving away from a tall object in the field/sitting on the beach and watching some big ship going to the horizon. However, to me that does not prove immediately that globally the Earth has same/similar curvature. For example, maybe it's just a shape of a hemisphere. So, I want to prove to myself that the Earth is ball-shaped globally, and I don't want to move much to do this. Help me, or tell me that this is not possible and why, please. As an example, most of the answers in this popular thread only focus on showing the local curvature.
P.S. I think, asking how to use physics to derive global characteristics of an object from observing things only locally (with the help of the Sun and the Moon, of course) is a valid question, but if something can be improved in it, feel free to tell me. Thanks.
earth education
asked 1 hour ago
Ilya
1314
 |Â
show 4 more comments
up vote
5
down vote
favorite
I have been on a date recently, and everything went fine until the moment the girl has told me that the Earth is flat. After realizing she was not trolling me, and trying to provide her with a couple of suggestions why that may not be the case, I've faced arguments of the like "well, you have not been to the space yourself".
That made me think of the following: I myself am certain that the Earth is ball-shaped, and I trust the school physics, but being a kind of a scientist, I could not help but agree with her that some of the arguments that I had in mind were taken by me for granted. Hence, I have asked myself - how can I prove to myself that the earth is indeed ball-shaped, as opposed to being a flat circle (around which the moon and the sun rotate in a convenient for this girl manner).
Question: Ideally I want to have a proof that would not require travelling more than a couple of kilometers, but I am fine with using any convenient day (if e.g. we need to wait for some eclipse or a moon phase). For example, "jump an a plane and fly around the Earth" would not work for me, whereas "look at the moon what it is in phase X, and check the shape of the shade" would.
Trick is, I know that it is rather easy to verify local curvature of the Earth by moving away from a tall object in the field/sitting on the beach and watching some big ship going to the horizon. However, to me that does not prove immediately that globally the Earth has same/similar curvature. For example, maybe it's just a shape of a hemisphere. So, I want to prove to myself that the Earth is ball-shaped globally, and I don't want to move much to do this. Help me, or tell me that this is not possible and why, please. As an example, most of the answers in this popular thread only focus on showing the local curvature.
P.S. I think, asking how to use physics to derive global characteristics of an object from observing things only locally (with the help of the Sun and the Moon, of course) is a valid question, but if something can be improved in it, feel free to tell me. Thanks.
earth education
asked 1 hour ago
Ilya
1314
1
I thought about this as well and came to the conclusion that you need to trust someone in order to prove that the at least a patch of the Earth is a considerably curved surface. You have to trust an airplane crew during transport, or at least a friend a few thousand kilometers away. (You also have to trust the measurement of distance between the two of you.) Seeing that the latter is more likely, it is pretty easy to be on the phone with someone and see that the shadows have different lengths and/or the sun rises at a different time. That is inconsistent with flat Earth.
– Void
1 hour ago
1
Related: physics.stackexchange.com/q/26427/2451 and links therein.
– Qmechanic♦
1 hour ago
@Void: indeed, you can VC someone and see that it's night there, while it's day for you, but quite some things to trust here indeed.
– Ilya
1 hour ago
@Qmechanic: thanks for a reminder, looked at that question and wanted to mention that the reason for asking my separately is that answers there mostly focus on the local shape.
– Ilya
1 hour ago
1
Well, I understand the issue it broadening local proof as global proof. But even with local proof of local curvature, how does the flat-Earther explain that? How does local curvature of an ocean make any sense? Wouldn't acceptance of the local proof that lead to the conclusion that curvature is at least possible and a reality somewhere on Earth? And then, what would the next claim be? That Earth is half-flat-and-half-curved? That seems quite convenient.
– Steeven
1 hour ago
 |Â
show 4 more comments
up vote
5
down vote
favorite
up vote
5
down vote
favorite
I have been on a date recently, and everything went fine until the moment the girl has told me that the Earth is flat. After realizing she was not trolling me, and trying to provide her with a couple of suggestions why that may not be the case, I've faced arguments of the like "well, you have not been to the space yourself".
That made me think of the following: I myself am certain that the Earth is ball-shaped, and I trust the school physics, but being a kind of a scientist, I could not help but agree with her that some of the arguments that I had in mind were taken by me for granted. Hence, I have asked myself - how can I prove to myself that the earth is indeed ball-shaped, as opposed to being a flat circle (around which the moon and the sun rotate in a convenient for this girl manner).
Question: Ideally I want to have a proof that would not require travelling more than a couple of kilometers, but I am fine with using any convenient day (if e.g. we need to wait for some eclipse or a moon phase). For example, "jump an a plane and fly around the Earth" would not work for me, whereas "look at the moon what it is in phase X, and check the shape of the shade" would.
Trick is, I know that it is rather easy to verify local curvature of the Earth by moving away from a tall object in the field/sitting on the beach and watching some big ship going to the horizon. However, to me that does not prove immediately that globally the Earth has same/similar curvature. For example, maybe it's just a shape of a hemisphere. So, I want to prove to myself that the Earth is ball-shaped globally, and I don't want to move much to do this. Help me, or tell me that this is not possible and why, please. As an example, most of the answers in this popular thread only focus on showing the local curvature.
P.S. I think, asking how to use physics to derive global characteristics of an object from observing things only locally (with the help of the Sun and the Moon, of course) is a valid question, but if something can be improved in it, feel free to tell me. Thanks.
earth education
asked 1 hour ago
Ilya
1314
I have been on a date recently, and everything went fine until the moment the girl has told me that the Earth is flat. After realizing she was not trolling me, and trying to provide her with a couple of suggestions why that may not be the case, I've faced arguments of the like "well, you have not been to the space yourself".
That made me think of the following: I myself am certain that the Earth is ball-shaped, and I trust the school physics, but being a kind of a scientist, I could not help but agree with her that some of the arguments that I had in mind were taken by me for granted. Hence, I have asked myself - how can I prove to myself that the earth is indeed ball-shaped, as opposed to being a flat circle (around which the moon and the sun rotate in a convenient for this girl manner).
Question: Ideally I want to have a proof that would not require travelling more than a couple of kilometers, but I am fine with using any convenient day (if e.g. we need to wait for some eclipse or a moon phase). For example, "jump an a plane and fly around the Earth" would not work for me, whereas "look at the moon what it is in phase X, and check the shape of the shade" would.
Trick is, I know that it is rather easy to verify local curvature of the Earth by moving away from a tall object in the field/sitting on the beach and watching some big ship going to the horizon. However, to me that does not prove immediately that globally the Earth has same/similar curvature. For example, maybe it's just a shape of a hemisphere. So, I want to prove to myself that the Earth is ball-shaped globally, and I don't want to move much to do this. Help me, or tell me that this is not possible and why, please. As an example, most of the answers in this popular thread only focus on showing the local curvature.
P.S. I think, asking how to use physics to derive global characteristics of an object from observing things only locally (with the help of the Sun and the Moon, of course) is a valid question, but if something can be improved in it, feel free to tell me. Thanks.
earth education
earth education
asked 1 hour ago
Ilya
1314
asked 1 hour ago
Ilya
1314
edited 1 hour ago
asked 1 hour ago
Ilya
1314
asked 1 hour ago
Ilya
1314
asked 1 hour ago
Ilya
1314
1314
1
I thought about this as well and came to the conclusion that you need to trust someone in order to prove that the at least a patch of the Earth is a considerably curved surface. You have to trust an airplane crew during transport, or at least a friend a few thousand kilometers away. (You also have to trust the measurement of distance between the two of you.) Seeing that the latter is more likely, it is pretty easy to be on the phone with someone and see that the shadows have different lengths and/or the sun rises at a different time. That is inconsistent with flat Earth.
– Void
1 hour ago
1
Related: physics.stackexchange.com/q/26427/2451 and links therein.
– Qmechanic♦
1 hour ago
@Void: indeed, you can VC someone and see that it's night there, while it's day for you, but quite some things to trust here indeed.
– Ilya
1 hour ago
@Qmechanic: thanks for a reminder, looked at that question and wanted to mention that the reason for asking my separately is that answers there mostly focus on the local shape.
– Ilya
1 hour ago
1
Well, I understand the issue it broadening local proof as global proof. But even with local proof of local curvature, how does the flat-Earther explain that? How does local curvature of an ocean make any sense? Wouldn't acceptance of the local proof that lead to the conclusion that curvature is at least possible and a reality somewhere on Earth? And then, what would the next claim be? That Earth is half-flat-and-half-curved? That seems quite convenient.
– Steeven
1 hour ago
 |Â
show 4 more comments
1
I thought about this as well and came to the conclusion that you need to trust someone in order to prove that the at least a patch of the Earth is a considerably curved surface. You have to trust an airplane crew during transport, or at least a friend a few thousand kilometers away. (You also have to trust the measurement of distance between the two of you.) Seeing that the latter is more likely, it is pretty easy to be on the phone with someone and see that the shadows have different lengths and/or the sun rises at a different time. That is inconsistent with flat Earth.
– Void
1 hour ago
1
Related: physics.stackexchange.com/q/26427/2451 and links therein.
– Qmechanic♦
1 hour ago
@Void: indeed, you can VC someone and see that it's night there, while it's day for you, but quite some things to trust here indeed.
– Ilya
1 hour ago
@Qmechanic: thanks for a reminder, looked at that question and wanted to mention that the reason for asking my separately is that answers there mostly focus on the local shape.
– Ilya
1 hour ago
1
Well, I understand the issue it broadening local proof as global proof. But even with local proof of local curvature, how does the flat-Earther explain that? How does local curvature of an ocean make any sense? Wouldn't acceptance of the local proof that lead to the conclusion that curvature is at least possible and a reality somewhere on Earth? And then, what would the next claim be? That Earth is half-flat-and-half-curved? That seems quite convenient.
– Steeven
1 hour ago
1
1
I thought about this as well and came to the conclusion that you need to trust someone in order to prove that the at least a patch of the Earth is a considerably curved surface. You have to trust an airplane crew during transport, or at least a friend a few thousand kilometers away. (You also have to trust the measurement of distance between the two of you.) Seeing that the latter is more likely, it is pretty easy to be on the phone with someone and see that the shadows have different lengths and/or the sun rises at a different time. That is inconsistent with flat Earth.
– Void
1 hour ago
I thought about this as well and came to the conclusion that you need to trust someone in order to prove that the at least a patch of the Earth is a considerably curved surface. You have to trust an airplane crew during transport, or at least a friend a few thousand kilometers away. (You also have to trust the measurement of distance between the two of you.) Seeing that the latter is more likely, it is pretty easy to be on the phone with someone and see that the shadows have different lengths and/or the sun rises at a different time. That is inconsistent with flat Earth.
– Void
1 hour ago
1
1
Related: physics.stackexchange.com/q/26427/2451 and links therein.
– Qmechanic♦
1 hour ago
Related: physics.stackexchange.com/q/26427/2451 and links therein.
– Qmechanic♦
1 hour ago
@Void: indeed, you can VC someone and see that it's night there, while it's day for you, but quite some things to trust here indeed.
– Ilya
1 hour ago
@Void: indeed, you can VC someone and see that it's night there, while it's day for you, but quite some things to trust here indeed.
– Ilya
1 hour ago
@Qmechanic: thanks for a reminder, looked at that question and wanted to mention that the reason for asking my separately is that answers there mostly focus on the local shape.
– Ilya
1 hour ago
@Qmechanic: thanks for a reminder, looked at that question and wanted to mention that the reason for asking my separately is that answers there mostly focus on the local shape.
– Ilya
1 hour ago
1
1
Well, I understand the issue it broadening local proof as global proof. But even with local proof of local curvature, how does the flat-Earther explain that? How does local curvature of an ocean make any sense? Wouldn't acceptance of the local proof that lead to the conclusion that curvature is at least possible and a reality somewhere on Earth? And then, what would the next claim be? That Earth is half-flat-and-half-curved? That seems quite convenient.
– Steeven
1 hour ago
Well, I understand the issue it broadening local proof as global proof. But even with local proof of local curvature, how does the flat-Earther explain that? How does local curvature of an ocean make any sense? Wouldn't acceptance of the local proof that lead to the conclusion that curvature is at least possible and a reality somewhere on Earth? And then, what would the next claim be? That Earth is half-flat-and-half-curved? That seems quite convenient.
– Steeven
1 hour ago
 |Â
show 4 more comments
2 Answers
2
active
oldest
votes
up vote
2
down vote
I love this question, because it's a very simple demonstration of how to do science. While it's true that in science one should never accept anything 'without evidence', it's also true that blind skepticism of everything and anything gets one nowhere - skepticism has to be combined with rational inquiry. Your date has gotten the 'skepticism' part of science, but she's failed to grasp the equally-crucial part where one looks at the evidence and thinks about what the evidence implies. You cannot just refuse to think or accept evidence. If your goal is to learn nothing, then nothing is what you'll learn.
There are many, many ways of verifying that the Earth is not flat, and most of them are easy to think about and verify. You certainly do not need to go to space to realize the Earth is round!
If the Earth is flat, why can't you see Mt. Kilimanjaro from your house?
Mt. Kilimanjaro is tall, probably taller than anything in your immediate neighborhood (unless you live in a very deep valley) and so the question is why wouldn't you be able to see it from anywhere on Earth? Or, for that matter, why can't you see it from even closer? You have to be really close, in planetary terms, to be able to see it. This wouldn't be true if the Earth were flat!
One might argue that this is just because of the scattering of the atmosphere. Distant objects appear paler, so probably after some distance you can't see anything at all.
So then let's think about things that are closer. Stand on the ground and the horizon appears only a few km away. Go to the top of a hill, or a large tower, and suddenly you can see things much farther away. Why is this the case if the Earth is flat? Why would your height above ground have anything to do with it? If I raise or lower my eyes with respect to a flat table, I can still see everything on that table. The 'horizon' of the table never appears closer.
If the Earth is flat, why do time zones exist?
Hopefully your date realizes that time zones exist. If not, it's pretty easy to verify by doing a video call with someone in a distant location. The reason for time zones, of course, is that the sun sets and rises at different times at different parts of the globe. Why would this be the case? On a flat Earth, the sun would rise and set at the same time everywhere.
If the Earth is flat, why is the Moon round?
The moon is round and not a flat disc, as you can see by the librations of the moon. What makes the Earth special, then?
Further, all the planets are round, although to verify this you need a good telescope. Again, what makes the Earth special?
If the Earth is flat, then what is on its 'underside'?
Hanging dirt and leaves? A large tree? Turtles? Those who reject the roundness of Earth either have no explanation or their explanation is based on much less solid grounding than the pro-round arguments (which, of course, is because the Earth is not flat).
If there is 'nothing' under the Earth, then lunar eclipses would make no sense as the Earth needs to be between the Moon and the Sun.
EDIT: As to the question of whether the Earth is round or some weird hemisphere/pear/donut shape, among other things those would all lead to a situation where gravity is wrong. For a hemisphere for example, gravity would not point down (towards the Earth) at any point on the Earth's surface unless if you were sitting right at the top of the hemisphere. Similar arguments can be made for the other shapes.
Sure, it's possible to make it 'work' by doing even stranger things like altering the distribution of mass and so on, but at that point you've gone very far into violating Occam's razor.
answered 47 mins ago
Al Nejati
1,310213
add a comment |Â
up vote
1
down vote
Look at the Moon during a lunar eclipse.
Source: From Twitter tweet by Niel deGrasse Tyson
Or during any other Moon phase for that matter, where part of the Moon is shaded.
Sure, it is possible that the arrangement of Sun-Earth-Moon shows a circular shade. But then just wait for the next lunar ecplise or Moon phase. Or for the next 100 ones. Surely, at some point you must be seeing the shade from another angle giving an elliptic shade. Or a thin shape as the picture.
This can be done with our own naked eyes. And we have never, ever observed that.
answered 57 mins ago
Steeven
24.7k558102
Please, elaborate on the "surely, at some point..." part. Why would not sun always come from the round side of the Earth? Also, the question does not pose "ball vs circle" dilemma, rather than - how to show that it is (almost) a ball, and not something else
– Ilya
54 mins ago
@Ilya If the Moon was straight above your head and the Sun exactly below you (below the disk of Earth), then you would see the round shade no the Moon. Now, actually the Moon is not straight above your head very often. For a Moon not centered on the disk, how is a round shade possible? Regardless of where the Sun would be, the shade would be squeezed into an ellipsis.
– Steeven
38 mins ago
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
I love this question, because it's a very simple demonstration of how to do science. While it's true that in science one should never accept anything 'without evidence', it's also true that blind skepticism of everything and anything gets one nowhere - skepticism has to be combined with rational inquiry. Your date has gotten the 'skepticism' part of science, but she's failed to grasp the equally-crucial part where one looks at the evidence and thinks about what the evidence implies. You cannot just refuse to think or accept evidence. If your goal is to learn nothing, then nothing is what you'll learn.
There are many, many ways of verifying that the Earth is not flat, and most of them are easy to think about and verify. You certainly do not need to go to space to realize the Earth is round!
If the Earth is flat, why can't you see Mt. Kilimanjaro from your house?
Mt. Kilimanjaro is tall, probably taller than anything in your immediate neighborhood (unless you live in a very deep valley) and so the question is why wouldn't you be able to see it from anywhere on Earth? Or, for that matter, why can't you see it from even closer? You have to be really close, in planetary terms, to be able to see it. This wouldn't be true if the Earth were flat!
One might argue that this is just because of the scattering of the atmosphere. Distant objects appear paler, so probably after some distance you can't see anything at all.
So then let's think about things that are closer. Stand on the ground and the horizon appears only a few km away. Go to the top of a hill, or a large tower, and suddenly you can see things much farther away. Why is this the case if the Earth is flat? Why would your height above ground have anything to do with it? If I raise or lower my eyes with respect to a flat table, I can still see everything on that table. The 'horizon' of the table never appears closer.
If the Earth is flat, why do time zones exist?
Hopefully your date realizes that time zones exist. If not, it's pretty easy to verify by doing a video call with someone in a distant location. The reason for time zones, of course, is that the sun sets and rises at different times at different parts of the globe. Why would this be the case? On a flat Earth, the sun would rise and set at the same time everywhere.
If the Earth is flat, why is the Moon round?
The moon is round and not a flat disc, as you can see by the librations of the moon. What makes the Earth special, then?
Further, all the planets are round, although to verify this you need a good telescope. Again, what makes the Earth special?
If the Earth is flat, then what is on its 'underside'?
Hanging dirt and leaves? A large tree? Turtles? Those who reject the roundness of Earth either have no explanation or their explanation is based on much less solid grounding than the pro-round arguments (which, of course, is because the Earth is not flat).
If there is 'nothing' under the Earth, then lunar eclipses would make no sense as the Earth needs to be between the Moon and the Sun.
EDIT: As to the question of whether the Earth is round or some weird hemisphere/pear/donut shape, among other things those would all lead to a situation where gravity is wrong. For a hemisphere for example, gravity would not point down (towards the Earth) at any point on the Earth's surface unless if you were sitting right at the top of the hemisphere. Similar arguments can be made for the other shapes.
Sure, it's possible to make it 'work' by doing even stranger things like altering the distribution of mass and so on, but at that point you've gone very far into violating Occam's razor.
answered 47 mins ago
Al Nejati
1,310213
add a comment |Â
up vote
2
down vote
I love this question, because it's a very simple demonstration of how to do science. While it's true that in science one should never accept anything 'without evidence', it's also true that blind skepticism of everything and anything gets one nowhere - skepticism has to be combined with rational inquiry. Your date has gotten the 'skepticism' part of science, but she's failed to grasp the equally-crucial part where one looks at the evidence and thinks about what the evidence implies. You cannot just refuse to think or accept evidence. If your goal is to learn nothing, then nothing is what you'll learn.
There are many, many ways of verifying that the Earth is not flat, and most of them are easy to think about and verify. You certainly do not need to go to space to realize the Earth is round!
If the Earth is flat, why can't you see Mt. Kilimanjaro from your house?
Mt. Kilimanjaro is tall, probably taller than anything in your immediate neighborhood (unless you live in a very deep valley) and so the question is why wouldn't you be able to see it from anywhere on Earth? Or, for that matter, why can't you see it from even closer? You have to be really close, in planetary terms, to be able to see it. This wouldn't be true if the Earth were flat!
One might argue that this is just because of the scattering of the atmosphere. Distant objects appear paler, so probably after some distance you can't see anything at all.
So then let's think about things that are closer. Stand on the ground and the horizon appears only a few km away. Go to the top of a hill, or a large tower, and suddenly you can see things much farther away. Why is this the case if the Earth is flat? Why would your height above ground have anything to do with it? If I raise or lower my eyes with respect to a flat table, I can still see everything on that table. The 'horizon' of the table never appears closer.
If the Earth is flat, why do time zones exist?
Hopefully your date realizes that time zones exist. If not, it's pretty easy to verify by doing a video call with someone in a distant location. The reason for time zones, of course, is that the sun sets and rises at different times at different parts of the globe. Why would this be the case? On a flat Earth, the sun would rise and set at the same time everywhere.
If the Earth is flat, why is the Moon round?
The moon is round and not a flat disc, as you can see by the librations of the moon. What makes the Earth special, then?
Further, all the planets are round, although to verify this you need a good telescope. Again, what makes the Earth special?
If the Earth is flat, then what is on its 'underside'?
Hanging dirt and leaves? A large tree? Turtles? Those who reject the roundness of Earth either have no explanation or their explanation is based on much less solid grounding than the pro-round arguments (which, of course, is because the Earth is not flat).
If there is 'nothing' under the Earth, then lunar eclipses would make no sense as the Earth needs to be between the Moon and the Sun.
EDIT: As to the question of whether the Earth is round or some weird hemisphere/pear/donut shape, among other things those would all lead to a situation where gravity is wrong. For a hemisphere for example, gravity would not point down (towards the Earth) at any point on the Earth's surface unless if you were sitting right at the top of the hemisphere. Similar arguments can be made for the other shapes.
Sure, it's possible to make it 'work' by doing even stranger things like altering the distribution of mass and so on, but at that point you've gone very far into violating Occam's razor.
answered 47 mins ago
Al Nejati
1,310213
add a comment |Â
up vote
2
down vote
up vote
2
down vote
I love this question, because it's a very simple demonstration of how to do science. While it's true that in science one should never accept anything 'without evidence', it's also true that blind skepticism of everything and anything gets one nowhere - skepticism has to be combined with rational inquiry. Your date has gotten the 'skepticism' part of science, but she's failed to grasp the equally-crucial part where one looks at the evidence and thinks about what the evidence implies. You cannot just refuse to think or accept evidence. If your goal is to learn nothing, then nothing is what you'll learn.
There are many, many ways of verifying that the Earth is not flat, and most of them are easy to think about and verify. You certainly do not need to go to space to realize the Earth is round!
If the Earth is flat, why can't you see Mt. Kilimanjaro from your house?
Mt. Kilimanjaro is tall, probably taller than anything in your immediate neighborhood (unless you live in a very deep valley) and so the question is why wouldn't you be able to see it from anywhere on Earth? Or, for that matter, why can't you see it from even closer? You have to be really close, in planetary terms, to be able to see it. This wouldn't be true if the Earth were flat!
One might argue that this is just because of the scattering of the atmosphere. Distant objects appear paler, so probably after some distance you can't see anything at all.
So then let's think about things that are closer. Stand on the ground and the horizon appears only a few km away. Go to the top of a hill, or a large tower, and suddenly you can see things much farther away. Why is this the case if the Earth is flat? Why would your height above ground have anything to do with it? If I raise or lower my eyes with respect to a flat table, I can still see everything on that table. The 'horizon' of the table never appears closer.
If the Earth is flat, why do time zones exist?
Hopefully your date realizes that time zones exist. If not, it's pretty easy to verify by doing a video call with someone in a distant location. The reason for time zones, of course, is that the sun sets and rises at different times at different parts of the globe. Why would this be the case? On a flat Earth, the sun would rise and set at the same time everywhere.
If the Earth is flat, why is the Moon round?
The moon is round and not a flat disc, as you can see by the librations of the moon. What makes the Earth special, then?
Further, all the planets are round, although to verify this you need a good telescope. Again, what makes the Earth special?
If the Earth is flat, then what is on its 'underside'?
Hanging dirt and leaves? A large tree? Turtles? Those who reject the roundness of Earth either have no explanation or their explanation is based on much less solid grounding than the pro-round arguments (which, of course, is because the Earth is not flat).
If there is 'nothing' under the Earth, then lunar eclipses would make no sense as the Earth needs to be between the Moon and the Sun.
EDIT: As to the question of whether the Earth is round or some weird hemisphere/pear/donut shape, among other things those would all lead to a situation where gravity is wrong. For a hemisphere for example, gravity would not point down (towards the Earth) at any point on the Earth's surface unless if you were sitting right at the top of the hemisphere. Similar arguments can be made for the other shapes.
Sure, it's possible to make it 'work' by doing even stranger things like altering the distribution of mass and so on, but at that point you've gone very far into violating Occam's razor.
answered 47 mins ago
Al Nejati
1,310213
I love this question, because it's a very simple demonstration of how to do science. While it's true that in science one should never accept anything 'without evidence', it's also true that blind skepticism of everything and anything gets one nowhere - skepticism has to be combined with rational inquiry. Your date has gotten the 'skepticism' part of science, but she's failed to grasp the equally-crucial part where one looks at the evidence and thinks about what the evidence implies. You cannot just refuse to think or accept evidence. If your goal is to learn nothing, then nothing is what you'll learn.
There are many, many ways of verifying that the Earth is not flat, and most of them are easy to think about and verify. You certainly do not need to go to space to realize the Earth is round!
If the Earth is flat, why can't you see Mt. Kilimanjaro from your house?
Mt. Kilimanjaro is tall, probably taller than anything in your immediate neighborhood (unless you live in a very deep valley) and so the question is why wouldn't you be able to see it from anywhere on Earth? Or, for that matter, why can't you see it from even closer? You have to be really close, in planetary terms, to be able to see it. This wouldn't be true if the Earth were flat!
One might argue that this is just because of the scattering of the atmosphere. Distant objects appear paler, so probably after some distance you can't see anything at all.
So then let's think about things that are closer. Stand on the ground and the horizon appears only a few km away. Go to the top of a hill, or a large tower, and suddenly you can see things much farther away. Why is this the case if the Earth is flat? Why would your height above ground have anything to do with it? If I raise or lower my eyes with respect to a flat table, I can still see everything on that table. The 'horizon' of the table never appears closer.
If the Earth is flat, why do time zones exist?
Hopefully your date realizes that time zones exist. If not, it's pretty easy to verify by doing a video call with someone in a distant location. The reason for time zones, of course, is that the sun sets and rises at different times at different parts of the globe. Why would this be the case? On a flat Earth, the sun would rise and set at the same time everywhere.
If the Earth is flat, why is the Moon round?
The moon is round and not a flat disc, as you can see by the librations of the moon. What makes the Earth special, then?
Further, all the planets are round, although to verify this you need a good telescope. Again, what makes the Earth special?
If the Earth is flat, then what is on its 'underside'?
Hanging dirt and leaves? A large tree? Turtles? Those who reject the roundness of Earth either have no explanation or their explanation is based on much less solid grounding than the pro-round arguments (which, of course, is because the Earth is not flat).
If there is 'nothing' under the Earth, then lunar eclipses would make no sense as the Earth needs to be between the Moon and the Sun.
EDIT: As to the question of whether the Earth is round or some weird hemisphere/pear/donut shape, among other things those would all lead to a situation where gravity is wrong. For a hemisphere for example, gravity would not point down (towards the Earth) at any point on the Earth's surface unless if you were sitting right at the top of the hemisphere. Similar arguments can be made for the other shapes.
Sure, it's possible to make it 'work' by doing even stranger things like altering the distribution of mass and so on, but at that point you've gone very far into violating Occam's razor.
answered 47 mins ago
Al Nejati
1,310213
edited 20 mins ago
answered 47 mins ago
Al Nejati
1,310213
answered 47 mins ago
Al Nejati
1,310213
answered 47 mins ago
Al Nejati
1,310213
1,310213
add a comment |Â
add a comment |Â
up vote
1
down vote
Look at the Moon during a lunar eclipse.
Source: From Twitter tweet by Niel deGrasse Tyson
Or during any other Moon phase for that matter, where part of the Moon is shaded.
Sure, it is possible that the arrangement of Sun-Earth-Moon shows a circular shade. But then just wait for the next lunar ecplise or Moon phase. Or for the next 100 ones. Surely, at some point you must be seeing the shade from another angle giving an elliptic shade. Or a thin shape as the picture.
This can be done with our own naked eyes. And we have never, ever observed that.
answered 57 mins ago
Steeven
24.7k558102
Please, elaborate on the "surely, at some point..." part. Why would not sun always come from the round side of the Earth? Also, the question does not pose "ball vs circle" dilemma, rather than - how to show that it is (almost) a ball, and not something else
– Ilya
54 mins ago
@Ilya If the Moon was straight above your head and the Sun exactly below you (below the disk of Earth), then you would see the round shade no the Moon. Now, actually the Moon is not straight above your head very often. For a Moon not centered on the disk, how is a round shade possible? Regardless of where the Sun would be, the shade would be squeezed into an ellipsis.
– Steeven
38 mins ago
add a comment |Â
up vote
1
down vote
Look at the Moon during a lunar eclipse.
Source: From Twitter tweet by Niel deGrasse Tyson
Or during any other Moon phase for that matter, where part of the Moon is shaded.
Sure, it is possible that the arrangement of Sun-Earth-Moon shows a circular shade. But then just wait for the next lunar ecplise or Moon phase. Or for the next 100 ones. Surely, at some point you must be seeing the shade from another angle giving an elliptic shade. Or a thin shape as the picture.
This can be done with our own naked eyes. And we have never, ever observed that.
answered 57 mins ago
Steeven
24.7k558102
Please, elaborate on the "surely, at some point..." part. Why would not sun always come from the round side of the Earth? Also, the question does not pose "ball vs circle" dilemma, rather than - how to show that it is (almost) a ball, and not something else
– Ilya
54 mins ago
@Ilya If the Moon was straight above your head and the Sun exactly below you (below the disk of Earth), then you would see the round shade no the Moon. Now, actually the Moon is not straight above your head very often. For a Moon not centered on the disk, how is a round shade possible? Regardless of where the Sun would be, the shade would be squeezed into an ellipsis.
– Steeven
38 mins ago
add a comment |Â
up vote
1
down vote
up vote
1
down vote
Look at the Moon during a lunar eclipse.
Source: From Twitter tweet by Niel deGrasse Tyson
Or during any other Moon phase for that matter, where part of the Moon is shaded.
Sure, it is possible that the arrangement of Sun-Earth-Moon shows a circular shade. But then just wait for the next lunar ecplise or Moon phase. Or for the next 100 ones. Surely, at some point you must be seeing the shade from another angle giving an elliptic shade. Or a thin shape as the picture.
This can be done with our own naked eyes. And we have never, ever observed that.
answered 57 mins ago
Steeven
24.7k558102
Look at the Moon during a lunar eclipse.
Source: From Twitter tweet by Niel deGrasse Tyson
Or during any other Moon phase for that matter, where part of the Moon is shaded.
Sure, it is possible that the arrangement of Sun-Earth-Moon shows a circular shade. But then just wait for the next lunar ecplise or Moon phase. Or for the next 100 ones. Surely, at some point you must be seeing the shade from another angle giving an elliptic shade. Or a thin shape as the picture.
This can be done with our own naked eyes. And we have never, ever observed that.
answered 57 mins ago
Steeven
24.7k558102
answered 57 mins ago
Steeven
24.7k558102
answered 57 mins ago
Steeven
24.7k558102
answered 57 mins ago
Steeven
24.7k558102
24.7k558102
Please, elaborate on the "surely, at some point..." part. Why would not sun always come from the round side of the Earth? Also, the question does not pose "ball vs circle" dilemma, rather than - how to show that it is (almost) a ball, and not something else
– Ilya
54 mins ago
@Ilya If the Moon was straight above your head and the Sun exactly below you (below the disk of Earth), then you would see the round shade no the Moon. Now, actually the Moon is not straight above your head very often. For a Moon not centered on the disk, how is a round shade possible? Regardless of where the Sun would be, the shade would be squeezed into an ellipsis.
– Steeven
38 mins ago
add a comment |Â
Please, elaborate on the "surely, at some point..." part. Why would not sun always come from the round side of the Earth? Also, the question does not pose "ball vs circle" dilemma, rather than - how to show that it is (almost) a ball, and not something else
– Ilya
54 mins ago
@Ilya If the Moon was straight above your head and the Sun exactly below you (below the disk of Earth), then you would see the round shade no the Moon. Now, actually the Moon is not straight above your head very often. For a Moon not centered on the disk, how is a round shade possible? Regardless of where the Sun would be, the shade would be squeezed into an ellipsis.
– Steeven
38 mins ago
Please, elaborate on the "surely, at some point..." part. Why would not sun always come from the round side of the Earth? Also, the question does not pose "ball vs circle" dilemma, rather than - how to show that it is (almost) a ball, and not something else
– Ilya
54 mins ago
Please, elaborate on the "surely, at some point..." part. Why would not sun always come from the round side of the Earth? Also, the question does not pose "ball vs circle" dilemma, rather than - how to show that it is (almost) a ball, and not something else
– Ilya
54 mins ago
@Ilya If the Moon was straight above your head and the Sun exactly below you (below the disk of Earth), then you would see the round shade no the Moon. Now, actually the Moon is not straight above your head very often. For a Moon not centered on the disk, how is a round shade possible? Regardless of where the Sun would be, the shade would be squeezed into an ellipsis.
– Steeven
38 mins ago
@Ilya If the Moon was straight above your head and the Sun exactly below you (below the disk of Earth), then you would see the round shade no the Moon. Now, actually the Moon is not straight above your head very often. For a Moon not centered on the disk, how is a round shade possible? Regardless of where the Sun would be, the shade would be squeezed into an ellipsis.
– Steeven
38 mins ago
add a comment |Â
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fphysics.stackexchange.com%2fquestions%2f434634%2fsimple-check-for-the-global-shape-of-the-earth%23new-answer', 'question_page');
);
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
1
I thought about this as well and came to the conclusion that you need to trust someone in order to prove that the at least a patch of the Earth is a considerably curved surface. You have to trust an airplane crew during transport, or at least a friend a few thousand kilometers away. (You also have to trust the measurement of distance between the two of you.) Seeing that the latter is more likely, it is pretty easy to be on the phone with someone and see that the shadows have different lengths and/or the sun rises at a different time. That is inconsistent with flat Earth.
– Void
1 hour ago
1
Related: physics.stackexchange.com/q/26427/2451 and links therein.
– Qmechanic♦
1 hour ago
@Void: indeed, you can VC someone and see that it's night there, while it's day for you, but quite some things to trust here indeed.
– Ilya
1 hour ago
@Qmechanic: thanks for a reminder, looked at that question and wanted to mention that the reason for asking my separately is that answers there mostly focus on the local shape.
– Ilya
1 hour ago
1
Well, I understand the issue it broadening local proof as global proof. But even with local proof of local curvature, how does the flat-Earther explain that? How does local curvature of an ocean make any sense? Wouldn't acceptance of the local proof that lead to the conclusion that curvature is at least possible and a reality somewhere on Earth? And then, what would the next claim be? That Earth is half-flat-and-half-curved? That seems quite convenient.
– Steeven
1 hour ago