# The Naked Scientists Forum

### Author Topic: Is the earth flat?  (Read 4901 times)

#### puppypower

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##### Re: Is the earth flat?
« Reply #25 on: 10/07/2016 12:03:39 »
According to GR, doesn't mass and gravity cause space-time to curve. So, it is possible that space-time is curved, but the earth is flat?

In other words, if the earth suddenly loss all its mass, but retained all its substance (without mass) space-time around the earth would lose curvature, therefore wouldn't the earth flatten? Satellites would not be able to follow a curved path around the earth with GR=0, and would treat the earth like it was a plain.

#### Tim the Plumber

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##### Re: Is the earth flat?
« Reply #26 on: 10/07/2016 16:41:16 »
The best, well I think so, way of demonstrating that the earth rotates, thus it must be round given that the sun comes up and sets at different times as you go East/West is the droped rock experiment;

Get a rock and tie a piece of cotton thread arond it so you can suspend it from a high point. This will have to be done in doors where there is no wind to push it off course. Churches are good for this but any high place will do, stairwell for example.

Have the rock dangle from the high point so it touches the ground. Make sure it's settled down and is not swinging about. Mark the position on the floor.

Then take the rock up to the top of what ever you suspended it from, a nail or hook or what ever. It will swing about horizontaly as you do this. Calm it down and have it a couple of inches below the high point.

The position you have marked on tghe floor is directly below the high point where you now have the rock.

Cut the cotton thread with something that will impart no sideways motion. Burning through it with a lighter will do nicely.

The rock will drop down and hit the floor a little East of the point directly below the high point.

This is because the ceiling is traveling faster than the floor. When the rock leaves the ceiling it has the same speed as the ceiling and whilst it is dropping down to the floor it is traveling slightly faster than the bits of wall it's passing.

It might be good to use a sand tray to both mark the position and to drop the rock onto as this will show the difference between the two and stop the rock bouncing all over the place.

You can calculate the size of the earth and your lattitude from this should you want to do the maths.

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#### PmbPhy

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##### Re: Is the earth flat?
« Reply #27 on: 10/07/2016 16:44:06 »
The best evidence that the world is flat is the way projectiles move under the influence of gravity, it is widely reported that they move in a parabolic path which only happens because the world is flat and of infinite extent.
if the earth was spherical they would take an elliptical path
Ha ha. Very funny. :/

#### PmbPhy

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##### Re: Is the earth flat?
« Reply #28 on: 10/07/2016 17:02:13 »
Quote from: puppypower
According to GR, doesn't mass and gravity cause space-time to curve. So, it is possible that space-time is curved, but the earth is flat?
Mass can cause spacetime to curve. However its incorrect to say that gravity causes it to curve because spacetime curvature manifests itself as gradients in the gravitational field. In other words, spacetime curvature and tidal gradients are exactly the same thing.

Quote from: puppypower
In other words, if the earth suddenly loss all its mass, but retained all its substance ...
Which is impossible.

Quote from: puppypower
..(without mass) space-time around the earth would lose curvature, therefore wouldn't the earth flatten?
No. There would be no reason for a spherical body to change its shape if it started out as spherical and no external forces are acting on it.

#### Villi

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##### Re: Is the earth flat?
« Reply #29 on: 16/07/2016 04:44:16 »
Telescope is arriving in a week I hope.

I don't have access to satellites or projectiles, unless it's a bb gun. Maybe I can do an experiment with that.

I like the rock experiment Tim. Might take a bit of work setting it up. If my telescope experiment suggests the earth is flat (disproves spherical model) then I'll do the rock thing next.

Honestly, I think it's a bit exciting if the earth is flat. Makes you wonder and changes your whole world view.

#### Alan McDougall

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##### Re: Is the earth flat?
« Reply #30 on: 16/07/2016 06:12:31 »
Why so many posts with an obvious answer.

"No, the earth is not flat Period case closed!

Alan

#### hamdani yusuf

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##### Re: Is the earth flat?
« Reply #31 on: 16/07/2016 06:23:09 »
The best, well I think so, way of demonstrating that the earth rotates, thus it must be round given that the sun comes up and sets at different times as you go East/West is the droped rock experiment;

Get a rock and tie a piece of cotton thread arond it so you can suspend it from a high point. This will have to be done in doors where there is no wind to push it off course. Churches are good for this but any high place will do, stairwell for example.

Have the rock dangle from the high point so it touches the ground. Make sure it's settled down and is not swinging about. Mark the position on the floor.

Then take the rock up to the top of what ever you suspended it from, a nail or hook or what ever. It will swing about horizontaly as you do this. Calm it down and have it a couple of inches below the high point.

The position you have marked on tghe floor is directly below the high point where you now have the rock.

Cut the cotton thread with something that will impart no sideways motion. Burning through it with a lighter will do nicely.

The rock will drop down and hit the floor a little East of the point directly below the high point.

This is because the ceiling is traveling faster than the floor. When the rock leaves the ceiling it has the same speed as the ceiling and whilst it is dropping down to the floor it is traveling slightly faster than the bits of wall it's passing.

It might be good to use a sand tray to both mark the position and to drop the rock onto as this will show the difference between the two and stop the rock bouncing all over the place.

You can calculate the size of the earth and your lattitude from this should you want to do the maths.
Contrary to Foucault pendulum,  your experiment works best at equator and won't work at earth poles.
You would need a considerably tall building to get noticeable result.

#### Alan McDougall

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##### Re: Is the earth flat?
« Reply #32 on: 16/07/2016 07:31:30 »
Telescope is arriving in a week I hope.

I don't have access to satellites or projectiles, unless it's a bb gun. Maybe I can do an experiment with that.

I like the rock experiment Tim. Might take a bit of work setting it up. If my telescope experiment suggests the earth is flat (disproves spherical model) then I'll do the rock thing next.

Honestly, I think it's a bit exciting if the earth is flat. Makes you wonder and changes your whole world view.

You would have bought the worst telescope ever made if it proves the earth is flat!

#### Villi

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##### Re: Is the earth flat?
« Reply #33 on: 26/07/2016 03:55:59 »
I have my telescope. Magnification is 90x, so I really hope this is sufficient. It does seem like a POS though.

Going to use a ship tracking website and a very nice spot that can see ship traffic for quite a distance. I'm hoping that I'll have good timing and either watch a ship sink into or appear from the horizon or neither.

#### Ethos_

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##### Re: Is the earth flat?
« Reply #34 on: 26/07/2016 04:18:31 »
The best evidence that the world is flat is the way projectiles move under the influence of gravity, it is widely reported that they move in a parabolic path which only happens because the world is flat and of infinite extent.
if the earth was spherical they would take an elliptical path
Ha ha. Very funny. :/
It's threads like this that cause me to question my participation here at TNS. If it weren't so amusing, as Pete has suggested, it would simply be a waste of valuable time to even respond to such nonsense.

#### Tim the Plumber

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##### Re: Is the earth flat?
« Reply #35 on: 26/07/2016 13:04:50 »
Telescope is arriving in a week I hope.

I don't have access to satellites or projectiles, unless it's a bb gun. Maybe I can do an experiment with that.

I like the rock experiment Tim. Might take a bit of work setting it up. If my telescope experiment suggests the earth is flat (disproves spherical model) then I'll do the rock thing next.

Honestly, I think it's a bit exciting if the earth is flat. Makes you wonder and changes your whole world view.

You should be able to do it in a cave. You should then be able to work out how far north south you are from the distance it lands away from the point directly below it's drop point and the time the earth takes to rotate and the size of the earth. Or any 1 of the 3 when you know the others.

At least I think so, it's been 30 years since I did any such maths... I might need help....

#### alancalverd

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##### Re: Is the earth flat?
« Reply #36 on: 28/07/2016 17:23:59 »

Contrary to Foucault pendulum,  your experiment works best at equator and won't work at earth poles.
You would need a considerably tall building to get noticeable result.

If the earth is flat, it won't have an equator or poles.

#### Villi

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##### Re: Is the earth flat?
« Reply #37 on: 31/07/2016 21:22:36 »
So I came across a youtube video of a man jumping 25000ft with no parachute and I could clearly see the curvature of the earth. However, I think the flat earthers would say that it's all green screen or video magic lol

EDIT: Some people are actually saying it's fake
« Last Edit: 31/07/2016 21:31:12 by Villi »

#### alancalverd

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##### Re: Is the earth flat?
« Reply #38 on: 02/08/2016 08:58:56 »
Who cares what anyone else says? Other people believe in all sorts of drivel and even vote for Trump. All that matters in science is what you do, what you observe, and how you explain it. There's sometimes a consensus among sane and honest people, but even that can be wrong.

#### Tim the Plumber

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##### Re: Is the earth flat?
« Reply #39 on: 02/08/2016 09:39:01 »
Who cares what anyone else says? Other people believe in all sorts of drivel and even vote for Trump. All that matters in science is what you do, what you observe, and how you explain it. There's sometimes a consensus among sane and honest people, but even that can be wrong.

There are thsoe out there who believe (I'm always a little stretched by the word in this context) that the world is flat. This guy (the OP) wants to check.

That is science.

Well done.

#### hamdani yusuf

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##### Re: Is the earth flat?
« Reply #40 on: 02/08/2016 10:33:56 »

If the earth is flat, it won't have an equator or poles.
If the earth is flat, it may have one pole and one boundary.
The circle centered at the pole having radius half the earth's radius is then called the equator.
They often refer to UN emblem.

#### puppypower

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##### Re: Is the earth flat?
« Reply #41 on: 02/08/2016 11:22:49 »
Quote from: puppypower
According to GR, doesn't mass and gravity cause space-time to curve. So, it is possible that space-time is curved, but the earth is flat?
Mass can cause spacetime to curve. However its incorrect to say that gravity causes it to curve because spacetime curvature manifests itself as gradients in the gravitational field. In other words, spacetime curvature and tidal gradients are exactly the same thing.

Quote from: puppypower
In other words, if the earth suddenly loss all its mass, but retained all its substance ...
Which is impossible.

Quote from: puppypower
..(without mass) space-time around the earth would lose curvature, therefore wouldn't the earth flatten?
No. There would be no reason for a spherical body to change its shape if it started out as spherical and no external forces are acting on it.

The spherical body may not change, but the tides and orbits will change unable to follow curved space-time; flat orbits. The point I was making is the theory of the flat earth, was around before they knew of GR. Therefore, GR would not have been one of the variables they could have used. If you factor GR out from all consideration, you also need to factor out the curvature of space-time. I am not saying the earth is flat, only the logic of the old theory would have become limited by lack of this premise. 20/20 hindsight always gives one an advantage.

#### Tim the Plumber

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##### Re: Is the earth flat?
« Reply #42 on: 02/08/2016 11:57:30 »

If the earth is flat, it won't have an equator or poles.
If the earth is flat, it may have one pole and one boundary.
The circle centered at the pole having radius half the earth's radius is then called the equator.
They often refer to UN emblem.

Then the pendulum thing would work everywhere. Given it does not work at the equator this idea is out.

#### Solium

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##### Re: Is the earth flat?
« Reply #43 on: 03/08/2016 04:09:14 »
Best example ever.  I don't know how to place a hyper link. Replace "x's" with "t's" in "hxxps".

« Last Edit: 03/08/2016 04:13:52 by Solium »

#### Villi

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##### Re: Is the earth flat?
« Reply #44 on: 14/08/2016 06:08:33 »
Hoping to do my first expedition soon but the weather is incredibly hot and I'll cook under the sun in the couple hours I need to do this.

#### Blame

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##### Re: Is the earth flat?
« Reply #45 on: 14/08/2016 09:33:30 »
Of course the earth is flat... there is so much here to prove it......

http://www.theflatearthsociety.org/home/index.php/flat-earth-library/library-books

LOL.

#### Villi

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##### Re: Is the earth flat?
« Reply #46 on: 16/08/2016 05:22:25 »
Of course the earth is flat... there is so much here to prove it......

http://www.theflatearthsociety.org/home/index.php/flat-earth-library/library-books

LOL.

A dozen or so books is at least something. But compared to the thousands (or more) on globe earth or based on it?

#### Villi

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##### Re: Is the earth flat?
« Reply #47 on: 04/09/2016 18:53:15 »
I finished the experiment. Here's the video:

I wonder what people think.

EDIT: link not working, maybe this: youtu.be/QwQExaWbzSw
« Last Edit: 04/09/2016 18:58:13 by Villi »

#### Villi

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##### Re: Is the earth flat?
« Reply #48 on: 09/09/2016 01:23:35 »
Okay so my math needs some corrections (I blame you guys lol), I think. According to some other forums, because the buildings are partially visible, the earth is round. I'm going to spend some time soon correcting the math to support the hypothesis that objects disappear under curvature.

#### The Naked Scientists Forum

##### Re: Is the earth flat?
« Reply #48 on: 09/09/2016 01:23:35 »