Atmosphere

Really, really, sincerely, this is Tom's territory. You're usually so much smarter than this.

The FAQ puts forward the proposition that the earth has a diameter of 24,900 miles:

Quote

Q: "What is the circumference and diameter of the Earth?"

A: "Circumference: 78225 miles, Diameter: 24,900 miles

The spherical earth proposition is that the earth is a sphere of radius 6,378 km.

Quote from: http://en.wikipedia.org/wiki/Earth_radius

The Earth's shape, like that of all major planets, approximates a sphere. A true sphere has a unique radius, but on Earth the distance from the mean sea level at each point on the surface to the center (the radius of the Earth at a point on the surface) varies slightly from place to place. With few exceptions, this variation ranges from 6,356.750 km to 6,378.135 km

It's therefore a clear logical fallacy to assume that you provide proof positive that the earth is flat by, as Tom puts it, "looking out of my window"

Now if you look a little further, perhaps to the horizon, you could make som interesting observations.

The radius of the earth stems from calculations going back to the ancient Greeks, about 200 years BC.

On a spherical earth, under normal conditions a person standing on a shore should be able to see no further than (very roughly) 3 miles.

That's a person observing the horizon, not objects on the horizon.

From Pythagoras:

d = sqrt(m^2 + 2.r.m)

d = distance to horizon
m = height of man
r = radius of earth

To prove a flat earth you need to prove that you can see much further than the 3 miles to horizon commonly (and observably) accepted.

Samuel Rowbotham tried to do this, and failed spectactularly.

There's a nice graph and stuff on the wiki page:

http://en.wikipedia.org/wiki/Horizon

It would make my day to see you team up with Tom and defend Sammy Robotham.

That doesn't really prove anything at all, nor does it really disprove my previous point. You, in your frame of reference, are using some high school mathematics to debunk Flat Earth by trying to realize the physical characteristics of a Round Earth. Of course, that's different from actually seeing the shape of the Earth. When I'm standing at the surface of the Earth (in my local frame of reference), do I have a picture of the Earth's shape? Nope. You can't tell the shape of the Earth in your local frame of reference. In a frame of reference outside of the Earth (e.g. space), however, the shape of the Earth becomes apparent to you.

You like to be ignorant to science. Don't worry, you aren't the first ignorant RE'er that I've seen.

That sounds like nonsense to me.

If I am on the ground then I am not moving, with respect to the ground (i.e. ignoring The Earth's rotation). And if I am not moving I cannot be accelerating.

Of course, relativity sounds like nonsense to high school students.

Now that is definitely nonsense!

Anything moving with "constant velocity" is not, by definition "accelerating".

You fail Physics 101.

I'm a non-inertial observer on the ground. I am undergoing an upward proper acceleration. When a ball falls, it is following the geodesics in spacetime, traveling at constant velocity. Thus, relative to me, the ball is accelerating.

Something makes me think you don't really understand what you are talking about.

I guess my question was way out of your league.

I'm a non-inertial observer on the ground. I am undergoing an upward proper acceleration. When a ball falls, it is following the geodesics in spacetime, traveling at constant velocity. Thus, relative to me, the ball is accelerating.

What, pray, is causing that "upward proper acceleration"?

What, pray, is causing that "upward proper acceleration"?

Electrostatic repulsion.

Next time, please try and combine all of them into one post. This is known as spamming.

Spamming is the abuse of electronic messaging systems to indiscriminately send unsolicited bulk messages:

http://en.wikipedia.org/wiki/Spam_(electronic)

[Forum] Spam is the posting of advertisements, abusive, or unneeded messages on Internet forums. It is generally posted by automated spambots:

http://en.wikipedia.org/wiki/Forum_spam

So I wasn't spamming.

Quote from: 3 Tesla on October 05, 2008, 09:20:08 AM

What, pray, is causing that "upward proper acceleration"?

Electrostatic repulsion.

Please explain.

Please explain.

Electrons repel other electrons.

Relativity is not inherent or obvious. 

Isn't it also practically irrelevant unless you are travelling at velocities which approach the speed of light?

In our day-to-day existence Newtonian Mechanics is perfectly adequate.

Newtonian Mechanics is a perfectly adequate way of describing the motion of the planets in the Solar System (if you ignore some minor issues with Mercury).

I really can't see why you need Realtivity to explain the shape of The Earth.

To me, bringing up relativity is just a way of trying to confuse people and hide the fact that The Earth isn't flat.

It is a sledge-hammer to crack a nut, as the saying goes.

Quote from: 3 Tesla on October 05, 2008, 09:20:08 AM

What, pray, is causing that "upward proper acceleration"?

Electrostatic repulsion.

Does E.Jack agree with this statement?

Push your hand against something.  What is preventing your hand from going through that object?

Does E.Jack agree with this statement?

I feel certain that he would.

Quote from: 3 Tesla on October 05, 2008, 09:25:31 AM

Please explain.

Electrons repel other electrons.

Please try to give complete answers. Being vague then acting smug when not understood isn't clever. He misunderstands because you are both thinking in different reference frames. It's obvious, stop being a dick.

3 Tesla: From within an inertial reference frame (i.e. one in free fall) an observer standing on Earth's surface appears to be accelerating upwards. This is the "upward proper acceleration". The person is held in place on Earth's surface (rather than being in free-fall) because of electrostatic repulsion with the ground.

3 Tesla: From within an inertial reference frame (i.e. one in free fall) an observer standing on Earth's surface appears to be accelerating upwards. This is the "upward proper acceleration". The person is held in place on Earth's surface (rather than being in free-fall) because of electrostatic repulsion with the ground.

Thanks for that!

I will go away and 'brush up' my relativity.

Quote from: 3 Tesla on October 05, 2008, 06:35:07 AM

That sounds like nonsense to me.

If I am on the ground then I am not moving, with respect to the ground (i.e. ignoring The Earth's rotation). And if I am not moving I cannot be accelerating.

Of course, relativity sounds like nonsense to high school students.

True.

But it can also sound like nonsense to Biology graduates or Applied Physics graduates like me.

(We were too busy with lasers, semi-conductors, MRI and magnetism to touch on Relativity.)

It would have helped if you had 'signposted' your comments with something like:

"In General Relativity ..."

Then I would have seen that your comments were high-level physics rather than Flat-Earth gobbledygook (like Rowbotham's).

I guess my question was way out of your league.

More like it was in a different sport.

Super League rugby league players and Premier League footballers live in different worlds, but they are both world-class athletes.

Alternatively: Pro hockey players and pro basketball players live in different worlds, but they are both world-class athletes.

How did we get from the atmosphere to General Relativity anyway?

(And thanks for assuming that I was in high school rather than elementary!)

You're right, this really is high school science. It's high school science, because it's easily understood, easily demonstratable, easy to perform, and easy to verify. (and has neat history lessons attached too)

Hence, easily falsified.

Relativity doesn't enter into it at all, although I love the way you like to try and lure people into believing relativity is relavent.

So, how is relativity not relevant?

To all intents and purposes we could be stood on a hollow sphere floating through space, neither accelerating, nor exhibiting any gravitational force. It would still be observable as a sphere.

False, not in our local frame of reference.

And I'm not trying to "realise" the physical characteristics of a flat earth. I applied theory to observations to confirm the belief of a round earth. The results did not contradict the theory. You can perform the test yourself.

The experiment can of course be done in reverse to measure the radius of the earth.

I'm sincerely worried that you're able to quote equations from General Relativity yet fail to grasp simple concepts that have been around more than 2000 years.

Yet again, you still haven't refute my point.

Your point has been torn apart and fed to the dogs.

Wow, so you actually believe I can see the shape of the Earth while sitting on my chair in my room? 

Keep trying.

Relativity doesn't apply because this is basic geometry.

That still doesn't answer my question: how is relativity irrelevant to FE?

I gave an example of a massless sphere sitting stationary in space. It would still be observable as a sphere, we'd still only be able to see 3 miles away. You've yet to prove that wrong.

I have proved it wrong: You can't tell the shape of the Earth in your local frame of reference relative to it.

And why does it have to be massless?

Quote from: goldstein on October 06, 2008, 03:15:48 AM

Your point has been torn apart and fed to the dogs.

Wow, so you actually believe I can see the shape of the Earth while sitting on my chair in my room? 

How about going outside?

Or are you a Goth who is allergic to sunlight?

Only kidding!

Seriously, though: how do Relativistic frames of reference stop you measuring The Earth's curvature?

If I were to recreate the infamous Bedford Level Experiment (http://en.wikipedia.org/wiki/Bedford_Level_Experiment) and show, like Wallace, that the waterway was curved over a stretch of a few miles, wouldn't that count?

Or does Relativity mess up our localised perception somehow?

So I can see the Earth's true shape while going outside?

Hmmm. It looks straight in my local FoR. Thus, based on your unsophisticated refutation, the Earth's shape must be flat.

Another victory to FE!

So I can see the Earth's true shape while going outside?

Yes if you (properly) survey a 'flat' stretch of water like The Bedford Level with a theodolite and some poles.

(The poles in the middle look higher than the pole at the very end, apparently.)

Yes if you (properly) survey a 'flat' stretch of water like The Bedford Level with a theodolite and some poles.

(The poles in the middle look higher than the pole at the very end, apparently.)

**done, in my frame of reference relative to the Earth**

Nope, I still couldn't see the spherical shape of the Earth as a whole.

Quote from: 3 Tesla on October 06, 2008, 07:26:00 AM

Yes if you (properly) survey a 'flat' stretch of water like The Bedford Level with a theodolite and some poles.

(The poles in the middle look higher than the pole at the very end, apparently.)

**done, in my frame of reference relative to the Earth**

Nope, I still couldn't see the spherical shape of the Earth as a whole.

Niether the flatness, 'because with our human eyes, it'd be impossible.
Can you take aside that stupid argument, please?

Niether the flatness, 'because with our human eyes, it'd be impossible.

Nice! At least one of the RE'ers is intelligent enough to agree with me.

Quote from: E.Jack on October 06, 2008, 03:55:30 AM

So I can see the Earth's true shape while going outside?

Yes if you (properly) survey a 'flat' stretch of water like The Bedford Level with a theodolite and some poles.

(The poles in the middle look higher than the pole at the very end, apparently.)

Interseting fact about Gyrotheodolites:

A gyrotheodolite comprises a normal theodolite with an attachment that contains a gyroscope mounted so as to sense rotation of the Earth and from that the alignment of the meridian. The meridian is the plane that contains both the axis of the Earth’s rotation and the observer. The intersection of the meridian plane with the horizontal contains the true north-south geographic reference bearing required. The gyrotheodolite is usually referred to as being able to determine or find true north.

Convincing proof the Earth is rotating?

Quote from: Kira-SY on October 06, 2008, 07:50:07 AM

Niether the flatness, 'because with our human eyes, it'd be impossible.

Nice! At least one of the RE'ers is intelligent enough to agree with me.

I agree with you in the concept of FoR, and the limitations of human senses. But not in how you are applicating them.

But not in how you are applicating them.

Like?

Quote from: 3 Tesla on October 06, 2008, 07:26:00 AM

Quote from: E.Jack on October 06, 2008, 03:55:30 AM

So I can see the Earth's true shape while going outside?

Yes if you (properly) survey a 'flat' stretch of water like The Bedford Level with a theodolite and some poles.

(The poles in the middle look higher than the pole at the very end, apparently.)

Interseting fact about Gyrotheodolites:

Quote from: Wikipedia

A gyrotheodolite comprises a normal theodolite with an attachment that contains a gyroscope mounted so as to sense rotation of the Earth and from that the alignment of the meridian. The meridian is the plane that contains both the axis of the Earth’s rotation and the observer. The intersection of the meridian plane with the horizontal contains the true north-south geographic reference bearing required. The gyrotheodolite is usually referred to as being able to determine or find true north.

Convincing proof the Earth is rotating?

Not to most Flat Earthers, I suspect.

They explain the properties of gyroscopes by the action (gravity?) of the rotating "celestial bodies" in the sky (c. 3,000 miles up).

How is that considered trolling when I am explaining my point using science? That doesn't make sense.

Seriously, though: how do Relativistic frames of reference stop you measuring The Earth's curvature?

If I were to recreate the infamous Bedford Level Experiment (http://en.wikipedia.org/wiki/Bedford_Level_Experiment) and show, like Wallace, that the waterway was curved over a stretch of a few miles, wouldn't that count?

Or does Relativity mess up our localised perception somehow?

Can anyone explain how General/Special Relativity interferes with a Bedford Level-type (surveying) experiment?

It's not my fault if you can't even use logic to think that it's impossible to tell the shape of the Earth in our local frame of reference. At least Kira gets it; you're just... nevermind.

I've carefully explained where you're going wrong.

No, you didn't.