The 'Highest' Spot on Earth?

[n2doc]

April 7, 2007
Well, we all know that Mount Everest, at 29,035 feet above sea level, is the highest spot on our planet and is likely to remain so for a long, long time… unless we think about the word "highest" in a different way.

Suppose I asked you to find the spot on Earth where you would be closest to the moon, the stars and outer space. In other words, the point on Earth that is closest to "out there."

Most of us, again, would point to Mount Everest.

But here's something you may not know: the Earth is not a perfect sphere.

Mount Chimborazo, in the Andes, is a 20,000-plus-foot peak sitting on top of a bulge on the Earth. Mount Everest is a 29,000-plus-foot peak sitting lower down on that same bulge. Because Chimborazo is a bump on a bigger part of the bulge, it is higher.

According to Senne, Chimborazo is 1.5 miles higher than Everest! Or, if you will, 1.5 miles closer to outer space.

more:

http://www.npr.org/templates/story/story.php?storyId=9428163

or, it could be where he is...

[tridim]

1. But wouldn't the space-time at the equator be compressed..

more than the space-time at the poles?

That is, the perceived distance from the moon may be different, but the actual distance is the same.

[n2doc]

2. I don't think the Earth is rotating fast enough for that to be a big factor n/t

[tridim]

3. It's about the extra mass at the equator.

More mass = more curved space-time.

I think this is also why gravity is pretty much a constant on the entire surface of Earth. The extra mass at the equator (that generates more gravity) cancels out the centrifugal force generated by the spin.

Then again I could be completely wrong. I just love talking about this kind of stuff. :)

[M155Y_A1CH]

4. You are absolutely right

You might be completely wrong. :hi:

[tridim]

5. Or maybe I'm so right that I just blew your mind..

:)

http://en.wikipedia.org/wiki/Earth's_gravity

Apparent gravity is weaker nearer the equator because the Earth's rotation produces an apparent centrifugal force.

Gravity provides centripetal force, keeping objects on the surface (and indeed the surface itself) moving in a circular motion. Consider that if the gravity of the Earth were to shut off, objects would fly off into space in the direction of their motion in accordance with Newton's First Law of Motion. Alternatively, if Earth's gravity were weakened so as to match the centrifugal force (at, say, the equator where rotational speed is largest) then objects there would appear to float. At the poles the radius of curvature is zero, so only this weakened gravity would contribute to weight and objects would not float. In this sense, local gravity (gravity at a particular point on the surface of the Earth) felt as weight is gravity due to the Earth's mass minus the centrifugal force. Because rotational speed decreases as one moves towards the poles, local gravity, g, increases from 9.789 m·s−2 at the equator to 9.832 m·s−2 at the poles.<3>

The second major cause for the difference in gravity at different latitudes is that the Earth's equatorial bulge (itself also caused by centrifugal force) causes objects at the equator to be farther from the planet's centre than objects at the poles. Because the force due to gravitational attraction between two bodies (the Earth and the object being weighed) varies inversely with the square of the distance between them, objects at the equator experience a weaker gravitational pull than objects at the poles.

In combination, the equatorial bulge and the effects of centrifugal force mean that sea-level gravitational acceleration increases from about 9.780 m·s−2 at the equator to about 9.832 m·s−2 at the poles, so an object will weigh about 0.5% more at the poles than at the equator.<4>

The same two factors influence the direction of the effective gravity. Anywhere on Earth away from the equator or poles, effective gravity points not exactly toward the centre of the Earth, but rather perpendicular to the surface of the geoid, which, due to the flattened shape of the Earth, is somewhat toward the opposite pole. About half of the deflection is due to centrifugal force, and half because the extra mass around the equator causes a change in the direction of the true gravitational force relative to what it would be on a spherical Earth.

[M155Y_A1CH]

6. It's the curved space/time thingy

Is it related more to rotation plus gravity and not just gravity or mass?
If we were not rotating would we still be bending time?

Hmmm...you might be right, I'll have to ponder it. :shrug:

[M155Y_A1CH]

7. Ton of feathers/ton of bricks?

So, I pondered up this thought to add.

Frame dragging occurs when the rotation of a large body 'twists' nearby space and time.

Gravity is not an actual force like centrifugal force, but caused by the distortion of space/time by a large mass.

I suspect a mountain or bulge has little influence in the overall effect of the entire mass and it's rotation.

It's not the shape that defines the mass.

[tridim]

8. You're right, shape doesn't define mass.

But that's not my point.

All I'm saying is that as far as space-time is concerned, the surface of the Earth (sea level) is flat. Earth's shape is defined by the distorted space-time created by its own gravity. IMO, sea level should always be measured as zero regardless of the perceived distance from the center of mass.

Same deal with the tides caused by the Moon. A tidal bulge is still flat when gravity is included in the equation because space-time is distorted by the gravity at the point where the measurement is taken. If we could measure these things with a physical ruler the results would agree because the ruler would become shorter or longer depending on how much space-time is distorted at the observation point.

It's all relative. :)

[M155Y_A1CH]

9. Good one

"It's all relative" LOL

I'm just not sure how to approach this idea.
I would suspect though that space/time would be more stretched at the equator
due to greater velocity, rather than more compressed. The rotation is dragging space and time with it so the distortion should be greater where the motion is greatest. Maybe we should say the distortion is greater but not more compressed. I think it is the idea of compression that I am having a hard time with?

[muriel_volestrangler]

11. No, 'curved space-time' has nothing to do with centrifugal forces

or tides, or the larger radius of the earth at the equator. The latter are all analysable under normal Newtonian mechanics, without any reference to relativity at all. The relatvistic effects on earth are tiny; they've managed to measure them with atomic clocks travelling in planes, as far as I remember, but it's nowhere near as big as the 1% difference in acceleration that the Wikipedia page is about.

FWIW, I've stood at the top of Chimborazo. :)

[RT Atlanta]

10. K&R for Cheech!

Seriously though, this is an interesting topic and I will have to review the article. Thanks for posting.

[pokerfan]

12. but the TALLEST mountain on earth is Mauna Kea

at 33,476 feet but only 13,796 ft of that is above sea level. Then there's the tallest mountain in the solar system...

[krispos42]

13. Willie Nelson's tour bus?

:P

[damyank913]

14. I thought all mountain heights were measured relative to sea level.

Except of course anything underwater. Are you saying that the bulge includes the surface of the ocean. Sorry-I'm still on my 1st cup of coffee-too early for all this book larnin stuff...