Earths Magnetic Field

[webolife]

Jacmac... ok ok I might agree, but who wants that?
Are you saying freefall is the same as weightlessness? I see them occurring together here, but not the same phenomenon...

[comingfrom]

Sorry, I can't believe those explanations.

Yes, I understand the weightlessness experienced in a plane descending in altitude, or in a roller coaster ride,
but the ISS is not descending towards the Earth, so the gravity vector should not be reduced to the astronaut. But the fact remains, there is no gravity vector to the astronauts at all, let alone one that can be reduced by the ISS' motion.

Do people weigh less in while riding the bullet train, or a supersonic jet, due to the forward velocity?
And their weight returns when the train or plane stops?
I never heard of that.

The forward motion of the ISS is constant, and the astronaut is at rest relative to the ISS, (they don't get pressed against the back wall). But the astronauts are not at rest relative to the earth and it's gravity, which, if it is at 86% should still be significant. A forward thrust plus a downward thrust should equal a curved trajectory, not a cancelled trajectory.

I would expect the slight curve of the ISS going around the earth might reduce the gravity vector somewhat, but the ISS is not falling. so I would not expect it's slight downwards trajectory to be enough to completely cancel [even 86%] gravity.

In fact, when a rocket is leaving the earth, near the surface the gravity intensifies [for the astronauts on board], due to the acceleration against the vector of gravity. But as soon as the rocket pops out past the ionosphere, the astronauts experience complete weightlessness, even while their craft is still accelerating away from Earth.

I've become convinced that gravity is an electrostatic attraction, which occurs only near the surface of planets.
Once you are out past the ionosphere, then you are outside of the gravity field.
~Paul

[JHL]

Sorry, I can't believe those explanations.

~Paul

(Six paragraphs of nonsense snipped.) So in other words, Paul, all the water in all the world's oceans should be sloshing over to one side and pouring off, right? Because the Earth is orbiting the Sun, as you'll recall, but you just surmised you can't believe those explanations.

Do people weigh less in [sic] while riding the bullet train, or a supersonic jet, due to the forward velocity?

Are you somehow unfamiliar with the shape of the earth and why it's so?

http://curious.astro.cornell.edu/about- ... termediate

It's rubbish like this - people actually disputing the nature of an orbit - that can give the EU a bad name. Why does this happen?

[nick c]

JHL,

It's rubbish like this - people actually disputing the nature of an orbit - that can give the EU a bad name. Why does this happen?

What makes you think that is the EU position? Please refer to the caveat at the top, the Forum Headliner:

The ideas and opinions expressed on this forum do not necessarily reflect those of T-Bolts Group Inc or The Thunderbolts Project(TM)

[webolife]

Back to Comingfrom,
Not sure what exactly prompted your weightless comments, but let's just get down some fundaments:
1. Gravitation is a universal phenomenon, just as Sir Isaac and contemporaries understood.
2. Gravitation is an action, not a "thing".
3. The causes of gravitation are often in dispute, here at TB, as well as in the mainstream, but its existence "in space" is not controversial despite a prevalent primary school misconception that astronaut weightlessness means there is no gravity in space.
4. Galileo's view of gravitation as the confinement of an object's motion to a circular path or shell was superceded by Kepler's understanding that an action across a distance moved objects in an ellipse, later modeled by Newton.
5. Although Newton described gravitation in terms of "attraction", because there is no conceivable attractive force mechanism it is more electrically and physically "friendly" to think of gravity as a "push" toward the centroid of a system, what I refer to as "centropic pressure". In this sense, there is not any doubt that objects such as, say the moon and the ISS, along with 100's of other earth-orbiting objects, are in fact vectored toward the earth centroid/barycenter, and would fall in direct collision were it not for their angular/tangential velocity balancing this acceleration into the resultant elliptical path. All objects move in curved paths that involve both the centropic [gravitational] vector and vectors of angular momentum.
6. Although Einstein conceived of gravitation as a curvature in spacetime caused by the presence of mass, it is more natural to think of gravitation as being the fundamental mechanism of mass, ie. the pressure that results in aggregation of matter. Once again, this is easily described as a centropic vector pressure. The "field" concept certainly infers "space" to be a player in gravitation, but as I've found in many dialogues it is difficult to justify the agentic role of vector space to strict mechanists.

Whether an electrigravitic or aetheric or some other mechanism is visualized, there is really no way around the description of gravitation as a "downward" action, so in the observation of motions it remains only to locate that centroid to which "down" refers; and if the ISS and its occupants were not in a constant downward fall toward earth [we call it an orbit], they'd all be "lost in space".

[comingfrom]

So in other words, Paul, all the water in all the world's oceans should be sloshing over to one side and pouring off, right?

No, gravity works well at the surface, to hold all the water, and air, in place.

Are you somehow unfamiliar with the shape of the earth and why it's so?

No.
I am also not unfamiliar with misdirection.

What has the shape of earth to do with gravity 400 kms up?

http://curious.astro.cornell.edu/about- ... termediate

It's rubbish like this - people actually disputing the nature of an orbit - that can give the EU a bad name. Why does this happen?

Rubbish like that article from Cornell University?

I was disputing that gravity at 400 kms is 86% of G, as witnessed by the weightlessness of astronauts.
I wasn't talking about the nature of an orbit.

We know there are variations in gravity. NASA makes maps to show it.

~Paul

[comingfrom]

JHL,

It's rubbish like this - people actually disputing the nature of an orbit - that can give the EU a bad name. Why does this happen?

What makes you think that is the EU position? Please refer to the caveat at the top, the Forum Headliner:

The ideas and opinions expressed on this forum do not necessarily reflect those of T-Bolts Group Inc or The Thunderbolts Project(TM)

Thank you, Nick.

Sometimes I just open my mouth.
I know I am probably wrong somehow, and maybe someone can show me why.
But if I don't express it, how will anyone know to show me?

I love reproof, if it is sound.
~Paul

[comingfrom]

Expanding on my point above, any thoughtful person can realize that gravity is a per se placeholder for a phenomenon we don't understand. Pretty much everything is. Gravity is a mechanical record of that phenomenon, so to put it.

But it's fruitless to surmise that gravity is a phenomenon that escapes those mechanics, especially with terms relating to a local planetary scale - Neptune isn't a planet with a gravitational relationship with the primary? There's no gravitational component at the galactic level, dark matter fiction notwithstanding?

Now you are expressing your opinions, which is at odds with the typical EU views.

Gravity can't escape mechanics, but Neptune, and galaxies, escaped gravity?
Sorry, but that sounds preposterous to me. Completely illogical

It's one thing to question a phenomenon but it's a completely different thing to assert it to violate classic mechanics without any basis.

I first started pondering this question when I was a youth, in the days of Apollo, and Skylab, and MIR.

When I saw the astronauts become weightless immediately upon leaving the atmosphere, I wondered why they didn't fall towards the Sun, after they got outside the hold of the Earth's gravity.

The way gravity was taught to me, it is what holds the planets in their orbits,
so, logically, unless you are perched precisely on the cusp where earth and Sun's gravities are equal, one should be accelerating either towards one or the other. But that is not what we see.

~Paul

[comingfrom]

Would? It's not even remotely apparent, Nick, that someone would ascribe fanciful notions to the EU. I didn't claim that. I said could - I simply divided sensible theory from surmised nonsense. You keep putting words in my mouth.

If you'd ask me directly, which you haven't, I'd say that it seems readily apparent that disputing conventional orbital mechanics without basis is akin to Martian artifact theory or flat-earthism, oddball ideas that, lacking basis, can be lumped in with EU thought in decidedly EU context such as this we're commenting in, in some cases even by EU proponents.

One hopes that stuff gets filed under an appropriate other category, regardless of disclaimers. Clear now?

I hoped one would correct my misconception, if they surmised it to be nonsense.

Instead I got one who thought I was talking about the nature of an orbit, and tried to imply I don't know the shape of earth.

While you see fit to remodel my intent, Nick, I won't allow myself to do the same to yours: The EU disclaimer exists in much the same was as a commenter might (or should) disclaim bizarre notions presented within a serious, thoughtful community: That's why disclaimers and commentary exist. Which, if you actually think about it, is what I did. I can't see how you'd invert that into something it wasn't.

Well, let me issue a disclaimer then.

I don't know what is right.
I just saw that interactive chart, which seasmith linked above, showed the earth's gravity is still 86% of G where astronauts already experience complete weightlessness. That stimulated me to remember my long standing problem that I have, in understanding why complete weightlessness occurs while still so close to earth.

Kindly stop divorcing the one thing from another. I'd think you'd be a little less forgiving of nonsense than you are about calling it what it is.

What about your nonsense, about Neptune not having a gravity relationship with the primary [I'm guessing you mean the Sun]?
And no gravity component in galaxies?

The Solar system is in a galaxy, and it has gravity components,
doesn't it?

Kind regards
~Paul

[webolife]

Comingfrom,

The way gravity was taught to me, it is what holds the planets in their orbits,
so, logically, unless you are perched precisely on the cusp where earth and Sun's gravities are equal, one should be accelerating either towards one or the other. But that is not what we see.

Once again you seem to be missing some basics on orbital dynamics...
Accelerating toward the "primary" or centroid of the system is exactly what we see happening.
That is why, instead of heading off into space a la Newton's ideal first law, orbiting bodies [and ultimately all bodies are orbiting something], a satellite falls toward it's local centroid. It's falling motion is at a rate that exactly matches its tangential motion, so instead of falling "down" [following the gravitational vector] or flying away [following the tangential momentum vector], it happily and effortlessly takes the elliptical path described by Kepler's laws and is directly observed by us doing so [despite your fear to the contrary]. In fact, that lunar orbiter is not only accelerating toward the moon, it is also accelerating toward the earth, and toward the sun, and toward the galactic center, and while we're at it also accelerating toward the direction of the "Great Attractor" near Virgo.
It is all the while under the influence of gravitation, and moving in a somewhat complexly curved path that we can observe [despite your fears].

[comingfrom]

Thank you, Webolife.

Once again you seem to be missing some basics on orbital dynamics...

Oh goody.
I look forward to hearing your understanding.

Accelerating toward the "primary" or centroid of the system is exactly what we see happening.

Is it?

Then how come, after more than 4 billion years, we are still accelerating towards the Sun.
Shouldn't all the planets have been consumed by now?

That is why, instead of heading off into space a la Newton's ideal first law, orbiting bodies [and ultimately all bodies are orbiting something], a satellite falls toward it's local centroid. It's falling motion is at a rate that exactly matches its tangential motion, so instead of falling "down" [following the gravitational vector] or flying away [following the tangential momentum vector], it happily and effortlessly takes the elliptical path described by Kepler's laws and is directly observed by us doing so [despite your fear to the contrary].

An ellipse can be described as a bounce, or a wave motion.

For two parts of the orbit planets are falling in, and for the other two parts, the planets are moving outward.

A perfect balance would make a perfect circle.

With everything else in gravity theory, the smaller body follows the curve of the rubber mat fabric of space/time into the primary.

Planetary momentum should have washed off, by crashing through the Sun's charge field, and the solar wind.

In fact, that lunar orbiter is not only accelerating toward the moon, it is also accelerating toward the earth, and toward the sun, and toward the galactic center, and while we're at it also accelerating toward the direction of the "Great Attractor" near Virgo.

And yet, an astronaut in the space station is not attracted to anything in any direction.

It is all the while under the influence of gravitation, and moving in a somewhat complexly curved path that we can observe [despite your fears].

I am not afraid.
I am trying to understand.

But your understanding hasn't helped any.
You went on about orbits, and the lunar orbiter, and avoided the weightlessness of near earth astronauts altogether.
And you offered the standard mainstream explanation, which I do already know.

Even so, thank you
~Paul

[comingfrom]

I may have been a bit hasty.

Are you implying that the astronaut has acquired tangential velocity, from the craft, and so is in his own independent orbit, while floating in the middle of the cabin space (or while on an EVA)?

I can see someone believing that.
But it still is a problem, for me. The mass of the astronaut is very different to that of his craft.
With a different mass, but the same tangential velocity, and gravity, shouldn't the astronaut tend to want to drift to another orbit, where the tangential force equalizes the force of gravity upon him, or her? And so will still fall, or float up, within the cabin of the craft.

No fear. Eyes open
~Paul

[webolife]

As Galileo was first to observe [from his pendulum experiments], the acceleration due to gravity is independent of the mass of an object. Heavy objects and light ones both fall at the same rate. The ellipse is the result of the balancing of momentum and gravitation [a circle is a special case of an ellipse; no perfectly circular motion is seen in the universe, even in the rotation of the earth, except when limited to a peculiar point of reference]. The astronaut and the orbiting satellite are both under the influence of the same vectors, are both falling at the same rate, and thus weightlessness is equally perceived by both. Your observation about the planets not falling into the sun is based on the same physics. Orbits will continue as they are unless acted upon by additional outside influences, hence the EU [and my] interest in catastrophic interplanetary disturbances. Outside influences could be planetoid collisions or flybys, interplanetary medium, solar wind, and fluctuations in the electrical and magnetic environments between the planets and the sun. Interestingly however, and contrary to expectation, angular momentum in the solar system is greater at distance from the sun; this is the reverse of the nebular condensation model for system formation, which concentrates angular momentum toward the system centroid. This introduces additional stability to the outer planets, and raises the question of how the solar system came to be in this state? The Saturn hypothesis, which I don't particularly favor, is an alternative explanation for this phenomenon. Since we don't see this same reverse relation in other stellar planetary systems [thus far], the question of design comes into play for me.

[comingfrom]

Thank you webolife. Thank you for your patience.

As Galileo was first to observe [from his pendulum experiments], the acceleration due to gravity is independent of the mass of an object. Heavy objects and light ones both fall at the same rate.

I have seen the experiment with a bowling ball and a feather falling in a vaccum. It is mind bending, isn't it.

The ellipse is the result of the balancing of momentum and gravitation [a circle is a special case of an ellipse; no perfectly circular motion is seen in the universe, even in the rotation of the earth, except when limited to a peculiar point of reference].

So, what you are saying is, when the earth (or any orbiter) is at the closest point to the Sun, she puts on a spurt of tangential acceleration to increase her momentum, so she doesn't fall in. A bit later she takes her foot off the accelerator, so she doesn't end up flying out of the solar system?

The astronaut and the orbiting satellite are both under the influence of the same vectors, are both falling at the same rate, and thus weightlessness is equally perceived by both.

That is sounding feasible to me now. Thank you. Thank you for reminding me that mass is not a factor.

But now I wonder about the astronaut in a rocket that is going to the moon. I know the flight path is not straight, but neither is it orbiting the earth. Are astronauts heavier on such a flight path, due the forward momentum vector adding to earth's gravity vector (rather than the vectors being balanced as in orbital paths)? Or only when the rocket's engine is doing a burn?

Your observation about the planets not falling into the sun is based on the same physics. Orbits will continue as they are unless acted upon by additional outside influences, hence the EU [and my] interest in catastrophic interplanetary disturbances.

There are always outside forces. Ours is not the only planet in the system.

Outside influences could be planetoid collisions or flybys, interplanetary medium, solar wind, and fluctuations in the electrical and magnetic environments between the planets and the sun. Interestingly however, and contrary to expectation, angular momentum in the solar system is greater at distance from the sun; this is the reverse of the nebular condensation model for system formation, which concentrates angular momentum toward the system centroid. This introduces additional stability to the outer planets, and raises the question of how the solar system came to be in this state?

Because it flys in the face of the dust accretion and gravitational collapse model?

The Saturn hypothesis, which I don't particularly favor, is an alternative explanation for this phenomenon. Since we don't see this same reverse relation in other stellar planetary systems [thus far], the question of design comes into play for me.

By question of design, I'm guessing you mean, whether it is mechanically possible, or not.

If that theory does nothing more than make us look at our old theories of orbital mechanics again, I reckon it is worth it. The current unresolved problems has not made mainstream re-examine them.
~Paul

[webolife]

Good points, all.
Be careful of assigning willfulness to the behavior of orbiting bodies... I'm sure you were just being tongue-in-cheek, but the gravitational laws explain the speeding up of an object closer to its centroid/locus and the slowing down when further away. This taken together with basic inertia should help you to understand the experience of astronauts on their way to the moon. Watch the movie "Apollo 13", or "The Martian" -- both do a pretty good job with the physics of momentum.