https://www.geogebra.org/m/dfv4bsrwthere are two bodies next to each other, standing still without pushing
In my animation
https://www.geogebra.org/m/dfv4bsrwthere are two bodies next to each other, standing still without pushing
each other (and the dynamometer proves it).
They don't push each other because nothing pushing body A to the right
and nothing pushing body B to the left.
But if the two bodies A and B have electromagnetic charge (as seen by clicking on the "Electromagnetic interaction" button), the external
force that pushes body A to the right and body B to the left, is there.
In this case there is an external action (the blue electromagnetic
attraction between the two opposite charges) that pushes the two bodies towards each other and all this generates an opposite internal red
reaction (in the contact zone) direct in the opposite direction to
contrast the approach of the two bodies.
Red forces exist as a reaction to blue forces and would not exist
without them.
Is it correct to say that the situation is completely analogous to the
one seen by clicking on the "Gravitational interaction" button, where
the reciprocal red force (of action-reaction between bodies A and B)
exists only thanks to the blue gravitational force?
clicking on "Gravitational interaction" we see two bodies without anyhttps://www.geogebra.org/m/dfv4bsrw
Luigi Fortunati venerd=C4=9B 23/09/2022 alle ore 10:01:54 ha scritto:
In my animation
https://www.geogebra.org/m/dfv4bsrwthere are two bodies next to each other, standing still without pushing each other (and the dynamometer proves it).
They don't push each other because nothing pushing body A to the right
and nothing pushing body B to the left.
But if the two bodies A and B have electromagnetic charge (as seen by clicking on the "Electromagnetic interaction" button), the external
force that pushes body A to the right and body B to the left, is there.
In this case there is an external action (the blue electromagnetic attraction between the two opposite charges) that pushes the two bodies towards each other and all this generates an opposite internal red
reaction (in the contact zone) direct in the opposite direction to
contrast the approach of the two bodies.
Red forces exist as a reaction to blue forces and would not exist
without them.
Is it correct to say that the situation is completely analogous to theToo bad I didn't have any answers, for me the question is very
one seen by clicking on the "Gravitational interaction" button, where
the reciprocal red force (of action-reaction between bodies A and B)
exists only thanks to the blue gravitational force?
important.
I will try to simplify question.
In my animation
clicking on "Gravitational interaction" we see two bodies without any electric charge exerting a compressive force in the contact area,https://www.geogebra.org/m/dfv4bsrw
measured by the dynamometer.
m
Here is the question: is the force that compresses the contact zone
between the two bodies, whether due to Newton's gravity or Einstein's spacetime curvature, real (it always exists) or is it apparent (and disappears under certain conditions)?
In my animation
https://www.geogebra.org/m/dfv4bsrwthere are two bodies next to each other, standing still without pushing
each other (and the dynamometer proves it).
They don't push each other because nothing pushing body A to the right
and nothing pushing body B to the left.
But if the two bodies A and B have electromagnetic charge (as seen by clicking on the "Electromagnetic interaction" button), the external
force that pushes body A to the right and body B to the left, is there.
In this case there is an external action (the blue electromagnetic
attraction between the two opposite charges) that pushes the two bodies towards each other and all this generates an opposite internal red
reaction (in the contact zone) direct in the opposite direction to
contrast the approach of the two bodies.
Red forces exist as a reaction to blue forces and would not exist
without them.
Is it correct to say that the situation is completely analogous to the
one seen by clicking on the "Gravitational interaction" button, where
the reciprocal red force (of action-reaction between bodies A and B)
exists only thanks to the blue gravitational force?
Luigi,
However, the point that I and others have tried to make is that in general relativity the natural path for each object near the other is one that accelerates towards the other, as viewed in this center of mass frame.
And that despite there is in fact a correspondence in magnitude
between all the forces involved due to the fact that the two bodies
press on each other by the same exact amount that the two bodies
are attracting each other.
Richard Livingston martedÃ¬ 27/09/2022 alle ore 10:36:00 ha scritto:
Luigi,
However, the point that I and others have tried to make is that in general >> relativity the natural path for each object near the other is one that
accelerates towards the other, as viewed in this center of mass frame.
Meanwhile, I want to specify that the two bodies "accelerate" towards each other in space but not in space-time where the forces (and the consequent accelerations) do not exist.
Look at my animation
https://www.geogebra.org/m/pzts2ks7
set in space-time.
When you press "Start", the two bodies move towards each other, following (as you say) their natural path (not accelerated, I say) towards the center of mass.
But when, after the inelastic collision, the two bodies *stop* approaching each other, their old geodesics no longer exist!
From that moment on, the two bodies become a single body following a single geodesic (see what happens at the end of the animation).
There are no longer two "natural paths" but only one.
Julio Di Egidio mercoledÃ¬ 28/09/2022 alle ore 09:14:59 ha scritto:
And that despite there is in fact a correspondence in magnitude
between all the forces involved due to the fact that the two bodies
press on each other by the same exact amount that the two bodies
are attracting each other.
The two bodies attract each other because they follow their different "natural paths" and that's okay.
But why do they keep attracting each other even when they stop getting
close to each other and become one body with a single "natural path"
instead of two? 1
https://www.geogebra.org/m/gpv6f5pn
In English
https://www.geogebra.org/m/gpv6f5pn
https://www.geogebra.org/m/ne77y6j4
Julio Di Egidio mercoledÄ=9B 28/09/2022 alle ore 09:14:59 ha scritto:
And that despite there is in fact a correspondence in magnitude
between all the forces involved due to the fact that the two bodies
press on each other by the same exact amount that the two bodies
are attracting each other.
The two bodies attract each other because they follow their different "natural paths" and that's okay.
But why do they keep attracting each other even when they stop getting
close to each other and become one body with a single "natural path"
instead of two?
The two bodies attract each other because they follow their different "natural paths" and that's okay.
But why do they keep attracting each other even when they stop getting
close to each other and become one body with a single "natural path"
instead of two?
The same question can be asked of each atom in each of the bodies:
Why do they not accelerate toward the center of mass of the body?
Richard Livingston gioved=C4=97 29/09/2022 alle ore 17:44:00 ha scritto=:
The same question can be asked of each atom in each of the bodies:=20=20
Why do they not accelerate toward the center of mass of the body?=20
The answer is electromagnetic forces, the same ones that keep your=20
feet from sinking into the earth. These EM forces cause the atoms
to accelerate w/in the curved space-time generated by all the mass
in the objects. and the result is the common motion of the combined
mass.
They don't accelerate (I think) because there's another atom below=20 blocking it.
In GR, proper acceleration is physical, while coordinate acceleration
can be merely an artifact of the coordinates used (as happens here for Luigi's choice [#]). Gravitation never generates proper acceleration,
but real forces, such as EM, always do.
You both are using too imprecise terminology, with a PUN on "accelerate"
here -- WHAT TYPE of acceleration do you mean?
[#] Luigi chose coordinates relative to which the
accelerations of atoms are zero, even though their proper
accelerations are nonzero.
Tom Roberts <tjrobe...@sbcglobal.net> wrote:
In GR, proper acceleration is physical, while coordinate accelerationAs someone who has never studied GR, this is an eye-opener for me.
can be merely an artifact of the coordinates used (as happens here for Luigi's choice [#]). Gravitation never generates proper acceleration,
but real forces, such as EM, always do.
If gravity is not a real force, is there a need for gravitons? Perhaps
trying to unify gravity with the other three forces in a grand unified
theory is a misguided adventure? I'm asking as someone who is
largely ignorant in these fields.
Cheers,
Rob Komar
Sysop: | Keyop |
---|---|
Location: | Huddersfield, West Yorkshire, UK |
Users: | 342 |
Nodes: | 16 (2 / 14) |
Uptime: | 28:55:13 |
Calls: | 7,513 |
Calls today: | 10 |
Files: | 12,713 |
Messages: | 5,641,944 |
Posted today: | 2 |