The relativity of a straight path through space

[Maartenn100]

I post this topic in the section 'speculations', because it is speculative.

The relativity of a straight path through space

Mass curves space and time. That's what the GR of Einstein tells us and that what's been proven with the comparison of atomic clocks and with the relativistic corrections of GPS.

The arguments for my hypothesis:

If an object orbits a massive object in space, it follows a straight line in curved space (curved by mass/gravity).

If an astronaut in a spaceship orbits Earth (due to gravity), he/she will not experience centripetal forces. The reason is: he/she follows a straight path through (curved) space. That's also the reason why we, on Earth, do not feel that we rotate on Earth, that we move in the Solar System, move in the Galaxy etc. It's as following straight paths through (curved) space, without any centripetal forces.

Therefore, every observer has his/its own particular idea of a straight path through space.

An observer orbiting the sun, or an observer orbiting a black hole. Both observers will disagree about what's a straight line. Because they have their own particular idea of a straight path through space. Because their spacetime environement is curved.

And, therefore, whatever he or she will observe further away as being curved/expanded space, depends on his particular idea of a straight line locally in his own curved spacetime environement.

 

Edited May 3, 2018 by Maartenn100

[swansont]

2 hours ago, Maartenn100 said:

 The arguments for my hypothesis:

If an object orbits a massive object in space, it follows a straight line in curved space (curved by mass/gravity).

If an astronaut orbits Earth, he/she will not experience centripetal forces. The reason is: he/she follows a straight path through (curved) space.

You are mixing Galilean/Newtonian physics with relativity. You need to pick one or the other. In GR there is no centripetal force in this case, but then, gravity isn't a force.

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That's also the reason why we, on Earth, do not feel that we rotate on Earth, that we move in the Solar System, move in the Galaxy etc. It's as following straight paths through (curved) space, without any centripetal forces.

No, that's not the reason. We don't feel it because it is a relatively small effect. We can detect it if we look — we have the Foucault pendulum, we have Coriolis forces. If we use relativity and ignore rotation, we will get the wrong answer because we have ignored the Sagnac effect.

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Therefore, every observer has his/its own particular idea of a straight path through space.

An observer orbiting the sun, or an observer orbiting a black hole. Both observers will disagree about what's a straight line. Because they have their own particular idea of a straight path through space. Because their spacetime environement is curved.

 

This sounds suspiciously like the timing argument in the thread that was just closed. The underlying misconception is the same. Don't waste our time by going down that rabbit hole again.

[Strange]

Close. A line that just follows curved space would appear straight to us (a geodesic). Like great circles on the surface of the Earth. It is the fact that objects or light travel through curved space-time that we can detect the change in direction caused by passing a massive object.

[Maartenn100]

The corioliseffect is the proof that what's a straight path for one observer, is a curved path for another observer.

What's a straight path for an astronaut above Earth, far away from Earth, observing Earth's rotation. (not influenced by Earth's spacetimecurvature)? (with different clocks)

 And what's a straight path for someone on Earth?  standing still, relative to Earth? (in Earth's curved spacetime-environement)? (same clocks)

In my opinion, it's the difference from a point of view outside the influence of the curvature of spacetime of a massive body (different clocks), versus the view inside a curved spacetime-environement of a massive body. (same clocks)

Edited May 4, 2018 by Maartenn100

[Strange]

1 hour ago, Maartenn100 said:

The corioliseffect is the proof that what's a straight path for one observer, is a curved path for another observer.

Not really.

The person experiencing the Coriolis force knows they are not longer travelling in a straight line, because a force is acting on them.

The "external" observer knows they are not travelling in a straight line but for a different reason: there is no force, but they are moving in a rotating frame of reference.

[Maartenn100]

 

ok, but don't you agree that all observers will disagree about the path followed in space, being straight versus being curved. (or spiral)?

Let's make my point clear with the following image: (see  image below)

In the following image, you see three perpectives:

1. An observer seeing only Earth's rotation (moving with the Earth around the sun), 

2. An observer outside the solar system, moving with the sun in the galaxy.

3. An observer outside the galaxy, observing the sun and the Earth moving in the galaxy.

 

These three observers will disagree about the path Earth is following through space.

They observe the same object, with a different clock. (different influence of observed massive body on their clock and ruler) 

Observer one observes that Earth is moving in 24 hours around its own axis. (rotation)

Observer two observes that Earth in not only moving in 24 hours around it's own axis, but is at the same time moving around the sun, relative to the sun, with a speed of 110,000 km/h. (rotation + circular motion)

Observer three will observe that Earth is not only moving in 24 hours around its own axis, but Earth is at the same time moving around the sun with 110.000 km/h and at the same time Earrth orbits the galaxy center with a speed of about 220 km/s. (rotation + spiral motion in the galaxy)

Etcetera.

The different observers will disagree about the speed of the same observed object, depending on their reference frame. They will disagree about the amount of space the object is moving through. And they will disagree on what's standing still , following a circular motion (around the sun) or following a spiral motion through space (in the galaxy).

Edited May 4, 2018 by Maartenn100

[Strange]

16 minutes ago, Maartenn100 said:

ok, but don't you agree that all observers will disagree about the path followed in space, being straight versus being curved. (or spiral)?

No.

17 minutes ago, Maartenn100 said:

These three observers will disagree about the path Earth is following through space.

If that were true then we (viewing things from perspective 1) would not know about the others. But we do, so we can see that those other paths exist. The fact that we feel as if we are stationary when sitting in a chair is irrelevant. We can still observe our rotation around the Earth and the Earth's movement around the galaxy.

You seem to be confusing the existence of different frames of reference with what can be known from each frame of reference.

For example, to right back to the basics of Galillean relativity (which is trivially true) if you are in a ship on a flat sea (or, nowadays, in outer space) and see a another ship passing in the opposite direction you don't know if you are stationary and they are passing you and vice versa. (And in fact, there is no difference.)

However, you both know each others speed and course as seen from your own frames of reference. And if one, or both of you, were on a curved path, you would be able to see that as well. And, furthermore, you would know if your pay was curved (because of things that can be measured, like the Coriolis force).

[Maartenn100]

ok, but why are the coriolis force and the Foucault pendulum not showing us that Earth is not only rotating on its axis but is at the same time moving around the sun with a speed of 110,000 km/h and moving in the galaxy, while rotating, with a speed of 220 km/h?  Earth is not only rotating on its axis. That's not its only motion, if you do not want to think in terms of relative motion. So the coriolis force and Foucault pendulum don't show us all these other movements.

Edited May 4, 2018 by Maartenn100

[Strange]

4 minutes ago, Maartenn100 said:

ok, but why are the coriolis force and the Foucault pendulum not showing us that Earth is not only rotating on its axis but is at the same time moving around the sun with a speed of 110,000 km/h and moving in the galaxy, while rotating, with a speed of 220 km/h?

And here we go again. Have you calculated how large these effect are?

[Maartenn100]

The effects must be measurable. We are also wobbling with a moon. No measurable effects? Wobbling with a moon, going at a speed   around the sun and moving with a speed of 220 km/s in the galaxy. Not measurable??? 

The pendulum and coriolisforce are able to show us the rotation of the Earth.

But they don't show us all the other movements the Earth's making? Not measurable?

And we are moving towards the Andromeda galaxy with enormous speeds. The faucault pendulum and coriolis force are not showing us Earth's motion towards the Andromeda galaxy. Why not? That must be measurable.

We can conclude that the coriolis force and the Faucault pendulum are not able to show us our relative motions in the galaxy, towards Andromeda etcetera. 

Conclusion, all these motions are relative. 

 

Edited May 4, 2018 by Maartenn100

[swansont]

1 hour ago, Maartenn100 said:

 ok, but don't you agree that all observers will disagree about the path followed in space, being straight versus being curved. (or spiral)?

No, not all observers. And this is why we make a distinction about whether one is in an inertial reference frame, or not. Such details matter.

1 hour ago, Maartenn100 said:

Let's make my point clear with the following image: (see  image below)

In the following image, you see three perpectives:

1. An observer seeing only Earth's rotation (moving with the Earth around the sun), 

2. An observer outside the solar system, moving with the sun in the galaxy.

3. An observer outside the galaxy, observing the sun and the Earth moving in the galaxy.

 

These three observers will disagree about the path Earth is following through space.

They observe the same object, with a different clock. (different influence of observed massive body on their clock and ruler) 

Observer one observes that Earth is moving in 24 hours around its own axis. (rotation)

Observer two observes that Earth in not only moving in 24 hours around it's own axis, but is at the same time moving around the sun, relative to the sun, with a speed of 110,000 km/h. (rotation + circular motion)

Observer three will observe that Earth is not only moving in 24 hours around its own axis, but Earth is at the same time moving around the sun with 110.000 km/h and at the same time Earrth orbits the galaxy center with a speed of about 220 km/s. (rotation + spiral motion in the galaxy)

Etcetera.

The different observers will disagree about the speed of the same observed object, depending on their reference frame. They will disagree about the amount of space the object is moving through. And they will disagree on what's standing still , following a circular motion (around the sun) or following a spiral motion through space (in the galaxy).

At best you have re-hashed the concepts around relativity, the best theory of which has been known for ~100 years. Do you have anything new to add to it?

 

4 minutes ago, Maartenn100 said:

 And we are moving towards the Andromeda galaxy with enormous speeds. The faucault pendulum and coriolis force are not showing us Earth's motion towards the Andromeda galaxy. Why not? That must be measurable.

Instruments have limits to their precision. You have to choose the right tool for the job. Just because a tape measure pretty much fails at driving in a nail doesn't mean it's impossible to drive in a nail.

4 minutes ago, Maartenn100 said:

We can conclude that the coriolis force and the Faucault pendulum are not able to show us our relative motions in the galaxy, towards Andromeda etcetera. 

See above about the right tool for the job.

4 minutes ago, Maartenn100 said:

Conclusion, all these motions are relative. 

Welcome to what we've known for a very, very long time.

[Maartenn100]

12 minutes ago, swansont said:

 

At best you have re-hashed the concepts around relativity, the best theory of which has been known for ~100 years. Do you have anything new to add to it?

 

I said earlier that, according to my idea, not only we have a particular idea of normal timeflow in our own frame of reference, but we also have a particular idea of a straight path trough space.(our own particular ruler)

I don't know wether the theory of relativity is stating that.

But, if the Faucault pendulum and coriolisforce can show us a difference of 1060 km/h (Earth's rotation on its axis), why do these effects not show Earth's rotation around the sun ( 107,000 km/h), in the galaxy (220 km/s) and towards Andromeda (300 km/s)?

Because all these motions, due to curvature of spacetime, are relative motions. 

 

Edited May 4, 2018 by Maartenn100

[Strange]

14 minutes ago, Maartenn100 said:

But, if the Faucault pendulum and coriolisforce can show us a difference of 1060 km/h (Earth's rotation on its axis), why do these effects not show Earth's rotation around the sun ( 107,000 km/h), in the galaxy (220 km/s) and towards Andromeda (300 km/s)?

Same reason you can't measure the size of a virus with a metre rule. Or see the galaxy GN-z11 with a pair of binoculars. 

Because some of them a bigger than others. 

If you hang a small weight from a couple of centimetres of thread to make a pendulum, it probably won't detect the Earth's rotation.

[swansont]

4 hours ago, Maartenn100 said:

I said earlier that, according to my idea, not only we have a particular idea of normal timeflow in our own frame of reference, but we also have a particular idea of a straight path trough space.(our own particular ruler)

I don't know wether the theory of relativity is stating that.

It might be worthwhile to learn what relativity predicts.

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But, if the Faucault pendulum and coriolisforce can show us a difference of 1060 km/h (Earth's rotation on its axis), why do these effects not show Earth's rotation around the sun ( 107,000 km/h), in the galaxy (220 km/s) and towards Andromeda (300 km/s)?

km/hr or km/s are not rotations. What is the rotation rate of the earth, or earth around the sun?

(hint: the latter will be smaller by about a factor of 365)

 

 

[Janus]

7 hours ago, Maartenn100 said:

I said earlier that, according to my idea, not only we have a particular idea of normal timeflow in our own frame of reference, but we also have a particular idea of a straight path trough space.(our own particular ruler)

I don't know wether the theory of relativity is stating that.

But, if the Faucault pendulum and coriolisforce can show us a difference of 1060 km/h (Earth's rotation on its axis), why do these effects not show Earth's rotation around the sun ( 107,000 km/h), in the galaxy (220 km/s) and towards Andromeda (300 km/s)?

 

 

A Foucault pendulum does not measure 1060 km/hr ( which is the tangential velocity at ~50° latitude), but measures the angular velocity of Earth's rotation of 7.29e -5 rad/sec. In fact a Foucault pendulum placed at the equator, where the tangential velocity is the greatest, will not show any precession. 

A Foucault pendulum is measuring the sidereal rotation of the Earth ( its rotation with respect to the stars. ) This is completely independent of the Earth's orbital motion around the Sun. The only difference the Earth orbit will make is that the period of precession for a Foucault pendulum will not match the length of a Solar day.   The Sun going from Noon to Noon will be a bit out of step with a Foucault pendulum. 

as far as galactic rotation goes, yes it would cause a small deviation from a true sidereal rotation measurement.  However, the galaxy takes 230 million years to complete a rotation and the the angular velocity the pendulum would have to be able to measure would be 1/84,000,000,000 that which it measures due to the Earth's rotation.  The practical limits involved in making a Foucault pendulum preclude making one that sensitive.  We are talking something that would take nearly 640,000 years to precess just 1 degree.