[Petrochemicals (OP)]

If we have an object such as a train moving at speed past your position, can you feel the gravitational attraction? A train if it moves past you on a platform you feel the vibration through the materials, and the turbulance of the air, do these factors mask the gravitational attraction that may be associated with the velocity?  An example of what i am asking is if a balanced centrifugal flight simulator is spinning behind an air tight screen, can you still feel the attraction as it passes your position ? Relativity states that an objects mass, and therefore its gravitational potential  is relative to the diference in velocity between the two points, light photons being essentially massleßs exept for there kinetic energy.

On the other hand if you are travelling at speed and have a near miss with a rock is there more percieved than just the turbulance
So can we feel it ?

[alancalverd]

In principle, yes. In practice, it's a very small force unless the moving object is very large.

Given several billion years and a lot of resonance effects, the motions of the moon and sun are responsible for moving tides. At the laboratory level, it is worthwhile considering Cavendish's experiment to determine G  by the effect of a large stationary mass on a moving object, as was Maskeleyne's use of a pendulum to measure the mass of a mountain. At the astronomical level, it is the perturbations of distant planetary orbits by "something moving" that led to the discovery of Neptune and Pluto.

[Professor Mega-Mind]

Dood , yu be missin' da point !
Do you feel a change in grav. attraction if the moving object changes mass (relativistically).  Bump Mach Effect , only S.R.  does this !  Tuff to build a reactionless drive on this though !  Also , lightwaves do exert grav. attraction .  Otay , head swelling , Need break .  Bye , bye .    P.M.

[PmbPhy]

If we have an object such as a train moving at speed past your position, can you feel the gravitational attraction?

No. The effect is far to small. to be felt by humans.

A train if it moves past you on a platform you feel the vibration through the materials, and the turbulance of the air, do these factors mask the gravitational attraction that may be associated with the velocity?

No. What you're asking is analogous to asking whether the sound made my Mac truck revving his engine right next to is the cause of the reason why you can't hear the wings of a butterfly flapping ten miles away.

... a balanced centrifugal flight simulator ..

What's that?

Relativity states that an objects mass, and therefore its gravitational potential  is relative to the diference in velocity between the two points, light photons being essentially massleßs exept for there kinetic energy.

What do you mean? What does mass and gravitational potential energy have to do with this? Your argument here is flawed. You're not making a lot of sense.

What level of GR are you knowledgeable at. E.g. that as explained to the masses are that taught at a university or in an advanced text which covers tensors etc.

So can we feel it ?

At best you'll only feel the motion of air.

[PmbPhy]

Bit are examples of what used to be called "relativistic" mass.   

It's still called that and is still widely used. In fact one of the physics labs at Harvard is about measuring relativistic mass. The experiment is described in the American Journal of Physics.

Apparatus to measure relativistic mass increase by John W. Luetzelschwab, Am. J. Phys., 71(9), Sep. (2003)

https://aapt.scitation.org/doi/10.1119/1.1561457

Abstract - An apparatus that uses readily available material to measure the relativistic mass increase of beta particles from a radioactive ²⁰⁴TI source is described. Although the most accurate analysis uses curve fitting or a Kurie plot, students may just use the raw data and a simple calculation to verify the relativistic mass increase.

There's numerous examples of its use in recent journal and text books.

[PmbPhy]

So far all such theories dealing with warp speed travel, time travel etc. rely on the introduction of such hypothetical ideas such as exotic matter ( matter with negative mass, etc.)  or infinities. (In order for The Gott time machine to work, the strings have to be infinitely long.)

The derivation only relies on the space being conical. If the string was closed and extremely long then the local geometry should be the same, i.e. similar to a straight string. BTW - all cosmic strings are either infinitely long or closed (like a loop). They also have zero active gravitational mass density.
[/quote]
On the other hand I'm not sure that locally a cosmic string would be the same for a loop as it would for a string. Gotta think more about that one. Give me a few years.

[Petrochemicals (OP)]

If we have an object such as a train moving at speed past your position, can you feel the gravitational attraction?

No. The effect is far to small. to be felt by humans.

A train if it moves past you on a platform you feel the vibration through the materials, and the turbulance of the air, do these factors mask the gravitational attraction that may be associated with the velocity?

No. What you're asking is analogous to asking whether the sound made my Mac truck revving his engine right next to is the cause of the reason why you can't hear the wings of a butterfly flapping ten miles away.

... a balanced centrifugal flight simulator ..

What's that?

Relativity states that an objects mass, and therefore its gravitational potential  is relative to the diference in velocity between the two points, light photons being essentially massleßs exept for there kinetic energy.

What do you mean? What does mass and gravitational potential energy have to do with this? Your argument here is flawed. You're not making a lot of sense.

What level of GR are you knowledgeable at. E.g. that as explained to the masses are that taught at a university or in an advanced text which covers tensors etc.

So can we feel it ?

At best you'll only feel the motion of air.

I'm glad to see thread has provided a bit of entertainment.

What I am asking is if a silenced and isolated from vibration truck passes your position could you feel it ie in space if the space shuttle passed within feet of you could you feel the gravity? As shows the level of reading of relativity is not high.

[axivasichempvtltd]

nice

[Colin2B]

nice

What isn’t so nice is your attempt to spam us with a commercial website link. This has now been removed.
And, by the way, you are banned.

[yor_on]

Well, time travel exist :)
We all do it, but it's a one way experience.

[yor_on]

As for the main question. Are you imagining equivalent proper mass passing you in space, at different uniform motions (relative you)? Asking whether the 'speed' then will give different results for you, standing on some scale?
=

Eh, not 'results', weights should be the correct word there.

[yor_on]

Let's take a hypothetical wormhole. We anchor it at our present time, accelerate the other end close to light speed, then bring it home. We now have one part anchored in the 'past' for the guys following the ship, and all others existing at that time. But it's not a time travel in the meaning of me jumping into some time machine setting the coordinates to prehistoric time. When you stay close to a black hole your 'universe' should be seen to speed up, and according to your clock you now 'travel' a lot faster into the universe's future (compared to the speed of evolving you normally expect the universe to have). So we have three definitions here of what a time travel might mean, actually four, as you already travel into the future, getting older :)

the only one I would consider a real 'time machine' is 3 you getting your time machine to take you to prehistoric times. The one with the worm hole I seriously doubt, but maybe? The one where you age is the one way time machine that already exist, including the black hole scenario.
=

Actually the one with the wormhole would demand bifurcations (splits) to not lead to inconsistencies . The universe would need to 'split' at each 'time traveler' going 'back' inside that wormhole. Think about it and you will see why

Which btw nicely then explains why we can't find any 'time travelers' here. It proves us to be of the main branch, with all other branches of a 'universe' then getting 'split away' by those dastardly time travelers pestering us.

see?

[Professor Mega-Mind]

To : Halc
Two relevant points :
A.- Your Relativistic Masses are in constant flux as the bodies orbit .
B.- Your answer is correct as far as between bodies goes , but passers-by will feel a greater attraction as the relativistic-mass rises .
C.- I'm really a system & design guy , Janus & Alan Calverd can check your formulation better than I ..P.

*To the O.P. ; apologies for "hi-jacking" your thread .
 I was on a mission of sorts , and kind of used it for the greater good .

[Colin2B]

Do you feel a change in grav. attraction if the moving object changes mass (relativistically).

Reactionless thrust aside, I never saw this point addressed, and I find it interesting.

You are right, the original question in this thread seems to have been highjacked by discussion on reactionless drive. If we have time we’ll separate these out.

@Petrochemicals  - apologies, your question seems to have got lost. The replies in the first part of the thread cover the situation at low speeds, but at speeds approaching the speed of light the added kinetic energy (relative to you) of the object will be seen by you as an increase of both it's inertia and it’s gravitational attraction, so you will feel an attraction as it goes past. The faster it goes, the greater the attraction.

[PmbPhy]

Do you feel a change in grav. attraction if the moving object changes mass (relativistically).

Reactionless thrust aside, I never saw this point addressed, and I find it interesting.

You are right, the original question in this thread seems to have been highjacked by discussion on reactionless drive. If we have time we’ll separate these out.

@Petrochemicals  - apologies, your question seems to have got lost. The replies in the first part of the thread cover the situation at low speeds, but at speeds approaching the speed of light the added kinetic energy (relative to you) of the object will be seen by you as an increase of both it's inertia and it’s gravitational attraction, so you will feel an attraction as it goes past. The faster it goes, the greater the attraction.

I addressed this in my first, and only (besides this one), post. I gave examples from my website too. In that site it gives an example of the gravitational field of light. I also posted a reference to a journal article about the exact question asked.

[Colin2B]

Do you feel a change in grav. attraction if the moving object changes mass (relativistically).

Reactionless thrust aside, I never saw this point addressed, and I find it interesting.

You are right, the original question in this thread seems to have been highjacked by discussion on reactionless drive. If we have time we’ll separate these out.

@Petrochemicals  - apologies, your question seems to have got lost. The replies in the first part of the thread cover the situation at low speeds, but at speeds approaching the speed of light the added kinetic energy (relative to you) of the object will be seen by you as an increase of both it's inertia and it’s gravitational attraction, so you will feel an attraction as it goes past. The faster it goes, the greater the attraction.

Sorry Pete, my fault for skimming through in a hurry. I think this thread would benefit from some pruning to cut out the dead wood.
I was looking at your paper on relativistic mass last month and found the only copy I had from arxiv has fonts which don’t display on ipad. I’ll check on pc and let you know.

[PmbPhy]

Do you feel a change in grav. attraction if the moving object changes mass (relativistically).

Reactionless thrust aside, I never saw this point addressed, and I find it interesting.

You are right, the original question in this thread seems to have been highjacked by discussion on reactionless drive. If we have time we’ll separate these out.

@Petrochemicals  - apologies, your question seems to have got lost. The replies in the first part of the thread cover the situation at low speeds, but at speeds approaching the speed of light the added kinetic energy (relative to you) of the object will be seen by you as an increase of both it's inertia and it’s gravitational attraction, so you will feel an attraction as it goes past. The faster it goes, the greater the attraction.

Sorry Pete, my fault for skimming through in a hurry. I think this thread would benefit from some pruning to cut out the dead wood.
I was looking at your paper on relativistic mass last month and found the only copy I had from arxiv has fonts which don’t display on ipad. I’ll check on pc and let you know.

That paper doesn't touch the subject directly but the one on mass does. See also the various articles at
http://www.newenglandphysics.org/physics_world/gr/gr.htm

[PmbPhy]

Read this and then we'll talk: http://www.newenglandphysics.org/physics_world/gr/grav_force.htm

Notice where the force depends on velocity such as the weight of a moving body depends on its speed (Eq. 20-21).

I noticed hat you used Newtonian ideas for GR. That's bad juju.   You can't use F =- GMm/r^2 in GR. Also you tried to use force equations from SR to think about GR - also bad juju. So to answer your question - You're not correct.

The answer to the question "Can we feel gravitational attraction from objects at different velocities?" is Yes. In fact see:
Measuring the active gravitational mass of a moving object by D.W. Olson and R.C. Guarino, Am. J. Phys., 53(7), Jul. (1985) - The abstract is online at - https://aapt.scitation.org/doi/10.1119/1.14280

Note: I'm less chatty nowadays because I'm in more pain. Posting is painful because I have to sit upright for a while and that's painful.

[Colin2B]

I tried SR, but this is gravity we're talking about and it isn't covered by SR.  I'm fine with being wrong.  I suspected as much.

The change in energy can be handled in SR and it is this added energy that results in the increased inertia and gravitational attraction. The inertia and attraction will be equivalent to a mass m_rel=m₀γ where γ is the Lorentz factor.
Particle physicists don’t like to talk about variable mass, so tend to deal in energy, but for everyday problems the above works quite well.
For your problem of orbiting masses viewed from afar, I will be interested in how @PmbPhy approaches it.

[PmbPhy]

The change in energy can be handled in SR and it is this added energy that results in the increased inertia and gravitational attraction.

Don't forget about gravitational energy!

The inertia and attraction will be equivalent to a mass m_rel=m₀γ where γ is the Lorentz factor.
Particle physicists don’t like to talk about variable mass, so tend to deal in energy, but for everyday problems the above works quite well.

In a gravitational field that relation only holds for what's called "time orthogonal spacetimes" which means that terms like dx*dt don't appear in the spacetime interval.

For your problem of orbiting masses viewed from afar, I will be interested in how @PmbPhy approaches it.

I found his question confusing so I was unable to give a reasonable reply. Sorry mate!