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a reply to: stormbringer1701
I wouldn't characterize it as "plainly admitting", rather it's a theoretical calculation which according to this paper may be too small to measure:

It's Hard to Learn How Gravity and Electromagnetism Couple

We construct the most general effective Lagrangian coupling gravity and electromagnetism up to mass dimension 6 by enumerating all possible non-minimal coupling terms respecting both diffeomorphism and gauge invariance. In all, there are only two unique terms after field re-definitions; one is known to arise from loop effects in QED while the other is a parity violating term which may be generated by weak interactions within the standard model of particle physics. We show that neither the cosmological propagation of light nor, contrary to earlier claims, solar system tests of General Relativity are useful probes of these terms. These non-minimal couplings of gravity and electromagnetism may remain a mystery for the foreseeable future. ...

as already alluded to in the introduction, observations are unlikely to ever reach a level of precision to even probe Λ 1,2 -scales of the same magnitude of the photon energies involved.

So if it's too small to measure, there are at least two problems:

1. It will be difficult to confirm experimentally if theoretical calculations are correct, and
2. It's probably not useful in any practical sense.

A question on gravity:

Does a fast-moving massive object such as a planet, have a trailing gravitic wake or tail?

originally posted by: Arbitrageur
a reply to: stormbringer1701
I wouldn't characterize it as "plainly admitting", rather it's a theoretical calculation which according to this paper may be too small to measure:

It's Hard to Learn How Gravity and Electromagnetism Couple

We construct the most general effective Lagrangian coupling gravity and electromagnetism up to mass dimension 6 by enumerating all possible non-minimal coupling terms respecting both diffeomorphism and gauge invariance. In all, there are only two unique terms after field re-definitions; one is known to arise from loop effects in QED while the other is a parity violating term which may be generated by weak interactions within the standard model of particle physics. We show that neither the cosmological propagation of light nor, contrary to earlier claims, solar system tests of General Relativity are useful probes of these terms. These non-minimal couplings of gravity and electromagnetism may remain a mystery for the foreseeable future. ...

as already alluded to in the introduction, observations are unlikely to ever reach a level of precision to even probe Λ 1,2 -scales of the same magnitude of the photon energies involved.

So if it's too small to measure, there are at least two problems:

1. It will be difficult to confirm experimentally if theoretical calculations are correct, and
2. It's probably not useful in any practical sense.

1 is certainly true.

but 2 is only probably true. even some seemingly trivial connection may be of use if it is subject to amplification some sort of way. but in GUT or the forerunners thereof it isn't just electromagnetism that is coupled to gravity. unitarian analysis suggests the strong force is related to gravity and at a coupling level that may be as big as 1:2.

unitarity is an mathematical method that was developed because for the remaining mysteries of the universe Feynman's technique is increasingly unwieldy. for further development Feynman analysis results in thousands of diagrams that must be checked tediously and individually. Unitarity has been checked against known valid completed feynman diagrams and feynman analysis that was not complete but in progress during the deployment of unitarian analysis of the same problems. it won it's developers the Sakurai Prize in Physics.

and when unitarity methods are used on gravitons the result resembles a doubled feynman diagram for the gluon. I'm not a scientist; not a mathematician. but it looks to me like this relates gravity and the strong force. and if a doubled gluon is equal to a graviton then the coupling should probably be 2 to one also.

www.preposterousuniverse.com...

originally posted by: Woetra
A question on gravity:

Does a fast-moving massive object such as a planet, have a trailing gravitic wake or tail?

sort of and how wake like depends on whose description of reality you follow. Ernst Mach had inertia and gravity depending on the masses distributed throughout the universe effecting each other. GR has frame dragging and gravity waves.any of these would fit your description to more or less fidelity.

originally posted by: Woetra
A question on gravity:

Does a fast-moving massive object such as a planet, have a trailing gravitic wake or tail?

They are called "Gravitational waves" not to be confused with gravity waves which refer to something else.

Gravitational waves

Most scientists describe gravitational waves as "ripples in space-time." Just like a boat sailing through the ocean produces waves in the water, moving masses like stars or black holes produce gravitational waves in the fabric of space-time. A more massive moving object will produce more powerful waves, and objects that move very quickly will produce more waves over a certain time period.

It's probably hard to measure them from a planet. That's why they talk about black holes, as extremely strong gravitational fields will make them easier to measure. While there has been a claim of indirect measurement of gravitational waves, it's unconfirmed so I think we can say we still aren't sure we've really measured them yet.

It may take a new, more sensitive experiment to measure them, assuming of course they exist as predicted by theory. NASA and the ESA were going to launch a satellite in 2011 called LISA but due to NASA budget problems, they dropped out of the project and now it's ESA only with a tentative launch date of 2034.

But now evgeny podkletnov is claiming gravity waves that can make holes in steel or concrete, but I cannot find any videos of him doing something like this. even ning li cannot be located on the internet.
a reply to: Arbitrageur

originally posted by: Nochzwei
But now evgeny podkletnov is claiming gravity waves that can make holes in steel or concrete, but I cannot find any videos of him doing something like this.

But you found a source of Podkletnov claiming this, and not an unreliable 3rd party claiming that's what Podkletnov claimed? Podkletnov never published any paper about this, right?

originally posted by: Arbitrageur

originally posted by: Nochzwei
But now evgeny podkletnov is claiming gravity waves that can make holes in steel or concrete, but I cannot find any videos of him doing something like this.

But you found a source of Podkletnov claiming this, and not an unreliable 3rd party claiming that's what Podkletnov claimed? Podkletnov never published any paper about this, right?

no he didn't publish any paper, but claimed as much on an video interview with tim ventura. Don't have the link handy but google may locate

originally posted by: Nochzwei
no he didn't publish any paper, but claimed as much on an video interview with tim ventura. Don't have the link handy but google may locate

You've overstated his claim. He said he discharged 5 million volts and something happened and he thinks it's got something to do with gravity but he's not sure and it's not confirmed that it's gravity. At least that's my interpretation of what he says in that interview:

www.intalek.com...

By the way I'm not that surprised that something happens when you discharge 5 million volts. I could have predicted that without even doing the experiment.

I have a question about the energy of empty-space or the vacuum. From QM, we know that the only systems that require a nonzero energy in their lowest state (or zero-point energy) are bound states. The energies of these systems are also discrete. However, for systems like the free-particle, the energy spectrum is continuous and there is no associated zero-point energy.

If empty space has a zero-point energy, would that not suggest it is a 'bound' state and would also mean that the energy levels of empty space are quantized?

originally posted by: Diablos
...From QM, we know that...

we know nothing from QM ! this is just a theory and not the certain truth... it suggests that...

the only systems that require a nonzero energy in their lowest state (or zero-point energy) are bound states. The energies of these systems are also discrete. However, for systems like the free-particle, the energy spectrum is continuous and there is no associated zero-point energy.

what kind of energy??

first someone should define what that energy actually is.
Potential energy means really nothing if there is no difference in some distance,
that allows exchange of... or better said, conversion of that potential energy into kinetic energy / movement. (Electric force is the only one known force that can be directly measured and influenced... gravity however is just an observable and not a force )

(back to empty space...)
Nothing can not move,
there can be a field of some strength pointing somewhere, but this is not energy,
it's direction,
but there is no energy if there is not at least two different potentials that build the bridge for any energy exchange to flow.

Zero-Point_energy means actually... the energy of the surrounding potentials... nothing really interesting or reliable.
see... it changes every place at every moment. This is the illusion of time and actual life... forward movement sort of to speak

If empty space has a zero-point energy, would that not suggest it is a 'bound' state and would also mean that the energy levels of empty space are quantized?

thinking in bounds is that problem... it comes from Number theory and algebra.. 1... 2... 3...
geometry in contrast can describe everything, like a circle for once... Pi is a constant ratio of radius to one spin, one infinite number in number theory however. 3.14...

there is no real continuity in numbers if you look closer... its always undefined or infinite between two of them.
this is the hard boundary you have to cross, the quanta made of a theory... numbers theory and all that comes after

lets go back to geometry...
a distance between two charges has no length's dimension if you look closer, only a value/potential difference in that distance. potential energy.
a measurement makes it a length we understand, like...
so many peaces of something else.. (smaller for best)
this is measurement and the quantization of things.

I hope you see that nothing is really quantized, not space, not energy fields.
There are peaks misinterpreted as quanta value... but hey... Einstein just wrote how he is seeing and understanding it... this really doesn't make it real or define the truth.

well... not all is continuous, and quantized values come from geometry itself, but only with two systems interacting and never from one single system.
In one system there is no interaction because there is nothing to interact with, without interaction no energy flow, better said no energy at all, energy is the difference between something two, and there is no difference in one.
.
.
.

I was thinking about rotating spacecraft and artificial gravity and I have another question.... Does a rotating spacecraft generate centrifugal force in deep space? Imagine that there aren't any stars around the craft. How would you know if it's rotating or not? What would the rotation be relative to so that the laws of physics would "know" to generate centrifugal force?

originally posted by: circlemaker
I was thinking about rotating spacecraft and artificial gravity and I have another question.... Does a rotating spacecraft generate centrifugal force in deep space?

Of course. That's first law of motion. Only it's centripetal force.

I have a ques. Every object emits infra red radiation by virtue of its temp, so how are these em waves generated when the electrons in the object are not exactly in any magnetic field or electric field although electron has its own elec and magfield?

a reply to: Nochzwei
Any movement of any charge creates a magnetic field. Any change in a magnetic field creates an electric field. A changing electric field generates a change in magnetic field. And so it goes, propagating on at the speed of light.

Movement of an electron, except when on an undisturbed orbital around the nucleus, is movement of a charge that gives rise to electromagnetic waves. Vibration of a molecule is the motion of charges, giving rise to electromagnetic waves. And so it goes.

a reply to: circlemaker
Imagine a person on or in that spacecraft. She is holding on to the ladders, so she is rotating together with the vehicle. When she lets go, she is no longer forced to move with the structure; instead, her inertia puts her in motion along a tangent to the last point where she was holding on to anything. If, however, there was no rotation, there would be no tangential motion and she would just float along instead of flowing along.

a reply to: Pirvonen

a reply to: Bedlam

You missed my point...

Here's perhaps a better example: If space was occupied by a single object, how would the object know when it's rotating? There would be nothing else in space to measure that rotation. Hence my question: what is it relative to? Is there some invisible frame of reference that's attached to the object at birth?

originally posted by: circlemaker
a reply to: Pirvonen

a reply to: Bedlam

You missed my point...

Here's perhaps a better example: If space was occupied by a single object, how would the object know when it's rotating? There would be nothing else in space to measure that rotation. Hence my question: what is it relative to? Is there some invisible frame of reference that's attached to the object at birth?

There is not ' nothing else in space '. The something else in space, is the centre of rotation. Hope that helps.

a reply to: circlemaker

Well, as Nochzwei said, it's relative to the center of rotation.

Are you talking about a solid object, a wheel, what? Not that it matters a lot to the physics, but it might make it easier for you to see if I use the same image you're using in your head.