How would gravitational field propulsion craft appear to an observer?

ChrisIB

Honorable
Would they just appear or would there be say a streak of light?

I am puzzled why, if we are visited, we have not seen ships in the solar system. Do they transition behind a planet or moon then cloak?

Which begs the question of why would they hide? At that distance we are no threat.

Do they think we would be able to work out the physics of their propulsion? or that it would be destabilizing for us?
Or is it nothing to do with us and being uncloaked is intrinsically dangerous?
 

nivek

As Above So Below
I am puzzled why, if we are visited, we have not seen ships in the solar system. Do they transition behind a planet or moon then cloak?

Do you know how much space there is in our solar system?...We only watch an extremely small portion of that space too, we don't have much surveillance at all of the space in our solar system...I doubt we have ever caught a ship or probe in our sights in space, much too small to pick up too...

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Do you know how much space there is in our solar system?...We only watch an extremely small portion of that space too, we don't have much surveillance at all of the space in our solar system...I doubt we have ever caught a ship or probe in our sights in space, much too small to pick up too...

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Yes, yet some people say "if we had aliens coming, we would see them".... please.

You have a hard time even finding a missing passenger plane on your own planet.

Besides im guessing if theyve arrived centuries ago and put up bases here or off world, they dont even have to "fly in". All the materials needed for maintaining could be taken from inside the solar system.
 
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nivek

As Above So Below
Do they transition behind a planet or moon then cloak?

There could be alien bases out of our sight on the moon or on Mars, I feel certain based upon USO sightings that there are alien bases deep in our oceans too...

Like @Spaceman spiff said, there may be no need for their ships to fly in and out of our star system...Resources they need could be here amongst our planets, or they could have some sort of wormhole tech...I assume some species have cloaking tech of some sort too, and a means of sending communications we cannot detect...

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nivek

As Above So Below
Yes, yet some people say "if we had aliens coming, we would see them".... please.

You have a hard time even finding a missing passenger plane on your own planet.

Indeed, also we cannot detect all of the asteroids in earth's path, we miss some all the time and surprise us when one flies by the moon or earth...An alien ship could be much smaller than many of those asteroids and traveling at a higher rate of speed...

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Standingstones

Celestial
I did an experiment last week. I was in the doctor’s office looking at the waiting patients. Three quarters of them were noodling on their phones. A grey alien and a seven foot Nordic being could have walked in and no one would have noticed. By the way I never take my phone into a doctor’s office. I find it rude when phones go off at maximum volume. Lock it in the glove box of your car. I promise you, you will survive without it.

The idea someone would be looking at the right time and place to see UFOs doesn’t seem all that feasible.
 

Sheltie

Fratty and out of touch.
I've come to believe that there is no technology capable of propelling a ship across the vast distances in space in a conventional manner. If alien craft are visiting the Earth they must be traveling through wormholes or some similar method. Because they are constantly coming and going through these doorways, they are rarely exposed to us visually.
 

Sheltie

Fratty and out of touch.
There could be alien bases out of our sight on the moon or on Mars, I feel certain based upon USO sightings that there are alien bases deep in our oceans too...

Like @Spaceman spiff said, there may be no need for their ships to fly in and out of our star system...Resources they need could be here amongst our planets, or they could have some sort of wormhole tech...I assume some species have cloaking tech of some sort too, and a means of sending communications we cannot detect...

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The aliens may very well be in nearby locations such as Mars or the Moon. In recent years scientists have discovered so many interesting things that have been dismissed as natural anomalies or coincidence.

Has Stonehenge been found on Mars? Ancient 'alien' stone circle discovered on Red Planet

mars_stonehenge.jpg
 
Would they just appear or would there be say a streak of light?
The first thing to realize is that gravitational field propulsion is a principle and not a specific type of technology like a jet. So just as the principle of reaction propulsion gives us a wide variety of flying devices ranging from helicopters to jets to rockets to parasails, gravitational field propulsion covers a wide variety of possible applications. We've only discovered two theoretically possible forms of it so far, and it's reasonable to expect many more to be discovered over the centuries ahead.

So not only are the observational signatures going to vary depending on the application, but the rate of motion will also modulate the observable characteristics. That's why there's no single answer to your question.

But given what we've seen with thousands of AAV/UFO sighting reports, it appears that lots of UFOs perform like the Tic-Tac in the USS Nimitz CSG incidents: they don't appear to generate any significant propulsion signature. Others appear to glow brightly in the atmosphere, but that appears to be an atmospheric ionization effect - in space there would be no radiant signature because there's no significant gas to ionize. UFOs would therefore be about as difficult to observe as a small dark rock - in other words, they'd be virtually impossible to detect with any modern astronomical technology.

They probably are detected with some regularity via the global military space radar surveillance networks, but the military has been FOIA'd for these "uncorrelated target" records and they've always refused to release any data about them.

I am puzzled why, if we are visited, we have not seen ships in the solar system. Do they transition behind a planet or moon then cloak?
We don't have the tech to observe small objects navigating the solar system unless they leave a long glowing trail of reflective gases and debris like a comet. Remember that 66ft meteor that exploded just above ground in Russia back in 2013? Nobody saw that coming until it was burning across the sky.

Which begs the question of why would they hide? At that distance we are no threat.
They don't seem to be hiding - people see them all the time. They simply just don't seem to like us enough to drop by for a spot of tea.

Do they think we would be able to work out the physics of their propulsion? or that it would be destabilizing for us?
Or is it nothing to do with us and being uncloaked is intrinsically dangerous?
Nobody knows what aliens think, but if we survive as a technological civilization I think it's inevitable that we'll replicate their propulsion technology. That probably will be destabilizing, because we humans use all technological advancements to perpetrate mass murder upon each other.

There are a lot of reports of cloaking and decloaking UFOs, so they seem to have that capability when they want to use it. That's pretty troubling, because we know that their propulsion systems are typically totally silent, and the craft themselves seem to elude most radar systems when they choose to - so they could be hovering right over your house right now and you'd never know it. I take comfort in the fact that I'm not interesting enough for an advanced alien being to spy on, but it's disquieting to realize that they could be all over the place and we'd never know it.

I've come to believe that there is no technology capable of propelling a ship across the vast distances in space in a conventional manner.
It depends on what you mean by "conventional." Gravitational field propulsion isn't "conventional" to us, but apparently it's commonplace among more advanced civilizations. And it violates no laws of physics. So apparently that's what they're using: not primitive rockets, but rather spacetime distortion technology which is indeed permitted by Einstein's general theory of relativity. Someday we'll use that kind of technology ourselves to rapidly traverse interstellar distances.

If alien craft are visiting the Earth they must be traveling through wormholes or some similar method.
A wormhole requires a device at each end to keep the wormhole open, so no - that's no way to travel to new places. But it might be a very useful way to make an expressway between two points that one would frequently like to visit.

In a sense, gravitational field propulsion is a means of "burrowing through spacetime," so it's basically as good as a wormhole. And much easier to build.

Because they are constantly coming and going through these doorways, they are rarely exposed to us visually.
But we don't see that happening - people see these craft moving very quickly from one place to another, not "jumping" through "doorways." And thousands of people see these craft every year. In my view, they appear to be gravitational field propulsion devices because that's exactly what they are - the predicted performance characteristics match the observations *perfectly*.
 

ChrisIB

Honorable
The first thing to realize is that gravitational field propulsion is a principle and not a specific type of technology like a jet. So just as the principle of reaction propulsion gives us a wide variety of flying devices ranging from helicopters to jets to rockets to parasails, gravitational field propulsion covers a wide variety of possible applications. We've only discovered two theoretically possible forms of it so far, and it's reasonable to expect many more to be discovered over the centuries ahead.

So not only are the observational signatures going to vary depending on the application, but the rate of motion will also modulate the observable characteristics. That's why there's no single answer to your question.
Bril, thank you. Looking at the space time footprint produced, are we talking small gravitational waves?
There are a lot of reports of cloaking and decloaking UFOs, so they seem to have that capability when they want to use it.
Speculatively, would you consider cloaking sinister or altruistic?


In observational terms, our technology isn't up to the job but it seems to be getting there, ESA:
Scanning and observing
Space object catalogues, as generated and maintained by space surveillance networks, are limited to larger objects, typically greater than 10 cm in low-Earth orbits (LEO, below about 2000 km) and greater than 0.3–1 m at geostationary orbits (GEO, about 36 000 km). These sensitivity thresholds are a compromise between system cost and performance.
 
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nivek

As Above So Below
I personally think if an alien species were using cloaking technology that it cannot be labeled sinister nor altruistic, it is neither of those things, but simply defensive, protecting themselves and their self interests...

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nivek

As Above So Below
But we don't see that happening - people see these craft moving very quickly from one place to another, not "jumping" through "doorways." And thousands of people see these craft every year. In my view, they appear to be gravitational field propulsion devices because that's exactly what they are - the predicted performance characteristics match the observations *perfectly*.

That is a good point but maybe this cannot be achieved in an atmosphere, if ships were jumping through doorways or portals to another point in space, maybe it can only be achieved in the vacuum of space...

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ChrisIB

Honorable
I personally think if an alien species were using cloaking technology that it cannot be labeled sinister nor altruistic, it is neither of those things, but simply defensive
Yep, perhaps simply defensive, given we have been permitted to irradiate lumps of the planet, I see no altruism.

Our level of development precludes interest other than from ethologists (and a few TV channels, world wars are probably good for ratings).
 
Bril, thank you. Looking at the space time footprint produced, are we talking small gravitational waves?
You're welcome. It's fun to talk about this subject; it's a lifelong obsession for me.

I've given the question of gravitational waves a lot of thought, and I still think about it. I see two reasons why we wouldn't detect any gravitational waves from these devices:

1.) Gravitational radiation - unlike electromagnetic radiation - requires a changing mass quadrupole moment (whereas electromagnetic radiation such as a broadcast antenna only requires a changing charge dipole moment). This is because electromagnetism is a spin-1 field (a vector field), but gravitation is a spin-2 field (a tensor field). But it only requires a changing mass dipole moment in order to produce any change in acceleration that a craft would need. So a gravitational field propulsion device doesn't have to produce any gravitational radiation as it maneuvers.

2.) Gravitational radiation represents a loss of field energy; it's an inefficiency. So if one wishes to design a gravitational field propulsion device with maximum efficiency, one would design the system so that it doesn't produce a changing mass quadrupole moment and waste energy in the form of gravitation radiation. Basically gravitational radiation is analogous to the acoustic noise generated by a gasoline engine: a Harley-Davidson motorcycle makes a lot of noise because it's inefficient - some energy is wasted to produce noise rather than being used to produce the work of horsepower. If you want to build a very efficient UFO, then you'd want to reduce its waste-energy/noise as close to zero as possible. And like I said, I see no reason why a changing mass quadrupole moment would be useful for propulsion purposes, so it's not required anyway.

Speculatively, would you consider cloaking sinister or altruistic?
I think of it as wildlife cinematographers camouflaging themselves with underbrush - I tend to assume that extraterrestrials visiting our planet camouflage themselves for the same reason: to not alarm the wildlife (us).

In observational terms, our technology isn't up to the job but it seems to be getting there, ESA:
Scanning and observing
That's interesting - I'll have to look into it more closely. There's a significant question regarding the detection of objects following non-ballistic trajectories at high rates of speed - I'm doubtful that this system is set up to recognize such objects; they seem to be talking only about orbital debris moving at essentially constant (or steadily changing) speed. Fast-moving objects performing erratic maneuvers might be discarded as "noise" in the system.

That is a good point but maybe this cannot be achieved in an atmosphere, if ships were jumping through doorways or portals to another point in space, maybe it can only be achieved in the vacuum of space...
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The thing is, "portals" (and I assume you mean "wormholes") require machines at both ends to remain open. If they're actually feasible at all. Dr. Kip Thorne - the world's leading expert on wormholes, has found that the mouth of a wormhole will collapse so quickly that even a photon can't pass through it, unless some kind of Very exotic technology keeps the mouth of the wormhole open. We haven't detected any wormhole machines in space. And frankly I don't think they're necessary - there's no upper limit to the speed that a gravitational field propulsion device can move through spacetime (it depends only on the technological sophistication of the engineering), so why maintain a pair of wormhole devices when you can burrow through spacetime at an arbitrary rate? Ultimately the results are the same anyway.

Yep, perhaps simply defensive, given we have been permitted to irradiate lumps of the planet, I see no altruism.
I think it's a mistake to hold alien visitors responsible for permitting our own insanity. We have to learn how to stop being murderous psychopaths. That can't happen if they intervene.

And I think that they've showed enormous benevolence by remaining discrete. Imagine the global epidemic of terror and insanity if they landed on the White House lawn and forced us to acknowledge their presence. That single act alone could doom our species to self-inflicted extinction from the resulting aftermath of fear and confusion.

Or maybe they're being so covert because they're slowly infiltrating our population and hybridizing us with their genome....it's hard to say one way or the other. Sleep tight everyone =)
 

ChrisIB

Honorable
I've given the question of gravitational waves a lot of thought, and I still think about it. I see two reasons why we wouldn't detect any gravitational waves from these devices:

1.) Gravitational radiation - unlike electromagnetic radiation - requires a changing mass quadrupole moment (whereas electromagnetic radiation such as a broadcast antenna only requires a changing charge dipole moment). This is because electromagnetism is a spin-1 field (a vector field), but gravitation is a spin-2 field (a tensor field). But it only requires a changing mass dipole moment in order to produce any change in acceleration that a craft would need. So a gravitational field propulsion device doesn't have to produce any gravitational radiation as it maneuvers.

2.) Gravitational radiation represents a loss of field energy; it's an inefficiency. So if one wishes to design a gravitational field propulsion device with maximum efficiency, one would design the system so that it doesn't produce a changing mass quadrupole moment and waste energy in the form of gravitation radiation. Basically gravitational radiation is analogous to the acoustic noise generated by a gasoline engine: a Harley-Davidson motorcycle makes a lot of noise because it's inefficient - some energy is wasted to produce noise rather than being used to produce the work of horsepower. If you want to build a very efficient UFO, then you'd want to reduce its waste-energy/noise as close to zero as possible. And like I said, I see no reason why a changing mass quadrupole moment would be useful for propulsion purposes, so it's not required anyway.
Again thanks, almost worryingly clear, you should so write a textbook!
And I think that they've showed enormous benevolence by remaining discrete.
Hope so but we are at the bottom of the galactic food chain and it's probably teeming with technological gods and demigods.
 

Sheltie

Fratty and out of touch.
You're welcome. It's fun to talk about this subject; it's a lifelong obsession for me.

I've given the question of gravitational waves a lot of thought, and I still think about it. I see two reasons why we wouldn't detect any gravitational waves from these devices:

1.) Gravitational radiation - unlike electromagnetic radiation - requires a changing mass quadrupole moment (whereas electromagnetic radiation such as a broadcast antenna only requires a changing charge dipole moment). This is because electromagnetism is a spin-1 field (a vector field), but gravitation is a spin-2 field (a tensor field). But it only requires a changing mass dipole moment in order to produce any change in acceleration that a craft would need. So a gravitational field propulsion device doesn't have to produce any gravitational radiation as it maneuvers.

2.) Gravitational radiation represents a loss of field energy; it's an inefficiency. So if one wishes to design a gravitational field propulsion device with maximum efficiency, one would design the system so that it doesn't produce a changing mass quadrupole moment and waste energy in the form of gravitation radiation. Basically gravitational radiation is analogous to the acoustic noise generated by a gasoline engine: a Harley-Davidson motorcycle makes a lot of noise because it's inefficient - some energy is wasted to produce noise rather than being used to produce the work of horsepower. If you want to build a very efficient UFO, then you'd want to reduce its waste-energy/noise as close to zero as possible. And like I said, I see no reason why a changing mass quadrupole moment would be useful for propulsion purposes, so it's not required anyway.

So in a nutshell, in laymen's terms, how does gravitational field propulsion get around Einstein's Special Theory of Relativity which states that nothing can exceed the speed of light? I understand how warp drive can theoretically bend the rules but I'm not clear when it comes to gravitational field propulsion.
 
So in a nutshell, in laymen's terms, how does gravitational field propulsion get around Einstein's Special Theory of Relativity which states that nothing can exceed the speed of light? I understand how warp drive can theoretically bend the rules but I'm not clear when it comes to gravitational field propulsion.
Here's the deal: the special theory of relativity only describes a very special subset of conditions within the general theory of relativity. Specifically, special relativity only describes situations where the local spacetime geometry is flat, aka Minkowski spacetime. But there's some level of spacetime curvature nearly everywhere in the universe, so special relativity is ultimately just an approximation, similar to how Newtonian gravitation is a useful approximation to general relativity in the weak field limit.

Gravitational field propulsion is an effect that exploits curved spacetime - the foundation of the general theory of relativity. So by its very nature, special relativity has nothing to say about it - you must use general relativity to model it.

So the key difference is that reaction propulsion involves the conservation of momentum - equal and opposite reactions accelerating a device such as a rocket through spacetime; but gravitational field propulsion is completely different - it generally involves manipulating the spacetime around a device so that the deformation of spacetime relocates the device from one position to another...rather than forcing the device through spacetime like a rocket, a gravitational field propulsion device remains at rest and the warping of spacetime around it changes its position. There is no momentum transfer with gravitational field propulsion, there are no g-forces, and the device acquires no relativistic mass-energy - the device remains "still" on its local patch of spacetime, which is moving around by virtue of the changes in spacetime geometry around the device. If you were an occupant on board such a device, you could move at hypersonic velocity in one direction and virtually instantaneously reverse direction at the same speed, and you'd feel nothing, and there would be no stresses exerted on your craft, because the device is at rest with respect to its local reference frame.

You can see why "warp drive" is a synonym for gravitational field propulsion; the device warps the spacetime metric around it in order to change position.

And because the device is technically at rest within its local reference frame at all times - regardless of its relative state of motion with respect to an observer on the Earth for example, the constraints of special relativity don't apply to this method of propulsion. And there's no known upper limit to the rate at which spacetime can be deformed - a conservative estimate of the rate of spacetime expansion during the inflationary era of the early universe gives a rate of 10^54 times the speed of light by my calculation. In fact that was the theoretical motivation that spurred Alcubierre to write his 1994 paper on the physics of warp drive aka gravitational field propulsion: he reasoned that since the early universe expanded at dozens of orders of magnitude faster than the speed of light, then general relativity should provide a means to produce superluminal velocities within the known laws of physics, and he was correct.

So according to general relativity it is possible after all to travel to the Andromeda galaxy for breakfast, and be back home on the Earth in time for lunch, with no time dilation effects and no expenditure of energy (other than any existing intrinsic technological system inefficiencies).

We don't hear much about these kinds of incredibly exotic effects associated with general relativity, simply because we have essentially no technological capability to experiment with gravitational fields in the lab yet. But when we do arrive at an "applied general relativity" technology, we're going to hear about all kinds of mind-boggling phenomena that make quantum field theory effects like quantum entanglement seem quaint by comparison.
 

Shadowprophet

Truthiness
Well, aesthetically, Gravity is a dip/pull/fall in spacetime, Even light will bend to the slightest gravitational changes. Check gravitational lensing. So, A black hole would be invisible to the naked eye, they say this is because No light will reflect from them because it's all more or less absorbed by the singularity. So, A force that's expelling antigravitation, In my general thinking, This would be a very bright light, because it would scatter push any ambient light in every direction.

I believe an antigravitational force. At least in the toy box of my mind, Would play upon the hypothetical idea of a white hole. Being the opposite gravitational force. A white hole "though hypothetical" would be a very bright easily seen object that indeed does nothing but produce matter and expel gravitational force.

People, that know physics very well, I'd like to ask a question, Could not an anti-gravitational device Also possibly produce and expel physical matter? That much energy just flowing right to that very specific point, I know that physical matter is not the goal here, but what I am getting at is, Would this not be a possibility? or even a malfunction that an antigravity device could possess?

and if it did expel matter, Would this not be with greater force than a ballistic missile?
 

Shadowprophet

Truthiness
In my thinking, The fact that spacetime even exists prooves Quantum theory. IF everything wasn't waves then why would gravity affect light, That proves Gravity is a wave right there. No need for a hundred years of research. It's a wave, But hindsight is 20/20...
 
People, that know physics very well, I'd like to ask a question, Could not an anti-gravitational device Also possibly produce and expel physical matter?
Produce? No. Repel, yes. Robert L. Forward provided a simple schematic for a device that can do that in his 1963 paper "Guidelines to Antigravity."

and if it did expel matter, Would this not be with greater force than a ballistic missile?
The demise of a black hole is a lot like that if Hawking was correct about Hawking radiation - in the final moments of black hole evaporation they would erupt in a blast of energy, emitting the last of their mass as high-energy radiation. In fact they looked for that signature in the LHC experiments, in case the higher-dimensional theories were correct, but they never saw it.

In my thinking, The fact that spacetime even exists prooves Quantum theory.
No, quantum field theory doesn't explain the existence of spacetime. Not in its current form anyway. General relativity is our model of spacetime, and - oddly, it doesn't speak the same language as quantum field theory (which is still a huge problem in theoretical physics; unifying the two).

IF everything wasn't waves then why would gravity affect light, That proves Gravity is a wave right there. No need for a hundred years of research. It's a wave, But hindsight is 20/20...
No, gravity isn't a wave. In the weak field limit gravitational charge is analogous to electrical charge, with a reverse sign interaction, which is why Coulomb's law has the same structure as Newton's law of gravitation:

ScreenHunter_1600 Nov. 11 03.42.jpg

ScreenHunter_1601 Nov. 11 03.43.jpg

Electromagnetic waves are radiated whenever an electric charge distribution has a changing charge dipole (or higher) moment, and gravitational waves are radiated whenever a mass distribution has a changing mass quadrupole (or higher) moment, but that doesn't mean that the electric and gravitational fields generating those waves, are waves themselves. Electric and gravitational charges have the same radial spherical symmetry.

Surprisingly though, electromagnetic waves can be converted into gravitational waves when they pass through a very intense magnetic field at the proper angle - this is called the Gertsenshtein effect:

"Wave resonance of light and gravitational waves," Mikhail Gertsenshtein, Soviet Physics Journal of Experimental and Theoretical Physics, 1961
http://www.jetp.ac.ru/cgi-bin/dn/e_014_01_0084.pdf
 
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