Hi,
Gravity is probably the least understood property of the universe. This is doubly true if either dark matter or dark energy have their origin in the behavior of gravity (an open question at this time). The accelerating expansion of the universe takes something analogous to pressure except that the pressure seems to be causing the expansion of the framework with everything in that framework being carried along. Since gravity is the structure of space-time caused by mass-energy, then whatever is causing the acceleration could be a potential for "anti-gravity". Which is why, on many of these issues, the best answer is "I don't know."
Hardly a good basis for anything but noodling or writing SF stories. In the '50s, everybody wrote fiction about interplanetary travel and even interstellar travel. And all those craft were piloted by people using slide-rulers. Sixty years later, we still have no interstellar travel and only the most primitive interplanetary travel. But the slide-rulers have disappeared, replaced by calculators that almost none of those '50s authors imagined.
This is tough. To begin with, the equivalence principle says that in a local space, gravitational attraction and acceleration are the same thing (or, if you prefer, inertial mass and gravitational mass are equivalent). So, in that sense you are right. Second, there's the question of what you mean by 'extreme speed'. We are a 3 mph organism. Mach 1, over 200 times faster, is an extreme speed for us. But, even if you are speaking of FTL, the speed, the acceleration, the jerk, are all different entities.
One speculative (I refuse to call it theoretical, since while there is no known principle that renders it impossible, there is no developed theory that renders it possible) way of exceeding the speed of light is to move the frame. By contracting space-time in front if you and expanding it behind, you can move your reference frame at any velocity relative to the surrounding reference frame. Since it is the speed of light within a reference frame that is the limit, you can, potentially, achieve any speed your gravity generators/manipulators are capable of supplying. Within your reference frame, you remain stationary, so that you experience neither acceleration nor jerk. Of course, we have absolutely no way of knowing if this is even possible, much less of how to do it.
What I'm trying to say is that we're not like the Wright brothers, who knew they could achieve powered flight if they could refine an existing technology (internal combustion engines) to get an adequate power to weight ration. We are more like the Greeks that made up the story of Icarus. We think (or maybe hope is a better word) that someday man would fly, but we have no science or technology to support that hope.
I'm not sure just what you mean by "the speed of gravity". The speed at which the effects of a gravitational event would propagate? That would be the speed of light in the appropriate reference frame.
And I only mentioned aliens because of the two choices, namely aliens or secret government research, a UFO over a populated area is more like the first than the second. Not that either is a high probability event.
We are very poor judges of velocities and, especially, accelerations. An aircraft taking off a few hundred meters away looks like it is moving very fast, but it's probably doing 200 kt or so. The same aircraft, going 550 kt or more at 30,000 ft looks like it is just loafing along.
I don't have anything to add to what I said on this subject in my first reply.
--Pete
(02-09-2011, 05:03 AM)MEAT Wrote: "Anti-gravity" is not possible IMO.
Gravity is probably the least understood property of the universe. This is doubly true if either dark matter or dark energy have their origin in the behavior of gravity (an open question at this time). The accelerating expansion of the universe takes something analogous to pressure except that the pressure seems to be causing the expansion of the framework with everything in that framework being carried along. Since gravity is the structure of space-time caused by mass-energy, then whatever is causing the acceleration could be a potential for "anti-gravity". Which is why, on many of these issues, the best answer is "I don't know."
(02-09-2011, 05:03 AM)MEAT Wrote: ... using technology beyond what we currently know, ...
Hardly a good basis for anything but noodling or writing SF stories. In the '50s, everybody wrote fiction about interplanetary travel and even interstellar travel. And all those craft were piloted by people using slide-rulers. Sixty years later, we still have no interstellar travel and only the most primitive interplanetary travel. But the slide-rulers have disappeared, replaced by calculators that almost none of those '50s authors imagined.
(02-09-2011, 05:03 AM)MEAT Wrote: ... leads me to believe that there is a technology to travel at extreme speeds in a matter of seconds by manipulating gravity.
This is tough. To begin with, the equivalence principle says that in a local space, gravitational attraction and acceleration are the same thing (or, if you prefer, inertial mass and gravitational mass are equivalent). So, in that sense you are right. Second, there's the question of what you mean by 'extreme speed'. We are a 3 mph organism. Mach 1, over 200 times faster, is an extreme speed for us. But, even if you are speaking of FTL, the speed, the acceleration, the jerk, are all different entities.
One speculative (I refuse to call it theoretical, since while there is no known principle that renders it impossible, there is no developed theory that renders it possible) way of exceeding the speed of light is to move the frame. By contracting space-time in front if you and expanding it behind, you can move your reference frame at any velocity relative to the surrounding reference frame. Since it is the speed of light within a reference frame that is the limit, you can, potentially, achieve any speed your gravity generators/manipulators are capable of supplying. Within your reference frame, you remain stationary, so that you experience neither acceleration nor jerk. Of course, we have absolutely no way of knowing if this is even possible, much less of how to do it.
What I'm trying to say is that we're not like the Wright brothers, who knew they could achieve powered flight if they could refine an existing technology (internal combustion engines) to get an adequate power to weight ration. We are more like the Greeks that made up the story of Icarus. We think (or maybe hope is a better word) that someday man would fly, but we have no science or technology to support that hope.
(02-09-2011, 05:03 AM)MEAT Wrote: People often make the mistake of thinking the speed of gravity is terminal velocity of Earth's own pull, but this is not correct!
I'm not sure just what you mean by "the speed of gravity". The speed at which the effects of a gravitational event would propagate? That would be the speed of light in the appropriate reference frame.
(02-09-2011, 05:03 AM)MEAT Wrote: The only reason I mentioned aliens at all was because you brought it up.
And I only mentioned aliens because of the two choices, namely aliens or secret government research, a UFO over a populated area is more like the first than the second. Not that either is a high probability event.
(02-09-2011, 05:03 AM)MEAT Wrote: I was thinking when I saw that video, if a human were inside of that cockpit when it went up that quickly, they would probably loose consciousness.
We are very poor judges of velocities and, especially, accelerations. An aircraft taking off a few hundred meters away looks like it is moving very fast, but it's probably doing 200 kt or so. The same aircraft, going 550 kt or more at 30,000 ft looks like it is just loafing along.
(02-09-2011, 05:03 AM)MEAT Wrote: I got to thinking of The Abyss, and how they used a synthetic mixture of oxygenated fluid to dive deeper than you could breathing air, and I remember a report on the Discovery channel in which they confirmed the Military had developed this substance already (probably where the script idea came from), but the costs where prohibitively high. Then I started to imagine how a thicker fluid than air would be able to absorb much of the shock of the sudden acceleration.
I don't have anything to add to what I said on this subject in my first reply.
--Pete
How big was the aquarium in Noah's ark?