Near speed of light?

[Fireskull]

http://www.physorg.com/news10789.html

I am no expert about this topic... but I am sure someone else in the forum will have something to add about the subject.

[chuck_starchaser]

The article explains nothing at all. The one thing that makes me suspicious is reading the author's byline. The guy is heavily involved with defense and security and government, and owns a business. Not your typical researcher. And usually when a new discovery is made in physics, standard procedure is to publish, so that the scientific community can review and comment and/or repeat the experiment, or come up with alternative explanations. The guy, instead, will present this at a Space Tech Center in Aubuquerque? At the end of the article it says "Source: Starmark", which happens to be the guy's own company...

EDIT: I decided to do a bit of googling around. First I searched for starmark and there's a gazillion companies called "starmark" but none involved in any kind of research.
Searching for "starmark felber" returned numerous news sites re-publishing the same news piece. Only one link of any seriousness that came up was:

[PDF] STAIF-2006 F. Symposium on New Frontiers and Advanced Concepts
File Format: PDF/Adobe Acrobat - View as HTML
Felber, Franklin/Starmark, Inc. 858-676-0055 felber@san.rr.com. 096/Exact
Relativistic ‘Antigravity’ Propulsion. Page 6. F03 Propulsion and Power Concepts ...
http://www.americanantigravity.com/docu ... 5Nov05.pdf "

The document shows the list of lecturers at the simposium he'll be exposing this stuff at. Notice a great number of the titles are so farfetched as to be almost crazy:
* "Generation of Gravitational Waves with Nuclear Reactions and Space Applications"
* "Piezoelectric-Crystal-Resonator High-Frequency Gravitational Wave Generation and Synchro-Resonance
(Gravitation is not yet understood; we don't even know whether there's such a thing as "gravitational waves", but this guy is already "miniaturizing the technology"?!!)
* "Ultra-High-Intensity Lasers for Gravitational Wave Generation and Detection"
('nother one...)
* "The Alcubierre Warp Drive in Higher Dimensional Spacetime"
(We'd need Dark Matter to test Alcubierre's theory; so adding more dimensions to the pot may be a good intellectual exercise, but nothing more, unless we can find Dark Matter in those other dimensions...)
* "Traveling in The Computational Universe"
(You tell me what that means...)
* "Experimental Concepts for Generating Negative Energy in the Laboratory"
(Ahem... well, might be something there if by "negative energy" it is meant lower energy than the quantum energy level of vacuum...)

There are more serious presentations, too; but obviously this is not a hard to get into simposium... More like "insert coins to reserve your presentation time" kind of simposium.

and then, at the very end of the program...
* "Exact Relativistic ‘Antigravity’ Propulsion"
by this guy.

Notice his email; which is in that program: his name at "san.rr.com".
rr.com is "Road Runner", a hosting place that I often run into when tracking spammers, using Sam Spade...

I say this guy is planning to pull an IPO.

[www2]

@chuck_starchaser
i think also that dis a hoax is...

[klauss]

Sounds hoaxy.
Anyway, chuck, gravitational waves do exist.
They're postulated by Einstein's theory of special relativity, I think, in that no event can travel faster than c. Within that category lays gravitational field fluctuations. So, a massive change in the gravitational field would ripple through the universe in what would behave as a wave. The real question... though... is how to create such a change? The only measurable examples of that up to date are supernovas, AFAIK.

[Zeog]

... Anyway, chuck, gravitational waves do exist.
They're postulated by Einstein's theory of special relativity, I think, in that no event can travel faster than c. Within that category lays gravitational field fluctuations. So, a massive change in the gravitational field would ripple through the universe in what would behave as a wave. The real question... though... is how to create such a change? The only measurable examples of that up to date are supernovas, AFAIK.

Nope, not special relativity (extension of classical mechanics to high velocities), but general relativity (gravity is the same as the geometry of space-time). Since general relativity contains the special one, there is finite porpagation speed of events. However, there is a difference between the retardation of potentials due to that as in electrodynamics, for expample, and the "rippling" of space-time. A finite propagation speed does not imply a wave phenomon. In electrodynamics one generates waves essentially by using dipols (an oscillating positive charge-negative charge pair). But there is no negative mass-"charge"!
In fact, gravitational waves have not been observed yet. There are experiments, but the measurements' background is tremendous! A truck driving by and even a low pressure area in atmosphere changes the measurement. So, physicists are still trying to understand the background and trying to extract the signals. The signals they are looking for are not supernovas, though, but binary neutron stars, binary black holes, the merging of two black holes, IIRC. Stuff like that can only been "seen" by the current detectors.

[klauss]

Nope, not special relativity (extension of classical mechanics to high velocities), but general relativity (gravity is the same as the geometry of space-time).

I do remember special relativity postulating finite propagation speed of events. However, the conclusion that such thing could theoretically produce gravitational waves may have been made after the theory of general relativity - my mistake then.

However, there is a difference between the retardation of potentials due to that as in electrodynamics, for expample, and the "rippling" of space-time. A finite propagation speed does not imply a wave phenomon. In electrodynamics one generates waves essentially by using dipols (an oscillating positive charge-negative charge pair). But there is no negative mass-"charge"!

Of course not... but the behavior is similar nonetheless. At least that's what's been theorized... for what I know which... granted... is quite superficial.

Probably I should have said "gravitational wave theory does exist" instead.

[Zeog]

Probably I should have said "gravitational wave theory does exist" instead.

No need for that. I knew what was meant (or so I think). I just wanted to make the point that we're all eagerly waiting for the results and I've been to a talk from one of the GEO600 guys explaining all these troubles they're having.

(There really is no need to put a "theory" behind everything. This post explains all my fun.)

[chuck_starchaser]

Exactly; we don't have a complete theory of gravity yet; more like various hypothesis. Einstein thought gravity was a 4-pole field; individual gravitons have never been detected; and neither has been the Higgs boson to explain mass, which is also pretty much essential to understand, since gravity is closely related to mass. For all we know gravity could be like a continuous or DC field. Notice also that the popular representation of gravity as a deformation of space acting like a funnel is a bit of a circular definition: in zero gravity, a funnel fails to attract objects towards its center. If deforming space into a funnel shape onto a fourth dimension attracts objects towards the center of the funnel, that presumes another kind of gravity acting vertically along that "fourth" dimension.

Lastly, when upcoming experiments designed to detect gravity waves come online, they are likely to confuse a lot of people. The theory is that when two massive objects in a binary, such as a black hole and a nutron star, spiral towards each other, they should produce a **massively modulated** gravitational field. Chances are we will observe those modulations. But calling those modulations "gravity waves" is a bit disingenious, since they are ***modulations of amplitude***, and will in no way verify the ***wave nature*** of gravity itself. The main purpose of those experiments is to verify whether the frequency of those modulation waves changes as our detection rigs travel around the sun, so as to verify if indeed gravity travels at the speed of light, or wheter it is instantaneous as some believe.

[Fireskull]

oh uhm


Thanks for the info

[Zeog]

individual gravitons have never been detected; and neither has been the Higgs boson to explain mass...

There have been some events that could have been the Higgs at the LEP experiment at CERN. The running time of this experiment was extented because of this. But then they needed to shut it down in order to start building the LHC. Those few signals got the people in the comunity pretty excited, but they don't have enough data yet in order to call it a "signifiant" signal or a new particle. The LHC, however, will see the Higgs or completely rule it out.

... gravity is closely related to mass.

It indeed is, but keep in mind, that all kinds of energy is a source for gravity. Photons, binding energy of molecules etc. and what is stored in a body's mass. Mass, however, dominates all other forms of energy in our every day life. But this is not the case in particle accelerators, for example.

Lastly, when upcoming experiments designed to detect gravity waves come online,...

They already are! The first results have been published.

[chuck_starchaser]

I thought there had been a single Higgs-like event at LEP.

The future experiments I was thinking about are those 3 probes that will go to the L4 or L5 Lagrange point and orbit each other like thousands of kilometers apart, and have suspended reference masses in them serving as interferometry mirrors. Can't remember the name of the project now. I didn't know results were in for the Earth-based experiments. So, what are the results? I can't seem to find a link written in plain English...

[Zeog]

The future experiments I was thinking about are those 3 probes that will go to the L4 or L5 Lagrange point and orbit each other like thousands of kilometers apart, and have suspended reference masses in them serving as interferometry mirrors. Can't remember the name of the project now.

That's LISA (see also the background science links therein).

I didn't know results were in for the Earth-based experiments. So, what are the results? I can't seem to find a link written in plain English...

The link I gave is in English, the main page as well. But it seems a little out of date.
Here is a list of all earth bases gravity wave observatories and a short, plain English version of the first results (with original references). So far they didn't manage to nail down some values but found upper bounds for the waves' amplitudes of a particular origin.

[chuck_starchaser]

Damn! Launch date 2014 for LISA; I wasn't planning to live that long.

So, that's what I thought I'd read --'upper bounds'--, IOW "nothing" (*that*'s what I call "plain English" ).

[dandandaman]

Ya, at this stage the none of the interferometers are operating at their designed limits. The one in Western Australia should be at a sensitivity to detect about 10 a year in the next one to two years, I'm not sure about the other instruments around the world. So far none of the instruments have had anything but calibration/testing runs ... but of course, they don't just let the data from those go to waste, hence the paper ... this year and next things should start to get interesting.

[chuck_starchaser]

I have no doubt they will see the waves produced by neutron star binaries. What I can't wait for is empirical data on the speed of gravity. I came up with a thought experiment years ago. Suppose you're orbiting the sun on a space ship, in a circular orbit. You see the sun exactly to your left, through the side window.
Now: If the speed of gravity is infinite (instantaneous), then the simple model applies, in which your instantaneous speed vector is exactly at 90 degrees to the sun's gravitational attraction vector.
But if the speed of gravity is finite, say c, then the sun's center of mass will appear to you to be at, say, 89.99 degrees relative to your speed vector.
If this were the case, your orbital speed would continuously accelerate.
If this were the case, where exactly would the energy be coming from?

[dandandaman]

I would say we *have* empirical data on the speed of gravity, but I don't have time to look for the paper I've seen, so I won't. But in case you want to, I remember it being measured by looking at the deflection of some stellar object as the disc of Jupiter approached and crossed in front of it. Not sure about the specifics, and I remember that there was some controversy, but I don't know which way the consensus went (if there was one), so my point may be moot ... and man it's been a long day.

But wrt the phenomenon you described...that's frame dragging, and the energy comes from the rotational kinetic energy of the massive object (at least I think it does, I'm trying to remember from last year's lectures). But even so, that makes sense to me.