Antigravity and Discovery Channel's Credibility

[Chronos]

Deja vu. What part of cowpie did I miss? This gets old after awhile.

 

[russ_watters]

Dark energy is not a fringe topic. I don't get your point.

Right, dark energy is not a fringe topic: anti-gravity, wrt this thread (ie, relating to perpetual motion, gravitational field generators, etc), is. You seemed to be trying to compare the two: they are not the same thing.

 

[zoobyshoe]

Also, let's get real folks. When we say anti-gravity we mean a new force in nature that works oppositely to gravity - that produces a repulsive force in proportion to the mass of the object.

All the matter that produces this repulsive force has already done so. Once in a while a guy will be digging a hole and an anti-gravity rock will fly out of it past his face, but good luck to him trying to prove it.

 

[El Hombre Invisible]

Vis a vis the whole accelerating expansion of the universe malarky... the expansion is equal everywhere, isn't it. I mean, if you have a mile of empty space in one place and another mile in another, they will expand to equal sizes in equal amounts of time?

If there was some form of energy (dark energy) pushing galaxies away from us, would the rate at which a given galaxy was moved not depend on the mass of the galaxy, not the distance it is from us? I mean, if galaxy A weighs 1, galaxy B weighs 2 and galaxy C weighs 3 and they were equidistance on a straight line, if some force were pushing galaxies A and C away from B, you would expect C to recede more slowly, no? I'm sure the brains have got it covered, but I wonder what their thinking is.

 

[selfAdjoint]

Vis a vis the whole accelerating expansion of the universe malarky... the expansion is equal everywhere, isn't it. I mean, if you have a mile of empty space in one place and another mile in another, they will expand to equal sizes in equal amounts of time?

If there was some form of energy (dark energy) pushing galaxies away from us, would the rate at which a given galaxy was moved not depend on the mass of the galaxy, not the distance it is from us? I mean, if galaxy A weighs 1, galaxy B weighs 2 and galaxy C weighs 3 and they were equidistance on a straight line, if some force were pushing galaxies A and C away from B, you would expect C to recede more slowly, no? I'm sure the brains have got it covered, but I wonder what their thinking is.

According to the standard account the expansion is uniform everywhere. But ther is a new theory that we are in the remains of a huge bubble expanded from early in the universe's age, and our expansion is less than the space outside the bubble.

The expansion is a feature of space, and calling it anti-gravity confuses this. So it only depends on space, not on the matter that happens to be around. The galaxies aren't themselves accelerated, it's the space between them that has accelerated expansion. In addition to its time dependence it has volume dependence, so a volume of 8 cubic light years would have 8 times the expansion in a given time as a volume of one cubic light year.

 

[Ivan Seeking]

Fair enough; no known mass dependency makes it pretty clear that this is not anti-gravity. But I still take issue with citing violations of the laws of physics since we don't have a quantum theory of gravity. For all that we know, a complete theory may demand that anti-gravity exists; or even that this missing variable is partly why the famed TOE is so elusive.

 

[russ_watters]

But I still take issue with citing violations of the laws of physics since we don't have a quantum theory of gravity. For all that we know, a complete theory may demand that anti-gravity exists; or even that this missing variable is partly why the famed TOE is so elusive.

Since the ToE must be compatible with GR, I still can't see why you have an issue with it.

 

[Ivan Seeking]

Since the ToE must be compatible with GR, I still can't see why you have an issue with it.

This assumes that we can measure and or would recognize the effects. Is it possible that the data to support this idea already exists somewhere but is interpreted incorrectly, or buried in the noise? And I guess that there is also the idea that it could only be produced artificially.

Edit for clarity.

 

[Ivan Seeking]

Oh yes, and could it be that this effect is buried within normal gravity, and what we see is the net of the two forces?

I don't mean to suggest that it's there. But I don't see how we can claim that it's not, with certainty.

 

[Ivan Seeking]

Just out of curiosity I did a quick check, and there is plenty out there. For example:

...Antigravity and the impossibility arguments

Proposed by Morrison [7] in a celebrated paper, antigravity is known to violate the sacrosanct CPT symmetry, contradict the results of the Eötvös-Dicke-Panov experiments [10], exclude the existence of the long-lived component in the neutral kaon system in the presence of the Earth gravitational field [8], violate energy conservation and imply vacuum instability [7,11]. The arguments against antigravity then appear to be so compelling that it may seem presomptuous or even foolish to reconsider them
[12]. However, Nieto and Goldman have recently reviewed critically these arguments [13] and we refer the reader to their recent review for a thorough discussion and an historical perspective on these impossibility arguments (see also Ref. 14). Here, we will only insist on the points necessary to the following discussion and on those parts of Nieto and Goldman's review with which we disagree. Concerning the first two impossibility arguments, let it suffice to say that the CPT theorem has not generally been demonstrated on curved spacetime and that the ineluctability of a past singularity imposed by the theorems of Penrose and Hawking [15] make it doubtful that the CPT
theorem can ever be demonstrated without modification for gravitation 16,17].

Similarly, Goldman and Nieto have repeatedly stressed [18] that Schiff's argument on the Eötvös-Dicke-Panov experiments [10] is invalid because of his incorrect renormalization procedure. Attempts have been made to consider some adjustable vector interaction which, added to the tensor (and therefore always attractive) interaction dictated by general relativity, would lead to a violation of the equivalence principle applied to matter and antimatter. This arbitrariness is aesthetically objectionable, but Morrison's original antigravity [7] appears even worse : Goldman 3 and Nieto themselves reject the possibility of such a gross violation of the equivalence principle where antimatter would “fall up”, the total force on a static e+ e– pair, e.g.,being zero, since it would lead to a violation of energy conservation. We will come back later to the argument of energy non-conservation and first turn to Good's argument which appears to impose the most stringent constraint on antigravity.

http://www-dapnia.cea.fr/Phocea/file.php?class=std&&file=Doc/Publications/Archives/spp-92-07.pdf .

 

[sd01g]

The probability of an antigravity particles is about the same an antiphoton particle--almost zero. How do I know? Just check for any real evidence. There is none.

 

[skeptic]

To get back to a point which was made near to the start of this thread: all of the antigravity nonsense on the internet is one thing, having clearly-crackpot ideas being discussed by NASA and peer-reviewed academic journals is quite another. For instance, a long review in Progress in Aerospace Sciences (Jan. 2003) treated classical crackpot anti-gravity claims as if they were of value. And I am talking about real codswallop here. One device (apparently being tested by BAE Systems, following advice from the review's author!) was a 'centrifugal drive'. You know, one of those daft machines that flails a couple of variable-length arms around and is supposed to 'swim' through outer space (just because it works on a shiny floor). And yes, I do know that Dr Wisdom (what an apt name) has recently suggested that a variable-geometry object might be able to exploit space-time curvature for propulsion purposes. But was the reviewer the sort of person who would have known that?

 

[Chronos]

Having been intimately involved in the design, development and deployment of vibratory mechanical equipment, I can assure you there is no free energy [i.e., anti- gravity] lurking between oscillations. I made numerous trips to customer facilities to fix the dang thing when it broke. I would not volunteer for a deep space mission that employed such a device for propulsion. Aside from being hugely inefficient, the spare parts payload would be prohibitively expensive.

 

[zoobyshoe]

Having been intimately involved in the design, development and deployment of vibratory mechanical equipment, I can assure you there is no free energy [i.e., anti- gravity] lurking between oscillations. I made numerous trips to customer facilities to fix the dang thing when it broke. I would not volunteer for a deep space mission that employed such a device for propulsion. Aside from being hugely inefficient, the spare parts payload would be prohibitively expensive.

Have you ever read about the Dean Drive? It got big press in the 1960s, and then suddenly dissappeared.

I was tempted once or twice to try and build one to see what it was all about. It isn't so complex that a mechanic couldn't juryrig one together in his garage. That's a lot of work just to prove exactly why it wouldn't work as claimed, though. It just occurred to me that it might be worth it to someone involved in the manufacture of industrial vibratory machines, since it might offer a new way to make things vibrate that has some sort of advantage in some particular application.

 

[MadIce]

Two new Antigravity papers from arXiv.org:

Weak 'Antigravity' Fields in General Relativity by F. S. Felber.

Exact Relativistic 'Antigravity' Propulsion by F. S. Felber.

 

[skeptic]

The Dean Drive disappeared suddenly because it was rubbish. It was based upon a patent for a free-ribbon feeding (or fixed-ribbon climbing) device. Nothing wrong with that. However, Dean started claiming that the machine could carry its own bit of ribbon along with it and thus defy gravity: rather like the indian-rope trick, but with the rope being used again and again, to climb higher and higher. Pure twaddle. It came to notice only because it was backed by the editor of Analog SF magazine. He had also done a lot to promote 'radionics' and scientology (2 scams which unfortunately survive to the present day) so he was clearly in moral free-fall. The Dean Drive was interesting only because it sucked in so many people who should have known better, and revealed the dubious value of their academic qualifications. In particular, an engineer who made his living analysing oscillating and rotating machinery (and wrote books about it) declared that it should work. However, he had made a 'schoolboy' error while inverting a Laplace transform. This error resulted in a spurious predicted displacement of the Dean Drive. The problem of 'expert engineers' who do not understand simple physics is still with us today. Read the review (in Progress in Aerospace Sciences) which I mentioned above.

 

[Omegatron]

The probability of an antigravity particles is about the same an antiphoton particle--almost zero. How do I know? Just check for any real evidence. There is none.

Of course, if there were antigravity particles, they would have all repelled from the Earth a long time ago...