## Podkletnov's gravity shielding

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Jorpho
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### Podkletnov's gravity shielding

A good many years ago I read an enthusiastic blurb about a supposed discovery of an antigravity device. Said blurb discussed how one member of a group of physicists often smoked his pipe in the lab, and noticed that the smoke from his pipe seemed to rise considerably faster when it passed over some sort of extra-powerful eletromagnet they were working with.

A bit of Googling brings up the name of Podkletnov and suggests that it was a rotating disk of superconductor. But I'm having bit of trouble sorting out the pseudoscience sites from the vehemently-antipseudoscience sites. Was there ever anything to this?

taby
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### Re: Podkletnov's gravity shielding

http://en.wikipedia.org/wiki/Eugene_Podkletnov

It's intuitive that the smoke would rise faster in a region of lesser gravitation. The pressure causing upward motion is counteracted to a lesser degree.

Now, whether it's actually a reduction of gravitation is another matter altogether... They used a non-magnetic material to show that it wasn't the same effect as superconductor-based levitation (a well-known phenomenon), but obviously not everyone's convinced.

jaap
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### Re: Podkletnov's gravity shielding

taby wrote:It's intuitive that the smoke would rise faster in a region of lesser gravitation. The pressure causing upward motion is counteracted to a lesser degree.

It's not so intuitively obvious. Less gravity means that air weighs less, and that therefore by the Archimedes Principle there is a smaller upwards force, and so smoke rises more slowly. In a weightless situation, hot air and smoke does not rise at all.
This is if gravity is reduced everywhere. If however you had some kind of small directional anti-gravity device on Earth, then the air above the device (whether it contains smoke or not) undergoes a smaller gravitational force and so all the air above it is displaced upwards by heavier columns of air flowing in from the side and becoming lighter. A kind of convection occurs.
On the other hand, I would doubt that any anti-gravity device could be directional. I think the gravity field would remain conservative and that the anti-gravity device would repel matter in all directions equally. Then there would be no air rushing in from the side, becoming lighter, and being pushed upwards, because the air from the side would be repelled as well.

Charlie!
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### Re: Podkletnov's gravity shielding

I'm quite suspicious. However, I suppose that it's, er... concievable. Probably not possible though, given the infinitne energy that comes our of making gravity a nonconservative force.

It's also a tad suspicious that I can't find much about duplication. Apparently some people (including "NASA," which I take to mean "one guy at nasa") are cited as working on duplicating the effect, which shouldn't be hard if it just consists of plonking down a scale above a superconductor. However, most or all of these accounts have disappeared, which my cynical big-proven-confirmation-bias-aware self interpret as negative results.
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### Re: Podkletnov's gravity shielding

Charlie! wrote:It's also a tad suspicious that I can't find much about duplication. Apparently some people (including "NASA," which I take to mean "one guy at nasa") are cited as working on duplicating the effect, which shouldn't be hard if it just consists of plonking down a scale above a superconductor. However, most or all of these accounts have disappeared, which my cynical big-proven-confirmation-bias-aware self interpret as negative results.

Indeed. The story has the same feel as the usual pseudoscience, what with all the mainstream media being involved, the lack of duplication, the sketchy of details, and whatnot. It could of course be real science, but I remain skeptical.
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taby
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### Re: Podkletnov's gravity shielding

jaap wrote:
taby wrote:It's intuitive that the smoke would rise faster in a region of lesser gravitation. The pressure causing upward motion is counteracted to a lesser degree.

It's not so intuitively obvious. Less gravity means that air weighs less, and that therefore by the Archimedes Principle there is a smaller upwards force, and so smoke rises more slowly. In a weightless situation, hot air and smoke does not rise at all.
This is if gravity is reduced everywhere.

Yes, but just like you said... weightless implies a lack of gravitation altogether (or a global reduction anyway). We're talking about a small difference in non-negligible gravitation at a very local scale (the lab scale), and not a lack of gravitation on a more global scale, so I'm not sure why you would bother to correct me then put in a disclaimer saying that your correction doesn't apply to the situation that you're correcting me on. Strange, but I suppose I've heard stranger arguments.

If it helps you to see how intuitive it is... Try standing on a block of solid ice, then try standing on a block of liquid water. One substance obviously has stronger intermolecular bonds, and so counteracts the strength of the Earth's gravitation more successfully. You would sink less. This is the opposite of the smoke situation (here gravity is being counteracted, not pressure). Obviously the difference in electromagnetic bond stability is on a very local scale, like in the opposite situation.

As for the hypothetically perfect expansion of a gas in a vacuum, it would be omnidirectional. Technically, it would be rising in ALL directions equally, which is very much different than not rising at all. Now add a gravitational point source at the centre of the gas, but only apply the field to one hemisphere of the gas. Obviously one half will rise better than the other, though there is no atmosphere proper to confuse the situation.

Tass
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### Re: Podkletnov's gravity shielding

The smoke should only rise faster if the "shielding" made the gravitational field non-conservative, generating upwards air movement above the thing.

If it was shielded the way electric or magnetic fields are it should rise slower.

jaap
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### Re: Podkletnov's gravity shielding

taby wrote:
jaap wrote:
taby wrote:It's intuitive that the smoke would rise faster in a region of lesser gravitation. The pressure causing upward motion is counteracted to a lesser degree.

It's not so intuitively obvious. Less gravity means that air weighs less, and that therefore by the Archimedes Principle there is a smaller upwards force, and so smoke rises more slowly. In a weightless situation, hot air and smoke does not rise at all.
This is if gravity is reduced everywhere.

If it helps you to see how intuitive it is... Try standing on a block of solid ice, then try standing on a block of liquid water. One substance obviously has stronger intermolecular bonds, and so counteracts the strength of the Earth's gravitation more successfully. You would sink less. This is the opposite of the smoke situation (here gravity is being counteracted, not pressure). Obviously the difference in electromagnetic bond stability is on a very local scale, like in the opposite situation.

So are you saying that less gravity means the smoke rises faster? And the more you were to reduce gravity, the faster the smoke would rise? And if you reduce gravity to nothing, so everything is weightless, how fast does it rise then?
I'm saying the exact opposite. Assuming the gravity is reduced for all the air in the room, less gravity means less weight difference between hot air and normal air, and so slower movement of the smoke. As gravity is reduced to zero, the speed of the rising smoke is also reduced to zero.

taby
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### Re: Podkletnov's gravity shielding

I think that the satisfaction you're looking for can only be found by writing to either Podkletnov or the editor of J Phys D, and asking yourself. Obviously the smoke rises faster in a region of weaker gravitation. J Phys D wouldn't have accepted the paper if this wasn't true. I'm smart enough to know that any further attempts to rationalize with you are pointless. However, I'm patient enough to wait to see what response you get from them. Please post it here for the benefit of everyone (including myself).

Until then, I want you to focus on the word hot, and what it implies. Remember, smoke is hot, and comes out of burning stuff (like pipe tobacco).
Last edited by taby on Sun Dec 28, 2008 1:38 am UTC, edited 1 time in total.

gmalivuk
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### Re: Podkletnov's gravity shielding

Smoke rises because of the difference in density between the hot smoke and the cool air around it. And this density difference is proportionally affected by gravity, so the less dense material rises.

But, see, if there's less gravity, the difference in gravitational effect is less, which means the force raising the smoke is smaller.

Which means smoke rises slower. Just like how a helium balloon will move backwards as a moving car slows down, even though bodies and other heavy things in the car move forward.
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taby
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### Re: Podkletnov's gravity shielding

gmalivuk wrote:Smoke rises because of the difference in density...

http://www.telegraph.co.uk/htmlContent. ... rav01.html :
"We thought it might be a mistake," Dr Podkletnov said, "but we have taken every precaution". Yet the bizarre effects persisted. The team found that even the air pressure vertically above the device dropped slightly, with the effect detectable directly above the device on every floor of the laboratory.

I'll leave it at that, for at least gmalivuk will know why this all works out. I'm going back to my happy cave now and leave you and jaap to sort it out -- assuming jaap can learn how to include pressure in their ENTIRE argument, not just where it makes sense to them, and can get over the fact that a local region of reduced gravitation is not a global region of reduced gravitation.

To imply that I don't believe in atmospheric density just because I attempted to demonstrate the uselessness of the globally vanishing gravitational field argument in this discussion is just... strange. It just doesn't apply, and I don't know how to convince you otherwise.

Charlie!
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### Re: Podkletnov's gravity shielding

Does anyone know of a proposed solution to the infinite energy problem that follows from this?
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BlackSails
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### Re: Podkletnov's gravity shielding

gmalivuk wrote:Smoke rises because of the difference in density between the hot smoke and the cool air around it. And this density difference is proportionally affected by gravity, so the less dense material rises.

But, see, if there's less gravity, the difference in gravitational effect is less, which means the force raising the smoke is smaller.

Which means smoke rises slower. Just like how a helium balloon will move backwards as a moving car slows down, even though bodies and other heavy things in the car move forward.

Ah, but imagine the air column before it reaches equilibrium. What we have is a dynamic equilibrium, with a restoring force (the pressure) balanced by the deforming force (gravity). Suddenly, gravity is reduced. If gravity is increased, the whole column will be squashed towards the ground. If gravity is suddenly decreased, the air column will expand upwards. If the ring is in this column, it will expand upwards with the column.

to Charlie!:
No, which is one of the reasons I think that Podkletnov is FOS.

Tass
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### Re: Podkletnov's gravity shielding

Charlie! wrote:Does anyone know of a proposed solution to the infinite energy problem that follows from this?

If it indeed did produce a nonconservative "gravity" field, then I would guess the energy would be taken from the device so that the faster the air collumn rises the more power is needed to keep it running.

Strilanc
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### Re: Podkletnov's gravity shielding

My guess to what would happen:
If you lowered gravity in a small column, the air within it would suddenly be at a lower pressure. Air from the sides would force itself in, more so towards the bottom where the pressure difference was greatest, and the net effect would be an inward then upward wind. Therefore the smoke could indeed rise faster. Once the air had risen far enough that the pressure difference was negligible, it would spread back out and presumably eventually make its way back down to ground since we're sucking air from down there.

The 'infinite energy' problem can probably be solved by simply requiring that your shield use the maximum amount of energy it could possibly create. Gravity decreases with the square of distance, so a particle can only gain a finite amount of energy traveling along it, and you can only fit so many particles in your shield... a maximum should exist.
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Carnildo
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### Re: Podkletnov's gravity shielding

Strilanc wrote:The 'infinite energy' problem can probably be solved by simply requiring that your shield use the maximum amount of energy it could possibly create. Gravity decreases with the square of distance, so a particle can only gain a finite amount of energy traveling along it, and you can only fit so many particles in your shield... a maximum should exist.

Put a chunk of neutronium above the shield. Better yet, put a black hole above it. Now, how much energy are you using?

Charlie!
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### Re: Podkletnov's gravity shielding

Tass wrote:
Charlie! wrote:Does anyone know of a proposed solution to the infinite energy problem that follows from this?

If it indeed did produce a nonconservative "gravity" field, then I would guess the energy would be taken from the device so that the faster the air collumn rises the more power is needed to keep it running.

Ah, but this is the cool part. Let's assume that we've discovered room-temperature superconductors, to make this easier on the brain.

So take a chunk of superconductor and just let it sit there. Now put a wheel half-in the field so that you got more energy by dropping the "out" side than it takes to raise the "in" side. Begin extracting energy. By conservation of energy you reasonably suggest that the energy should come from the superconductor. But it's just laying there, a chunk of material with no particular power input! What energy does it have? The most reasonable option it has (barring perfect mass-energy conversion or the like) is to simply get colder. But now you have less heat energy and more macroscopic kinetic energy in the universe, which means that, in order to obey conservation of energy, you have to violate thermodynamics. This is not a big improvement
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jmorgan3
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### Re: Podkletnov's gravity shielding

The experiment involved a rotating superconducting disk, so the energy could come from the rotational kinetic energy of the disk.
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BlackSails
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### Re: Podkletnov's gravity shielding

jmorgan3 wrote:The experiment involved a rotating superconducting disk, so the energy could come from the rotational kinetic energy of the disk.

I had to estimate the mass of air above a square meter of ground for an astrophyiscs test. Believe me, even a .2% (or whatever it is) reduction in gravity is more energy than any reasonable disk spinning at a reasonable speed and provide.

++$_ Mo' Money Posts: 2370 Joined: Thu Nov 01, 2007 4:06 am UTC ### Re: Podkletnov's gravity shielding BlackSails wrote:Ah, but imagine the air column before it reaches equilibrium. What we have is a dynamic equilibrium, with a restoring force (the pressure) balanced by the deforming force (gravity). Suddenly, gravity is reduced. If gravity is increased, the whole column will be squashed towards the ground. If gravity is suddenly decreased, the air column will expand upwards. If the ring is in this column, it will expand upwards with the column. Just for fun, let's calculate by how much. At 0 degrees C, the pressure at ground level is like 101,300 N/m2. Let's not worry too much about the exact numbers. Let's also assume that the acceleration due to gravity is 10 m/s2 under normal conditions (making it 9.97 m/s2 under 0.3% reduced gravity). If Podkletnov's account is true, the increase in speed of the pipe smoke would have to be noticeable under these conditions. Now, let's start by assuming that the column of air is small enough that it has no time to approach equilibrium. So the density of the air at the bottom is the same as the density of air outside the column. Let's say that the column has an area of 1 square meter, and that the ceiling is 3 meters high. Okay, then under normal conditions, the pressure at the ceiling would be 101,300 Pa - (the weight of 3 cubic meters of air). So we need the density of air at any given pressure. This can be worked out from the ideal gas law. We want to know n/V = P/rT. So density varies linearly with pressure, and the constant of proportionality is (0.02897 kg/mol) / ( (8.314472 m3Pa/(K mol)) * (273 K)) = 1.276295x10-5. (No, we don't really have this much precision.) Call this constant k. So what's the pressure at the ceiling? This needs a differential equation: ${dP \over dh} = -g\rho(P)$But this is really just a constant function. So we end up with [imath]P(h) = Ce^{-kgh}[/imath], and of course, C is the pressure at the surface; namely, 101,300 Pa. Okay. That means the pressure at the ceiling is 101261.22 Pa, under normal gravity. All right; now what about under reduced gravity? Suppose we visit a planet where the air at the surface is at the same temperature and has the same density as the air on Earth. The pressure at the surface is still 101,300 Pa. The pressure at the ceiling is obtained by using the previous formula with the new value for g; we get 101261.34 Pa. So the pressure difference at equilibrium was 35.892 Pa. What about in Podkletnov's lab, where we don't get the chance to reach equilibrium? On Earth, the air at the surface has a pressure of 101,300 Pa. The air at the ceiling has a pressure of 101,261.22 Pa, exactly as before So the 0.3% reduction in gravity means that the pressure at the ceiling is actually 100,957.22 Pa, but it wants to be 100,957.34 Pa. This is the pressure difference that causes the upwards airflow. The difference is about 1 part in a million, which is not going to cause any significant airflow. (For comparison, imagine that you have some smoke rising in a column (with a volume of 3 cubic meters), and someone in the ceiling sucks out 3 cubic centimeters of air. Do you think that the resulting air current would cause the smoke to rise noticeably faster? Of course not.) EDIT: The figures were wrong before, but they are right now. Tass Posts: 1909 Joined: Tue Nov 11, 2008 2:21 pm UTC Location: Niels Bohr Institute, Copenhagen. ### Re: Podkletnov's gravity shielding Not that it matters much, but I think you overestimate the pressure differences needed to move air. One tenths of a pascals difference is still ten grams across a square meter. If the air is still that should be sufficient to make a slow convecting motion making smoke rise. A homebuild blimb I made with a total mass of roughly 400 grammes (thereby displacing roughly half a cubic meter), moved rather fast with a thrust of only a few grams. ++$_
Mo' Money
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### Re: Podkletnov's gravity shielding

I don't dispute that this kind of pressure difference would make smoke rise. Obviously it would do so. The thing is that the smoke is rising already, and the pressure difference that's causing it to rise is about 39 Pa (across the 3 meters of the room) if my figures are right.

This means that another 0.1 Pa across that distance wouldn't be anywhere near as noticeable as it would be if the smoke were in equilibrium with the air (as your blimp probably was).

Of course, the other point is that a slight air current in the room (possibly related to the heat produced by friction while the semiconductor rotates, someone breathing, someone moving across the lab, etc.) would easily be enough to duplicate this 0.1 Pa effect (or, I suspect, vastly exceed it).

Jorpho
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### Re: Podkletnov's gravity shielding

I don't suppose it would make any difference that the smoke is actually a bunch of tiny particulates rather than "air", would it?

IIAOPSW
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### Re: Podkletnov's gravity shielding

Good news everyone, i came from the portal physics forum and we came up with something that applies here. we came up with a conjecture that "no object may create an isolated spot where gravity cannot penetrate." the reason for this is that in a lower gravitational potential, you could jump up and then move to the side thereby entering a higher gravitational potential, thereby gaining free energy and violating conservation of mass and energy. we assumed the gravity blocking object (a portal) used no energy itself. this on the other hand does use energy so the question becomes; is it possible to gain energy from this device?

if i jump with x energy in one gravity i can tell how high i go(h=x/mg1). then, knowing my hight i can compute how much energy i get by moving over to the second gravity(x-mg2h). also, knowing the acceleration due to the gravity's, i can compute the time it would take to do this(Sqrt(g1h)+Sqrt(g2h)). if i know the power output of the device per second then i can show if conservation of mass and energy is violated or not((x-mg2(x/mg1)/(Sqrt(g1h)+Sqrt(g2h))<energy per second of machine). if it is then the experiment is a fraud. anyone care to graph possible energy gained v. time and energy output of machine v. time. if those lines cross at any point then conservation is violated.
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BlackSails
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### Re: Podkletnov's gravity shielding

I wonder if the effect could be caused by having a really cold plate underneath the smoke rings causing convection currents.

++$_ Mo' Money Posts: 2370 Joined: Thu Nov 01, 2007 4:06 am UTC ### Re: Podkletnov's gravity shielding BlackSails wrote:I wonder if the effect could be caused by having a really cold plate underneath the smoke rings causing convection currents. The convection would go the wrong way, wouldn't it? But if there were some kind of refrigeration equipment involved, that would generate some heat (and a convection current in the right direction). BlackSails Posts: 5315 Joined: Thu Dec 20, 2007 5:48 am UTC ### Re: Podkletnov's gravity shielding ++$_ wrote:
BlackSails wrote:I wonder if the effect could be caused by having a really cold plate underneath the smoke rings causing convection currents.
The convection would go the wrong way, wouldn't it?

Well yeah, but what are the odds that the guy leaned right over the spinny thing with his smoke?

Charlie!
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### Re: Podkletnov's gravity shielding

IIAOPSW wrote:Good news everyone, i came from the portal physics forum and we came up with something that applies here. we came up with a conjecture that "no object may create an isolated spot where gravity cannot penetrate." the reason for this is that in a lower gravitational potential, you could jump up and then move to the side thereby entering a higher gravitational potential, thereby gaining free energy and violating conservation of mass and energy. we assumed the gravity blocking object (a portal) used no energy itself. this on the other hand does use energy so the question becomes; is it possible to gain energy from this device?

if i jump with x energy in one gravity i can tell how high i go(h=x/mg1). then, knowing my hight i can compute how much energy i get by moving over to the second gravity(x-mg2h). also, knowing the acceleration due to the gravity's, i can compute the time it would take to do this(Sqrt(g1h)+Sqrt(g2h)). if i know the power output of the device per second then i can show if conservation of mass and energy is violated or not((x-mg2(x/mg1)/(Sqrt(g1h)+Sqrt(g2h))<energy per second of machine). if it is then the experiment is a fraud. anyone care to graph possible energy gained v. time and energy output of machine v. time. if those lines cross at any point then conservation is violated.

We've already beaten you to the punch and are implicitly considering the remote possibility that the device works by emitting a different, unknown force.

Or at least we were, and now we're just making fun of it and talking about smoke.

P.S. Convection currents would totally cause a downdraft all the way to the ceiling. Anything else would require the air to make sharp, orderly right turns. Or, more fancily, it wouldn't have air flow down the pressure gradient at all places.
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IIAOPSW
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### Re: Podkletnov's gravity shielding

We've already beaten you to the punch and are implicitly considering the remote possibility that the device works by emitting a different, unknown force.
funny you should say that. I read something in New Scientist (which seems reasonably reputable) suggesting an unknown, extremely small force related to spin. it was observed to affect spacecraft entering earth orbit (above the atmosphere). depending on the angle made with the equator and the direction the craft would enter it would gain a small boost either in support or opposition to the initial direction. you can find the article in the march 2008 edition of new scientist or here:
http://www.newscientist.com/article/dn1 ... craft.html
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