Has anyone measured g for bismuth to high degree of accuracy? I read that it undergoes gravitational acceleration slightly faster than other objects/elements in a vacuum

Found this by googling:

http://prola.aps.org/abstract/PR/v19/i2/p187_1

Could you post a reference to where you read that?

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"They reasoned that an object situated at the center and related equally to the extremes in every direction can have no impulse to move in any specific direction. In fact, they compared the situation of such an object with that of a man violently but equally hungry and thirsty, standing at the same distance from food and drink and unable to decide in which direction to move." - Aristotle

Where did you read that? I would think that would be pretty big news, but I'd never heard of it. I did a quick google and just turned up a few "UFO" webpages with, let us say, rather questionable statements. I especially liked this one:

Bismuth's atomic number is 83.

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Nice find. Note that this reference goes back to 1921.

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Ununpentium (the real element 115) is right below it on the periodic table. Someone probably saw the "115" below the "Bi" and failed to note that they belonged to different elements, so bismuth likely has nothing at all to do with the actual claims. Robert Lazar apparently has something of an obsession with ununpentium as a fuel source and anti gravity material. I'm not particularly familiar with his claims, but...he doesn't seem to be the most reliable of sources. The strong diamagnetism of bismuth (strong enough to levitate a small rare earth magnet against Earth's gravity) might have added to the confusion.

There is no theoretical basis that I am aware of for an element to have any variation in the gravity it produces for a given mass. In fact, unless I'm mistaken, a difference between gravitational and inertial mass would allow for perpetual momentum machines to be constructed...

It had never occurred to me that there was anything inherently wrong with the possibility that gravitational and inertial masses might be entirely different. Since electric charge - which affects the magnitude of the force on a particle in an electric field - is uncorrelated with inertial mass, why not gravitational mass? So how does this perpetual motion machine work?

I've been trying to remember. I may well be misremembering something related to the similar problems with antigravity in general.

Move to ATM, please?
Before this gets really irritating?
(Important new work! Published in 1920. Can't remember where I read this - misremembered reference is no reference. Sigh. And this used to be a science based website.)

John

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Everything I need to know I learned through Googling.

Sounds like so much bismuth to me.

Only if they're very, very large...

Apparently, the bismuth of the situation hasn't sunk...

Oh, nevermind. We all need a little levity.

Perpetual momentum? Blah. Well, Ivan knew what I meant.
One difference between a system of 3 gravitational bodies, one with a different gravity to mass ratio, and 3 charged bodies with a similar difference, is that all of the former attract each other while two of the latter must repel each other. However, I haven't yet found anything about conservation law violations due to equivalence principle violations, other than GR assuming the equivalence principle is true and that gravitational acceleration is thus equivalent to other accelerations.

JohnD: I'm sorry. I'm only human. I don't have a perfect memory, and have a limited amount of time in which to compose posts, and from time to time I need to sleep. However, I also did not claim to have absolute knowledge or even great certainty, and if I had found something useful as a reference, I would have posted it. There was the possibility that someone else would find a reference if I brought it up, so I did.

I'm honestly not sure what provoked your reaction. If it was my post in particular, maybe you misread my post as a claim that perpetual motion or antigravity was possible...I did not say that. The thread as a whole...a question was asked, there were requests for clarifications, and answers were given. That seems to fit in this section.

Your link mentioned Brush

Here is a paper describing his experiment which found different gravitational pull on same mass/weight/size/shape pendulum bobs composed of different materials

http://books.google.com/books?id=6lc...yKAmkA#PPP1,M1

Brush was very eminent scientist and inventor of course

This goes back to 1923. Without widespread confirmation, this is pretty useless.

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This

http://prola.aps.org/abstract/PR/v19/i2/p187_1

Goes back even further to 1922

so it is in the same boat

Are there more recent experiments to determine if this gravitational effect is real or not?

Pretty clearly, there has not been serious confirmation since then.

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Of either position?

Thanks for the reference rodin,

It appears that his claim was considered/published by mainstream science at the time as evidenced by this New York Times article.

However there does not seem to be any followup support.

In the hindsight I would question the validity of any such experiments/measurement to a high degree of accuracy unless performed behind magnetic shielding (ie in a room/box with superconducting walls).

Otherwise all metals' motions will be somewhat dampened and to different degrees due to eddy currents produced in reaction to magnetic fields present throughout the Earth.

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"They reasoned that an object situated at the center and related equally to the extremes in every direction can have no impulse to move in any specific direction. In fact, they compared the situation of such an object with that of a man violently but equally hungry and thirsty, standing at the same distance from food and drink and unable to decide in which direction to move." - Aristotle

I simply note in passing that the author of this paper is Harry Potter (OK, the name is Harold, but Harry is an appropriate nickname for Harold).
None that I can find. Not surprising, why would anyone do such an experiment? Potter already did it.

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

As just mentioned, the experiments are not in vacuum, nor in the absence of magnetic fields. The results were on the order of 1 part in 50,000 so I'm going to stick with Einstein and say that gravitational mass is equivalent to inertial mass and is not dependent on the material.

Heh I noted that as well. Surely JK Rowling had never heard of him? Or had she? lol

We have 2 experiments - one published in 1922 by Harry Potter (what do we know about him) and another published in 1923 by Brush (eminent scientist). The latter is discarded, the former accepted, and no-one has ever verified which of the two scientists was correct.

Really I am astonished.

How difficult/expensive would it be to conduct a similar experiment nearly 100 years later using modern technology like (I am guessing) LASER interferometry or even simple fast photography? One part in 50,000 is eminently detectable surely, even on a small scale (say shielded room or even box) and electronic triggering of drop?

My Experiment Idea

One could fix granulated materials in a matrix of resin, with the materials:resin ratio chosen for identical density. Setting of the matrix to be done in conditions of homogeneity. The composite material can then machined to a specific shape/dimension consistent across all samples. Then all you have to do is drop down an evacuated and magnetically shielded tube and re-measure until results are statistically significant to an accuracy >> 50,000:1

The experiment could be repeated with a non-evacuated tube since air resistance should be same over all samples having same density, size and profile, but evacuation adds another level of certainty of validity of experiment since one could theoretically argue that different composites present different surface drag in air.

I suggest we as the science community do and repeat this experiment forthwith. What say you?

The book you referenced was published in 1923. That wasn't when the Bismuth claim was made. The abstract of the Potter paper (dated November 11, 1921) clearly was about testing Brush's claim:

And the New York Times article a1call linked to was dated April 23, 1921. So, a claim was made, it was tested and found wanting. As for Potter, why don't you research him?

If you're really interested in this, and aren't just trying to push random ATM ideas on Q&A, I'd suggest you do a serious literature search. That wouldn't be something you'd do on the internet.

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Sleep? Please define the term, "sleep." You state that you are human. We thought this was a joke.

You are Netizen, right? Not human? If so, why this preoccupation with such a human concept as "sleep?"

Perhaps you're running low on bismuth...

Well U r right about one thing. Googling Harry Potter Scientist Gravity never leads to the 1920's

http://www.telegraph.co.uk/sciencean...e-fiction.html

Information on the original Harry Potter will be gratefully received

Try The Expanding Worlds of General Relativity
By Hubert Goenner, Jurgen Renn, Jim Ritter, Tilman Sauer, available on Google Books. The first part covers the early experiments in gravitational absorption.

We know that Harold Potter was in the Physics Research Department at King's College in London, and we know that he published his results in the Physical Review. We know that King's College is not a diploma-mill and we know that Physical Review is perhaps the single most highly respected physics journal around, or at least its close to that, and has been for a long time. They don't publish fairy tales. I am not prepared to accept that our routine behavior should be to believe the famous guy just because he is a famous guy. After all, famous guys have been wrong before. And it is not at all true that "no-one has ever verified which of the two scientists was correct", it's just that the verification comes in a form you are unaware of.

Good enough for an amateur doing physics in their garage workshop, but woefully inadequate for any professional research. We laugh at 50,000:1, modern inverse square and equivalence principle tests work with torsion balance pendulums and are good to about 1 part in 10⁹ at the sloppiest.

And that's where the verification you are unaware of is done. Laboratory tests of the equivalence principle (the universality of free fall) are done by comparing the gravitational acceleration of test masses made of different material. This is done, for instance, at the Eöt-Wash Laboratory at the University of Washington in Seattle, or at the Gravity Laboratory at the University of California at Irvine. At the Eöt-Wash laboratory they have directly measured the relative gravitational accelerations of Beryllium, Copper, Aluminum & Silicon, for example, and find that they are accelerated the same by gravity, to roughly 1 part in 10¹², which beats the heck out of 1 part in 50,000. You can go to the Eöt-Wash website and download the PDF of "Review of Recent Tests of the Universality of Free Fall", which was recent in 1998. For something more recent than that, see for instance Schlamminger, et al., 2008, which finds that Beryllium & Titanium have the same acceleration under gravity to within about 10^-15 m/sec². Whether or not anyone has specifically used Bismuth I don't know, but it hardly matters. There is no experimental evidence of any kind that gravity cares what anything is made of, and there is a lot of experimental evidence that gravity in fact does not care what anything is made of.

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The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell

Thanks Tim.

So in other words, if you want to build your antigravity flying saucer, you can forget Beryllium, Copper, Aluminum, Titanium & Silicon.

Bismuth might still work for you .... because it is magic. Unless of course you are a Muggle. Then it's rockets for you sucker.

Magically diamagnetic!
I suspect this is part of it. People seem to persist in thinking of magnets as...well, magic. They ascribe healing and disease-causing powers or try to extract energy out of them. And bismuth acts weird even in terms of magnetism...in particular, with the correct configuration of magnets and bismuth blocks, a strong and lightweight magnet will levitate between two blocks of bismuth without any active stabilization. It's just diamagnetism, no weird cancellation of gravity or anything...but the rest is just normal ferromagnetism, and that doesn't stop people from doing the things described above.

Scitoys.com: Magnetism

Image there, a small magnet hovering between two bismuth plates. Above, out of frame, fighting gravity, are a stack of magnets pulling the little magnet up. The diamagnetic property of bismuth, and some tuning, keeps the forces balanced.

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