Gravity experiment: Has this been done?

Question

You take two small objects say- five killogram lead weights, and you hold them one millimeter apart in zero gravity, then let them go. Then you wait days. Weeks. Years. Do the two objects EVER touch? I realize it would be impossible even with robotics to make a perfect release, so lets call it a really good one- synchronized down to a trillionth of a second. I'm wondering what concrete evidence we've found showing gravitational (non-magnetic) attraction in ALL things. Math can prove anything provided you know the rules. The problem is the rules envolving gravity are all theory. We still don't know for sure what gravity is and what creates it.

I can't accept Henry Cavendish's explaination because his experiment was done on Earth and there are too many forces that can interfear with the results.

I get the feeling that this is one of those questions where I can't explain the conditions precisely enough. There's always going to be more dimensions.

Most of you have been very helpful, but this was not meant to be a trick question; although it is a very relative one. Thanks for your time. I'll keep searching.

Answer 1

something similar is currently done in a nasa mission named 'Gravity Probe B'
if you say the effects of gravitation are too severe to get clear results then you should keep in mind that there is no such place in the universe without gravitation.
sooo how precise do you think one must be to get to clear results.
i think the experiments with lead balls were precise enough to get proper results.

on the other hand .. there's possibly something wrong with gravitation.
I think they still search for an anomaly regarding the course and location of the pioneer spacecraft. And on the big scale observation of other galaxies rotatation seems to be odd, pretending that there must be more matter than we observe.

sooo .. the theory put 'dark matter' or WIMP's into the pod, to fix a few things theoretically.
This is something hard to discover even with most precise experiments, cause gravitation is the weakest force we have to deal with (if it in fact IS a force)

so if you want to know how gravity is on the testbed today checkout the link

Answer 2

What does it matter whether this specific experiment, which you have imagined, actually has or has not been done?

There is a whole theory of gravitation which mathematically predicts all its effects, and every single prediction which could be confirmed by observation, has been confirmed. This theory predicts that your two weights will indeed gravitate towards each other. It is just useless to point to a single impracticable experiment like yours, and claim that the theory is suspect because this experiment is too difficult to perform exactly.

If you have a different theory which says that your weights won't gravitate towards each other, then you would need to make other predictions with it too, and test them against the results of experiments which can be set up in the laboratory. That's what the other theorists have been brave enough to do.

Answer 3

There's an experiment where you take two led balls, two feet in diameter each, and hang them so they're only 1/2" apart. Slowly, the two balls "fall" toward each other, and close the gap inside of 3 or 4 minutes.
No magnetics.

While we can measure gravity, use gravity, experience gravity - we don't know for sure what the mechanism is that creates it, or how it's broadcast. Still a theory works until you find a case where it's proven wrong.

Answer 4

I can't remember the exact details nor the experimenter, but it seems to me that this experiment has been conducted (in Microgravity). I believe it was incidental to the overall experiment that was being conducted - could have been looking for the graviton or Planck length or some sort of quantum physics experiment.

I'll try to locate the source of this information and get back to you.


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I scanned several articles and can't find the direct reference to what the experiment was. There were several references to the fact that we have been able to measure gravity down to .1 mm. These references were made in conjunction with Quantum physics at the Quantum scale.

As I remember the experiment, it was conducted in a vacuum under microgravitational conditions. It consisted of two pieces of foil that were brought to within .1 mm and measured for the gravitational force. So far, we do not have the technology to conduct experiments on a smaller scale. This experiment was to try to prove the inverse square law of gravity, and at this scale, mathematical and theoretical models appear to be substantiated. Of course, quantum theory is in its prime. It is hoped that when the Large Hadron Collider comes online (this year) that experiments will be conducted to refine this measurement.

I found other references to the Laser Interferometer Gravitational Wave Observatory (LIGO) and to the Laser Interferometer Space Antenna (LISA). These are dedicated projects to determine "what" gravity is. If you do and go search on these, they would probably have the most up-to-date information.

Answer 5

No, that particular experiment has not been done. It can't be done, because there is nowhere we can reach that has zero gravity.

The equations involving gravity are well known. We can use them to predict the orbits of the planets and moon and stars to extreme accuracy. Many scientists, when asked what gravity is, would say that it's a force that matches those equations, and that is all we can know about gravity.

In fact, that's all we can know about anything in physics: the equations that predict what the thing will do.

Answer 6

Our knowledge of gravity works well enough for most purposes.

There has been some evidence that could suggest that the laws of gravitation are not 100% correct, however there are other things which may just as easily explain the evidence.

Answer 7

you raise 2 points
A. Whether gravity will actually pull the 2 things together
B. Whether we know what gravity is.

You can create a measureable eletrical spark without knowing that electricity is the flow of electrons. You are right that we don't fundamentally understand whether gravity is from a particle (graviton) or a function of warping space or something else. But what do we "fundamentally" understand? Do we know "why" electrons jump from one orbital to another? Nope. Do we know whether electrons orbit atoms or are some smeared out probabilty wave? Not really. Our science still works.

Answer 8

Basically that experiment was done in 1798 by Henry Cavendish, but with the masses suspended on wires and not in space. I did that experiment myself in physics lab. It is necessary to do that to determine the value of the universal gravitational constant.

Answer 9

If you did the experiment just the way you said the two balls would eventually merge.
Gravity is a weak force but it would act on the objects and they would eventually touch.

Answer 10

Problem is, where is 'zero gravity' if everything in our solar system is affected by the gravitational forces of our sun and all the solar systems within a galaxy are affected by the galactic core and galaxies are affected by other galaxies!
Perhaps something new?
Because we cannot measure it, does that mean anything?
Check this out...
http://video.google.com/videoplay?docid=4773590301316220374