## Gravitation of subatomic particles

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no,location=no, scrollbars=yes,resizable=yes,status=no,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Some people seem to think that Gravitation only\nhappens between large groups of particles, and\nnot between individual particles. Have any\nexperiments actually measured gravitational\nacceleration of single particles?\n\nIf not, then how about this:\nStart with two of those special magnetic-field\ndevices that can trap neutrons. Fill one and\nplace it at altitude. Put the empty one below\nit. Turn off the upper trap. The time it\ntakes for any neutrons to end up in the lower\ntrap will depend on their initial speed (we\nknow that, right?) and gravitational\nacceleration. IF they are affected by that,\nof course. I think they will. For those\nwho think otherwise, could this experiment\nrefute them with proof?\n\nThanks!\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">&nbsp;&nbsp;View this Usenet post in original ASCII form </a></div><P></jabberwocky>Some people seem to think that Gravitation only
happens between large groups of particles, and
not between individual particles. Have any
experiments actually measured gravitational
acceleration of single particles?

devices that can trap neutrons. Fill one and
place it at altitude. Put the empty one below
it. Turn off the upper trap. The time it
takes for any neutrons to end up in the lower
trap will depend on their initial speed (we
know that, right?) and gravitational
acceleration. IF they are affected by that,
of course. I think they will. For those
who think otherwise, could this experiment
refute them with proof?

Thanks!

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"vernonner3voltazim" wrote in message news:42336979.0406250620.11b2526a@posting.google.com... > Some people seem to think that Gravitation only > happens between large groups of particles, and > not between individual particles. Have any > experiments actually measured gravitational > acceleration of single particles? > > If not, then how about this: > Start with two of those special magnetic-field > devices that can trap neutrons. Fill one and > place it at altitude. Put the empty one below > it. Turn off the upper trap. The time it > takes for any neutrons to end up in the lower > trap will depend on their initial speed (we > know that, right?) and gravitational > acceleration. IF they are affected by that, > of course. I think they will. For those > who think otherwise, could this experiment > refute them with proof? When proposing such an experiment, it helps to do some back of the envelope calculations, and to know a bit more physics. For the second suggestion: Read up on quantum mechanics and then think about the difficulty in measuring the position and velocity of the neutrons simultaneously. That is a fundamental source of uncertainty in your measurements. For the back of the envelope: Next, figure out the differential force of attraction between a neutron and the earth and a neutron and a neutron plus the earth. This is not so hard as it sounds. Two simple models to propose: 1: $f = mMG/r^2$ Force between small mass m (neutron) and that of the earth (M). $F = m(M+m)G/r^2$ Force between small mass m (Neutron) and that of the earth with an extra neutron at its center. 2. Exercise left to the reader. How would you apply linear superposition of forces to find the relationship between the force between neutron 10 meters above the earth ,and the earth plus a neutron 1 meter above the surface of the earth? 3. Here is a subtle question: Is there an easier method of finding this out than what I proposed above? :-) Now compare the change in velocity from that force dependence and the error intrinsic in the quantum mechanical uncertainty principle and see which is greater. Then you have to consider the technical problems. How do you make and trap single neutrons? You have to make your measurements quickly because the neutron has a high probability of decaying into a proton, an electron and an electron-neutrino within about 15 min. How will this decay effect your apparatus and its detectors. Goodness! Of course, this does not mean that an experiment to measure the force of gravity between two particles is impossible... but you have to constrain your proposals within the bounds of physics.



vnemitz@pinn.net (vernonner3voltazim) wrote in message news:<42336979.0406250620.11b2526a@p...google.com>... > Some people seem to think that Gravitation only > happens between large groups of particles, and > not between individual particles. Have any > experiments actually measured gravitational > acceleration of single particles? Have a look at: Nesvizhevsky V.V., Boerner H.G., Petukhov A.K., Abele H., Baessler S., Ruess F.J., Stoeferle T., Westphal A., Gagarski A.M., Petrov G.A., Strelkov A.V. - Quantum states of neutrons in the earth's gravitational field Nature Vol. 415 pp$. 297-299,$ 2002 Code Number: ILL02NE146 Subject: NUCLEAR AND PARTICLE PHYSICS Instrument used at the ILL: PN3 $\gamma-ray$ spectrometer cheers, Patrick.