some questions about gravity [Archive]

alistair

Sep22-04, 03:45 AM

<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>\n\nTwo large spherical masses initially at rest, will accelerate towards\none another because of gravity.How do the gravitational waves produced\nby the accelerating masses behave:do they interfere constructively in\nthe space between the masses? And does the amplitude of the waves\nincrease as the masses get closer together?As the masses get very\nclose they will become non-spherical.How would this affect the\ngravitational waves between them?\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">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Two large spherical masses initially at rest, will accelerate towards
one another because of gravity.How do the gravitational waves produced
by the accelerating masses behave:do they interfere constructively in
the space between the masses? And does the amplitude of the waves
increase as the masses get closer together?As the masses get very
close they will become non-spherical.How would this affect the
gravitational waves between them?

Uncle Al

Sep24-04, 08:11 AM

<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>alistair wrote:\n>\n> Two large spherical masses initially at rest, will accelerate towards\n> one another because of gravity.How do the gravitational waves produced\n> by the accelerating masses behave:do they interfere constructively in\n> the space between the masses? And does the amplitude of the waves\n> increase as the masses get closer together?As the masses get very\n> close they will become non-spherical.How would this affect the\n> gravitational waves between them?\n\n\n1) Gravitational waves are not produced by dipole interactions.\nYou need at least quadrupole interactions. Learn what that means.\n\n2) Interaction cross-section of gravitational waves with anything\nis incredibly small - much smaller than EM interactions. Compare G\nwith the Fine Structure constant. Remember to square them (why?).\nNow then, what is the probability of photon-photon scattering?\n\n3) Google; http://www.arXiv.org/ If you care enough to know you\ncare enough to look it up.\n\n<http://darkwing.uoregon.edu/~rrahkola/ligo_refs.html>\nhttp://www.phys.lsu.edu/mog/\nNumber 24.\n\n--\nUncle Al\nhttp://www.mazepath.com/uncleal/\n(Toxic URL! Unsafe for children and most mammals)\nhttp://www.mazepath.com/uncleal/qz.pdf\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">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>alistair wrote:
>
> Two large spherical masses initially at rest, will accelerate towards
> one another because of gravity.How do the gravitational waves produced
> by the accelerating masses behave:do they interfere constructively in
> the space between the masses? And does the amplitude of the waves
> increase as the masses get closer together?As the masses get very
> close they will become non-spherical.How would this affect the
> gravitational waves between them?

1) Gravitational waves are not produced by dipole interactions.
You need at least quadrupole interactions. Learn what that means.

2) Interaction cross-section of gravitational waves with anything
is incredibly small - much smaller than EM interactions. Compare G
with the Fine Structure constant. Remember to square them (why?).
Now then, what is the probability of photon-photon scattering?

3) Google; http://www.arXiv.org/ If you care enough to know you
care enough to look it up.

<http://darkwing.uoregon.edu/~rrahkola/ligo_refs.html>
http://www.phys.lsu.edu/mog/
Number 24.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

Jim Graber

Sep25-04, 05:00 AM

<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>alistair@goforit64.fsnet.co.uk (alistair) wrote in message news:<861c1b21.0409210633.211fc907@posting.google. com>...\n> Two large spherical masses initially at rest, will accelerate towards\n> one another because of gravity.How do the gravitational waves produced\n> by the accelerating masses behave:do they interfere constructively in\n> the space between the masses?\nYes, and also destructively, but only to a very negligible extent,\nas far as the infall itself and the generation and transmission of the\nwaves is concerned.\n> And does the amplitude of the waves\n> increase as the masses get closer together?\nYes.\n> As the masses get very\n> close they will become non-spherical.How would this affect the\n> gravitational waves between them?\nIn a very complicated way. Unless the two masses are black holes or\nneutron stars, they collide or get torn up long before there is any\nsignificant effect from the gravitational waves.\n\nEven two black holes colliding head on only radiate about one or at\nmost a few percent of their rest mass energy in gravitational waves.\nIf two blackholes spiral into each other in a nearly circular orbit,\nthe percent of energy radiated may get up in the neighborhood of 30%.\n\nBest,\nJim Graber\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">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>alistair@goforit64.fsnet.co.uk (alistair) wrote in message news:<861c1b21.0409210633.211fc907@posting.google.com>...
> Two large spherical masses initially at rest, will accelerate towards
> one another because of gravity.How do the gravitational waves produced
> by the accelerating masses behave:do they interfere constructively in
> the space between the masses?
Yes, and also destructively, but only to a very negligible extent,
as far as the infall itself and the generation and transmission of the
waves is concerned.
> And does the amplitude of the waves
> increase as the masses get closer together?
Yes.
> As the masses get very
> close they will become non-spherical.How would this affect the
> gravitational waves between them?
In a very complicated way. Unless the two masses are black holes or
neutron stars, they collide or get torn up long before there is any
significant effect from the gravitational waves.

Even two black holes colliding head on only radiate about one or at
most a few percent of their rest mass energy in gravitational waves.
If two blackholes spiral into each other in a nearly circular orbit,
the percent of energy radiated may get up in the neighborhood of 30%.

Best,
Jim Graber

alistair

Sep26-04, 03:20 AM

<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>Jim Graber wrote in message:\n>Unless the two masses are black holes or\n>neutron stars, they collide or get torn up long before there is any\n>significant effect from the gravitational waves.\n\nAre gravitational waves generated in all directions by a quadrupole\nmoment,and how much energy is carried by the gravitational waves\ngenerated by the oscillations of two up quarks and one down quark, in\nthe protons of our Sun?\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">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Jim Graber wrote in message:
>Unless the two masses are black holes or
>neutron stars, they collide or get torn up long before there is any
>significant effect from the gravitational waves.

Are gravitational waves generated in all directions by a quadrupole
moment,and how much energy is carried by the gravitational waves
generated by the oscillations of two up quarks and one down quark, in
the protons of our Sun?