Path: csiph.com!aioe.org!news.cmpublishers.com!nntp.club.cc.cmu.edu!micro-heart-of-gold.mit.edu!newsswitch.lcs.mit.edu!nntp.TheWorld.com!.POSTED!not-for-mail From: moroney@world.std.spaamtrap.com (Michael Moroney) Newsgroups: sci.physics,alt.astronomy Subject: Re: The (4D) timescape is static. Date: Thu, 2 Jul 2015 16:44:50 +0000 (UTC) Organization: The World : www.TheWorld.com : Since 1989 Lines: 24 Message-ID: References: NNTP-Posting-Host: shell01.theworld.com X-Trace: pcls7.std.com 1435855490 15590 192.74.137.71 (2 Jul 2015 16:44:50 GMT) X-Complaints-To: abuse@TheWorld.com NNTP-Posting-Date: Thu, 2 Jul 2015 16:44:50 +0000 (UTC) User-Agent: nn/6.6.5 Xref: aioe.org sci.physics:504058 alt.astronomy:270386 Jeff-Relf.Me <@.> writes: >Gravity is "exergy" (energy that can do work). >Net Net, it's consumed away, never to return. >The (4D) timescape is static. Not really. Gravitational energy is the potential energy of a system. For example, two gravitating masses a certain distance apart has a certain amount of gravitational potential energy. If undisturbed, it will stay like that forever. If you allow the masses to get closer to each other you can extract energy from it. Like any other energy, some can be irreversibly lost once you have done so, but this is not necessarily so. For example, a mass orbiting another in a highly elliptical orbit will exchange energy between kinetic energy of motion and gravitational potential energy as the orbiting mass gets closer to and further from the primary mass, forever(1). (1) GR predicts orbiting masses radiate away gravitational waves so such a system does lose energy after all if this part of GR is correct. Plus friction with intersteller matter etc., so if a system otherwise survives trillions or even quadrillions of years unperturbed, orbiting masses will eventually spiral into each other. So maybe there's a little truth to your silly spammed posts after all.