Re: TIME warp
Hi guys, Time travel is actually possible, as long as you are consistent (i.e. Novikov self-consistency principle). Please consider the argument for it, beginning at: http://www.reddit.com/r/askscience/comments/hr4x2/physicists_what_do_you_think_of_the_following/ Continue the discussion there at reddit if you would like. Thank you! F.H. On Fri, Jun 3, 2011 at 12:09 PM, Travis Garrett wrote: > Hi Roc, > > Sure. Let me go ahead and start by assuming that we need to exist > in an environment that began in a state of low entropy (so that life > can evolve during the "increasing entropy phase" - I could also > examine this assumption, but that's another discussion...). GR then > does some interesting things. First, gravity in GR couples to energy > and momentum, and everything has energy and momentum, so, er, it > couples to everything (binding them all together like the one ring I > suppose). It can thus essentially "get everybody on the same page" > when things are starting out - forcing "everybody" (all the particle > species) to "pay attention" and synchronize their behavior... > > GR can then do something quite cool. If you feed the Einstein > equations with a scalar field that happens to have much more potential > energy than kinetic energy, then the spacetime responds by growing > exponentially (i.e. the curvature is in the time direction - the > spatial directions are driven to be very flat (i.e. the angles inside > a triangle add up to 180 degrees), with the overall scale factor > growing exponentially (i.e. the overall size of the triangle is > growing exponentially in time)). Thus, consider some complex universe > with a lot of entropy. Entropy is an extensive quantity, and thus if > we consider some tiny volume element dV then there can't be much > "stuff" inside dV, and therefore there is very little entropy inside > dV. If we can get a scalar field inside that dV to satisfy the > condition that its potential energy is much larger than its kinetic > energy, then blammo, we get inflation and that dV region can grow > larger than our Hubble volume in a tiny fraction of a second (and then > scalar field can decay, ending inflation, to be followed by a > "standard" big bang...). > > It is by no means an open and shut case - there are lots of details > to be filled in - but I think the overall picture makes a lot of > sense... > > Sincerely, > Travis > > On Jun 2, 6:35 am, Roc wrote: >> nice answer. >> could you elaborate on this, though? >> >> Why then should spacetime be curved? There are at least 2 good reasons: >> >> 1) it allows for a big bang to happen, thus "starting things off" in a state >> >> > of low entropy. >> >> thanks > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To post to this group, send email to everything-list@googlegroups.com. > To unsubscribe from this group, send email to > everything-list+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/everything-list?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
Re: TIME warp
Hi Roc, Sure. Let me go ahead and start by assuming that we need to exist in an environment that began in a state of low entropy (so that life can evolve during the "increasing entropy phase" - I could also examine this assumption, but that's another discussion...). GR then does some interesting things. First, gravity in GR couples to energy and momentum, and everything has energy and momentum, so, er, it couples to everything (binding them all together like the one ring I suppose). It can thus essentially "get everybody on the same page" when things are starting out - forcing "everybody" (all the particle species) to "pay attention" and synchronize their behavior... GR can then do something quite cool. If you feed the Einstein equations with a scalar field that happens to have much more potential energy than kinetic energy, then the spacetime responds by growing exponentially (i.e. the curvature is in the time direction - the spatial directions are driven to be very flat (i.e. the angles inside a triangle add up to 180 degrees), with the overall scale factor growing exponentially (i.e. the overall size of the triangle is growing exponentially in time)). Thus, consider some complex universe with a lot of entropy. Entropy is an extensive quantity, and thus if we consider some tiny volume element dV then there can't be much "stuff" inside dV, and therefore there is very little entropy inside dV. If we can get a scalar field inside that dV to satisfy the condition that its potential energy is much larger than its kinetic energy, then blammo, we get inflation and that dV region can grow larger than our Hubble volume in a tiny fraction of a second (and then scalar field can decay, ending inflation, to be followed by a "standard" big bang...). It is by no means an open and shut case - there are lots of details to be filled in - but I think the overall picture makes a lot of sense... Sincerely, Travis On Jun 2, 6:35 am, Roc wrote: > nice answer. > could you elaborate on this, though? > > Why then should spacetime be curved? There are at least 2 good reasons: > > 1) it allows for a big bang to happen, thus "starting things off" in a state > > > of low entropy. > > thanks -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
Re: TIME warp
nice answer. could you elaborate on this, though? Why then should spacetime be curved? There are at least 2 good reasons: 1) it allows for a big bang to happen, thus "starting things off" in a state > of low entropy. thanks -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
Re: TIME warp
Hi Selva, A straightforward and dry answer would be: "it is a consequence of the Einstein field equations of General Relativity (GR)", and one could then go on to do a derivation which demonstrates the time dilation near a large dense mass. The more interesting question (which I think is what you are really getting at) is: "Well, ok, fine, but why do we exist in a universe which is governed by the equations of GR?" I think the answer to this intriguing question lies in a combination of (at least) three parts. The first is that GR includes Special Relativity (SR) as the limit in flat spacetime (and also in "small, local" regions in curved spacetime). SR essentially stems from having an absolute speed limit (in our case the speed of light), and an absolute speed limit is "useful" because it makes causality well defined (e.g. the toddler threw their juice on the floor because they weren't allowed any more cookies, the dog then licks up the juice, the dog proceeds to pee on the rug, etc. etc., the dad drives out to the beer store, etc. etc...). SR then links together space and time in a way which is quite non-intuitive to us (which isn't too surprising since the speed of light is so much faster than anything we deal with at the everyday level) - so that for instance a clock moving past at high velocity runs more slowly. As noted SR is then essentially embedded within the curved spacetime of GR. Why then should spacetime be curved? There are at least 2 good reasons: 1) it allows for a big bang to happen, thus "starting things off" in a state of low entropy. And also: 2) GR includes Newtonian gravity as the standard limiting case, which allows for very long-lived orbits (in 3 spatial dimensions) as needed by biological evolution to generate complex organisms. And, now that I think about it, eternal inflation (essentially preceding the big bang) allows for "viable" effective field theories to be found among a landscape of vacua, so that in total the big bang produces viable (~ Standard Model) environments in an initial state of low entropy. I'd thus roughly guess that time dilation near massive bodies is essentially a "side effect" of the equations that produce these other vital effects... (althought conceivably there could also be some reason for time dilation to be "useful" at some distant point in the future...) Sincerely, Travis On May 29, 2:39 pm, selva wrote: > why is there time dilation near a heavy mass ?? > > On May 17, 12:31 am, selva wrote: > > > > > hi everyone, > > > can someone explain me what a time warp is ? or why there is a time > > warp ? > > well yes,it is due to the curvature of the space-time graph near a > > heavy mass. > > but how does it points to the center of the mass,how does it finds > > it.. > > and explanation at atomic level plz.. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
Re: TIME warp
why is there time dilation near a heavy mass ?? On May 17, 12:31 am, selva wrote: > hi everyone, > > can someone explain me what a time warp is ? or why there is a time > warp ? > well yes,it is due to the curvature of the space-time graph near a > heavy mass. > but how does it points to the center of the mass,how does it finds > it.. > and explanation at atomic level plz.. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
Re: TIME warp
i was not talking about going back in time..but slowing time.. it happens near a huge mass right ? On Sun, May 22, 2011 at 8:32 PM, 1Z wrote: > > > On May 18, 12:56 pm, ronaldheld wrote: > > Are you talking about a "Star Trek" term or for certain space-times, > > the ability to go forwards or backwards in time relative to a distant > > observer? > > > > Ronald > > > > On May 16, 3:31 pm, selva wrote: > > > > > hi everyone, > > > > > can someone explain me what a time warp is ? or why there is a time > > > warp ? > > > well yes,it is due to the curvature of the space-time graph near a > > > heavy mass. > > > but how does it points to the center of the mass,how does it finds > > > it.. > > > and explanation at atomic level plz.. > > http://en.wikipedia.org/wiki/Closed_timelike_curve > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To post to this group, send email to everything-list@googlegroups.com. > To unsubscribe from this group, send email to > everything-list+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/everything-list?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
Re: TIME warp
On May 18, 12:56 pm, ronaldheld wrote: > Are you talking about a "Star Trek" term or for certain space-times, > the ability to go forwards or backwards in time relative to a distant > observer? > > Ronald > > On May 16, 3:31 pm, selva wrote: > > > hi everyone, > > > can someone explain me what a time warp is ? or why there is a time > > warp ? > > well yes,it is due to the curvature of the space-time graph near a > > heavy mass. > > but how does it points to the center of the mass,how does it finds > > it.. > > and explanation at atomic level plz.. http://en.wikipedia.org/wiki/Closed_timelike_curve -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
Re: TIME warp
Are you talking about a "Star Trek" term or for certain space-times, the ability to go forwards or backwards in time relative to a distant observer? Ronald On May 16, 3:31 pm, selva wrote: > hi everyone, > > can someone explain me what a time warp is ? or why there is a time > warp ? > well yes,it is due to the curvature of the space-time graph near a > heavy mass. > but how does it points to the center of the mass,how does it finds > it.. > and explanation at atomic level plz.. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
TIME warp
hi everyone, can someone explain me what a time warp is ? or why there is a time warp ? well yes,it is due to the curvature of the space-time graph near a heavy mass. but how does it points to the center of the mass,how does it finds it.. and explanation at atomic level plz.. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
