Talk:Light cone

message: Maybe this page could be turned into a history of the ice cream cone.  Here is a site to check for some data.  But probably the name  of the article would be changed. Rednblu 04:33, 3 Sep 2003 (UTC)
replies: text: Light cones don't have anything to do with ice cream; it's a general relativity thing. Whoever wrote the current version of the article was just making stuff up. —Paul A 04:39, 3 Sep 2003 (UTC)
replies: text:  Exactly.  I am reviewing my relativistic mechanics notes to see if I could assemble a rough draft for us to improve. Rednblu 13:36, 3 Sep 2003 (UTC)
thread_title: Untitled

message: I've made a few changes to this article. I want to make major changes to it though. I have a version in my sandbox which people can edit.---Mpatel  (talk) 14:50, August 28, 2005 (UTC)
:The biggest concern is to have another article on absolute future and absolute past, which are global concepts which should be contrasted with the light cone, which is defined at the level of tangent spaces.---CH  (talk) 23:30, 14 September 2005 (UTC)
thread_title:  New version 

message: The volume of the light cone should be mentioned as (1/3)*pi*r^2*h whereas the one-third is relational to clopen conditions.  —Preceding unsigned comment added by 24.22.111.99 (talk) 04:21, August 29, 2007 (UTC) 
: Not relevant is it? h=t, time passed, by the way, but the metric is odd, being r^2-(ct)^2, so does this volume make sense? 51kwad (talk) 11:35, 27 January 2011 (UTC)
thread_title:  Volume of the Light cone 

message: Would you please comment on the new "light cone" image we have prepared. The intention was to imply the correct scale of space-time relative to the observer. Interstellar light-years vs years scales seemed appropriate. Thoughts? Dhatfield (talk) 11:55, 27 June 2008 (UTC)
thread_title:  New image 

message: Assume A is an event within the past cone of B, and B is within the past cone of C. Is it true that A will always be within the cone of C? This would seem to be consistent with the idea that no information can travel faster than light, even through an intermediary. It also fits the simplified 2D block diagram. But since spacetime is curved and multi-dimensional, could B ever "see" an event A that C cannot see? Or is it true that (assuming I am observer C) I can see everything that B can see? A note in the article with your answer would be great. 72.208.56.42 (talk) 13:20, 7 October 2008 (UTC)
thread_title:  Cone within my cone 

message: The space-time interval is always zero between two events connected by a light speed path BUT the slant edge of cone which is GREATER than the speed of light "c" represents the true motion of a pulse [world line ] in both space and time, therefore, isn’t time dilating even in a stationary light clock due to extra distance covered by a pulse in its world-line? 68.147.52.247 (talk) 02:53, 21 December 2011 (UTC)
thread_title:  Slant edge of a Light Cone 

message: Sorry, but somehow I don't understand the diagram.
If time moves forward from bottom to top, where does the "Past Light Cone" come from? If the Flash of light has only been fired at the center of the visualized coordinate system, it only came into existence right there and thus cannot exist in the past.
Can someone clarify?  — Preceding unsigned comment added by 80.187.102.21 (talk) 16:08, 2 December 2012 (UTC)
replies: text: The past light cone is the set of all possible light paths that could reach you at that moment, whether or not any actual light shines along that path. Similarly, the future light cone is the set of all possible light paths that originate from you at that moment, whether or not you are actually shining in any particular direction. Anyways, the past light cone can certainly be full of light: for example, you are in a lit room, in every direction you look some light is coming to you. --174.118.1.24 (talk) 03:49, 18 February 2013 (UTC)
thread_title:  Diagram must be wrong 

message: :but the concept is easier to visualize with the number of spatial dimensions reduced from three to two.[citation needed]
Erm, OK, really? Do you really need a citation to "prove" that it's easier to visualize anything if it has less dimensions? Especially if you're talking about 4 dimensions which is not visualizable at all in 3D space, much less in 2D space (computer monitor)...  — Preceding unsigned comment added by 80.187.102.21 (talk) 20:42, 2 December 2012 (UTC)
replies: text: Trivial. Fully agree with the removal. - DVdm (talk) 17:40, 4 February 2013 (UTC)
thread_title:  "Citation needed" 

message: The light cone is described in this article as the trajectory of a flash of light. This description is problematic. First, the past cone represents light converging to a point. The whole celestial sphere of star light provides the image of incoming photons from different directions. The "flash" image is wrong for the past cone. Further, in spacetime, light does not move, it just persists in rays between emission and absorption: the facility of isotropic lines from complex geometry is used to fit light between temporal and spatial separations. — Rgdboer (talk) 21:50, 6 September 2016 (UTC)
thread_title:  Flash 

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thread_title:  External links modified 

message: It doesn't look to me that light Cone slope 45° in the picture.  — Preceding unsigned comment added by 101.161.162.162 (talk) 10:51, 21 May 2017 (UTC)
replies: text: I made a little change to the text where it talks about the light cone angle. This should clarify things, and explain why you don't see a 45° angle in the picture. It does look like bisection, right? - DVdm (talk) 11:46, 21 May 2017 (UTC)
thread_title:  Light Cone angle in the picture