# Stephen Hawking

• June 16th, 2006, 03:31 AM
D231988
Stephen Hawking
I went through Hawking's 'Brief History of Time'. I came across a lot of stuff on light cones.

What actually are they ???
• June 16th, 2006, 07:48 AM
Zelos
oh god.
space is 3d, time is 1 d, but we can only visualise 3D, so scientists ahve turned the 3 dimensions into 2 dimensions, where the alst dimension on the paper or computer represent time, then imagen light going away from somekinda object at time 0, then let it go on, the value on the time axis increase, then it will form a cone where everything inside the cone can have been effected by even in question, everything outside cant
• June 18th, 2006, 12:34 AM
mitchellmckain
The light cone is a 3 dimensional projection of the Minkowsky structure of 4 dimensional space-time, where one of the axes in a 3d coordinate space represents time rather than one of the spatial coordinates. The light cone has this coordinate for time going right up through the middle of it, and the surface of the cone represents the speed of light separating all of space-time into time-like distances from the origin (inside the cone) and space-like distances from the origin (outside the cone). The space-like distances cannot causally connected, that is one cannot be the cause of the other. The time like distances are causally connected and are sharply divided into those in the past (lower half of the two-sided cone) and those in the future (upper half of the two-sided cone).