Moving light bulb sphere of photons

[Dreads]

Hello Dreads.

Think of it this way. The centre of the expanding sphere of photons is at rest in EVERY frame. So for ANY observers present at the point of emission, no matter what their relative velocities, the expanding sphere of photons behaves as if any and all of the observers are, and remain, central to it. It is non intuitive and makes no "common sense" but it is due to the speed of light being the same in all inertial frames and is at the very heart of relativity.

Matheinste

is this for real ?

so what you are saying is if we have three observers, OB1, OB2 (and OBkenobee3 sorry couldn't resist that) Ob3 tarvelling along the x, y and z axis and they all intersect at T0 at the origin of a cartersian coor sys. At the origin is a light bulb that turns on at T0

Ob1 is traveling at seed 1 km/h, 0b2 at 0.5 C and ob3 at c what you are saying is that they will all see the same a sphere of photons expanding outwardly in all directions and each observer will percieve themelves at the centre of the sphere?

 

[Dreads]

sorry I am a hopeless speller, can't spell striat :)

 

[JesseM]

is this for real ?

so what you are saying is if we have three observers, OB1, OB2 (and OBkenobee3 sorry couldn't resist that) Ob3 tarvelling along the x, y and z axis and they all intersect at T0 at the origin of a cartersian coor sys. At the origin is a light bulb that turns on at T0

Ob1 is traveling at seed 1 km/h, 0b2 at 0.5 C and ob3 at c

What are these speeds relative to? The light bulb, perhaps? Keep in mind all speeds are relative in SR. Also, if OB3 is traveling at c, then OB3 does not have his own inertial rest frame, because the only valid inertial frames are ones moving slower than light--maybe we could modify the example so that OB3 is traveling at 0.99c relative to the bulb?

what you are saying is that they will all see the same a sphere of photons expanding outwardly in all directions and each observer will percieve themelves at the centre of the sphere?

As long as they are inertial observers moving slower than light, then yes, in each of their own inertial rest frames they will remain at the center of the sphere of photons.

 

[ZikZak]

is this for real ?

so what you are saying is if we have three observers, OB1, OB2 (and OBkenobee3 sorry couldn't resist that) Ob3 tarvelling along the x, y and z axis and they all intersect at T0 at the origin of a cartersian coor sys. At the origin is a light bulb that turns on at T0

Ob1 is traveling at seed 1 km/h, 0b2 at 0.5 C and ob3 at c what you are saying is that they will all see the same a sphere of photons expanding outwardly in all directions and each observer will percieve themelves at the centre of the sphere?

Absolutely correct, except that no observer can travel at c. If we allow that observer to travel at nearly c, then the speed of light is c in all three frames. Therefore, each observer observes a sphere of photons, centered on himself, expanding at speed c.