image
Physics Forums Logo
image
image
* Register * Upgrade Blogs Library Staff Rules Mark Forums Read
image
image   image
image

image special relativity Share It Thread Tools Search this Thread image
Old Jun21-09, 01:09 AM                  #1
keepitmoving

keepitmoving is Offline:
Posts: 87
special relativity

if a flashlight is moving at half the speed of light and sending out light at a relative speed of c and then the flashlight runs into an asteroid and wham, it stops moving relative to the asteroid, does the light that has already been sent out put on its retro rockets so that is can resume its speed at c relative to the smashed flashlight?
  Reply With Quote
Old Jun21-09, 01:23 AM                  #2
poopcaboose

poopcaboose is Offline:
Posts: 33
Blog Entries: 1
Re: special relativity

That is the theory of relativity, time changes not velocity.
  Reply With Quote
Old Jun21-09, 01:34 AM                  #3
GiftOfPlasma

GiftOfPlasma is Offline:
Posts: 8
Re: special relativity

Light leaves the flashlight traveling at c, and it travels at c with respect to both the flashlight and asteroid. The main difference is measuring while traveling with the flashlight you would get one frequency and measuring with the asteroid you would get another higher frequency. This is called the relativistic Doppler shift.
  Reply With Quote
Old Jun21-09, 06:07 AM                  #4
Borg
 
Borg's Avatar

Borg is Offline:
Posts: 52
Blog Entries: 1
Recognitions:
PF Contributor PF Contributor
Re: special relativity

Originally Posted by keepitmoving View Post
if a flashlight is moving at half the speed of light and sending out light at a relative speed of c and then the flashlight runs into an asteroid and wham, it stops moving relative to the asteroid, does the light that has already been sent out put on its retro rockets so that is can resume its speed at c relative to the smashed flashlight?
The main premise of relativity is that all obsevers measure light to be traveling at c no matter what their speed is relative to another observer. This doesn't change if an observer's speed changes. Phrases like the ones above will cause you confusion.
  Reply With Quote
Old Jun21-09, 09:07 PM                  #5
Libohove90

Libohove90 is Offline:
Posts: 5
Re: special relativity

You have not grasped the idea that the speed of light is universal. This is VERY important to understanding relativity.

Simply put, light moves at c from all reference points. It does not matter if the flashlight was moving at .5c or .999999c or .0000000001c, light moves at c at all costs.

If you were racing with a beam of light, and you moved at .9999c, you would say that light is moving .0001 c faster than you right? Wrong. It is moving at c relative to you. You would wonder how is it possible that its moving at c relative to you even tho u are moving at .9999c...well that is because space and time change in order for light to remain at c from ANY reference point.
  Reply With Quote
Old Jun21-09, 09:27 PM                  #6
keepitmoving

keepitmoving is Offline:
Posts: 87
Re: special relativity

i always wondered about the possibility of intervening events as far as conflicting observations.
  Reply With Quote
image image
Reply
Thread Tools


Similar Threads for: special relativity
Thread Thread Starter Forum Replies Last Post
How much is Special Relativity a needed foundation of General Relativity lalbatros Special & General Relativity 74 Nov10-09 12:18 PM
Special Relativity tanzl Advanced Physics 14 Oct15-08 01:11 PM
Special Relativity vs. General Relativity IndustriaL Special & General Relativity 25 Jun14-05 03:05 PM

Powered by vBulletin Copyright ©2000 - 2009, Jelsoft Enterprises Ltd. © 2009 Physics Forums
Sciam | physorgPhysorg.com Science News Partner
image
image   image