Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Nizzle on 04/11/2011 10:54:51
-
Hi,
As far as my understanding of general relativity goes, if you travel at speed of light, time stands still.
So if you hit the "Record" button on a camcorder traveling at speed of light, it would not start filming?
But on the other hand, general relativity also states that the camcorder could say it was standing still and all the rest of the universe was passing by at the speed of light.
In this case, if you hit the "Record" button, it should start filming since time does not stand still when your speed is 0.
What am i missing here?
-
Hi,
As far as my understanding of general relativity goes, if you travel at speed of light, time stands still.
So if you hit the "Record" button on a camcorder traveling at speed of light, it would not start filming?
But on the other hand, general relativity also states that the camcorder could say it was standing still and all the rest of the universe was passing by at the speed of light.
In this case, if you hit the "Record" button, it should start filming since time does not stand still when your speed is 0.
What am i missing here?
No material object is able to reach the speed of light because that would require infinite mass, which is impossible.
As you travel faster your local time does not appear to change but it does to an observer moving at a different speed to you. This means your camcorder would film things as normal within your local frame of reference.
-
You are right in assuming that all uniform motion is equal, that is, could be said to be 'at rest' relative all other relatively moving objects. But matter is not light, and what light does matter can't. As for defining the whole universe as 'moving' relative your uniform motion, do you include space too there :)
There is always a way of defining yourself as moving too, you can use the CBR or infalling lights blue and red shift for it. Neither of them is a absolute frame of reference, but they will tell you if you are moving or not.
==
You can also use so called 'fixed stars', so far away that they, to you, will seem to be 'still'.
-
Hmm, thinking of it the red and blue shift of light can't be used, other than possibly statistically. That means that although you find one source (sun) to give you a blue shift, it might be so that this source is moving towards you, relativity seen :) So, to be sure you will have to test all sources in front of you, and aft of your motion.
It should be so that if some large percentage of all light aft are red shifted and the same is true for a blue shift in front of your 'motion', you should be 'moving'. Don't know where that percentage/probability makes it a 'absolute motion' though? CBR should work in a simpler fashion though as it is measured to be nearly isotropically distributed in the known universe.
And the best is probably those very distant stars.
-
As you approach the speed of light CMBR would look like gamma radiation !
-
As you approach the speed of light CMBR would look light gamma radiation !
Approach the speed of light with respect to what? :p
-
Yeah :)
"In addition to the search for evidence of intrinsic cosmic anisotropies, such as night be due to aspheric expansion or large scale anisotropies in the primeval matter distribution, an impetus for the lame angular scale isotropy experiments has been the measurement of the kinematic anisotropy associated with the earth's motion relative to the distant sources of the CBR.
This anisotropy had to exist at least on a level of 10-4 due to the earth's orbital motion around the sun in the unlikely case that the sun were at rest with respect to these sources. The anisotropy, now definitely observed at a 10-3 level is easily derived by a special relativistic calculation of the intensity measured by an observer moving relative to the walls of a blackbody cavity. The anisotropy retains a Planck spectrum but with an observation angle-dependent temperature (dipole term)"
I have a vague recollection that there is a experiment done relatively early when they started to research on CBR, finding a 'red shift' and 'blue shift' relative Earth's 'motion'? MEASUREMENTS OF THE LARGE ANGULAR SCALE INTENSITY DISTRIBUTION OF THE CBR. (http://ned.ipac.caltech.edu/level5/March03/Weiss/Weiss3.html)