Which frame's time and distance give the velocity of frame 2 WRT frame 1?

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aditya23456
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I meant which frames distance divided by which frames time gives the velocity of frame 2 wrt frame 1..I guess the 'v' measured from rest frame is different from v measured from other frame right(concerning time dilution since time always dilutes in frame 2 only).?
Btw do u think their is a frame which is at rest and never accelerated since starting of big bang(or starting of universe..if yes,is it the oldest frame ever to exist..?
 
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Two observers in relative inertial motion will each measure the other ones speed to be the same using their own clocks and rulers. The same thing applies to frames.

Frames in Special Relativity were invented by Einstein and haven't existed prior to 1905.
 
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ghwellsjr said:
Frames in Special Relativity were invented by Einstein and haven't existed prior to 1905.
Does this mean gravity did not exist (in nature) before Newton "invented" it? Things did not fall or orbit, way back then, eh :devil:

More seriously, people do not invent the laws of physics, they discover them and the laws generally existed before they were discovered. Sort of like the continents we call America and Australia existed before Columbus and Captain Cook discovered them. Just ask the indigenous native populations :wink:
 
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yuiop said:
Does this mean gravity did not exist (in nature) before Newton "invented" it? Things did not fall or orbit, way back then, eh :devil:

More seriously, people do not invent the laws of physics, they discover them and the laws generally existed before they were discovered. Sort of like the continents we call America and Australia existed before Columbus and Captain Cook discovered them. Just ask the indigenous native populations :wink:

This conversation is heading in a direction that may get it moved to a different forum...

But with that said, two of your points invite response.
1) Strictly speaking, Newton did not discover gravity, he discovered a mathematical theory of gravitation. There's no doubt in my mind that things fell and orbited before he discovered this theory and would have continued to do so even if he never had discovered it - just as they fell and orbited before and after Aristotle discovered his much less satisfying earlier theory, and Einstein discovered his much more satisfying later theory of gravity.

2) It is not all clear that a reference frame is "real" in the way that gravitational effects, or the gravity whose existence we propose based on our observations of those effects, are "real". I could reasonably claim that the reference frame is just a method for mapping "real" phenomena to abstractions that can be mathematically manipulated to produce useful predictions.
 


lol..but do u think there is a frame/location in universe that is as old as it reached maximum entropy condition and as ended(i don't think this is right word to use) as far as that part of universe is concerned.?
 
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aditya23456 said:
lol..but do u think there is a frame/location in universe that is as old as it reached maximum entropy condition and as ended(i don't think this is right word to use) as far as that part of universe is concerned.?
You asked about frames in Special Relativity. Special Relativity does not handle gravity and so is not relevant to your questions about the big bang nor the starting of the universe. There are numerous other problems with your questions. You really need to spend some significant time reading threads on this forum and other resources to learn about Special Relativity before you ask more questions. That's what I did for over a year before I even made my first post here.