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Postulates of Special Relativity

Open discussions on cosmology and astrophysics matters.

Postulates of Special Relativity

Postby light_image » Sun May 05, 2013 4:17 pm

The special theory of relativity is the physical theory of measurement in an inertial frame of reference proposed by Albert Einstein in his paper "On the Electrodynamics of Moving Bodies" on 1905. He based his special theory of relativity on two postulates:

1. All the laws of physics have the same form in all inertial reference frames that move uniformly with respect to one another.

2. The speed of light in vacuum has the same value in all inertial frames, regardless of the motion of the observer and the motion of the source emitting the light.That is, the speed of light is the same for all observers moving at constant velocities.

reference: Raymond A. Serway, Emeritus, James Madison University, Modern Physics.
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Re: Postulates of Special Relativity

Postby ZaggyLu » Sun May 12, 2013 3:13 pm

I have heard about the Einstein's Theory of Relativity back in high school... Didn't understand a word of it. In college, I encountered it anew but I just couldn't wrap my head around it. Its only when I became a amateur astronomer that I fully understand what it meant. For 'Special Relativity', the most simple way to describe it would be like this, 'If an object is traveling equal or close to the speed of light, time for that object will slow down'. This signifies two important points:

1.) Time is not set to a definite reference frame but relative to the observer.
2.) That Time and Space are one in the same. Recognizing the two concepts as the same, it should not be called 'Time & Space' but should be called 'Time/Space'.
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Re: Postulates of Special Relativity

Postby Burr » Mon May 13, 2013 4:34 am

Thank You ZaggyLu, That helps
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Re: Postulates of Special Relativity

Postby KuyaMak » Fri Jan 10, 2014 6:03 am

It's interesting that Einstein drew on Maxwell's equations for electromagnetism which showed the speed of light to be a constant. In other words, two competent observers traveling relative to each other would derive the same equations where C is constant in their own frame of reference.

It's also interesting Einstein drew on Lorentz's mathematical transformations to explain the dilation of time and space. Lorentz completed his mathematical work years prior. It turns out, the Galilean transformations just did not do the trick in that time and space are held constant. In order for two observers to derive the same experimental results, one need simply factor out the velocity difference between them.

That no longer works if the speed of light in constant. So, it's not velocity that affects the outcome, it's the other two variables of time and distance that must be changed to make experimental results consistent between two observers in motion relative to each other. It's no longer the speed of the ball on the moving train, it's the distance it travels and the time it takes to do so. If you adjust those two variables, then the velocity of the ball can be made to agree between both reference frames.
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Re: Postulates of Special Relativity

Postby Corlykins » Thu Nov 13, 2014 4:58 am

Not sure if you can access this but MIT online has free college courses (no credit) for tons of science topics. Great place to get good info!

http://ocw.mit.edu/courses/find-by-topi ... trophysics

Course # Course Title Level
8.224 Exploring Black Holes: General Relativity & Astrophysics Undergraduate
8.282J Introduction to Astronomy Undergraduate
8.284 Modern Astrophysics Undergraduate
8.286 The Early Universe Undergraduate
8.901 Astrophysics I Undergraduate
12.400 The Solar System Undergraduate
12.409 Hands-On Astronomy: Observing Stars and Planets Undergraduate
12.425 Extrasolar Planets: Physics and Detection Techniques Undergraduate
8.902 Astrophysics II Graduate
8.942 Cosmology Graduate
12.472 Building Earth-like Planets: From Nebular Gas to Ocean Worlds Graduate
22.611J Introduction to Plasma Physics I (Fall 2006) Graduate
22.611J Introduction to Plasma Physics I (Fall 2003) Graduate
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