What is the difference between the special theory of realtivity and the general theory of relativity?

Also, did I spell everything in the title right? It looks sort of funny.

This is really werid. This was discussed just today in my history of science class! This is how it was described to us: (I am not a physics majoy, I am just repeating what my professor said)

1.Special relativity: the laws of physics are the same for all observers in uniform motion.

2. General relativity:
Adds saying that it allows different frames of reference due to acceleration.

This is all with the assumtion of a constant veliocity of the speed of light.

So basically with the equation v=d/t than with a constant v, distance and time have to change/distort. So if everyone was moving at the speed of light, nobody will notice a difference. But if one person was moving slower, his perception of time or distance would change relative to the other person.



Yah i know its confusing. I barely understand it and i am very sure i got it wrong. But this is what i have down in my note (well I edited out some other stuff). If i am wrong can someone correct me please?

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It gets much more complicated on both a physics and mathematical level (I'm reading myself into it now).

Essentially, special relativity has two main postulates:
1) the speed of light is constant in all inertial reference frames
2) the laws of physics will remain the same no matter which reference frame they are applied.

General relativity has 3 main ideas:
1) spacetime is curved and can be described by mathematical "things" called pseudo-Riemannian manifolds
2) there are locally inertial reference frames (flat coordinates) in which the physics in GR are the same as in SR (known as the principle of equivalence - there is no experement that can distinguish an accelerating reference frame from a gravitational field)
3) mass curves spacetime (think of a bowling ball on a stretched out blanket; the ball makes a "dent" in the fabric, curving the are around it)

I think that's about it. Hope that helps

WhooHoo! i had the basics right. :-D

Everyone always like to go over relativity in terms of a train traveling at the speed of light. Without getting scientific at all, the basic difference is:

• Special relativity explains what happens when you are on a train traveling at the speed of light.
• General relativity explains what happens when a train traveling at the speed of light goes by you.

With my luck I've probably got that backa**wards, but if I remember the math and physics (which I hopefully remember more of than I do of trains), I think that makes sense.

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Matt Bisgaier
http://www.mattster.com/

Relativity explains why your train can't go the speed of light.

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Oops... make that very close to the speed of light. I knew there was a reason why I shouldn't be up early in the morning, much less up early in the morning trying to make sense. Coffee time!

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Matt Bisgaier
http://www.mattster.com/

Special relativity applies the experimental result that the speed of light is the same in all inertial frames to extend Newtonian physics to relativistic speeds.

General relativity explains why a person standing on a platform appears to accelerate backwards when you're in a departing train by introducing the idea of equivalence between gravity and acceleration.

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The train analogy doesn't work for me. Wouldn't both the person on the train as well as the person standing at the station platform simply be 2 different inertial frames of reference, hence both fit snuggly into the realm of SR? I guess I always thought of GR simply as SR, but with accelleration taken into account (accel. being any "curve" in the path of an object). A simplistic view, granted, but I'm a simplistic kind of guy!

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No. The passenger on the platform observes you. He sees you accelerate relative to him with the train out of the station because of the ballet of forces with train. Everything fits. You are accelerating because there is a force applied to you.

Now, you observe the passenger on the platform. You seem him accelerate relative to you. But there is no force causing him to do that. Acceleration without force? Defies Newton's Second Law. You're in a non-inertial frame because the frame is accelerating with respect to an inertial one. That's where Newtonian mechanics fails. It applies only to inertial frames. It cannot be applied to non-inertial frames. An inertial frame is one where all accelerations observed are due to forces according to Newton's Second Law. An non-inertial frame is one that is accelerating relative to an inertial one.

The way to account for this is to presume a gravitational field acting in the opposite direction to your acceleration relative to the inertial. That explains why you feel like you're being pushed back into your seat and why the passenger on the platform appears to accelerate. It's this gravity equivalence.

General relativity found a way to consider the equivalence to be not only apparent, but actual.

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Freedom For Fission A breath of fresh Iodine-131

I think if you're fixated on using a train analogy, you have to have the train accelerating for the general relativity. SR will work for either observer for a train moving at constant speed.

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"I have a cunning plan that cannot fail."
S. Baldrick

Yes. The train is accelerating.

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Freedom For Fission A breath of fresh Iodine-131

This may not be the difference you're looking for, but....

Special theory: easy.
General theory: hard.

The special theory is actually fairly easy to understand. And a high school student who's fair in math can handle the mathematics involved.

The general theory... well, the general idea isn't so tremendously strange. For the general theory Einstein adds the (very relevant) ideas of gravitation and acceleration into the mix, which were not treated in the special theory. And the math is considerably harder (but I guess something always seems harder when you don't have a good handle on it).

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glom:

That is part of Special Relativity, too.

ljbrs :wink:

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"There is in the universe neither center nor circumference." Giordano Bruno Born 1548. Torched 1600.

Which part? The equivalence of gravity and acceleration is not a part of special relativity.

Special relativity covers inertial frames only.

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Freedom For Fission A breath of fresh Iodine-131

#-o I think I need a very, VERY big Tylenol and a practice nap.

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But even Einstein's original 1905 paper dealt with non-inertial effects (the "twin paradox"). Perhaps that is what she is referring to.

The twin paradox comes about because both see the other's clock as moving slow while the flight is in progress. The paradox is that on the return the space faring twin is younger. Since SR is limited to inertial (non-accelerated) referance frames, it cannot explain why there is an age difference. Hence the paradox.

In GR, which does include accelerated frames, there is no paradox. The space faring twin undergoes two major accelerations the ground-based one does not. The first is to launch the ship in the first place. The second is to turn the ship around at its destination and return it to earth. General relativity makes the correct predictions for the age difference of the twins and the reasons why are well understood and no longer paradoxical.

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