Why is Tau-AB^2 not t^2 + x^2?

In summary, the metric in special relativity is defined as Tau-AB^2 = t^2 - x^2, not t^2 + x^2 as in Euclidean geometry. This is because special relativity operates in a Minkowskian geometry, which differs from Euclidean geometry in how lines and angles are interpreted.
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BLevine1985
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question about proof page 21
why is Tau-AB^2 equal to t^2 - x^2 ?It seems it should be t^2 + x^2 according to the geometry of the diagram...
 

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BLevine1985 said:
why is Tau-AB^2 equal to t^2 - x^2 ?
Because that's how the metric is defined in an inertial frame in special relativity.

BLevine1985 said:
It seems it should be t^2 + x^2 according to the geometry of the diagram...
No, because the diagram is not depicting a Euclidean geometry. It's depicting a Minkowskian geoemetry. That means you cannot interpret lines and angles in the diagram as if they were Euclidean; they aren't.
 
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Thank you. That was very helpful!
 
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BLevine1985 said:
Thank you. That was very helpful!
You're welcome!

Also, welcome to PF!
 
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1. Why is Tau-AB^2 not t^2 + x^2?

The reason Tau-AB^2 is not equal to t^2 + x^2 is because they are different mathematical expressions. Tau-AB^2 represents the product of Tau and the square of AB, while t^2 + x^2 represents the sum of the squares of t and x. These two expressions have different operations and cannot be equated.

2. Can Tau-AB^2 and t^2 + x^2 be simplified to be equal?

No, Tau-AB^2 and t^2 + x^2 cannot be simplified to be equal because they have different operations and cannot be combined or simplified using mathematical rules.

3. Is Tau-AB^2 the same as (Tau-A)(Tau-B)^2?

No, Tau-AB^2 and (Tau-A)(Tau-B)^2 are not the same. The first expression represents the product of Tau and the square of AB, while the second expression represents the product of Tau-A and the square of Tau-B. These are different expressions and cannot be equated.

4. Why is Tau-AB^2 not equal to Tau(A+B)^2?

Tau-AB^2 and Tau(A+B)^2 are not equal because they have different operations. The first expression represents the product of Tau and the square of AB, while the second expression represents the product of Tau and the square of (A+B). These operations are not equivalent and cannot be equated.

5. Can Tau-AB^2 and t^2 + x^2 have the same value?

No, Tau-AB^2 and t^2 + x^2 cannot have the same value because they are different expressions with different operations. Even if the values of Tau, A, and B are the same, the two expressions will still have different values.

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