Tachyonic Energies in a Minkowski Metric

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Discussion Overview

The discussion revolves around the properties of tachyons within the context of a Minkowski metric, specifically addressing a problem from a physics textbook related to their four-velocity, four-momentum, and energy-momentum relationship. The scope includes theoretical considerations and mathematical reasoning regarding tachyonic energies.

Discussion Character

  • Exploratory, Technical explanation, Mathematical reasoning

Main Points Raised

  • The original poster (OP) presents their findings on the four-velocity and four-momentum of tachyons, expressing uncertainty about the sign of the four-velocity and seeking assistance in determining the energy given the relationship p=mu.
  • One participant notes a discrepancy in the reference to the problem in Hartle, suggesting it pertains to a different chapter and expressing confusion about the OP's question.
  • Another participant confirms the correction regarding the chapter reference.
  • The OP later claims to have resolved their issue, stating that they found the energy-momentum relationship for tachyons to be E^2=p^2-m^2.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the original problem's reference, and there is a lack of clarity regarding the OP's initial question. However, the OP ultimately claims to have resolved their dilemma regarding the energy-momentum relationship.

Contextual Notes

The discussion includes uncertainties about the correct problem reference and the assumptions underlying the OP's calculations, particularly concerning the signs of the four-velocity.

gravitowell
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So I'm working on a problem (Hartle problem 6, chapter 6) dealing with tachyons. So far, I have determined the four-velocity and the four-momentum (up to a sign) of a tachyon. I have, with the four-velocity being a unit spacelike four-vector,
u^{\alpha}=\frac{\pm 1}{\sqrt{\vec{V}^2-1}}(1,\vec{V})<br />

(Sorry about the bad formatting...).

I don't want to just assume the positive values of u^{\alpha}.

I need help figuring out how to find the energy E given that p=mu.

I realize I may have not phrased my dilemma well, so please ask for clarification.
 
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I couldn't find this problem in Hartle. Problem 6 in chapter 6 is about transforming into the coordinates of an accelerated frame. I'm also not really sure what your question is.
 
Don't really have time to comment on the OP's dilemma, but I believe it's ch.5 problem 23.
 
Yes, you're right. I was about to change it. Thanks for noting.
 
I figured it out. I found my energy-momentum for tachyons to be given by

E^2=p^2-m^2.
 

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