Mass Increase in SR: Clarification of Popular Belief

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SUMMARY

The discussion clarifies misconceptions surrounding mass increase in Special Relativity (SR) and the relationship between mass and the speed of light. It establishes that nothing with mass can reach light speed, as described by the Lorentz transformation. The term "relativistic mass" is defined as the increase in kinetic energy rather than a change in mass itself, which is invariant across reference frames. Additionally, it emphasizes that objects traveling at light speed are massless yet can still possess momentum.

PREREQUISITES
  • Understanding of Lorentz transformation in Special Relativity
  • Familiarity with the concept of invariant mass
  • Knowledge of kinetic energy and its relationship to relativistic speeds
  • Basic principles of momentum in physics
NEXT STEPS
  • Study the Lorentz transformation equations in detail
  • Explore the concept of invariant mass versus relativistic mass
  • Learn about the implications of massless particles in quantum physics
  • Investigate the relationship between energy and momentum in relativistic contexts
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Physics students, educators, and anyone interested in understanding the principles of Special Relativity and the nature of mass and energy at relativistic speeds.

ShayanJ
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I often hear from laymen who study some SR that if sth reaches the speed of light,it completely turns into energy!
Where did this crazy idea came from?

Any way,mass increase in SR seems really mysterious to me
E.g. when mass tends to infinity as velocity tends to c
Can someone clarify more?

Thanks
 
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Nothing that has mass can reach the speed of light. Relativistic mass, i.e. the mass increase due to relativistic speeds is not mass in the modern sense, it is really kinetic energy. In modern texts mass is an invariant, i.e. a property that is the same in any reference frame.

Therefore anything that is traveling at light speed is massless but can possesses momentum.
 

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