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Let's say I were to have made a train that travels at $60$ $mph$. Let's also say that I have another train inside of the first train that is also moving at $60$ $mph$ in the same direction. So from an observer standing outside of both trains, the interior train would be moving at $120$ $mph$ whereas the exterior train would be moving at $60$ $mph$. Theoretically, would you be able to have multiple trains moving inside one another eventually reaching the speed of light?

Qmechanic
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Kuplar
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1 Answers1

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The velocity addition you have done pertains primarily to Newtonian mechanics. In special Relativity, we use a different velocity addition formula

$u = \frac{u'+v'}{1+\frac{u' v'}{c^2}}$

Here you can see that if there exists a train travelling at speed of light $0.8c$ and then shoots particle at 0.8c, Galilean velocity addition would give you $1.6c$ whereas the above formula would give you $0.97c$. This condition has arrived because no particle can travel faster than the speed of light. The speed of light being the speed limit is a primary postulate of Special relativity.

joseph h
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Anagh Venneti
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