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Relativity says $E=mc^2$ From which we can get, $c^2=E/m$

So speed of light squared is inversely proportional to mass

Qmechanic
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Venkat Nitish
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  • Yes, so what is your question? – QuIcKmAtHs Feb 03 '18 at 10:53
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    $E=mc^2$ only applies to things that are not moving. The full equation is $E^2=\left(mc_0^2\right)^2+(pc)^2$ with $E$ being the energy, $c$ being the speed of light, $m_0$ being the rest mass, and $p$ being the momentum – Anders Gustafson Feb 03 '18 at 10:59
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    Speed of light squared is what you get when you divide the rest energy to mass. Saying that the speed of light squared is inversely proportional to mass is meaningless. $c^2$ is a proportionality factor that allows to transform between mass and rest energy. – Nemo Feb 03 '18 at 11:07
  • We say A is proportional to B to evidentiate that when B increases, A also increases. For example: kinetic energy is proportional to velocity. – Nemo Feb 03 '18 at 11:12
  • @AndreiGeanta The correct terms are rest mass, and energy. – Anders Gustafson Feb 03 '18 at 11:23
  • @AndersGustafson, It is redundant to say rest mass. Mass is the difference between energy squared and momentum squared. I said rest energy, which by the way is a term that is being used, to evidentiate that the formula is valid only when the object is at rest. – Nemo Feb 03 '18 at 11:32
  • Except that your formula is derived from the assumption that c is a constant. You can vary the mass by an amount of energy equal to delta m c^2 – Alchimista Feb 03 '18 at 13:15
  • This is kind of like saying $1=\frac{p}{mv}$, so $1$ is inversely proportional to velocity. – Chris Feb 03 '18 at 14:00

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So speed of light squared is inversely proportional to mass

$c$ is a universal constant, the invariant speed, while neither $E$ and $m$ are.

Your reasoning is as incorrect as this reasoning is:

Einstein says $E = h\nu$ from which we get $h = \frac{E}{\nu}$, so Planck's constant $h$ is inversely proportional to frequency

Alfred Centauri
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