If Supergirl and I travel around the globe in opposite directions at just over mach 7, we should be able to create enough centrifugal force to slow the Earth's rotation.
Is it really possible to do such thing in reality
Não. É completamente ridículo.
A física não funciona assim, nem o espaço-tempo.
De fato, a velocidade que eles mencionam "Mach 7" é ridiculamente lenta. A velocidade de escape (digamos, para Apollo ou o ônibus espacial) é Mach 33!
While this is a rather nice tribute to Superman: The Movie and the scene where Superman reverses time by spinning the planet backwards, the physics of what Barry suggests are completely nonsensical within the stated limits. While mass does increase with velocity (per Einstein's theory of special relativity) Mach 7 is nowhere near fast enough for two human bodies to influence a mass the size of the Earth. While gravity has been shown to alter the flow of time (read up on the "Hafele–Keating experiment" for the details) Kara and Barry can't come close to generating that level of power at that low a speed.
Basicamente, este é um retorno para o Superman onde ele fez exatamente a mesma coisa impossível .