Is Light our limit? Suppose something existed faster than light will we be able to perceive it?
And even if we encounter it wouldn't seem to travel with speed of light?
 A: Superluminal objects have a big problem with the relativistic mass equation:
$$
m = {m_0 \over {\sqrt{1-{v^2\over{c^2}}}}}
$$
If you set $v=2c$ in the equation, you get
$$
m = {m_0\over{\sqrt{-3}}} \approx 0.577im_0
$$
So you get an imaginary mass.
Goodness knows what that might mean... I'll have imaginary two kilos of potatoes please.
A: There exist hypothetical particles named Tachyons that would travel faster than light. They are merely hypothetical since Einstein's relativity does not forbid their existence but there is no experimental support for their existence at all.
If such particles existed they would to us also appear to travel faster than light. We would first observe them when they are inside our detector and only later would we see the light that reflected of the particle as it aproached our detector.
The following image shows the spacetime diagram of a tachyon and how it would be observed, I copied this image from this webpage

Notice that the order in which the particles are observed by the observer do not follow chronological order. Event 0, which happened long before event 6 is only observed after event 6.
Note: This image claims for the light of the particle to be blueshifted as it aproaches the observer and redshifted as it moves away. I personally am not so sure whether that is truly what happens since the equation for relativistic redshift is
$\lambda_{recieved} = \lambda_{emitted} \sqrt{\frac{1+\beta}{1-\beta}}$ which for $\beta > 1$ gives imaginary $\lambda_{recieved}$ which I would not know how to interpret.
