# Q & A: relativity is for real

Q:
if we have an object wich has a specific speed lets say that it has a similar speed to sound speed ok , what happenes to this object if it is moving in this speed without stopping? does it change its state (if it was solid for example)? please confirm as soon as possible
- ahmad abu eisheh (age 22)
dubai
A:

The laws of physics are the same acording to any observer moving at a fixed velocity. That principle (relativity) has been confirmed in many different ways. From the point of view of the object, its speed is zero. So it shows exactly the same behavior as it would if you happened to say its speed was zero. Of course if the object is going through some sort of atmosphere that's not moving along with it, then the relative velocity of the atmosphere and the object is very important. Friction will make the object heat up. Maybe that would be enough to cause a phase change.

Mike W.

(published on 12/28/2013)

## Follow-Up #1: black holes for speedsters?

Q:
If E=mc^2, then it means if an object moves fast enough, it would have gained enough mass from its kinetic energy to become a black hole. Am I right?
- Anonymous
A:

No, from the point of view of the object its speed is still just zero. So it doesn't turn into a black hole. For the point of view of somebody who says the object has big kinetic mass/energy, it also has big momentum.  that momentum also shows up in the equations for the form of spacetime around the object, and goives a different solution than the black hole you'd get for the same energy without that momentum.

Mike W.

posted without checking while Lee is in Puerto Vallarta as I shovel snow.

(published on 01/04/2014)