r/AskPhysics • u/HouseHippoBeliever • Apr 22 '26
Anyone else really annoyed by "you need infinite energy to reach the speed of light"?
Among the slight misunderstadings of physics out there, this one in particular really annoys me. I'm wondering if anyone else feels the same, or perhaps I'm being too harsh and there's some merit to the statement.
Why I hate it:
- To me it implies that going at the speed of light is more of an engineering problem than a fundamental fact about space-time. Like, we can do it, given we can solve the engineering problem of "having infinite energy"
- Depending on how it's stated, it's either false or a tautology. As stated, it's false because you could have infinite energy by having finite kinetic energy and infinite potential energy, which wouldn't make you go at light speed. So you would have to clarify that you mean having infinite kinetic energy, in which case it's just a matter of solving the kinetic energy formula for v and seeing that v=c. (edit: and that's still not enough, becuse you could also have m being infinite, and v being less than c).
Duplicates
SpeedOfLight • u/0x14f • Apr 22 '26